| SET search_path=query_test; | |
| DROP SCHEMA IF EXISTS query_test CASCADE; | |
| CREATE SCHEMA query_test; | |
| CREATE TABLE campaigns ( | |
| id int PRIMARY KEY, | |
| campaign_plan_id int | |
| ); | |
| INSERT INTO campaigns VALUES |
| SELECT version(); | |
| version | |
| ---------------------------------------------------------------------------------------------------------------------------------- | |
| PostgreSQL 11.5 (Debian 11.5-1.pgdg90+1) on x86_64-pc-linux-gnu, compiled by gcc (Debian 6.3.0-18+deb9u1) 6.3.0 20170516, 64-bit | |
| (1 row) | |
| -- Why is this returning true? | |
| -- I think { and [ are considered to sort equally on this machine's `en_US` collation, | |
| -- so the result is the same as `'{' < '{a'` | |
| SELECT '{' < '[a' COLLATE "en_US"; |
| SHOW LC_COLLATE; | |
| lc_collate | |
| ------------- | |
| en_US.UTF-8 | |
| (1 row) | |
| EXPLAIN ANALYZE | |
| SELECT g::text FROM generate_series(1, 10000) g ORDER BY 1; | |
| QUERY PLAN | |
| ------------------------------------------------------------------------------------------------------------------------------- |
| package main | |
| import "fmt" | |
| func main() { | |
| f1 := &Foo{} | |
| f2 := &Foo{} | |
| fmt.Printf("%p = %p\n", f1, f2) | |
| b1 := &Bar{} |
| package main | |
| import ( | |
| "bufio" | |
| "fmt" | |
| "io" | |
| "log" | |
| "net" | |
| "os" | |
| "sync" |
| encoded_in = "\x00\x00\x00\x03aaa\x00\x00\x00\x06Binary\x02\x00\x00\x00\fP\x00\x84A\xEB\xF9~?\x966\xE7\x8A\x00\x00\x00\x03ccc\x00\x00\x00\x06String\x01\x00\x00\x00\x04test\x00\x00\x00\x03zzz\x00\x00\x00\x06Number\x01\x00\x00\x00\a0230.01\x00\x00\x00\x10\xC3\xB6ther_encodings\x00\x00\x00\x06String\x01\x00\x00\x00\x05T\xC3\xBCst" | |
| class EncodedMessage | |
| attr_accessor :data | |
| attr_accessor :md5 | |
| def initialize(data, md5) | |
| @data = [data].pack('a*') | |
| @md5 = md5 | |
| # TODO(fg) verify md5 |
| * | |
| !**/*.go |
| psql (9.6.3, server 10.1) | |
| WARNING: psql major version 9.6, server major version 10. | |
| Some psql features might not work. | |
| Type "help" for help. | |
| postgres=# CREATE FUNCTION date_round(base_date timestamptz, round_interval INTERVAL) RETURNS timestamptz AS $BODY$ | |
| postgres$# SELECT TO_TIMESTAMP((EXTRACT(epoch FROM $1)::INTEGER + EXTRACT(epoch FROM $2)::INTEGER / 2) | |
| postgres$# / EXTRACT(epoch FROM $2)::INTEGER * EXTRACT(epoch FROM $2)::INTEGER) | |
| postgres$# $BODY$ LANGUAGE SQL STABLE; | |
| CREATE FUNCTION |
See http://randyzwitch.com/mapd-pjm-electricity-data/ for the data and pythons
script to create hourly_loads.csv (146MB) and
https://news.ycombinator.com/item?id=16458105 for discussion.
CREATE TABLE hourly_loads (
actual_date date,
zone_name text,
See my HN comment on the post The 3-minute SQL indexing quiz: Can you spot the five most common mistakes? . Do you agree that my answer ("Not enough information: Definite answer cannot be given") is correct? See proof in psql.txt below.
This question is different. First consider the following index and query:
CREATE INDEX tbl_idx ON tbl (a, date_column)
SELECT date_column, count(*)
FROM tbl