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linuxcbt postgresql

目录

http://www.postgresguide.com/

  1. Features of postgresql
  2. Installation
  3. psql
  4. Access Controls
  5. Logging
  6. Common Data Types
  7. CREATE
  8. DROP
  9. ALTER
  10. Constraints
  11. INSERT
  12. COPY Command
  13. SELECT
  14. JOINS
  15. VIEWS
  16. Aggregates
  17. UPDATE
  18. DELETE
  19. INDICES
  20. Built-In Functions
  21. Model: /var/log/messages
  22. Integration of Perl with PostgreSQL
  23. GRANT
  24. REVOKE
  25. DB Backup
  26. DB Restore
  27. Windows DB Restoration
  28. Installation on RedHat Enterprise Linux
  29. SSH Tunnels
  30. SSL Connections

###Features of PostgreSQL###

  1. Object Relational Database Management System (ORDBMS)

  2. Objects can be related in a hierarchy: Parent -> Child

  3. Transactional RDBMS:

Note: Transactional statements must execute: ALL or NONE

  1. SQL statements have implicit: BEGIN; COMMIT; statements

  2. SQL statements may also have explicit: BEGIN; COMMIT; statements

  3. Note/Feature:

  4. Developed originally @ UC Berkeley

  5. One process per connection - auto-spawns per new connection

  6. managed by master process: 'postmaster'

  7. Processes use only ONE CPU/Core

  8. Note: OS/Distro may spawn new connection on a different CPU/core

  9. Multiple helper processes, which appear as 'postgres' instances, run always

  10. Stats collector

  11. Background writer

  12. Autovacuum - clean-up/space reclaimer

  13. WALsender - write ahead log

  14. Max DB Size: Unlimited - limited by OS & available storage

Note: Consider deploying on 64-bit platform

  1. Max Table Size: 32TB - stored as multiple: 1GB files
  2. Max Row Size: 400GB
  3. Max Col Size: 1GB
  4. Max Indexes on a table: Unlimited
  5. Max Identifier (DB objects (table|column names, etc.): 63-bytes

Note: The limitation is extensible via source code

  1. Default Listener: TCP:5432
  2. You may install PostgreSQL as a non-privileged user
  3. Users are distinct from OS users - i.e. MySQL
  4. Users are shared across DBs
  5. Inheritance
  6. Tables lower in hierarchy may inherit columns from higher tables
  7. Caveat: No unique constraints or foreign keys support
  8. Case-insensitive commands - sans double quotes -i.e. 'select * from Syslog;'
  9. Case-sensitive commands - with double quotes - i.e. 'select & from "Syslog";'
  10. Three Primary Config Files: $POSTGRESROOT/data/*.conf
  11. 'pg_hba.conf' - controls host/user/DB connectivity
  12. 'postgresql.conf' - general settings
  13. 'pg_ident.conf' - user mappings
  14. Integrated Log Rotation|Management - Log Collection - 'postgresql.conf'
  15. Criteria: Age | Size

###Installation### Features:

  1. Download bin file from Enterprise DB

Tasks:

  1. Install

Note: You may optionally indicate that data files be stored independently of the source tree Note: A 'Database Cluster' is simply the management of more than 1 DB
Note: Default is to start the RDBMS post-installation

  1. Explore the footprint
  2. 'psql' - terminal monitor - i.e. akin to 'mysql'
  3. 'createdb|dropdb' - creates|drops DB
  4. 'createuser|dropuser' - creates|drops users
  5. 'postgres' - server daemon
  6. 'data/' - top-level data/config files/log files
  7. 'data/pg_log/' - log files (default is: STDERR)
  8. 'data/pg_xlog/' - Write Ahead Log (WAL) - maintains changes to DB files at all times
  9. 'data/postmaster.opts' - contains startup options
  10. '/etc/init.d/postgresql-9.0' - INITD manager

Note: Files, execpt INITD file, are contained within: /opt/postgresql/version hierarchy

  1. Provide access to docs via Apache

  2. 'ln -s /opt/PostgreSQL/9.0/doc/postgresql/html ./LinuxCBT/postgresqldocs '

  3. Update: $linuxcbt/.bashrc to reflect: /opt/PostgreSQL/9.0/bin - to access binaries

Note: PostgreSQL clients default to submitting the currently logged-in user's name as the DB user name Note: A workaround for this is to export the PGUSER variable, setting it to an existing DB user 'export PGUSER=postgres'

'psql'

Features:

  1. (Non)Interactive usage - i.e. 'mysql' terminal monitor
  2. Command history - up|down arrows
  3. Tab completion
  4. Commands terminate with semicolon and may wrap lines and have whitespace separators
  5. Defaults to supplying the currently-logged-in user

Tasks:

  1. Explore 'psql' a. 'psql --version' b. 'psql -l -U postgres' - lists DBs then exits Note: PostgreSQL installs 3 default DBs:
  2. 'postgres' - contains user accounts DB, etc.
  3. 'template0' - vanilla, original DB
  4. 'template1' - Copy of template0, and may be extended, and is used to generate new DBs c. 'psql' - enters interactive mode c1. trailing '#' indicates: super user: 'postgres' d. '\h' - returns SQL-specific help e. '?' - returns 'psql'-specific help - i.e. usable metasequences f. '\l[+]' - returns list of DBs g. '\du[+]' - returns list of users in system DB h. '!' - returns user to $SHELL i. '! command' - executes a specific command - non-interactively Note: Typical $SHELL semantics apply j. '\i filename' - executes command(s) in the file - i.e. 'psql' or SQL commands Note: Multiple commands can be run with one reference. Terminate set with: ';', use space between commands.

k. '\c DBNAME [REMOTE HOST]' - connects to different DB and optionally different host Note: current DB is echoed in the prompt. i.e. postgres=# || template1=#

l. '\d[S+]' - reveals tables, views, sequences and various DB objects m. '\q' - quits

###Access Controls###

Features:

  1. Users - Roles (Roles are users or groups)
  2. Config Files: a. 'pg_hba.conf | pg_ident.conf | postgresql.conf'
  3. Central accounts DB shared ALL DBs - accounts MUST be unique
  4. Default setup includes 1-User - 'postgres' - Super User
  5. Privileges are managed with: a. 'GRANT | REVOKE' b. 'ALTER' c. 'CREATE | DROP ROLE|USER' - SQL Statements (Key Words) d. 'createuser|dropuser' - commands - wrappers to SQL statements
  6. DB Object creators own those objects and can assign privileges to them
  7. To Change DB object ownership use: ALTER - sql key word
  8. Special role named: 'PUBLIC' grants assigned privilege to ALL system users a. 'PUBLIC' is a special group, to which ALL users are members

Tasks:

  1. Create another super user a. '\du' - enumerates current users|roles b. 'createuser -e -s -U postgres linuxcbt' - echoes SQL commands to STDOUT c. Confirm inability to connect to posgres as new role: 'linuxcbt' d. Set 'linuxcbt' password: '\password linuxcbt' - permits setting of user's password Note: Caveat: Upon connection to postgres, the client 'psql' attempts to connect the user to a DB named the $PGUSER

  2. Drop newly-created super user: 'linuxcbt' a. 'dropuser -e -U postgres linuxcbt' - removes user from DBMS

  3. Examine remote, TCP-based connectivity

###Logging### Features:

  1. Three types of logs supported: a. 'stderr'(Default) b. 'csvlog' - import into spreadsheets | DBs c. 'syslog'
  2. Controlled via: $POSTGRESROOT/data/postgresql.conf
  3. Simultaneous logging
  4. Ability to control verbosity
  5. Automatic log rotation based on criteria: age | size
  6. Logs handled by the included logger (stderr,csvlog) are stored in: $POSTGRESROOT/data/pg_log Note: Syslog-handled messages are routed according to syslog rules: /etc/rsyslog.conf
  7. The first process launched by master process

Tasks:

  1. Explore: $POSTGRESROOT/data/postgresql.conf

  2. Configure syslog a. Update syslog configuration for: 'LOCAL0' facility - Consider updating: LogRotate b. Update: $POSTGRESROOT/data/postgresql.conf - 'stderr,syslog'

  3. Configure csvlog a. Append: 'csvlog' to log_destination VAR: $POSTGRESROOT/data/postgresql.conf

Note: Caveat: Syslog is UDP-based and is subject to loss of messages

Common Data Types

Features:

  1. Allow us to control the type of data on a per column basis

Types: Numeric: a. 'smallint' - 16-bits (2-bytes) - whole numbers b. 'int' - integer - 32-bits (4-bytes) - whole number c. 'bigint' - Big Integer - 64-bits - whole numbers only d. 'numeric[(precision,scale)]' d1. precision = sig figs d2. scale = number of values to the right of the decimal point Note: 'numeric' sans precision or scale supports up to: 1000 digits of precision e. 'real' - 32-bits - variable - 6 decimal digits of precision f. 'double precision' - 64-bits - variable - 15 decimal digits of precision g. 'serial' - 32-bits (2^31) signed - auto-incrementing h. 'bigserial' - 64-bits (2^63) - auto-incrementing

Money: a. 'money' - 64-bits - 2^63 signed: i.e. -9EB - 9EB

Strings - Text a. 'text' - varchar - unlimited - preferred character storage type within PostgreSQL b. 'char(n)' - fixed-length, blank-padded if value stored is < 'n' length b1. i.e. 'char(9)' - 'linuxcbt' -> stored as: 'linuxcbt ' Note: char(n) truncates values that are > 'n' lenght b2. i.e. 'char'-> 'char(1)' - effectively becomes a 1-character field c. 'varchar(n)' - variable length with 'n' limit, if 'n' is present - Does NOT blank-pad c1. i.e. 'varchar(9)' - 'linuxcbt' -> stored as: 'linuxcbt' c2. i.e. 'varchar' -> variable length - Does NOT blank-pad

Note: Use 'text' or 'varchar' when storing strings

Dates & Time - Uses 'Julian Dates (from 4713 BC) -> 10^5+ years ahead' - in date calculations a. 'date' - 32-bits - date only b. 'time' - 64-bits - defaults to time 'without time zone' - microsecond precision c. 'time with time zone' - 96-bits - date & time with time zone - microsecond precision d. 'timestamp with time zone' - 64-bits - ... e. 'timestamp without time zone' - 64-bits - ... f. 'interval' - 96-bits - range of time - microsecond precision

Boolean - 8-bits - True(1)(on) | False(0)(off) Geometric Types - lines, circles, polygons, etc. Network Address Types a. 'cidr' - 7 or 19-bytes - IPv4 and IPv6 networks - i.e. '192.168.75.0/24' || '2002:4687:db25:2/64' b. 'inet' - 7 or 19-bytes - IPv4 and IPv6 hosts and networks c. 'macaddr' - 48-bits - i.e. 00:11:11:5b:70:53, 0011.115b.7053 , etc. XML Arrays et cetera.

###CREATE### Features:

  1. Limited to 63 characters for the definition of objects
  2. Identifiers (DB Objects) MUST begin with alpha characters
  3. Used to create: DBs, Schemas, Tables, Indexes, Functions, etc.

Note: PostgreSQL Hierarchy:

  1. DB
  2. -Schema(s) (Optional) - Default schema is named: 'public'
  3. -Objects (Tables, Functions, Triggers, etc.) Note: ALL DBs have: 'public' and 'pg_catalog' schemas Note: ALL users|roles have: 'CREATE' & 'USAGE' access to the 'public' schema for ALL DBs Note: Create distinct schemas if security beyond 'public' is necessary

Tasks:

  1. DB Creation a. Create a user named: 'linuxcbt' with 'CREATEROLE CREATEDB' rights a1. 'createuser -e -U postgres linuxcbt' b. Create a DB named 'linuxcbt' b1. 'CREATE DATABASE linuxcbt;' c. Create a Table named: 'linuxcbtmessages' c1. 'CREATE TABLE linuxcbtmessages (date date);' d. Create a user named 'linuxcbt2' with USAGE rights d1. 'CREATE ROLE linuxcbt2 LOGIN;' e. Create a SCHEMA named: 'logs' e1. 'CREATE SCHEMA logs;' f. Create a TABLE named: 'linuxcbtmessages' within the SCHEMA: 'linuxcbt.logs' f1. 'CREATE TABLE logs.linuxcbtmessages (date date);' f2. '\d linuxcbt.logs.linuxcbtmessages' - confirms the description of the table g. Check whether user: 'linuxcbt2' has access to: 'linuxcbt.logs' SCHEMA

###DROP### Features:

  1. Removes objects: DBs, Schemas, Tables, Functions, Triggers, etc. from ORDBMS
  2. Available from the $SHELL and within SQL interpreter: 'psql'

Tasks:

  1. Drop DB 'linuxcbt2' Note: Objects that are currently in-use will NOT be dropped by default a. 'drop database linuxcbt2;' Note: Dropping DBs will remove ALL sub-objects, including, but not limited to: a. Schemas b. Tables c. Triggers d. Functions, etc.

  2. Drop Tables a. 'DROP TABLE linuxcbt2messages;' - removes table if current user is owner or SUPERUSER b. 'DROP TABLE linuxcbtmessages;' - as user: 'linuxcbt2' - fails due to lack of permissions c. 'CREATE DATABASE TEST TEMPLATE linuxcbt;' - templates DB named: 'linuxcbt' Note: No active sessions must be ongoing in order for template process to work to ensure consistency with duplicated DB c. 'dropdb TEST' Note: Objects created within the 'public' schema are not readily accessible to other users sans the usage of the 'GRANT' command

d. Drop schema: 'linuxcbt.logs' d1. 'DROP SCHEMA logs;' - fails because there is a dependent table: 'linuxcbtmessages' d2. 'DROP SCHEMA logs CASCADE;' - forces recursive removal of objects

e. Re-create structure & DROP: e1. 'CREATE DATABASE linuxcbt2;' e2. '\c linuxcbt2 && CREATE SCHEMA logs' e3. 'CREATE TABLE linuxcbt2.logs.linuxcbt2messages (date date);' e4. 'DROP DATABASE linuxcbt2;'

###ALTER### Features:

  1. Changes Object (DB|Schema|Table|Index|etc.) - Name|Structure|Owner

Tasks:

  1. Confirm our environment by ensuring requisite objects

  2. Change DB Name a. 'ALTER DATABASE linuxcbt RENAME TO linuxcbt2;' Note: ALTER should be used sans connections to target objects

  3. Change DB Ownership a. 'ALTER DATABASE linuxcbt2 OWNER TO linuxcbt2;' - changes ownershipt to role: 'linuxcbt2'

  4. Test ability to DROP DB as new owner a. 'DROP DATABASE linuxcbt2;'

  5. Create and Rename Table: 'linuxcbt2messages' a. 'CREATE TABLE linuxcbt2messages (date date);' - creates table 'public.linuxcbt2messages' b. 'ALTER TABLE linuxcbt2messages RENAME TO messages;'

  6. Alter Table Structure: 'messages' a. 'ALTER TABLE messages ALTER COLUMN date SET DATA TYPE timestamp;' Note: Structurual (columnar) changes may result in data loss if target column type does NOT support source column data b. 'ALTER TABLE messages ADD ident text;' - ADDS, sequentially, a new column to table Note: Column names MUST be unique and may not be added more than once c. 'ALTER TABLE messages DROP COLUMN IF EXISTS ident;' - removes column named: 'ident' if exists Note: Be forewarned, that the dropping of a colum WILL remove existing DATA in the column

  7. ALTER existing ROLE a. 'ALTER ROLE linuxcbt2 SUPERUSER;' - makes user 'linuxcbt2' a SUPERUSER Note: This will ONLY work if you execute as a SUPERUSER. i.e. 'postgres' b. 'ALTER ROLE linuxcbt RENAME TO linuxcbt4;' - renames user: 'linuxcbt' TO 'linuxcbt4' Note: This will unset the user's MD5 password Note: This will update ownership of objects. i.e. DB::Test is now owned by: 'linuxcbt4' c. 'ALTER ROLE linuxcbt4 RENAME TO linuxcbt;'

###Constraints#### Features:

  1. Enforce storage requirements: per table | column
  2. May be applied per column
  3. Multiple constraints may be bound to a single column
  4. Optionally, constraints may be defined at the table level for one or more columns
  5. Default column rule is to accept NULLs

Data Types - basic constraint a. Restricts permitted column values i.e. 'date', 'smallint', 'char(9)', etc.

Not-Null | NULL Contraints a. Define a table using NOT NULL a1. 'create table messages (date date NOT NULL);' b. Alter table adding a new column (id) with constraint: NULL b1. 'ALTER TABLE messages ADD id in NULL;'

Unique Constraint - Applies to any type of column: i.e. 'int', 'numeric', 'text', etc. a. Define a table with a UNIQUE 'id' column a1. 'create table messages (date date, id bigint UNIQUE); ' Note: The creation of UNIQUE contraints generates implicit btree indices on column(s)

b. Define table with multiple UNIQUE columns b1. 'create table messages (date date, id bigint, message text, UNIQUE(id,message) );' Note: This ensures that the combination of: 'id' && 'message' is unique Sample Records that do NOT break the UNIQUE contraint: 2010-10-14 1 message 2010-10-14 2 message 2010-10-14 3 message

Sample Records that DO break the UNIQUE contraint: 2010-10-14 1 message 2010-10-14 1 message 2010-10-14 2 message

Primary Key Constraint - Combination of: 'UNIQUE' & 'NOT NULL' Constraints a. Create a table with primary key constraint on 1 column a1. 'create table messages (date date, id numeric PRIMARY KEY); ' b. Create a table with primary key constraint on 2 columns a1. 'create table messages (date date, id numeric, message text, PRIMARY KEY(id, message) ); ' Note: Standard SQL recommends that each table contain a primary key

Foreign Key Constraint - Links Tables - Referential Integrity a. Create messages table as parent table a1. 'create table messages (date date, id int PRIMARY KEY); ' b. Create subordinate table to categorize messages in parent table b1. 'create table messagesCategories (id int REFERENCES messages(id), category text;'

Check Constraint - confirms column values based on Boolean criteria: 'CHECK (expr)' a. Ensure that (id) contains values greater than 0 a1. 'create table messages (date date NOT NULL, id numeric CHECK (id > 0) );' b. Create the same constraint with a name Note: If unnamed, PostgreSQL will auto-name the constraint b1. 'create table messages (date date NOT NULL, id numeric CONSTRAINT positive_id CHECK (id > 0) ); '

c. Create CHECK constraint which summarizes ALL rules for ALL columns c1. 'create table messages (date date, id numeric CHECK (date IS NOT NULL AND id > 0 AND id IS NOT NULL) );

###INSERT### Features:

  1. Populates tables via various methods
  2. PostgreSQL inserts left-to-right

Usages:

  1. Insert into table with precise number of columns a. 'INSERT INTO messages VALUES ('2010-10-14','1');'

  2. Insert using specified field(s) a. 'INSERT INTO messages (date) VALUES('2010-10-14');'

  3. Insert more columns than are defined in the table - WILL NOT WORK a. 'INSERT INTO messages VALUES('2010-10-14', '5', 'Log Message'); '

  4. Insert multiple records wholesale a. 'INSERT INTO messages VALUES ('2010-10-14','6'),('10/14/2010','7'),('10/14/2010', '8'); ' Note: The date format in record 3 causes the entire transaction to fail, due to implicit: BEGIN & COMMIT statements

  5. Test Foreign Key Constraint a. 'create table messagesCategories (id int REFERENCES messages(id), category text);' Note: Because messages table does not have UNIQUE or PRIMARY KEY constraints on (id) column, the Foreign Key constraint will fail Note: Rectify by defining a Primary Key on messages table OR inserting unique values into (id) Note: PostgreSQL raises error and denies creation of subordinate table

b. Insert data into dependent table b1. 'INSERT INTO messagescategories VALUES ('4','VSFTPD'); ' - fails constraint b2. 'INSERT INTO messagescategories VALUES ('3','VSFTPD'); ' - passes constraint Note: Foreign Key constraint need not be based on a numeric

  1. Test Primary Key Constraint a. 'INSERT INTO messages VALUES ('10/14/2010','3');' - fails constraint b. 'INSERT INTO messages VALUES ('10/14/2010','4'); - passes constraint Note: Summarizes both: UNIQUE & NOT NULL constraints

###COPY Command### Features:

  1. Server-side command, unlike: '\copy' which is client-side
  2. Wholesale inserts (imports) | Exports from | to a file
  3. File MUST be on the server
  4. File MUST be viewable by the 'postgres' user
  5. Uses absolute $PATH to reference the file
  6. Defaults to importing based on: TAB separator|delimiter
  7. Able to copy the results of 'SELECT' query
  8. Does NOT work with VIEWS but will work with SELECT of VIEW
  9. Appends records to table

Tasks:

  1. Generate Import File a. 'for i in seq 100; do echo date +%F $i; done > ~linuxcbt/LinuxCBT_feat._PostgreSQL_Edition/messages.data'

  2. Import Data a. 'COPY messages FROM '/home/linuxcbt/LinuxCBT_feat._PostgreSQL_Edition/messages.data' DELIMITER ' '; ' Note: Truncate Table when necesary to clear data TRUNCATE table messages CASCADE; - removes data from dependent and parent tables

b. Vary delimiter b1. 'awk '{ print $1","$2 }' messages.data ' - formats output with comma delimiter b2. 'TRUNCATE table messages CASCADE;' b3. 'COPY messages FROM '/home/linuxcbt/LinuxCBT_feat._PostgreSQL_Edition/messages.data.csv' DELIMITER ','; '

  1. Export Data a. 'COPY messages TO '/home/linuxcbt/LinuxCBT_feat._PostgreSQL_Edition/messages.data.semicolon' DELIMITER ';';' - export with semicolon delimiter Note: Ensure that user: 'postgres' may write to target directory Note: Export does NOT append redirect, rather, it clobbers (overwrites) target file

###SELECT### Features:

  1. Performs queries: i.e. calculations, system stats, data retrieval
  2. Retrieves data from objects: table(s), view(s), etc.

Usage:

  1. 'SELECT * FROM messages; ' - Returns ALL rows from table: 'messages';
  2. 'SELECT rolname, rolcreaterole FROM pg_roles;' - returns just those 2 columns
  3. 'SELECT rolcreaterole, rolname FROM pg_roles;' - returns just those 2 columns, reversed
  4. 'SELECT rolname AS r, rolcreaterole AS rr FROM pg_roles;' - Constructs aliases for columns
  5. 'SELECT * FROM pg_roles WHERE rolname LIKE '%linuxcbt%';' - Simple string comparison
  6. 'SELECT * FROM messages ORDER BY id DESC;' - Changes sort order ON (id) column
  7. 'SELECT DISTINCT date FROM messages;' - Filters unique values per column, by not returning redundancies
  8. LIMITS & OFFSETS Features: Ability to extract a subset of records using SELECT Note: Use 'ORDER BY' clause when using 'LIMIT' to influence sort order because SQL does not guarantee sort order a. 'SELECT * FROM messages ORDER BY id asc LIMIT 10;' - returns first 10 records b. 'SELECT * FROM messages ORDER BY id desc LIMIT 10;' - returns last 10 records c. 'SELECT * FROM messages ORDER BY id LIMIT 10 OFFSET 10;' - returns records: 11-20 d. 'SELECT * FROM messages ORDER BY id LIMIT 10 OFFSET 9;' - returns records: 10-19 e. 'SELECT * FROM messages ORDER BY id LIMIT 11 OFFSET 9;' - returns records: 10-20 f. 'SELECT * FROM messages ORDER BY id desc LIMIT 10 OFFSET 10;' - returns records: 90-82

###JOINS### Features:

  1. Aggregates related data across tables: 2 or more
  2. Default: CROSS JOIN - i.e. 'select * from messages, messagescategories;' Note: CROSS JOIN produces: 'N * M' rows of data

Tasks:

  1. Populate the 'messagescategories' dependency (lookup) table a. 'INSERT INTO messagescategories VALUES (1,'VSFTPD'),(2, 'SSHD'),(3, 'XINETD'); '

  2. Standard JOIN using 'WHERE' Clause: a. 'SELECT * from messages AS m, messagescategories AS mc WHERE m.id = mc.id;' - INNER JOIN using 'WHERE' Clause b. Create JOIN with a third table b1. 'create table messagesalerts (id int NOT NULL, alert text NOT NULL);' b2. 'INSERT INTO messagesalerts VALUES (1, 'DEBUG'), (2, 'INFORMATIONAL'), (3, 'WARNING');' b3. 'SELECT * from messages AS m, messagescategories AS mc, messagesalerts AS ma WHERE m.id = mc.id AND m.id = ma.id;' b4. 'SELECT m.id, date, category, alert from messages AS m, messagescategories AS mc, messagesalerts AS ma WHERE m.id = mc.id AND m.id = ma.id;' - Returns one (id) column in result set

  3. INNER JOINs a. 'select * FROM messages AS m INNER JOIN messagescategories ON m.id = messagescategories.id;' - Functionally equivalent to JOIN with 'WHERE' Clause b. 'select * FROM messages AS m INNER JOIN messagescategories USING (id);' - Same as above but suppresses duplicate (id) column c. 'select m.id, m.date, category FROM messages AS m INNER JOIN messagescategories USING (id);'

  4. LEFT JOINs Features: Matches (id) from left table and includes only (id) from right table that match a. 'select * from messages as m LEFT JOIN messagescategories on m.id = messagescategories.id;' b. 'select * from messages as m LEFT JOIN messagescategories USING (id);' - Same as above but suppresses duplicate (id) column c. 'select m.id,m.date,messagescategories.category from messages as m LEFT JOIN messagescategories USING (id);' - Same as above but suppresses duplicate (id) column

  5. RIGHT JOINs Features: Matches (id) from right table and includes ONLY (id) from left table that match a. 'select * from messages as m RIGHT JOIN messagescategories on m.id = messagescategories.id;' b. 'select * from messages as m RIGHT JOIN messagescategories USING (id);' c. Insert a new category into table: 'messagescategories' c1. 'INSERT INTO messagescategories VALUES (101, 'UNKNOWN'); '

Note: Foreign Key Constraint prohibits the creation of values in: 'messagescategories' that DO NOT exist in table: 'messages' d. 'select m.id,m.date,messagescategories.category from messages as m RIGHT JOIN messagescategories USING (id);' - Same as above but suppresses duplicate (id) column

e. 'select m.id,m.date,messagescategories.category from messages as m INNER JOIN messagescategories USING (id) ORDER BY category;' - Same as above but suppresses duplicate (id) column and orders by 'category' ASC

###VIEWS### Features:

  1. Presents consolidated query-driven interfaces to data
  2. They may be based on 1 or more tables
  3. Not a real objects; rather, query is executed upon invocation
  4. Supports temporary VIEWS - lasts for session duration
  5. Column names are auto-derived from the query

Tasks:

  1. Define VIEW based on INNER JOIN of: 'messages' & 'messagescategories' a. 'CREATE VIEW messagesandcategories AS SELECT * FROM messages INNER JOIN messagescategories USING (id); ' - creates permanent view of inner-joined tables b. 'SELECT * FROM messagesandcategories;' - executes the VIEW

  2. Insert Records to both: 'messages' & 'messagescategories' & re-query VIEW a. 'INSERT INTO messagescategories VALUES(4, 'KERNEL'); '

  3. Use Aliases a. 'SELECT id AS i, date AS d, category AS c FROM messagesandcategories ORDER BY id;'

  4. Update VIEW a. 'CREATE OR REPLACE VIEW messagesandcategories AS SELECT id AS i, date AS d, category AS c FROM messages INNER JOIN messagescategories USING (id);' - Creates or Updates VIEW b. 'CREATE OR REPLACE VIEW messagesandcategories (i,d,c)AS SELECT id, date, category FROM messages INNER JOIN messagescategories USING (id); '

  5. Create TEMP VIEW a. 'CREATE TEMP view messagesandalerts (i,d,a) AS SELECT id,date,alert FROM messages INNER JOIN messagesalerts USING(id);' Note: TEMP VIEWs are not assigned to the default: 'public' schema Note: TEMP VIEWs are NOT available to other sessions

  6. Create TEMP VIEW based on a single table a. 'CREATE TEMP view messagesdates AS SELECT date FROM messages; '

###Aggregates### Features:

  1. Compute single results (scalars) from multiple inputs (rows)
  2. Values are computed after 'WHERE' has selected rows to analyze a. Consequently, aggregates may not be used within: 'WHERE" clause b. However, aggregates CAN be used with: 'HAVING' clause
  3. 'HAVING' is calculated post-aggregate computation(s)

Examples:

  1. 'SELECT count(*) FROM messages;' - counts rows a. 'SELECT count(date) FROM messages;' - counts rows as well
  2. 'SELECT sum(id) FROM messages;' - Adds values from each row
  3. 'SELECT avg(id) FROM messages;' - Averages values across ALL rows
  4. 'SELECT min(id) FROM messages;' - Finds min value across ALL rows
  5. 'SELECT max(id) FROM messages;' - Finds max value across ALL rows Note: 'min' and 'max' work with both numeric and date types
  6. 'SELECT min(id), max(id), avg(id), count(id) FROM messages;' - queries multiple aggregates simultaneously

Examples with WHERE, GROUP BY & HAVING 7. 'SELECT date, min(id) FROM messages GROUP BY date;' - groups 'min(id)' by 'date' Note: When referencing non-aggregated and aggregated columns in the same query, use the 'GROUP BY' clause to sort aggregated data by non-aggregated data

  1. 'SELECT date, min(id) FROM messages WHERE id < 51 GROUP BY date;' - restricts aggregate 'min(id)' to rows containing (id) < 51

  2. 'SELECT date, min(id) FROM messages WHERE id < 51 GROUP BY date HAVING min(id) < 30;' - Post-aggregate, restricts returned results to (id) < 30

  3. 'SELECT date, min(id), max(id) FROM messages WHERE id < 51 AND id > 40 GROUP BY date;' - Extract between 40>(id)<51

Boolean Aggregates:

  1. 'ALTER TABLE messages ADD enabled boolean NOT NULL DEFAULT false;' - extends table to include a boolean column: 'enabled'
  2. 'SELECT bool_and(enabled) FROM messages;' - returns TRUE if ALL are true
  3. 'SELECT bool_or(enabled) FROM messages;' - returns TRUE if 1 or more are true

String Aggregates:

  1. 'ALTER TABLE messages ADD message text NOT NULL DEFAULT 'syslog message';'
  2. 'SELECT string_agg(message, ' ') FROM messages;' - concatenates string(text) values with single-space delimiter

###UPDATE### Features:

  1. Updates table(s) based on criteri(on|a)
  2. Requires: name of table, column(s) to update, criteri(on|a) (WHERE) clause
  3. Updates table and sub-tables unless: 'ONLY' keyword is used
  4. Output indicates number of records updated
  5. WILL UPDATE ALL RECORDS if missing CRITERI(on|a)

Examples:

  1. 'UPDATE messages SET enabled='t' WHERE id = 100;' - updates 1 record to true

  2. 'UPDATE messages SET enabled='t' WHERE enabled = 'f'; updates many records to false

  3. 'UPDATE messages SET enabled='f' WHERE id >= 50;' - updates record with (id) >= 50 to false

  4. 'UPDATE messages SET enabled='1' WHERE id >=50;' - updates records with (id) >= 50 to true

  5. 'UPDATE messages SET enabled=0, message = 'new message' WHERE id = 100;' - updates multiple columns WHERE id = 100;

  6. 'UPDATE messages SET enabled = DEFAULT;' - resets column 'enabled' to default value for ALL rows

  7. 'select * from messages where message <> 'syslog message';' - checks for rows where column 'message' IS NOT 'syslog message'

  8. 'UPDATE messages SET message = DEFAULT WHERE id = 100;'

  9. 'UPDATE messages SET message = DEFAULT RETURNING * WHERE id = 100;' - returns ALL columns Note: 'RETURNING' - is PostgreSQL-specific Note: It is equivalent to running a post-UPDATE SELECT query

  10. 'UPDATE messages SET id = id+1 WHERE id = 102;' - increments (id) by 1

  11. 'UPDATE messages SET id = id+1 WHERE id = 100 RETURNING *;' - ERROR because of duplicate

  12. 'UPDATE messages SET id = id+1 WHERE id = 101 RETURNING *;' - ERROR because of foreign key constraint

  13. 'UPDATE messages set date = 'now' RETURNING *;'

###DELETE### Features:

  1. Removes entire records based on criteri(a|on)
  2. Does NOT remove individual column(s)
  3. Requires: name of table, and preferably criteri(a|on) (WHERE) clause
  4. Deletes recursively: Use 'ONLY' to avoid deleting child tables
  5. Returns number of (count) records deleted

Examples:

  1. 'DELETE FROM messages WHERE id = 103;' - removes a single record IF EXISTS

  2. 'DELETE FROM messages WHERE date = '2010-10-18' AND enabled = 'f' AND id >= 50;' - removes records with (id) >=50 Note: Fails because of foreign key constraint

  3. 'DELETE FROM messages WHERE date = '2010-10-18' AND enabled = 'f' AND id >= 50 AND id < 101;' - removes records with (id) >=50 a. 'SELECT count(*), min(id), max(id) FROM messages;'

  4. 'DELETE FROM messages WHERE id >= 40 AND id <= 50 RETURNING *;'

  5. 'DELETE FROM messages WHERE enabled = '1' RETURNING *;' - Boolean criterion Note: Foreign Key constraint prohibits the entire transaction

  6. 'DELETE FROM messages WHERE enabled = '1' AND id >= 30 AND id !=101 RETURNING *;'

  7. 'DELETE FROM MESSAGES;' - deletes ALL rows and rows of sub-tables recursively a. 'DROP CONSTRAINT IF EXISTS messagescategories_id_fkey;' - remove constraint from dependent table

  8. Reconstitute 'messages' table to include auto-generating 'SERIAL' type on (id) column and re-populate with data a. 'ALTER TABLE messages drop id CASCADE;' - drops column with CASCADE b. 'ALTER TABLE messages add id serial;' - creates auto-sequence generator c. 'for i in seq 10000; do echo date +%F; done > messages.date.10k' - generate 10k records d. 'COPY messages (date) FROM '$PATH_TO/messages.date.10k'; e. 'SELECT COUNT(*) FROM messages;'

###INDICES### Features:

  1. Speed data retrieval & writes (INSERT, UPDATE, DELETE)
  2. Indexes reference data locations, explicitly, for indexed columns, consequent reducing data retrieval time
  3. Without indices, SQL performs sequential table scans in search of data
  4. Create on columns that are frequently queried and/or JOINed
  5. Caveat: During creation, ONLY reads are permitted to table being indexed
  6. Max of 32 columns per index - multicolumn
  7. PostgreSQL auto-maintains indices

Tasks:

  1. 'EXPLAIN select * from messages;' - explains (does not execute) plan to execute query

  2. 'EXPLAIN select * from messages where id = 4000;'

  3. Drop & Recreate messages table a. 'DROP TABLE messages;' b. 'CREATE TABLE messages (date date, id SERIAL);' c. 'ALTER TABLE messages ADD primary key (id);' - generate btree index on: (id)

  4. Create an index on a column a. 'ALTER TABLE messages ADD messageid type numeric NOT NULL;' b. 'CREATE INDEX messages_id ON messages(messageid);' c. 'explain ANALYZE select messageid, date from messages where messageid = 5990;' - 'ANALYZE' causes query to execute, suppressing the output, returning useful statistics

  5. Enumerate Indices' info a. '\di[S+]' - enumerates ALL indices within public schema

  6. Drop Index a. 'DROP INDEX messages_id;'

###Built-In Functions### Features:

  1. Manipulate data in a variety of ways

Tasks:

  1. Cover Math Functions a. 'select abs(-5);' b. 'select sqrt(25); || select sqrt(id) FROM messages' c. 'select cbrt(125);' d. 'select ceil(95.4);' - returns next highest integer e. 'select floor(95.4);' - returns next lowest integer f. 'select div(25,5);' - performs division - returns least integer g. 'select log(1000);' h. 'select power(4,3);' - raises 4 to the 3rd power i. 'select random();' - returns random value between 0 and 1 - 10^-15 j. 'select round(35.4);' - rounds down or up k. 'select trunc(95.456, 1);' - useful for normalizing floating point l. 'select cos(0);' - returns 1 - other trig functions are available

  2. Cover Useful String Functions a. 'select bit_length('test bunny');' - 80-bits b. 'select bit_length(message) FROM messages;' - 112-bits c. 'select char_length('test bunny');' - 10 chars d. 'select char_length(message), message FROM messages;' - 14 chars e. 'select lower('Test Bunny');' - normalizes output to be lower case f. 'select lower(message) FROM messages;' - normalizes output to be lower case from column g. 'select upper(message) FROM messages;' - normalizes output to be upper case from column h. 'select message, initcap(message) FROM messages;' - Applies CAPS to first letter of each word i. 'select overlay('test' placing 'xx' from 2);' - string replacement j. 'select message, overlay(message placing ' ' from 1) FROM messages;' - applies to query k. 'select trim(both ' ' from ' LinuxCBT ');' - trims leading & trailing, not between l. 'select substring('syslog' from 4);' m. 'select message, substring(message from 4) FROM messages;' - applies to table n. 'select split_part('syslog message', ' ', 2);' - returns 2nd string using space delimiter o. 'select initcap(split_part(message, ' ', 2)) FROM messages LIMIT 10;' - nested functions

###Model: /var/log/messages### Features:

  1. Challenge of replicating a flat-file structure

Tasks:

  1. Examine and model: /var/log/messages a. Need: 'mId, mCatID, mTime (timestamp) transformation needed, mHost, mFacility, mMessage'

  2. Generate 'CREATE' statement a. 'CREATE TABLE messages (mid BIGSERIAL PRIMARY KEY, mcatid smallint NOT NULL DEFAULT 1, mtime timestamp NOT NULL DEFAULT now(), mhost text NOT NULL DEFAULT 'Unknown Host', mfacility text NULL DEFAULT NULL, mmessage text NOT NULL DEFAULT 'NO MESSAGE' ); '

  3. Test 'INSERT' statement for sample record a. 'INSERT INTO messages (mtime, mhost, mfacility, mmessage) VALUES ('Oct 17 07:53:42 2010', 'linuxcbtbuild1', 'kernel:', '[861929.262518] device eth0 left promiscuous mode)'); '

  4. Write Perl script to parse: /var/log/messages and transform data to suite PostgreSQL a. Also include logic to extract: ':' from the end of the facility name. i.e. 'kernel:' should become: 'kernel'

  5. Create new log file for Bulk Import a. './parselogs.pl /var/log/messages > messages.log.new'

  6. Bulk-load messages into: PostgreSQL a. 'COPY messages (mtime,mhost,mfacility,mmessage) FROM '/home/linuxcbt/LinuxCBT_feat._PostgreSQL_Edition/messages.log.new' DELIMITER ';'; ' - Bulk-imports contents of new syslog file

  7. Create category for joins a. 'INSERT INTO messagescategories VALUES('1', 'NOTICE'); '

Note: Sometimes you may need to select a different delimiter when parsing

  1. Perform join with 'messagescategories' a. 'SELECT mtime,mhost,mfacility,messagescategories.name, mmessage FROM messages as m INNER JOIN messagescategories ON messagescategories.cid = m.mcatid;' b. 'SELECT mtime,mhost,mfacility,messagescategories.name, mmessage FROM messages as m INNER JOIN messagescategories ON messagescategories.cid = m.mcatid WHERE mfacility <> 'kernel';'

Note: To post-process the log files, consider using: CRON

###Integration of Perl with PostgreSQL### Requires:

  1. 'libpg-perl' - PostgreSQL module for Perl Features:
  2. DBMS connectivity to Perl applications/scripts

Tasks:

  1. Install 'libpg-perl' a. 'aptitude install libpg-perl'

  2. Create sample script to connect to DB and query table

  3. Integrate INSERTs into Perl Script Note: Caveat: Bulk Copies are faster than INSERTs a. ' $conn->exec("INSERT INTO messages (mtime,mhost,mfacility,mmessage) VALUES ('$date2','$host','$facility','$message');" ); '

  4. Perform Bulk Copy via script after transformations Note: Move this section outside of loops a. ' $conn->exec("COPY messages (mtime,mhost,mfacility,mmessage) FROM '/home/linuxcbt/LinuxCBT_feat._PostgreSQL_Edition/messages.18.log.new' DELIMITER ';';" ); '

###GRANT### Features:

  1. Assigns Priviliges: a. SELECT - columns or tables b. INSERT - columns or tables c. UPDATE d. DELETE - row-based e. CREATE f. CONNECT g. EXECUTE h. TRIGGER i. USAGE j. TEMPORARY k. TRUNCATE l. REFERENCES
  2. Objects are owned by creators: owners/super-users a. non-super users have NO access to them
  3. Use: '\dp' - to reveal GRANTs on objects

Tasks:

  1. Create new user 'linuxcbt3' and try to SELECT data from existing tables 'CREATE ROLE linuxcbt3 LOGIN password 'abc123'; ' Note: UPDATE & DELETE privileges require SELECT for criteri[a|on] application

  2. Attempt to query tables owned by other users a. 'SELECT * FROM messages LIMIT 10;' - Fails

  3. Remedy scenario to allow user: 'linuxcbt3' to SELECT data from 'messages' table a. 'GRANT SELECT (mid,mcatid,mtime) ON messages TO linuxcbt3;' - Column-level privileges b. 'GRANT SELECT ON messages TO linuxcbt3; ' - Table-level privileges - supercedes column restrictions

  4. Attempt to INSERT new record into: 'messages' table a. 'INSERT INTO messages (mtime,mhost,mfacility,mmessage) VALUES ('Oct 21 10:48:46 2010','linuxcbtbuild1','test','TESTING INSERT PRIVILEGE'); ' b. 'GRANT INSERT ON messages TO linuxcbt3;' - grants INSERT on ALL columns c. 'GRANT USAGE ON messages_mid_seq TO linuxcbt3;' - grants USAGE on sequence Note: If using sequences, grant USAGE on sequence to user

  5. Attempt to UPDATE current records in: 'messages' table a. 'UPDATE messages SET mfacility = 'test2' WHERE mid = '204366'; ' b. 'GRANT UPDATE on messages TO linuxcbt3;' Note: UPDATE privilege allows user to update ANY record in the table

  6. Attempt to DELETE current records from: 'messages' table a. 'DELETE FROM messages WHERE mid = '204366'; ' b. 'GRANT DELETE on messages TO linuxcbt3;'

  7. Grant ALL privileges on : 'messages' table a. 'GRANT ALL on messages TO linuxcbt3;'

###REVOKE### Features:

  1. Converse of GRANT
  2. Unassigns privileges
  3. Sample permission set: linuxcbt2=arwdDxt/linuxcbt2 a = INSERT/Append r = Read/SELECT w = Write/UPDATE d = DELETE D = Truncate x = References t = Triggers /linuxcbt2 = permissions delegator/issuer

Tasks:

  1. 'REVOKE ALL on messages FROM linuxcbt3;' - removes ALL privileges from the user
  2. 'GRANT ALL ON messages TO linuxcbt3;' - reinstate privileges
  3. 'REVOKE ALL on messages,messages_mid_seq FROM linuxcbt3;' - removes ALL privileges from the user for both objects
  4. Grant & Revoke: INSERT | UPDATE | DELETE a. 'GRANT INSERT ON messages TO linuxcbt3;' b. 'GRANT USAGE ON messages_mid_seq TO linuxcbt3;' - sequence generator access Note: INSERT may be granted independently of SELECT, unlike: UPDATE & DELETE c. 'REVOKE INSERT ON messages FROM linuxcbt3; REVOKE USAGE ON messages_mid_seq FROM linuxcbt3;' - Two revocations: INSERT & USAGE d. 'GRANT UPDATE ON messages TO linuxcbt3;' e. 'UPDATE messages SET mfacility='TEST2' WHERE mid = '204371'; ' - Fails because the user has NO SELECT privilege to execute the criteria in the UPDATE query f. 'GRANT SELECT ON messages TO linuxcbt3;' g. 'REVOKE ALL ON messages,messages_mid_seq FROM linuxcbt3;' h. 'GRANT DELETE ON messages TO linuxcbt3;' i. 'DELETE FROM messages WHERE mid = 204371; ' j. 'GRANT SELECT ON messages TO linuxcbt3;'

Test WITH GRANT OPTION a. 'GRANT ALL on messages TO linuxcbt3 WITH GRANT OPTION;' - allows user: 'linuxcbt3' to GRANT ALL privileges on the object: 'messages' to other users b. 'CREATE ROLE linuxcbt4 LOGIN PASSWORD 'abc123'; ' c. 'GRANT SELECT ON messages TO linuxcbt4;' - run as: 'linuxcbt3' d. 'GRANT INSERT ON messages TO linuxcbt4;' - run as: 'linuxcbt3' e. 'GRANT UPDATE ON messages TO linuxcbt4;' - run as: 'linuxcbt3' f. 'GRANT DELETE ON messages TO linuxcbt4;' - run as: 'linuxcbt3'

Attempt to REVOKE PRIVILEGES FROM 'linuxcbt3' as user: 'linuxcbt2' OR super user a. 'REVOKE ALL ON messages FROM linuxcbt3;' - Fails due to privileges depency b. 'REVOKE ALL ON messages FROM linuxcbt3 CASCADE;' - Recursive

Note: If a permissions/privileges depency exists, use: 'CASCADE' option with 'REVOKE' command to descend the permissions/privileges hierarchy

Test direct removal of privileges from top-level to bottom a. 'GRANT ALL on messages TO linuxcbt3 WITH GRANT OPTION;' - run as: 'linuxcbt2' or super user b. 'GRANT SELECT,DELETE on messages TO linuxcbt4; ' - run as: 'linuxcbt3' c. 'REVOKE ALL on messages FROM linuxcbt4; ' - run as: 'linuxcbt2' OR super user - FAILS Note: Fails due to GRANT hierarchy d. 'REVOKE ALL ON messages FROM linuxcbt3 CASCADE;' - Recursive

###DB Backup### Features:

  1. Individual table, DB, or full DBMS backup
  2. 'pg_dump' & 'pg_dumpall'
  3. Operate on running DB
  4. Export SQL script or Archive (pg_dump) (used with pg_restore) formats
  5. SQL Script: Designed for full replay with: 'psql' utility
  6. Archive File: Designed to allow selective and/or reordered restores: a. '-Fp) - Default - Plain SQL script output - uncompressed b. '-Fc) - Custom, auto-compressed form - 'pg_restore' c. '-Ft) - Tar form - not compressed - restrictions on reordering - works with: 'tar' & 'pg_restore'

Tasks:

  1. Backup 'postgres' DB - Plain (-Fp) Format a. 'pg_dump postgres' - dumps to STDOUT b. 'pg_dump -v -f DB_Backup_postgres postgres ' - generates plain text SQL script file containing data Note: Uses 'COPY' to reconstruct data as opposed to: 'INSERT' c. 'pg_dump -v postgres > DB_BACKUP_postgres2' - performs as above d. 'pg_dump -v -s -f DB_Backup.schema postgres' - dumps SCHEMA ONLY e. 'pg_dump -v -t messages -t messagescategories -f DB_Backup.messages.cats.tables.only' f. 'pg_dump -v -t 'messages*' -f DB_Backup_ALL_messages_tables.only' - Archives ALL items in 'postgres' DB beginning with: 'messages'

  2. Backup 'postgres' DB - Compressed (-Fc) Format a. 'pg_dump -v -Fc -f DB_Backup.postgres.compressed postgres' - creates custom, compressed file to be used with: 'pg_restore'

  3. Backup 'postgres' DB - Tar (-Ft) Format a. 'pg_dump -v -Ft -f DB_Backup.postgres.tar postgres' - creates a tarball of DB

  4. Use 'pg_dumpall' to archive the entire DBMS a. 'pg_dumpall -v -f DB_Backup.ALL' b. Create auth file in: $HOME to obviate the need to authenticate to each DB c. 'echo 'localhost:::linuxcbt2:abc123' > ~/.pgpass && chmod 600 ~/.pgpass' d. Re-run 'pg_dumpall' as user: 'linuxcbt2' - defined in: $HOME/.pgpass e. 'pg_dumpall -v -U linuxcbt2 -f DB_Backup.ALL'

###DB Restore### Features:

  1. Two tools: 'psql' && 'pg_restore'

Tasks:

  1. Use 'pg_restore' to restore tables, DBs, etc. a. 'DROP table messages2, messagescategories;' b. 'pg_restore -v -d postgres DB_Backup.postgres.compressed' - full restoration using 'compressed' file c. 'pg_restore -v -d postgres DB_Backup.postgres.tar' - full restoration using 'tar' file

Note: Use: 'pg_restore -l backup_file' to enumerate items for selective/reordered restoration

  1. Backup 'linuxcbt2' DB and restore a. 'pg_dump -v -C -Fc -f DB_Backup.linuxcbt2.DB linuxcbt2' b. 'DROP DATABASE linuxcbt2;' c. 'pg_restore -v -C -d postgres DB_Backup.linuxcbt2.DB' - restores DB 'linuxcbt2' d. 'pg_dump -v -C -f DB_Backup.linuxcbt2.DB.sql linuxcbt2' d. 'DROP DATABASE linuxcbt2;' e. 'psql -f DB_Backup.linuxcbt2.DB' - Fails because source file is not SQL text

  2. Restore specific tables using: 'pg_restore' a. 'DROP table messages2, messagescategories;' b. 'pg_restore -v -d postgres -t messages2 DB_Backup.postgres.compressed' - restores 1 table c. 'pg_restore -v -d postgres -t messagescategories DB_Backup.postgres.tar' - restores 1 table

  3. Use 'psql' to restore selected backup items (tables, sequences, etc.) a. 'DROP table messages, messagescategories;' b. 'psql -f DB_Backup.messages.cats.tables.only' c. 'DROP table messages, messagescategories, messages2, messagesalerts;' d. 'psql -f DB_Backup_ALL_messages_tables.only;'

###Windows DB Restoration###

Tasks:

  1. Explore Windows PostgreSQL environment a. 'psql -h 192.168.75.105'
  2. Restore data to Windows instance a. 'psql -h 192.168.75.105 -f DB_Backup.ALL' - restores FULL DB to remote host
  3. Wreak Havoc on remote DB and Restore a. 'DROP TABLE messages, messages2, messagescategories;' b. 'pg_restore -v -h 192.168.75.105 -d postgres -t messages2 DB_Backup.postgres.compressed' - restores 1 table c. 'pg_restore -v -h 192.168.75.105 -d postgres -t messages DB_Backup.postgres.compressed' - restores 1 table d. 'pg_restore -v -h 192.168.75.105 -d postgres -t messagescategories DB_Backup.postgres.tar' - restores 1 table e. 'DROP TABLE messages, messagescategories, messages2, messagesalerts;'
    f. 'psql -h 192.168.75.105 -f DB_Backup_ALL_messages_tables.only;' Note: Ensure that remote system's HBA conf file accepts remote connections

###Installation on RedHat Enterprise Linux### Features:

  1. PostgreSQL support
  2. Ability to use the same binary used on the other distributions

Tasks:

  1. Copied binary from remote system to local RedHat system

  2. Executed it

  3. Confirm availability: 'ps -ef | grep -i postgres'

  4. Connect and confirm default environment

  5. Update ~linuxcbt $PATH & $PGUSER vars

  6. Source if necessary for active TTY a. '. ~/.bash_profile'

  7. Mirror contents of remote server a. Get 'DB_Backup.ALL' - use 'sftp' b. Populate RedHat instance of PostgreSQL with data from Debian box b1. 'psql -f DB_Backup.ALL'

  8. Remove tables and restore across the wire using: 'psql' a. Update HBA conf to allow network connectivity b. Restart 'postgres' to effect 'pg_hba.conf' change c. Restore items using: 'psql' from remote host c1. 'psql -U postgres -f DB_Backup.ALL postgres -h 192.168.75.20' - replays script on remote, RedHat Enterprise box

###SSH Tunnels### Features:

  1. Secure communications from point-to-point
  2. Encryption services
  3. Wrapper of communications
  4. Traffic is protected in transit, NOT at the endpoints
  5. Defaults to protecting loopback adapter address(es)

Tasks:

  1. Sniff PostgreSQL communications using: 'tcpdump' a. 'tcpdump -w postgres.dump.1 -v -i lo tcp port 5432' b. 'psql -h localhost' c. 'wireshark postgres.dump.1' - reveals sensitive data

  2. Apply SSH tunnels from Linux a. 'ssh -L 5433:192.168.75.20:5432 192.168.75.20' - creates a tunnel between: linuxcbtbuild1 (.101) -> linuxcbtserv1 (.20) b. 'netstat -ntl | grep 5433' - confirms existence of tunnel c. 'psql -h localhost -p 5433' - initiate connection

d. 'ssh -L 5433:192.168.75.101:5432 192.168.75.101' - creates a tunnel between: linuxcbtbuild1 (.101) -> linuxcbtserv1 (.20) e. 'psql -h 127.0.0.1 -p 5433' - initiate connection

  1. Apply SSH tunnel from Windows a. Ensure that PuTTY or equivalent SSH client is installed b. Setup session to forward TCP:5433 & TCP:5434 to TCP:5432 on Debian and RedHat boxes c. Test 'psql' client access across the tunnel from Windows Note: This will not work with Windows as the target SSH server sans Cygwin or compatible SSH service

###SSL Connections### Features:

  1. True end-to-end encryption protection - 100%
  2. Listens to same, clear-text port: TCP:5432
  3. Auto-negotiates with client connection type unless server config (pg_hba.conf) enforce Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:20 2010#linuxcbtbuild1#kernel#[963727.050042] arpalert[4847]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:20 2010#linuxcbtbuild1#kernel#[963727.050042] arpalert[4847]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:20 2010#linuxcbtbuild1#kernel#[963727.050042] arpalert[4847]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:20 2010#linuxcbtbuild1#kernel#[963727.050042] arpalert[4847]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:20 2010#linuxcbtbuild1#kernel#[963727.050042] arpalert[4847]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:20 2010#linuxcbtbuild1#kernel#[963727.050042] arpalert[4847]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:20 2010#linuxcbtbuild1#kernel#[963727.050042] arpalert[4847]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:20 2010#linuxcbtbuild1#kernel#[963727.050042] arpalert[4847]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:20 2010#linuxcbtbuild1#kernel#[963727.050042] arpalert[4847]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:20 2010#linuxcbtbuild1#kernel#[963727.050042] arpalert[4847]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000] Oct 18 12:10:20 2010#linuxcbtbuild1#kernel#[963727.050042] arpales type
  4. Supports server (default) & client certificates
  5. 'openssl version -d' - reveals config directory for OpenSSL

Requires:

  1. Server keypair: 'server.crt' (public) & 'server.key" (private) in: DATA directory
  2. 'server.key' - MUST be flagged 600
  3. Optionally, 'root.crt' & 'root.crl'
  4. 'ssl=on' - enabled via: 'postgresql.conf'

Tasks:

  1. Generate Server Keypair a. 'openssl req -new -text -out server.req' - Generates a request b. 'openssl rsa -in privkey.pem -out server.key' - removes passphrase c. 'rm privkey.pem' - because we now have an RSA version in: 'server.key' d. 'openssl req -x509 -in server.req -text -key server.key -out server.crt' - generates self-signed certificate (.crt) file e. 'chown postgres server.key && chmod 600 server.key'

  2. Configure PostgreSQL a. 'ssl=on' - postgresql.conf b. Restart postgresql

Note: Test inability to restart postgres when 'server.key' is not readable

  1. Test connectivity a. 'psql -U postgres -h localhost' - SSL was used because TCP/IP was used Note: SSL is not enabled when using Unix Domain Sockets b. 'psql -h 192.168.75.101' - SSL was used... c. 'psql ' - SSL was NOT used due to Unix Domain Sockets usage d. Connect to RedHat host and test connectivity

  2. Sniff SSL session with TCPDump

  3. Test from Windows a. 'psql -h 192.168.75.101' - It works with SSL...

# 目录
1. [Features of postgresql](#features-of-postgresql)
2. [Installation](#installation)
3. [psql](#psql)
4. [Access Controls](#access-controls)
5. [Logging](#logging)
6. [Common Data Types](#common-data-types)
7. [CREATE](#create)
8. [DROP](#drop)
9. [ALTER](#alter)
10. [Constraints](#constraints)
11. [INSERT](#insert)
12. [COPY Command](#copy-command)
13. [SELECT](#select)
14. [JOINS](#joins)
15. [VIEWS](#views)
16. [Aggregates](#aggregates)
17. [UPDATE](#update)
18. [DELETE](#delete)
19. [INDICES](#indices)
20. [Built-In Functions](#built-in-functions)
21. [Model: /var/log/messages](model-varlogmessages)
22. [Integration of Perl with PostgreSQL](#integration-of-perl-with-postgresql)
23. [GRANT](#grant)
24. [REVOKE](#revoke)
25. [DB Backup](#db-backup)
26. [DB Restore](#db-restore)
27. [Windows DB Restoration](#windows-db-restoration)
28. [Installation on RedHat Enterprise Linux](#installation-on-redhat-enterprise-linux)
29. [SSH Tunnels](#ssh-tunnels)
30. [SSL Connections](#ssl-connections)
###Features of PostgreSQL###
1. Object Relational Database Management System (ORDBMS)
1. Objects can be related in a hierarchy: Parent -> Child
2. Transactional RDBMS:
> Note: Transactional statements must execute: ALL or NONE
1. SQL statements have implicit: BEGIN; COMMIT; statements
1. SQL statements may also have explicit: BEGIN; COMMIT; statements
3. Note/Feature:
1. Developed originally @ UC Berkeley
4. One process per connection - auto-spawns per new connection
1. managed by master process: 'postmaster'
5. Processes use only ONE CPU/Core
1. Note: OS/Distro may spawn new connection on a different CPU/core
6. Multiple helper processes, which appear as 'postgres' instances, run always
1. Stats collector
1. Background writer
1. Autovacuum - clean-up/space reclaimer
1. WALsender - write ahead log
7. Max DB Size: Unlimited - limited by OS & available storage
> Note: Consider deploying on 64-bit platform
8. Max Table Size: 32TB - stored as multiple: 1GB files
9. Max Row Size: 400GB
10. Max Col Size: 1GB
11. Max Indexes on a table: Unlimited
12. Max Identifier (DB objects (table|column names, etc.): 63-bytes
> Note: The limitation is extensible via source code
13. Default Listener: TCP:5432
1. You may install PostgreSQL as a non-privileged user
14. Users are distinct from OS users - i.e. MySQL
15. Users are shared across DBs
16. Inheritance
1. Tables lower in hierarchy may inherit columns from higher tables
1. Caveat: No unique constraints or foreign keys support
17. Case-insensitive commands - sans double quotes -i.e. 'select * from Syslog;'
18. Case-sensitive commands - with double quotes - i.e. 'select & from "Syslog";'
19. Three Primary Config Files: $POSTGRESROOT/data/*.conf
1. 'pg_hba.conf' - controls host/user/DB connectivity
1. 'postgresql.conf' - general settings
1. 'pg_ident.conf' - user mappings
20. Integrated Log Rotation|Management - Log Collection - 'postgresql.conf'
1. Criteria: Age | Size
###Installation###
Features:
1. Download bin file from Enterprise DB
Tasks:
1. Install
> Note: You may optionally indicate that data files be stored independently of the source tree
> Note: A 'Database Cluster' is simply the management of more than 1 DB<br/>
> Note: Default is to start the RDBMS post-installation
2. Explore the footprint
1. 'psql' - terminal monitor - i.e. akin to 'mysql'
1. 'createdb|dropdb' - creates|drops DB
1. 'createuser|dropuser' - creates|drops users
1. 'postgres' - server daemon
1. 'data/' - top-level data/config files/log files
1. 'data/pg_log/' - log files (default is: STDERR)
1. 'data/pg_xlog/' - Write Ahead Log (WAL) - maintains changes to DB files at all times
1. 'data/postmaster.opts' - contains startup options
1. '/etc/init.d/postgresql-9.0' - INITD manager
> Note: Files, execpt INITD file, are contained within: /opt/postgresql/version hierarchy
3. Provide access to docs via Apache
1. 'ln -s /opt/PostgreSQL/9.0/doc/postgresql/html ./LinuxCBT/postgresqldocs '
4. Update: $linuxcbt/.bashrc to reflect: /opt/PostgreSQL/9.0/bin - to access binaries
> Note: PostgreSQL clients default to submitting the currently logged-in user's name as the DB user name
> Note: A workaround for this is to export the PGUSER variable, setting it to an existing DB user
'export PGUSER=postgres'
### 'psql' ###
Features:
1. (Non)Interactive usage - i.e. 'mysql' terminal monitor
2. Command history - up|down arrows
3. Tab completion
4. Commands terminate with semicolon and may wrap lines and have whitespace separators
5. Defaults to supplying the currently-logged-in user
Tasks:
1. Explore 'psql'
a. 'psql --version'
b. 'psql -l -U postgres' - lists DBs then exits
Note: PostgreSQL installs 3 default DBs:
1. 'postgres' - contains user accounts DB, etc.
2. 'template0' - vanilla, original DB
3. 'template1' - Copy of template0, and may be extended, and is used to generate new DBs
c. 'psql' - enters interactive mode
c1. trailing '#' indicates: super user: 'postgres'
d. '\h' - returns SQL-specific help
e. '\?' - returns 'psql'-specific help - i.e. usable metasequences
f. '\l[+]' - returns list of DBs
g. '\du[+]' - returns list of users in system DB
h. '\!' - returns user to $SHELL
i. '\! command' - executes a specific command - non-interactively
Note: Typical $SHELL semantics apply
j. '\i filename' - executes command(s) in the file - i.e. 'psql' or SQL commands
Note: Multiple commands can be run with one reference. Terminate set with: ';', use space between commands.
k. '\c DBNAME [REMOTE HOST]' - connects to different DB and optionally different host
Note: current DB is echoed in the prompt. i.e. postgres=# || template1=#
l. '\d[S+]' - reveals tables, views, sequences and various DB objects
m. '\q' - quits
###Access Controls###
Features:
1. Users - Roles (Roles are users or groups)
2. Config Files:
a. 'pg_hba.conf | pg_ident.conf | postgresql.conf'
3. Central accounts DB shared ALL DBs - accounts MUST be unique
4. Default setup includes 1-User - 'postgres' - Super User
5. Privileges are managed with:
a. 'GRANT | REVOKE'
b. 'ALTER'
c. 'CREATE | DROP ROLE|USER' - SQL Statements (Key Words)
d. 'createuser|dropuser' - commands - wrappers to SQL statements
6. DB Object creators own those objects and can assign privileges to them
7. To Change DB object ownership use: ALTER - sql key word
8. Special role named: 'PUBLIC' grants assigned privilege to ALL system users
a. 'PUBLIC' is a special group, to which ALL users are members
Tasks:
1. Create another super user
a. '\du' - enumerates current users|roles
b. 'createuser -e -s -U postgres linuxcbt' - echoes SQL commands to STDOUT
c. Confirm inability to connect to posgres as new role: 'linuxcbt'
d. Set 'linuxcbt' password: '\password linuxcbt' - permits setting of user's password
Note: Caveat: Upon connection to postgres, the client 'psql' attempts to connect the user to a DB named the $PGUSER
2. Drop newly-created super user: 'linuxcbt'
a. 'dropuser -e -U postgres linuxcbt' - removes user from DBMS
3. Examine remote, TCP-based connectivity
###Logging###
Features:
1. Three types of logs supported:
a. 'stderr'(Default)
b. 'csvlog' - import into spreadsheets | DBs
c. 'syslog'
2. Controlled via: $POSTGRESROOT/data/postgresql.conf
3. Simultaneous logging
4. Ability to control verbosity
5. Automatic log rotation based on criteria: age | size
6. Logs handled by the included logger (stderr,csvlog) are stored in: $POSTGRESROOT/data/pg_log
Note: Syslog-handled messages are routed according to syslog rules: /etc/rsyslog.conf
7. The first process launched by master process
Tasks:
1. Explore: $POSTGRESROOT/data/postgresql.conf
2. Configure syslog
a. Update syslog configuration for: 'LOCAL0' facility - Consider updating: LogRotate
b. Update: $POSTGRESROOT/data/postgresql.conf - 'stderr,syslog'
3. Configure csvlog
a. Append: 'csvlog' to log_destination VAR: $POSTGRESROOT/data/postgresql.conf
Note: Caveat: Syslog is UDP-based and is subject to loss of messages
### Common Data Types ###
Features:
1. Allow us to control the type of data on a per column basis
Types:
Numeric:
a. 'smallint' - 16-bits (2-bytes) - whole numbers
b. 'int' - integer - 32-bits (4-bytes) - whole number
c. 'bigint' - Big Integer - 64-bits - whole numbers only
d. 'numeric[(precision,scale)]'
d1. precision = sig figs
d2. scale = number of values to the right of the decimal point
Note: 'numeric' sans precision or scale supports up to: 1000 digits of precision
e. 'real' - 32-bits - variable - 6 decimal digits of precision
f. 'double precision' - 64-bits - variable - 15 decimal digits of precision
g. 'serial' - 32-bits (2^31) signed - auto-incrementing
h. 'bigserial' - 64-bits (2^63) - auto-incrementing
Money:
a. 'money' - 64-bits - 2^63 signed: i.e. -9EB - 9EB
Strings - Text
a. 'text' - varchar - unlimited - preferred character storage type within PostgreSQL
b. 'char(n)' - fixed-length, blank-padded if value stored is < 'n' length
b1. i.e. 'char(9)' - 'linuxcbt' -> stored as: 'linuxcbt '
Note: char(n) truncates values that are > 'n' lenght
b2. i.e. 'char'-> 'char(1)' - effectively becomes a 1-character field
c. 'varchar(n)' - variable length with 'n' limit, if 'n' is present - Does NOT blank-pad
c1. i.e. 'varchar(9)' - 'linuxcbt' -> stored as: 'linuxcbt'
c2. i.e. 'varchar' -> variable length - Does NOT blank-pad
Note: Use 'text' or 'varchar' when storing strings
Dates & Time - Uses 'Julian Dates (from 4713 BC) -> 10^5+ years ahead' - in date calculations
a. 'date' - 32-bits - date only
b. 'time' - 64-bits - defaults to time 'without time zone' - microsecond precision
c. 'time with time zone' - 96-bits - date & time with time zone - microsecond precision
d. 'timestamp with time zone' - 64-bits - ...
e. 'timestamp without time zone' - 64-bits - ...
f. 'interval' - 96-bits - range of time - microsecond precision
Boolean - 8-bits - True(1)(on) | False(0)(off)
Geometric Types - lines, circles, polygons, etc.
Network Address Types
a. 'cidr' - 7 or 19-bytes - IPv4 and IPv6 networks - i.e. '192.168.75.0/24' || '2002:4687:db25:2/64'
b. 'inet' - 7 or 19-bytes - IPv4 and IPv6 hosts and networks
c. 'macaddr' - 48-bits - i.e. 00:11:11:5b:70:53, 0011.115b.7053 , etc.
XML
Arrays
et cetera.
###CREATE###
Features:
1. Limited to 63 characters for the definition of objects
2. Identifiers (DB Objects) MUST begin with alpha characters
3. Used to create: DBs, Schemas, Tables, Indexes, Functions, etc.
Note: PostgreSQL Hierarchy:
1. DB
2. -Schema(s) (Optional) - Default schema is named: 'public'
3. -Objects (Tables, Functions, Triggers, etc.)
Note: ALL DBs have: 'public' and 'pg_catalog' schemas
Note: ALL users|roles have: 'CREATE' & 'USAGE' access to the 'public' schema for ALL DBs
Note: Create distinct schemas if security beyond 'public' is necessary
Tasks:
1. DB Creation
a. Create a user named: 'linuxcbt' with 'CREATEROLE CREATEDB' rights
a1. 'createuser -e -U postgres linuxcbt'
b. Create a DB named 'linuxcbt'
b1. 'CREATE DATABASE linuxcbt;'
c. Create a Table named: 'linuxcbtmessages'
c1. 'CREATE TABLE linuxcbtmessages (date date);'
d. Create a user named 'linuxcbt2' with USAGE rights
d1. 'CREATE ROLE linuxcbt2 LOGIN;'
e. Create a SCHEMA named: 'logs'
e1. 'CREATE SCHEMA logs;'
f. Create a TABLE named: 'linuxcbtmessages' within the SCHEMA: 'linuxcbt.logs'
f1. 'CREATE TABLE logs.linuxcbtmessages (date date);'
f2. '\d linuxcbt.logs.linuxcbtmessages' - confirms the description of the table
g. Check whether user: 'linuxcbt2' has access to: 'linuxcbt.logs' SCHEMA
###DROP###
Features:
1. Removes objects: DBs, Schemas, Tables, Functions, Triggers, etc. from ORDBMS
2. Available from the $SHELL and within SQL interpreter: 'psql'
Tasks:
1. Drop DB 'linuxcbt2'
Note: Objects that are currently in-use will NOT be dropped by default
a. 'drop database linuxcbt2;'
Note: Dropping DBs will remove ALL sub-objects, including, but not limited to:
a. Schemas
b. Tables
c. Triggers
d. Functions, etc.
2. Drop Tables
a. 'DROP TABLE linuxcbt2messages;' - removes table if current user is owner or SUPERUSER
b. 'DROP TABLE linuxcbtmessages;' - as user: 'linuxcbt2' - fails due to lack of permissions
c. 'CREATE DATABASE TEST TEMPLATE linuxcbt;' - templates DB named: 'linuxcbt'
Note: No active sessions must be ongoing in order for template process to work to ensure consistency with duplicated DB
c. 'dropdb TEST'
Note: Objects created within the 'public' schema are not readily accessible to other users sans the usage of the 'GRANT' command
d. Drop schema: 'linuxcbt.logs'
d1. 'DROP SCHEMA logs;' - fails because there is a dependent table: 'linuxcbtmessages'
d2. 'DROP SCHEMA logs CASCADE;' - forces recursive removal of objects
e. Re-create structure & DROP:
e1. 'CREATE DATABASE linuxcbt2;'
e2. '\c linuxcbt2 && CREATE SCHEMA logs'
e3. 'CREATE TABLE linuxcbt2.logs.linuxcbt2messages (date date);'
e4. 'DROP DATABASE linuxcbt2;'
###ALTER###
Features:
1. Changes Object (DB|Schema|Table|Index|etc.) - Name|Structure|Owner
Tasks:
1. Confirm our environment by ensuring requisite objects
2. Change DB Name
a. 'ALTER DATABASE linuxcbt RENAME TO linuxcbt2;'
Note: ALTER should be used sans connections to target objects
3. Change DB Ownership
a. 'ALTER DATABASE linuxcbt2 OWNER TO linuxcbt2;' - changes ownershipt to role: 'linuxcbt2'
4. Test ability to DROP DB as new owner
a. 'DROP DATABASE linuxcbt2;'
5. Create and Rename Table: 'linuxcbt2messages'
a. 'CREATE TABLE linuxcbt2messages (date date);' - creates table 'public.linuxcbt2messages'
b. 'ALTER TABLE linuxcbt2messages RENAME TO messages;'
6. Alter Table Structure: 'messages'
a. 'ALTER TABLE messages ALTER COLUMN date SET DATA TYPE timestamp;'
Note: Structurual (columnar) changes may result in data loss if target column type does NOT support source column data
b. 'ALTER TABLE messages ADD ident text;' - ADDS, sequentially, a new column to table
Note: Column names MUST be unique and may not be added more than once
c. 'ALTER TABLE messages DROP COLUMN IF EXISTS ident;' - removes column named: 'ident' if exists
Note: Be forewarned, that the dropping of a colum WILL remove existing DATA in the column
7. ALTER existing ROLE
a. 'ALTER ROLE linuxcbt2 SUPERUSER;' - makes user 'linuxcbt2' a SUPERUSER
Note: This will ONLY work if you execute as a SUPERUSER. i.e. 'postgres'
b. 'ALTER ROLE linuxcbt RENAME TO linuxcbt4;' - renames user: 'linuxcbt' TO 'linuxcbt4'
Note: This will unset the user's MD5 password
Note: This will update ownership of objects. i.e. DB::Test is now owned by: 'linuxcbt4'
c. 'ALTER ROLE linuxcbt4 RENAME TO linuxcbt;'
###Constraints####
Features:
1. Enforce storage requirements: per table | column
2. May be applied per column
3. Multiple constraints may be bound to a single column
4. Optionally, constraints may be defined at the table level for one or more columns
5. Default column rule is to accept NULLs
Data Types - basic constraint
a. Restricts permitted column values
i.e. 'date', 'smallint', 'char(9)', etc.
Not-Null | NULL Contraints
a. Define a table using NOT NULL
a1. 'create table messages (date date NOT NULL);'
b. Alter table adding a new column (id) with constraint: NULL
b1. 'ALTER TABLE messages ADD id in NULL;'
Unique Constraint - Applies to any type of column: i.e. 'int', 'numeric', 'text', etc.
a. Define a table with a UNIQUE 'id' column
a1. 'create table messages (date date, id bigint UNIQUE); '
Note: The creation of UNIQUE contraints generates implicit btree indices on column(s)
b. Define table with multiple UNIQUE columns
b1. 'create table messages (date date, id bigint, message text, UNIQUE(id,message) );'
Note: This ensures that the combination of: 'id' && 'message' is unique
Sample Records that do NOT break the UNIQUE contraint:
2010-10-14 1 message
2010-10-14 2 message
2010-10-14 3 message
Sample Records that DO break the UNIQUE contraint:
2010-10-14 1 message
2010-10-14 1 message
2010-10-14 2 message
Primary Key Constraint - Combination of: 'UNIQUE' & 'NOT NULL' Constraints
a. Create a table with primary key constraint on 1 column
a1. 'create table messages (date date, id numeric PRIMARY KEY); '
b. Create a table with primary key constraint on 2 columns
a1. 'create table messages (date date, id numeric, message text, PRIMARY KEY(id, message) ); '
Note: Standard SQL recommends that each table contain a primary key
Foreign Key Constraint - Links Tables - Referential Integrity
a. Create messages table as parent table
a1. 'create table messages (date date, id int PRIMARY KEY); '
b. Create subordinate table to categorize messages in parent table
b1. 'create table messagesCategories (id int REFERENCES messages(id), category text;'
Check Constraint - confirms column values based on Boolean criteria:
'CHECK (expr)'
a. Ensure that (id) contains values greater than 0
a1. 'create table messages (date date NOT NULL, id numeric CHECK (id > 0) );'
b. Create the same constraint with a name
Note: If unnamed, PostgreSQL will auto-name the constraint
b1. 'create table messages (date date NOT NULL, id numeric CONSTRAINT positive_id CHECK (id > 0) ); '
c. Create CHECK constraint which summarizes ALL rules for ALL columns
c1. 'create table messages (date date, id numeric CHECK (date IS NOT NULL AND id > 0 AND id IS NOT NULL) );
###INSERT###
Features:
1. Populates tables via various methods
2. PostgreSQL inserts left-to-right
Usages:
1. Insert into table with precise number of columns
a. 'INSERT INTO messages VALUES ('2010-10-14','1');'
2. Insert using specified field(s)
a. 'INSERT INTO messages (date) VALUES('2010-10-14');'
3. Insert more columns than are defined in the table - WILL NOT WORK
a. 'INSERT INTO messages VALUES('2010-10-14', '5', 'Log Message'); '
4. Insert multiple records wholesale
a. 'INSERT INTO messages VALUES ('2010-10-14','6'),('10/14/2010','7'),('10/14/2010', '8'); '
Note: The date format in record 3 causes the entire transaction to fail, due to implicit:
BEGIN & COMMIT statements
5. Test Foreign Key Constraint
a. 'create table messagesCategories (id int REFERENCES messages(id), category text);'
Note: Because messages table does not have UNIQUE or PRIMARY KEY constraints on (id) column, the Foreign Key constraint will fail
Note: Rectify by defining a Primary Key on messages table OR inserting unique values into (id)
Note: PostgreSQL raises error and denies creation of subordinate table
b. Insert data into dependent table
b1. 'INSERT INTO messagescategories VALUES ('4','VSFTPD'); ' - fails constraint
b2. 'INSERT INTO messagescategories VALUES ('3','VSFTPD'); ' - passes constraint
Note: Foreign Key constraint need not be based on a numeric
6. Test Primary Key Constraint
a. 'INSERT INTO messages VALUES ('10/14/2010','3');' - fails constraint
b. 'INSERT INTO messages VALUES ('10/14/2010','4'); - passes constraint
Note: Summarizes both: UNIQUE & NOT NULL constraints
###COPY Command###
Features:
1. Server-side command, unlike: '\copy' which is client-side
2. Wholesale inserts (imports) | Exports from | to a file
3. File MUST be on the server
4. File MUST be viewable by the 'postgres' user
5. Uses absolute $PATH to reference the file
6. Defaults to importing based on: TAB separator|delimiter
7. Able to copy the results of 'SELECT' query
8. Does NOT work with VIEWS but will work with SELECT of VIEW
9. Appends records to table
Tasks:
1. Generate Import File
a. 'for i in `seq 100`; do echo `date +%F` $i; done > ~linuxcbt/LinuxCBT_feat._PostgreSQL_Edition/messages.data'
2. Import Data
a. 'COPY messages FROM '/home/linuxcbt/LinuxCBT_feat._PostgreSQL_Edition/messages.data' DELIMITER ' '; '
Note: Truncate Table when necesary to clear data
TRUNCATE table messages CASCADE; - removes data from dependent and parent tables
b. Vary delimiter
b1. 'awk '{ print $1","$2 }' messages.data ' - formats output with comma delimiter
b2. 'TRUNCATE table messages CASCADE;'
b3. 'COPY messages FROM '/home/linuxcbt/LinuxCBT_feat._PostgreSQL_Edition/messages.data.csv' DELIMITER ','; '
3. Export Data
a. 'COPY messages TO '/home/linuxcbt/LinuxCBT_feat._PostgreSQL_Edition/messages.data.semicolon' DELIMITER ';';' - export with semicolon delimiter
Note: Ensure that user: 'postgres' may write to target directory
Note: Export does NOT append redirect, rather, it clobbers (overwrites) target file
###SELECT###
Features:
1. Performs queries: i.e. calculations, system stats, data retrieval
2. Retrieves data from objects: table(s), view(s), etc.
Usage:
1. 'SELECT * FROM messages; ' - Returns ALL rows from table: 'messages';
2. 'SELECT rolname, rolcreaterole FROM pg_roles;' - returns just those 2 columns
3. 'SELECT rolcreaterole, rolname FROM pg_roles;' - returns just those 2 columns, reversed
4. 'SELECT rolname AS r, rolcreaterole AS rr FROM pg_roles;' - Constructs aliases for columns
5. 'SELECT * FROM pg_roles WHERE rolname LIKE '%linuxcbt%';' - Simple string comparison
6. 'SELECT * FROM messages ORDER BY id DESC;' - Changes sort order ON (id) column
7. 'SELECT DISTINCT date FROM messages;' - Filters unique values per column, by not returning redundancies
8. LIMITS & OFFSETS
Features: Ability to extract a subset of records using SELECT
Note: Use 'ORDER BY' clause when using 'LIMIT' to influence sort order because SQL does not guarantee sort order
a. 'SELECT * FROM messages ORDER BY id asc LIMIT 10;' - returns first 10 records
b. 'SELECT * FROM messages ORDER BY id desc LIMIT 10;' - returns last 10 records
c. 'SELECT * FROM messages ORDER BY id LIMIT 10 OFFSET 10;' - returns records: 11-20
d. 'SELECT * FROM messages ORDER BY id LIMIT 10 OFFSET 9;' - returns records: 10-19
e. 'SELECT * FROM messages ORDER BY id LIMIT 11 OFFSET 9;' - returns records: 10-20
f. 'SELECT * FROM messages ORDER BY id desc LIMIT 10 OFFSET 10;' - returns records: 90-82
###JOINS###
Features:
1. Aggregates related data across tables: 2 or more
2. Default: CROSS JOIN - i.e. 'select * from messages, messagescategories;'
Note: CROSS JOIN produces: 'N * M' rows of data
Tasks:
1. Populate the 'messagescategories' dependency (lookup) table
a. 'INSERT INTO messagescategories VALUES (1,'VSFTPD'),(2, 'SSHD'),(3, 'XINETD'); '
2. Standard JOIN using 'WHERE' Clause:
a. 'SELECT * from messages AS m, messagescategories AS mc WHERE m.id = mc.id;' - INNER JOIN using 'WHERE' Clause
b. Create JOIN with a third table
b1. 'create table messagesalerts (id int NOT NULL, alert text NOT NULL);'
b2. 'INSERT INTO messagesalerts VALUES (1, 'DEBUG'), (2, 'INFORMATIONAL'), (3, 'WARNING');'
b3. 'SELECT * from messages AS m, messagescategories AS mc, messagesalerts AS ma WHERE m.id = mc.id AND m.id = ma.id;'
b4. 'SELECT m.id, date, category, alert from messages AS m, messagescategories AS mc, messagesalerts AS ma WHERE m.id = mc.id AND m.id = ma.id;' - Returns one (id) column in result set
3. INNER JOINs
a. 'select * FROM messages AS m INNER JOIN messagescategories ON m.id = messagescategories.id;' - Functionally equivalent to JOIN with 'WHERE' Clause
b. 'select * FROM messages AS m INNER JOIN messagescategories USING (id);' - Same as above but suppresses duplicate (id) column
c. 'select m.id, m.date, category FROM messages AS m INNER JOIN messagescategories USING (id);'
4. LEFT JOINs
Features: Matches (id) from left table and includes only (id) from right table that match
a. 'select * from messages as m LEFT JOIN messagescategories on m.id = messagescategories.id;'
b. 'select * from messages as m LEFT JOIN messagescategories USING (id);' - Same as above but suppresses duplicate (id) column
c. 'select m.id,m.date,messagescategories.category from messages as m LEFT JOIN messagescategories USING (id);' - Same as above but suppresses duplicate (id) column
5. RIGHT JOINs
Features: Matches (id) from right table and includes ONLY (id) from left table that match
a. 'select * from messages as m RIGHT JOIN messagescategories on m.id = messagescategories.id;'
b. 'select * from messages as m RIGHT JOIN messagescategories USING (id);'
c. Insert a new category into table: 'messagescategories'
c1. 'INSERT INTO messagescategories VALUES (101, 'UNKNOWN'); '
Note: Foreign Key Constraint prohibits the creation of values in: 'messagescategories' that DO NOT exist in table: 'messages'
d. 'select m.id,m.date,messagescategories.category from messages as m RIGHT JOIN messagescategories USING (id);' - Same as above but suppresses duplicate (id) column
e. 'select m.id,m.date,messagescategories.category from messages as m INNER JOIN messagescategories USING (id) ORDER BY category;' - Same as above but suppresses duplicate (id) column and orders by 'category' ASC
###VIEWS###
Features:
1. Presents consolidated query-driven interfaces to data
2. They may be based on 1 or more tables
3. Not a real objects; rather, query is executed upon invocation
4. Supports temporary VIEWS - lasts for session duration
5. Column names are auto-derived from the query
Tasks:
1. Define VIEW based on INNER JOIN of: 'messages' & 'messagescategories'
a. 'CREATE VIEW messagesandcategories AS SELECT * FROM messages INNER JOIN messagescategories USING (id); ' - creates permanent view of inner-joined tables
b. 'SELECT * FROM messagesandcategories;' - executes the VIEW
2. Insert Records to both: 'messages' & 'messagescategories' & re-query VIEW
a. 'INSERT INTO messagescategories VALUES(4, 'KERNEL'); '
3. Use Aliases
a. 'SELECT id AS i, date AS d, category AS c FROM messagesandcategories ORDER BY id;'
4. Update VIEW
a. 'CREATE OR REPLACE VIEW messagesandcategories AS SELECT id AS i, date AS d, category AS c FROM messages INNER JOIN messagescategories USING (id);' - Creates or Updates VIEW
b. 'CREATE OR REPLACE VIEW messagesandcategories (i,d,c)AS SELECT id, date, category FROM messages INNER JOIN messagescategories USING (id); '
5. Create TEMP VIEW
a. 'CREATE TEMP view messagesandalerts (i,d,a) AS SELECT id,date,alert FROM messages INNER JOIN messagesalerts USING(id);'
Note: TEMP VIEWs are not assigned to the default: 'public' schema
Note: TEMP VIEWs are NOT available to other sessions
6. Create TEMP VIEW based on a single table
a. 'CREATE TEMP view messagesdates AS SELECT date FROM messages; '
###Aggregates###
Features:
1. Compute single results (scalars) from multiple inputs (rows)
2. Values are computed after 'WHERE' has selected rows to analyze
a. Consequently, aggregates may not be used within: 'WHERE" clause
b. However, aggregates CAN be used with: 'HAVING' clause
3. 'HAVING' is calculated post-aggregate computation(s)
Examples:
1. 'SELECT count(*) FROM messages;' - counts rows
a. 'SELECT count(date) FROM messages;' - counts rows as well
2. 'SELECT sum(id) FROM messages;' - Adds values from each row
3. 'SELECT avg(id) FROM messages;' - Averages values across ALL rows
4. 'SELECT min(id) FROM messages;' - Finds min value across ALL rows
5. 'SELECT max(id) FROM messages;' - Finds max value across ALL rows
Note: 'min' and 'max' work with both numeric and date types
6. 'SELECT min(id), max(id), avg(id), count(id) FROM messages;' - queries multiple aggregates simultaneously
Examples with WHERE, GROUP BY & HAVING
7. 'SELECT date, min(id) FROM messages GROUP BY date;' - groups 'min(id)' by 'date'
Note: When referencing non-aggregated and aggregated columns in the same query, use the 'GROUP BY' clause to sort aggregated data by non-aggregated data
8. 'SELECT date, min(id) FROM messages WHERE id < 51 GROUP BY date;' - restricts aggregate 'min(id)' to rows containing (id) < 51
9. 'SELECT date, min(id) FROM messages WHERE id < 51 GROUP BY date HAVING min(id) < 30;' - Post-aggregate, restricts returned results to (id) < 30
10. 'SELECT date, min(id), max(id) FROM messages WHERE id < 51 AND id > 40 GROUP BY date;' - Extract between 40>(id)<51
Boolean Aggregates:
1. 'ALTER TABLE messages ADD enabled boolean NOT NULL DEFAULT false;' - extends table to include a boolean column: 'enabled'
2. 'SELECT bool_and(enabled) FROM messages;' - returns TRUE if ALL are true
3. 'SELECT bool_or(enabled) FROM messages;' - returns TRUE if 1 or more are true
String Aggregates:
1. 'ALTER TABLE messages ADD message text NOT NULL DEFAULT 'syslog message';'
2. 'SELECT string_agg(message, ' ') FROM messages;' - concatenates string(text) values with single-space delimiter
###UPDATE###
Features:
1. Updates table(s) based on criteri(on|a)
2. Requires: name of table, column(s) to update, criteri(on|a) (WHERE) clause
3. Updates table and sub-tables unless: 'ONLY' keyword is used
4. Output indicates number of records updated
5. WILL UPDATE ALL RECORDS if missing CRITERI(on|a)
Examples:
1. 'UPDATE messages SET enabled='t' WHERE id = 100;' - updates 1 record to true
2. 'UPDATE messages SET enabled='t' WHERE enabled = 'f'; updates many records to false
3. 'UPDATE messages SET enabled='f' WHERE id >= 50;' - updates record with (id) >= 50 to false
4. 'UPDATE messages SET enabled='1' WHERE id >=50;' - updates records with (id) >= 50 to true
5. 'UPDATE messages SET enabled=0, message = 'new message' WHERE id = 100;' - updates multiple columns WHERE id = 100;
6. 'UPDATE messages SET enabled = DEFAULT;' - resets column 'enabled' to default value for ALL rows
7. 'select * from messages where message <> 'syslog message';' - checks for rows where column 'message' IS NOT 'syslog message'
8. 'UPDATE messages SET message = DEFAULT WHERE id = 100;'
9. 'UPDATE messages SET message = DEFAULT RETURNING * WHERE id = 100;' - returns ALL columns
Note: 'RETURNING' - is PostgreSQL-specific
Note: It is equivalent to running a post-UPDATE SELECT query
10. 'UPDATE messages SET id = id+1 WHERE id = 102;' - increments (id) by 1
11. 'UPDATE messages SET id = id+1 WHERE id = 100 RETURNING *;' - ERROR because of duplicate
12. 'UPDATE messages SET id = id+1 WHERE id = 101 RETURNING *;' - ERROR because of foreign key constraint
13. 'UPDATE messages set date = 'now' RETURNING *;'
###DELETE###
Features:
1. Removes entire records based on criteri(a|on)
2. Does NOT remove individual column(s)
3. Requires: name of table, and preferably criteri(a|on) (WHERE) clause
4. Deletes recursively: Use 'ONLY' to avoid deleting child tables
5. Returns number of (count) records deleted
Examples:
1. 'DELETE FROM messages WHERE id = 103;' - removes a single record IF EXISTS
2. 'DELETE FROM messages WHERE date = '2010-10-18' AND enabled = 'f' AND id >= 50;' - removes records with (id) >=50
Note: Fails because of foreign key constraint
3. 'DELETE FROM messages WHERE date = '2010-10-18' AND enabled = 'f' AND id >= 50 AND id < 101;' - removes records with (id) >=50
a. 'SELECT count(*), min(id), max(id) FROM messages;'
4. 'DELETE FROM messages WHERE id >= 40 AND id <= 50 RETURNING *;'
5. 'DELETE FROM messages WHERE enabled = '1' RETURNING *;' - Boolean criterion
Note: Foreign Key constraint prohibits the entire transaction
6. 'DELETE FROM messages WHERE enabled = '1' AND id >= 30 AND id !=101 RETURNING *;'
7. 'DELETE FROM MESSAGES;' - deletes ALL rows and rows of sub-tables recursively
a. 'DROP CONSTRAINT IF EXISTS messagescategories_id_fkey;' - remove constraint from dependent table
8. Reconstitute 'messages' table to include auto-generating 'SERIAL' type on (id) column and re-populate with data
a. 'ALTER TABLE messages drop id CASCADE;' - drops column with CASCADE
b. 'ALTER TABLE messages add id serial;' - creates auto-sequence generator
c. 'for i in `seq 10000`; do echo `date +%F`; done > messages.date.10k' - generate 10k records
d. 'COPY messages (date) FROM '$PATH_TO/messages.date.10k';
e. 'SELECT COUNT(*) FROM messages;'
###INDICES###
Features:
1. Speed data retrieval & writes (INSERT, UPDATE, DELETE)
2. Indexes reference data locations, explicitly, for indexed columns, consequent reducing data retrieval time
3. Without indices, SQL performs sequential table scans in search of data
4. Create on columns that are frequently queried and/or JOINed
5. Caveat: During creation, ONLY reads are permitted to table being indexed
6. Max of 32 columns per index - multicolumn
7. PostgreSQL auto-maintains indices
Tasks:
1. 'EXPLAIN select * from messages;' - explains (does not execute) plan to execute query
2. 'EXPLAIN select * from messages where id = 4000;'
3. Drop & Recreate messages table
a. 'DROP TABLE messages;'
b. 'CREATE TABLE messages (date date, id SERIAL);'
c. 'ALTER TABLE messages ADD primary key (id);' - generate btree index on: (id)
4. Create an index on a column
a. 'ALTER TABLE messages ADD messageid type numeric NOT NULL;'
b. 'CREATE INDEX messages_id ON messages(messageid);'
c. 'explain ANALYZE select messageid, date from messages where messageid = 5990;' - 'ANALYZE' causes query to execute, suppressing the output, returning useful statistics
5. Enumerate Indices' info
a. '\di[S+]' - enumerates ALL indices within public schema
6. Drop Index
a. 'DROP INDEX messages_id;'
###Built-In Functions###
Features:
1. Manipulate data in a variety of ways
Tasks:
1. Cover Math Functions
a. 'select abs(-5);'
b. 'select sqrt(25); || select sqrt(id) FROM messages'
c. 'select cbrt(125);'
d. 'select ceil(95.4);' - returns next highest integer
e. 'select floor(95.4);' - returns next lowest integer
f. 'select div(25,5);' - performs division - returns least integer
g. 'select log(1000);'
h. 'select power(4,3);' - raises 4 to the 3rd power
i. 'select random();' - returns random value between 0 and 1 - 10^-15
j. 'select round(35.4);' - rounds down or up
k. 'select trunc(95.456, 1);' - useful for normalizing floating point
l. 'select cos(0);' - returns 1 - other trig functions are available
2. Cover Useful String Functions
a. 'select bit_length('test bunny');' - 80-bits
b. 'select bit_length(message) FROM messages;' - 112-bits
c. 'select char_length('test bunny');' - 10 chars
d. 'select char_length(message), message FROM messages;' - 14 chars
e. 'select lower('Test Bunny');' - normalizes output to be lower case
f. 'select lower(message) FROM messages;' - normalizes output to be lower case from column
g. 'select upper(message) FROM messages;' - normalizes output to be upper case from column
h. 'select message, initcap(message) FROM messages;' - Applies CAPS to first letter of each word
i. 'select overlay('test' placing 'xx' from 2);' - string replacement
j. 'select message, overlay(message placing ' ' from 1) FROM messages;' - applies to query
k. 'select trim(both ' ' from ' LinuxCBT ');' - trims leading & trailing, not between
l. 'select substring('syslog' from 4);'
m. 'select message, substring(message from 4) FROM messages;' - applies to table
n. 'select split_part('syslog message', ' ', 2);' - returns 2nd string using space delimiter
o. 'select initcap(split_part(message, ' ', 2)) FROM messages LIMIT 10;' - nested functions
###Model: /var/log/messages###
Features:
1. Challenge of replicating a flat-file structure
Tasks:
1. Examine and model: /var/log/messages
a. Need: 'mId, mCatID, mTime (timestamp) transformation needed, mHost, mFacility, mMessage'
2. Generate 'CREATE' statement
a. 'CREATE TABLE messages (mid BIGSERIAL PRIMARY KEY, mcatid smallint NOT NULL DEFAULT 1, mtime timestamp NOT NULL DEFAULT now(), mhost text NOT NULL DEFAULT 'Unknown Host', mfacility text NULL DEFAULT NULL, mmessage text NOT NULL DEFAULT 'NO MESSAGE' ); '
3. Test 'INSERT' statement for sample record
a. 'INSERT INTO messages (mtime, mhost, mfacility, mmessage) VALUES ('Oct 17 07:53:42 2010', 'linuxcbtbuild1', 'kernel:', '[861929.262518] device eth0 left promiscuous mode)'); '
4. Write Perl script to parse: /var/log/messages and transform data to suite PostgreSQL
a. Also include logic to extract: ':' from the end of the facility name. i.e. 'kernel:' should become: 'kernel'
5. Create new log file for Bulk Import
a. './parselogs.pl /var/log/messages > messages.log.new'
6. Bulk-load messages into: PostgreSQL
a. 'COPY messages (mtime,mhost,mfacility,mmessage) FROM '/home/linuxcbt/LinuxCBT_feat._PostgreSQL_Edition/messages.log.new' DELIMITER ';'; ' - Bulk-imports contents of new syslog file
7. Create category for joins
a. 'INSERT INTO messagescategories VALUES('1', 'NOTICE'); '
Note: Sometimes you may need to select a different delimiter when parsing
8. Perform join with 'messagescategories'
a. 'SELECT mtime,mhost,mfacility,messagescategories.name, mmessage FROM messages as m INNER JOIN messagescategories ON messagescategories.cid = m.mcatid;'
b. 'SELECT mtime,mhost,mfacility,messagescategories.name, mmessage FROM messages as m INNER JOIN messagescategories ON messagescategories.cid = m.mcatid WHERE mfacility <> 'kernel';'
Note: To post-process the log files, consider using: CRON
###Integration of Perl with PostgreSQL###
Requires:
1. 'libpg-perl' - PostgreSQL module for Perl
Features:
1. DBMS connectivity to Perl applications/scripts
Tasks:
1. Install 'libpg-perl'
a. 'aptitude install libpg-perl'
2. Create sample script to connect to DB and query table
3. Integrate INSERTs into Perl Script
Note: Caveat: Bulk Copies are faster than INSERTs
a. ' $conn->exec("INSERT INTO messages (mtime,mhost,mfacility,mmessage) VALUES (\'$date2\',\'$host\',\'$facility\',\'$message\');" ); '
4. Perform Bulk Copy via script after transformations
Note: Move this section outside of loops
a. ' $conn->exec("COPY messages (mtime,mhost,mfacility,mmessage) FROM '/home/linuxcbt/LinuxCBT_feat._PostgreSQL_Edition/messages.18.log.new' DELIMITER ';';" ); '
###GRANT###
Features:
1. Assigns Priviliges:
a. SELECT - columns or tables
b. INSERT - columns or tables
c. UPDATE
d. DELETE - row-based
e. CREATE
f. CONNECT
g. EXECUTE
h. TRIGGER
i. USAGE
j. TEMPORARY
k. TRUNCATE
l. REFERENCES
2. Objects are owned by creators: owners/super-users
a. non-super users have NO access to them
3. Use: '\dp' - to reveal GRANTs on objects
Tasks:
1. Create new user 'linuxcbt3' and try to SELECT data from existing tables
'CREATE ROLE linuxcbt3 LOGIN password 'abc123'; '
Note: UPDATE & DELETE privileges require SELECT for criteri[a|on] application
2. Attempt to query tables owned by other users
a. 'SELECT * FROM messages LIMIT 10;' - Fails
3. Remedy scenario to allow user: 'linuxcbt3' to SELECT data from 'messages' table
a. 'GRANT SELECT (mid,mcatid,mtime) ON messages TO linuxcbt3;' - Column-level privileges
b. 'GRANT SELECT ON messages TO linuxcbt3; ' - Table-level privileges - supercedes column restrictions
4. Attempt to INSERT new record into: 'messages' table
a. 'INSERT INTO messages (mtime,mhost,mfacility,mmessage) VALUES ('Oct 21 10:48:46 2010','linuxcbtbuild1','test','TESTING INSERT PRIVILEGE'); '
b. 'GRANT INSERT ON messages TO linuxcbt3;' - grants INSERT on ALL columns
c. 'GRANT USAGE ON messages_mid_seq TO linuxcbt3;' - grants USAGE on sequence
Note: If using sequences, grant USAGE on sequence to user
5. Attempt to UPDATE current records in: 'messages' table
a. 'UPDATE messages SET mfacility = 'test2' WHERE mid = '204366'; '
b. 'GRANT UPDATE on messages TO linuxcbt3;'
Note: UPDATE privilege allows user to update ANY record in the table
6. Attempt to DELETE current records from: 'messages' table
a. 'DELETE FROM messages WHERE mid = '204366'; '
b. 'GRANT DELETE on messages TO linuxcbt3;'
8. Grant ALL privileges on : 'messages' table
a. 'GRANT ALL on messages TO linuxcbt3;'
###REVOKE###
Features:
1. Converse of GRANT
2. Unassigns privileges
3. Sample permission set:
linuxcbt2=arwdDxt/linuxcbt2
a = INSERT/Append
r = Read/SELECT
w = Write/UPDATE
d = DELETE
D = Truncate
x = References
t = Triggers
/linuxcbt2 = permissions delegator/issuer
Tasks:
1. 'REVOKE ALL on messages FROM linuxcbt3;' - removes ALL privileges from the user
2. 'GRANT ALL ON messages TO linuxcbt3;' - reinstate privileges
3. 'REVOKE ALL on messages,messages_mid_seq FROM linuxcbt3;' - removes ALL privileges from the user for both objects
4. Grant & Revoke: INSERT | UPDATE | DELETE
a. 'GRANT INSERT ON messages TO linuxcbt3;'
b. 'GRANT USAGE ON messages_mid_seq TO linuxcbt3;' - sequence generator access
Note: INSERT may be granted independently of SELECT, unlike: UPDATE & DELETE
c. 'REVOKE INSERT ON messages FROM linuxcbt3; REVOKE USAGE ON messages_mid_seq FROM linuxcbt3;' - Two revocations: INSERT & USAGE
d. 'GRANT UPDATE ON messages TO linuxcbt3;'
e. 'UPDATE messages SET mfacility='TEST2' WHERE mid = '204371'; ' - Fails because the user has NO SELECT privilege to execute the criteria in the UPDATE query
f. 'GRANT SELECT ON messages TO linuxcbt3;'
g. 'REVOKE ALL ON messages,messages_mid_seq FROM linuxcbt3;'
h. 'GRANT DELETE ON messages TO linuxcbt3;'
i. 'DELETE FROM messages WHERE mid = 204371; '
j. 'GRANT SELECT ON messages TO linuxcbt3;'
Test WITH GRANT OPTION
a. 'GRANT ALL on messages TO linuxcbt3 WITH GRANT OPTION;' - allows user: 'linuxcbt3' to GRANT ALL privileges on the object: 'messages' to other users
b. 'CREATE ROLE linuxcbt4 LOGIN PASSWORD 'abc123'; '
c. 'GRANT SELECT ON messages TO linuxcbt4;' - run as: 'linuxcbt3'
d. 'GRANT INSERT ON messages TO linuxcbt4;' - run as: 'linuxcbt3'
e. 'GRANT UPDATE ON messages TO linuxcbt4;' - run as: 'linuxcbt3'
f. 'GRANT DELETE ON messages TO linuxcbt4;' - run as: 'linuxcbt3'
Attempt to REVOKE PRIVILEGES FROM 'linuxcbt3' as user: 'linuxcbt2' OR super user
a. 'REVOKE ALL ON messages FROM linuxcbt3;' - Fails due to privileges depency
b. 'REVOKE ALL ON messages FROM linuxcbt3 CASCADE;' - Recursive
Note: If a permissions/privileges depency exists, use: 'CASCADE' option with 'REVOKE' command to descend the permissions/privileges hierarchy
Test direct removal of privileges from top-level to bottom
a. 'GRANT ALL on messages TO linuxcbt3 WITH GRANT OPTION;' - run as: 'linuxcbt2' or super user
b. 'GRANT SELECT,DELETE on messages TO linuxcbt4; ' - run as: 'linuxcbt3'
c. 'REVOKE ALL on messages FROM linuxcbt4; ' - run as: 'linuxcbt2' OR super user - FAILS
Note: Fails due to GRANT hierarchy
d. 'REVOKE ALL ON messages FROM linuxcbt3 CASCADE;' - Recursive
###DB Backup###
Features:
1. Individual table, DB, or full DBMS backup
2. 'pg_dump' & 'pg_dumpall'
3. Operate on running DB
4. Export SQL script or Archive (pg_dump) (used with pg_restore) formats
5. SQL Script: Designed for full replay with: 'psql' utility
6. Archive File: Designed to allow selective and/or reordered restores:
a. '-Fp) - Default - Plain SQL script output - uncompressed
b. '-Fc) - Custom, auto-compressed form - 'pg_restore'
c. '-Ft) - Tar form - not compressed - restrictions on reordering - works with: 'tar' & 'pg_restore'
Tasks:
1. Backup 'postgres' DB - Plain (-Fp) Format
a. 'pg_dump postgres' - dumps to STDOUT
b. 'pg_dump -v -f DB_Backup_postgres postgres ' - generates plain text SQL script file containing data
Note: Uses 'COPY' to reconstruct data as opposed to: 'INSERT'
c. 'pg_dump -v postgres > DB_BACKUP_postgres2' - performs as above
d. 'pg_dump -v -s -f DB_Backup.schema postgres' - dumps SCHEMA ONLY
e. 'pg_dump -v -t messages -t messagescategories -f DB_Backup.messages.cats.tables.only'
f. 'pg_dump -v -t 'messages*' -f DB_Backup_ALL_messages_tables.only' - Archives ALL items in 'postgres' DB beginning with: 'messages'
2. Backup 'postgres' DB - Compressed (-Fc) Format
a. 'pg_dump -v -Fc -f DB_Backup.postgres.compressed postgres' - creates custom, compressed file to be used with: 'pg_restore'
3. Backup 'postgres' DB - Tar (-Ft) Format
a. 'pg_dump -v -Ft -f DB_Backup.postgres.tar postgres' - creates a tarball of DB
4. Use 'pg_dumpall' to archive the entire DBMS
a. 'pg_dumpall -v -f DB_Backup.ALL'
b. Create auth file in: $HOME to obviate the need to authenticate to each DB
c. 'echo 'localhost:*:*:linuxcbt2:abc123' > ~/.pgpass && chmod 600 ~/.pgpass'
d. Re-run 'pg_dumpall' as user: 'linuxcbt2' - defined in: $HOME/.pgpass
e. 'pg_dumpall -v -U linuxcbt2 -f DB_Backup.ALL'
###DB Restore###
Features:
1. Two tools: 'psql' && 'pg_restore'
Tasks:
1. Use 'pg_restore' to restore tables, DBs, etc.
a. 'DROP table messages2, messagescategories;'
b. 'pg_restore -v -d postgres DB_Backup.postgres.compressed' - full restoration using 'compressed' file
c. 'pg_restore -v -d postgres DB_Backup.postgres.tar' - full restoration using 'tar' file
Note: Use: 'pg_restore -l backup_file' to enumerate items for selective/reordered restoration
2. Backup 'linuxcbt2' DB and restore
a. 'pg_dump -v -C -Fc -f DB_Backup.linuxcbt2.DB linuxcbt2'
b. 'DROP DATABASE linuxcbt2;'
c. 'pg_restore -v -C -d postgres DB_Backup.linuxcbt2.DB' - restores DB 'linuxcbt2'
d. 'pg_dump -v -C -f DB_Backup.linuxcbt2.DB.sql linuxcbt2'
d. 'DROP DATABASE linuxcbt2;'
e. 'psql -f DB_Backup.linuxcbt2.DB' - Fails because source file is not SQL text
3. Restore specific tables using: 'pg_restore'
a. 'DROP table messages2, messagescategories;'
b. 'pg_restore -v -d postgres -t messages2 DB_Backup.postgres.compressed' - restores 1 table
c. 'pg_restore -v -d postgres -t messagescategories DB_Backup.postgres.tar' - restores 1 table
4. Use 'psql' to restore selected backup items (tables, sequences, etc.)
a. 'DROP table messages, messagescategories;'
b. 'psql -f DB_Backup.messages.cats.tables.only'
c. 'DROP table messages, messagescategories, messages2, messagesalerts;'
d. 'psql -f DB_Backup_ALL_messages_tables.only;'
###Windows DB Restoration###
Tasks:
1. Explore Windows PostgreSQL environment
a. 'psql -h 192.168.75.105'
2. Restore data to Windows instance
a. 'psql -h 192.168.75.105 -f DB_Backup.ALL' - restores FULL DB to remote host
3. Wreak Havoc on remote DB and Restore
a. 'DROP TABLE messages, messages2, messagescategories;'
b. 'pg_restore -v -h 192.168.75.105 -d postgres -t messages2 DB_Backup.postgres.compressed' - restores 1 table
c. 'pg_restore -v -h 192.168.75.105 -d postgres -t messages DB_Backup.postgres.compressed' - restores 1 table
d. 'pg_restore -v -h 192.168.75.105 -d postgres -t messagescategories DB_Backup.postgres.tar' - restores 1 table
e. 'DROP TABLE messages, messagescategories, messages2, messagesalerts;'
f. 'psql -h 192.168.75.105 -f DB_Backup_ALL_messages_tables.only;'
Note: Ensure that remote system's HBA conf file accepts remote connections
###Installation on RedHat Enterprise Linux###
Features:
1. PostgreSQL support
2. Ability to use the same binary used on the other distributions
Tasks:
1. Copied binary from remote system to local RedHat system
2. Executed it
3. Confirm availability: 'ps -ef | grep -i postgres'
4. Connect and confirm default environment
5. Update ~linuxcbt $PATH & $PGUSER vars
6. Source if necessary for active TTY
a. '. ~/.bash_profile'
7. Mirror contents of remote server
a. Get 'DB_Backup.ALL' - use 'sftp'
b. Populate RedHat instance of PostgreSQL with data from Debian box
b1. 'psql -f DB_Backup.ALL'
8. Remove tables and restore across the wire using: 'psql'
a. Update HBA conf to allow network connectivity
b. Restart 'postgres' to effect 'pg_hba.conf' change
c. Restore items using: 'psql' from remote host
c1. 'psql -U postgres -f DB_Backup.ALL postgres -h 192.168.75.20' - replays script on
remote, RedHat Enterprise box
###SSH Tunnels###
Features:
1. Secure communications from point-to-point
2. Encryption services
3. Wrapper of communications
4. Traffic is protected in transit, NOT at the endpoints
5. Defaults to protecting loopback adapter address(es)
Tasks:
1. Sniff PostgreSQL communications using: 'tcpdump'
a. 'tcpdump -w postgres.dump.1 -v -i lo tcp port 5432'
b. 'psql -h localhost'
c. 'wireshark postgres.dump.1' - reveals sensitive data
2. Apply SSH tunnels from Linux
a. 'ssh -L 5433:192.168.75.20:5432 192.168.75.20' - creates a tunnel between:
linuxcbtbuild1 (.101) -> linuxcbtserv1 (.20)
b. 'netstat -ntl | grep 5433' - confirms existence of tunnel
c. 'psql -h localhost -p 5433' - initiate connection
d. 'ssh -L 5433:192.168.75.101:5432 192.168.75.101' - creates a tunnel between:
linuxcbtbuild1 (.101) -> linuxcbtserv1 (.20)
e. 'psql -h 127.0.0.1 -p 5433' - initiate connection
3. Apply SSH tunnel from Windows
a. Ensure that PuTTY or equivalent SSH client is installed
b. Setup session to forward TCP:5433 & TCP:5434 to TCP:5432 on Debian and RedHat boxes
c. Test 'psql' client access across the tunnel from Windows
Note: This will not work with Windows as the target SSH server sans Cygwin or compatible SSH service
###SSL Connections###
Features:
1. True end-to-end encryption protection - 100%
2. Listens to same, clear-text port: TCP:5432
3. Auto-negotiates with client connection type unless server config (pg_hba.conf) enforce
Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:15 2010#linuxcbtbuild1#kernel#[963722.044003] arpalert[4845]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:20 2010#linuxcbtbuild1#kernel#[963727.050042] arpalert[4847]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:20 2010#linuxcbtbuild1#kernel#[963727.050042] arpalert[4847]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:20 2010#linuxcbtbuild1#kernel#[963727.050042] arpalert[4847]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:20 2010#linuxcbtbuild1#kernel#[963727.050042] arpalert[4847]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:20 2010#linuxcbtbuild1#kernel#[963727.050042] arpalert[4847]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:20 2010#linuxcbtbuild1#kernel#[963727.050042] arpalert[4847]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:20 2010#linuxcbtbuild1#kernel#[963727.050042] arpalert[4847]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:20 2010#linuxcbtbuild1#kernel#[963727.050042] arpalert[4847]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:20 2010#linuxcbtbuild1#kernel#[963727.050042] arpalert[4847]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:20 2010#linuxcbtbuild1#kernel#[963727.050042] arpalert[4847]: segfault at 126 ip b76b04cb sp bfd23c44 error 4 in libc-2.7.so[b763a000+155000]
Oct 18 12:10:20 2010#linuxcbtbuild1#kernel#[963727.050042] arpales type
4. Supports server (default) & client certificates
5. 'openssl version -d' - reveals config directory for OpenSSL
Requires:
1. Server keypair: 'server.crt' (public) & 'server.key" (private) in: DATA directory
2. 'server.key' - MUST be flagged 600
3. Optionally, 'root.crt' & 'root.crl'
4. 'ssl=on' - enabled via: 'postgresql.conf'
Tasks:
1. Generate Server Keypair
a. 'openssl req -new -text -out server.req' - Generates a request
b. 'openssl rsa -in privkey.pem -out server.key' - removes passphrase
c. 'rm privkey.pem' - because we now have an RSA version in: 'server.key'
d. 'openssl req -x509 -in server.req -text -key server.key -out server.crt' - generates self-signed certificate (.crt) file
e. 'chown postgres server.key && chmod 600 server.key'
2. Configure PostgreSQL
a. 'ssl=on' - postgresql.conf
b. Restart postgresql
Note: Test inability to restart postgres when 'server.key' is not readable
3. Test connectivity
a. 'psql -U postgres -h localhost' - SSL was used because TCP/IP was used
Note: SSL is not enabled when using Unix Domain Sockets
b. 'psql -h 192.168.75.101' - SSL was used...
c. 'psql ' - SSL was NOT used due to Unix Domain Sockets usage
d. Connect to RedHat host and test connectivity
4. Sniff SSL session with TCPDump
5. Test from Windows
a. 'psql -h 192.168.75.101' - It works with SSL...
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