Re: ANALYZE'ing table hierarchies

Hi,Nunks

I have a test just now,as follows:
Hope to help you!

music=> create table music(id int,name text,style text);
CREATE TABLE
music=> create table rock (check(style = 'rock')) inherits(music);
CREATE TABLE
music=> create table pop (check(style = 'pop')) inherits(music);
CREATE TABLE
music=> create table classic (check(style = 'classic')) inherits(music);
CREATE TABLE
music=> create table jazz (check(style = 'jazz')) inherits(music);
CREATE TABLE

music=> \dS+ music
Table "eric.music"
Column | Type | Modifiers | Storage | Stats target | Description
--------+---------+-----------+----------+--------------+-------------
id | integer | | plain | |
name | text | | extended | |
style | text | | extended | |
Child tables: classic,
jazz,
pop,
rock

music=> create index music_pop_id on pop (id);
CREATE INDEX
music=> create index music_rock_id on rock (id);
CREATE INDEX
music=> create index music_jazz_id on jazz (id);
CREATE INDEX
music=> create index music_classic_id on classic (id);
CREATE INDEX

music=> CREATE OR REPLACE FUNCTION music_insert_trigger()
music-> RETURNS TRIGGER AS
music-> $$
music$> BEGIN
music$> IF (NEW.style = 'rock') THEN
music$> INSERT INTO rock VALUES (NEW.*);
music$> ELSEIF (NEW.style = 'pop') THEN
music$> INSERT INTO pop VALUES (NEW.*);
music$> ELSEIF (NEW.style = 'pop') THEN
music$> INSERT INTO pop VALUES (NEW.*);
music$> ELSEIF (NEW.style = 'jazz') THEN
music$> INSERT INTO jazz VALUES (NEW.*);
music$> ELSEIF (NEW.style = 'classic') THEN
music$> INSERT INTO classic VALUES (NEW.*);
music$> END IF;
music$> RETURN NULL;
music$> END;
music$> $$
music-> LANGUAGE plpgsql ;
CREATE FUNCTION

music=> CREATE TRIGGER insert_music_trigger
music-> BEFORE INSERT ON music
music-> FOR EACH row EXECUTE PROCEDURE music_insert_trigger() ;
CREATE TRIGGER

music=> insert into music values(2,'Have a Nice Day','pop');
INSERT 0 0
music=> insert into music values(1,'21 Gun','rock');
INSERT 0 0

music=> select * from music;
id | name | style
----+-----------------+-------
1 | 21 Gun | rock
2 | Have a Nice Day | pop
(2 rows)

music=> select * from pop
music-> ;
id | name | style
----+-----------------+-------
2 | Have a Nice Day | pop
(1 row)

music=> select * from rock;
id | name | style
----+--------+-------
1 | 21 Gun | rock
(1 row)

music=> analyze verbose music
music-> ;
INFO: analyzing "eric.music"
INFO: "music": scanned 0 of 0 pages, containing 0 live rows and 0 dead rows; 0 rows in sample, 0 estimated total rows
INFO: analyzing "eric.music" inheritance tree
INFO: "rock": scanned 1 of 1 pages, containing 1 live rows and 0 dead rows; 1 rows in sample, 1 estimated total rows
INFO: "pop": scanned 1 of 1 pages, containing 1 live rows and 0 dead rows; 1 rows in sample, 1 estimated total rows
ANALYZE

music=> select relname, last_analyze from pg_stat_user_tables where relname = 'music';
relname | last_analyze
---------+-------------------------------
music | 2016-02-18 22:29:56.528758-08
(1 row)

music=> select relname, last_analyze from pg_stat_user_tables where relname = 'pop';
relname | last_analyze
---------+--------------
pop |
(1 row)

music=> select relname, last_analyze from pg_stat_user_tables where relname = 'rock';
relname | last_analyze
---------+--------------
rock |
(1 row)

music=> analyze verbose pop;
INFO: analyzing "eric.pop"
INFO: "pop": scanned 1 of 1 pages, containing 1 live rows and 0 dead rows; 1 rows in sample, 1 estimated total rows
ANALYZE
music=> select relname, last_analyze from pg_stat_user_tables where relname = 'rock';
relname | last_analyze
---------+--------------
rock |
(1 row)

music=> select relname, last_analyze from pg_stat_user_tables where relname = 'pop';
relname | last_analyze
---------+-------------------------------
pop | 2016-02-18 22:31:55.666556-08
(1 row)

music=> analyze verbose rock;
INFO: analyzing "eric.rock"
INFO: "rock": scanned 1 of 1 pages, containing 1 live rows and 0 dead rows; 1 rows in sample, 1 estimated total rows
ANALYZE
music=> select relname, last_analyze from pg_stat_user_tables where relname = 'rock';
relname | last_analyze
---------+-------------------------------
rock | 2016-02-18 22:34:16.526558-08
(1 row)

gaoqiangdba(at)163(dot)com

From: nunks
Date: 2016-02-19 10:02
To: pgsql-admin
Subject: [ADMIN] ANALYZE'ing table hierarchies
Hello,

I have a question about running ANALYZE on table hierarchies.

The documentation page for partitioning mentions the need to manually issue VACUUM and ANALYZEs for each partition (http://www.postgresql.org/docs/9.4/static/ddl-partitioning.html#DDL-PARTITIONING-CAVEATS) while the page for ANALYZE (http://www.postgresql.org/docs/9.4/static/sql-analyze.html) mentions it does gather statistics for the master table and its children.

When I ANALYZE a master table PostgreSQL says it is working on the entire hierarchy and automatically ANALYZEs the child tables. However, the last_analyze column stays empty for the child tables on pg_stat_user_tables.

I find this somewhat confusing, what is the expected behavior? I figure the child tables have been properly ANALYZEd, but I can't find it registered anywhere. It would be nice to be able to parse pg_stat_user_tables for analyze statistics without having to worry about hierarchies, since each partition seems to have its own statistics for everything else.

nunks=# analyze verbose tb05;
INFO: analyzing "public.tb05"
INFO: "tb05": scanned 0 of 0 pages, containing 0 live rows and 0 dead rows; 0 rows in sample, 0 estimated total rows
INFO: analyzing "public.tb05" inheritance tree
INFO: "tb05_2016": scanned 165 of 165 pages, containing 7465 live rows and 455 dead rows; 7465 rows in sample, 7465 estimated total rows
INFO: "tb05_2015": scanned 381 of 381 pages, containing 16281 live rows and 1504 dead rows; 16281 rows in sample, 16281 estimated total rows
ANALYZE

nunks=# select relname, last_analyze from pg_stat_user_tables where relname like 'tb05%';
relname | last_analyze
-----------+-------------------------------
tb05 | 2016-02-18 22:47:32.770076-02
tb05_2016 |
tb05_2015 |
(3 rows)

nunks=# \d+ tb05;
Table "public.tb05"
Column | Type | Modifiers | Storage | Stats target | Description
---------------------+-----------------------------+-----------+----------+--------------+-------------
a | character varying(8) | not null | extended | |
b | date | not null | plain | |
c | timestamp without time zone | not null | plain | |
d | timestamp without time zone | not null | plain | |
e | bigint | not null | plain | |
f | bigint | not null | plain | |
g | bigint | not null | plain | |
h | bigint | not null | plain | |
i | bigint | not null | plain | |
j | bigint | not null | plain | |
k | bigint | not null | plain | |
l | bigint | not null | plain | |
m | bigint | not null | plain | |
n | bigint | not null | plain | |
o | bigint | not null | plain | |
p | bigint | not null | plain | |
q | bigint | not null | plain | |
r | bigint | not null | plain | |
Indexes:
"tb05_pkey" PRIMARY KEY, btree (a, b)
Triggers:
tr_partition_tb05 BEFORE INSERT ON tb05 FOR EACH ROW EXECUTE PROCEDURE fn_partition_tb05()
Child tables: tb05_2015,
tb05_2016

Thanks!

Nunks