PostgreSQL Analyze分区表：主表与子表的统计信息问题-白红宇

1b656da9bc569039118355cd5b300d0b14f8960d

最近在PostgreSQL的Mail List中参与讨论了一个问题： ANALYZE'ing table hierarchies。

网友认为在Analyze分区表的时候，只能看到主表的analyze日期更新到最新，但是子表的日期没有变化，他认为analyze应该是在分析主表的时候会将与之相关的子表一起更新。

为此测试了一下，发现无论主表还是子表，需要单独的对其进行analyze才可以更新其最新的统计信息。

以下是实验部分：

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"

--------+---------+-----------+----------+--------------+-------------

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;

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 ;

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)