作者
digoal
日期
2021-01-17
标签
PostgreSQL , psql , 自定义统计信息 , dX
背景
PostgreSQL 14 psql客户端支持dX快捷命令, 展示自定义统计信息的内容.
https://git.postgresql.org/gitweb/?p=postgresql.git;a=commit;h=891a1d0bca262ca78564e0fea1eaa5ae544ea5ee
```
psql \dX: list extended statistics objects
The new command lists extended statistics objects, possibly with their
sizes. All past releases with extended statistics are supported.
Author: Tatsuro Yamada
Reviewed-by: Julien Rouhaud, Alvaro Herrera, Tomas Vondra
Discussion: https://postgr.es/m/c027a541-5856-75a5-0868-341301e1624b%40nttcom.co.jp_1
```
+-- Check printing info about extended statistics by \dX
+create table stts_t1 (a int, b int);
+create statistics stts_1 (ndistinct) on a, b from stts_t1;
+create statistics stts_2 (ndistinct, dependencies) on a, b from stts_t1;
+create statistics stts_3 (ndistinct, dependencies, mcv) on a, b from stts_t1;
+create table stts_t2 (a int, b int, c int);
+create statistics stts_4 on b, c from stts_t2;
+create table stts_t3 (col1 int, col2 int, col3 int);
+create statistics stts_hoge on col1, col2, col3 from stts_t3;
+create schema stts_s1;
+create schema stts_s2;
+create statistics stts_s1.stts_foo on col1, col2 from stts_t3;
+create statistics stts_s2.stts_yama (dependencies, mcv) on col1, col3 from stts_t3;
+insert into stts_t1 select i,i from generate_series(1,100) i;
+analyze stts_t1;
+\dX
+ List of extended statistics
+ Schema | Name | Definition | Ndistinct | Dependencies | MCV
+----------+------------------------+--------------------------------------+-----------+--------------+-----------
+ public | func_deps_stat | a, b, c FROM functional_dependencies | | built |
+ public | mcv_lists_arrays_stats | a, b, c FROM mcv_lists_arrays | | | built
+ public | mcv_lists_bool_stats | a, b, c FROM mcv_lists_bool | | | built
+ public | mcv_lists_stats | a, b, d FROM mcv_lists | | | built
+ public | stts_1 | a, b FROM stts_t1 | built | |
+ public | stts_2 | a, b FROM stts_t1 | built | built |
+ public | stts_3 | a, b FROM stts_t1 | built | built | built
+ public | stts_4 | b, c FROM stts_t2 | requested | requested | requested
+ public | stts_hoge | col1, col2, col3 FROM stts_t3 | requested | requested | requested
+ stts_s1 | stts_foo | col1, col2 FROM stts_t3 | requested | requested | requested
+ stts_s2 | stts_yama | col1, col3 FROM stts_t3 | | requested | requested
+ tststats | priv_test_stats | a, b FROM tststats.priv_test_tbl | | | built
+(12 rows)
+
+\dX stts_?
+ List of extended statistics
+ Schema | Name | Definition | Ndistinct | Dependencies | MCV
+--------+--------+-------------------+-----------+--------------+-----------
+ public | stts_1 | a, b FROM stts_t1 | built | |
+ public | stts_2 | a, b FROM stts_t1 | built | built |
+ public | stts_3 | a, b FROM stts_t1 | built | built | built
+ public | stts_4 | b, c FROM stts_t2 | requested | requested | requested
+(4 rows)
+
+\dX *stts_hoge
+ List of extended statistics
+ Schema | Name | Definition | Ndistinct | Dependencies | MCV
+--------+-----------+-------------------------------+-----------+--------------+-----------
+ public | stts_hoge | col1, col2, col3 FROM stts_t3 | requested | requested | requested
+(1 row)
+
+\dX+
+ List of extended statistics
+ Schema | Name | Definition | Ndistinct | Dependencies | MCV | Ndistinct_size | Dependencies_size | MCV_size
+----------+------------------------+--------------------------------------+-----------+--------------+-----------+----------------+-------------------+------------
+ public | func_deps_stat | a, b, c FROM functional_dependencies | | built | | | 106 bytes |
+ public | mcv_lists_arrays_stats | a, b, c FROM mcv_lists_arrays | | | built | | | 24 kB
+ public | mcv_lists_bool_stats | a, b, c FROM mcv_lists_bool | | | built | | | 386 bytes
+ public | mcv_lists_stats | a, b, d FROM mcv_lists | | | built | | | 294 bytes
+ public | stts_1 | a, b FROM stts_t1 | built | | | 13 bytes | |
+ public | stts_2 | a, b FROM stts_t1 | built | built | | 13 bytes | 40 bytes |
+ public | stts_3 | a, b FROM stts_t1 | built | built | built | 13 bytes | 40 bytes | 6126 bytes
+ public | stts_4 | b, c FROM stts_t2 | requested | requested | requested | 0 bytes | 0 bytes | 0 bytes
+ public | stts_hoge | col1, col2, col3 FROM stts_t3 | requested | requested | requested | 0 bytes | 0 bytes | 0 bytes
+ stts_s1 | stts_foo | col1, col2 FROM stts_t3 | requested | requested | requested | 0 bytes | 0 bytes | 0 bytes
+ stts_s2 | stts_yama | col1, col3 FROM stts_t3 | | requested | requested | | 0 bytes | 0 bytes
+ tststats | priv_test_stats | a, b FROM tststats.priv_test_tbl | | | built | | | 686 bytes
+(12 rows)
+
+\dX+ stts_?
+ List of extended statistics
+ Schema | Name | Definition | Ndistinct | Dependencies | MCV | Ndistinct_size | Dependencies_size | MCV_size
+--------+--------+-------------------+-----------+--------------+-----------+----------------+-------------------+------------
+ public | stts_1 | a, b FROM stts_t1 | built | | | 13 bytes | |
+ public | stts_2 | a, b FROM stts_t1 | built | built | | 13 bytes | 40 bytes |
+ public | stts_3 | a, b FROM stts_t1 | built | built | built | 13 bytes | 40 bytes | 6126 bytes
+ public | stts_4 | b, c FROM stts_t2 | requested | requested | requested | 0 bytes | 0 bytes | 0 bytes
+(4 rows)
+
+\dX+ *stts_hoge
+ List of extended statistics
+ Schema | Name | Definition | Ndistinct | Dependencies | MCV | Ndistinct_size | Dependencies_size | MCV_size
+--------+-----------+-------------------------------+-----------+--------------+-----------+----------------+-------------------+----------
+ public | stts_hoge | col1, col2, col3 FROM stts_t3 | requested | requested | requested | 0 bytes | 0 bytes | 0 bytes
+(1 row)
+
+\dX+ stts_s2.stts_yama
+ List of extended statistics
+ Schema | Name | Definition | Ndistinct | Dependencies | MCV | Ndistinct_size | Dependencies_size | MCV_size
+---------+-----------+-------------------------+-----------+--------------+-----------+----------------+-------------------+----------
+ stts_s2 | stts_yama | col1, col3 FROM stts_t3 | | requested | requested | | 0 bytes | 0 bytes
+(1 row)
+
+drop table stts_t1, stts_t2, stts_t3;
+drop schema stts_s1, stts_s2 cascade;
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