araqnid

create temp table t1(t1_id serial primary key, reference varchar(16) not null unique, value varchar(16) not null);
copy t1(reference, value) from stdin;
FOO	foo
BAR	bar
QUUX	quux
\.

create temp view t1_combined as
    select t1_id, reference, value, ctid, lp_flags, lp_off, case when t_ctid <> ctid then t_ctid end as t_ctid,
           t_xmin, xmin_visible, case when t_xmax::text <> '0' then t_xmax end as t_xmax, xmax_visible,

jboner

Latency Comparison Numbers (~2012)
----------------------------------
L1 cache reference                           0.5 ns
Branch mispredict                            5   ns
L2 cache reference                           7   ns                      14x L1 cache
Mutex lock/unlock                           25   ns
Main memory reference                      100   ns                      20x L2 cache, 200x L1 cache
Compress 1K bytes with Zippy             3,000   ns        3 us
Send 1K bytes over 1 Gbps network       10,000   ns       10 us
Read 4K randomly from SSD*             150,000   ns      150 us          ~1GB/sec SSD

MohamedAlaa

tmux shortcuts & cheatsheet

start new:

tmux

start new with session name:

tmux new -s myname

brendangregg

So I just found ZFS on my test Linux ubuntu system, and gave my perf-tools (https://github.com/brendangregg/perf-tools) a spin.

Per-second zfs* calls:

# ./funccount -Ti 1 'zfs*'
Tracing "zfs*"... Ctrl-C to end.

Tue Aug  5 00:51:41 UTC 2014
FUNC                              COUNT

wenzhixin

# install openjdk
sudo apt-get install openjdk-7-jdk

# download android sdk
wget http://dl.google.com/android/android-sdk_r24.2-linux.tgz

tar -xvf android-sdk_r24.2-linux.tgz
cd android-sdk-linux/tools

# install all sdk packages

johanndt

TL;DR

Install Postgres 9.5, and then:

sudo pg_dropcluster 9.5 main --stop
sudo pg_upgradecluster 9.3 main
sudo pg_dropcluster 9.3 main

bastman

Docker - How to cleanup (unused) resources

Once in a while, you may need to cleanup resources (containers, volumes, images, networks) ...

delete volumes

// see: https://github.com/chadoe/docker-cleanup-volumes

$ docker volume rm $(docker volume ls -qf dangling=true)

$ docker volume ls -qf dangling=true | xargs -r docker volume rm

akorotkov

#!/usr/bin/env python
# -*- coding: utf-8 -*-
# Draw psql output as iTerm2 v3 inline graph using matplotlib
# Author: Alexander Korotkov <a.korotkov@postgrespro.ru>

import sys
import re
import warnings
import matplotlib
matplotlib.use("Agg")

NikolayS

-- Installs "file_fdw" extension and creates foreign table to work with data from CSV file.
-- See also the comment below which helps to automate the process for Google Spreadsheets
-- Another option would be using Multicorn for Google Spreadsheets, but it requires additional steps  
-- (see https://wiki.postgresql.org/wiki/Foreign_data_wrappers).

create extension file_fdw;
create server "import" foreign data wrapper file_fdw;

create foreign table "table1" (
  col1 text,

delameko

TL;DR

Install Postgres 9.6, and then:

sudo pg_dropcluster 9.6 main --stop
sudo pg_upgradecluster 9.5 main
sudo pg_dropcluster 9.5 main