postgresql 查看索引是否有效及索引使用情况

查看索引是否有效

1.未使用索引前

jinbo=# explain analyze select * from jinbo.student where score < 80 and score < 90 and sex = 1;QUERY PLAN
----------------------------------------------------------------------------------------------------Seq Scan on student  (cost=0.00..220.45 rows=4 width=23) (actual time=0.030..2.195 rows=1 loops=1)Filter: ((score < 80) AND (score < 90) AND (sex = 1))Rows Removed by Filter: 11453Planning time: 0.119 msExecution time: 2.217 ms
(5 rows)

使用索引后

jinbo=# create index on jinbo.student(score, sex);
CREATE INDEX
jinbo=# explain analyze select * from jinbo.student where score < 80 and score < 90 and sex = 1;QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------Bitmap Heap Scan on student  (cost=4.40..10.54 rows=2 width=23) (actual time=0.063..0.064 rows=1 loops=1)Recheck Cond: ((score < 80) AND (score < 90) AND (sex = 1))Heap Blocks: exact=1->  Bitmap Index Scan on student_score_sex_idx  (cost=0.00..4.40 rows=2 width=0) (actual time=0.058..0.058 rows=1 loops=1)Index Cond: ((score < 80) AND (score < 90) AND (sex = 1))Planning time: 0.398 msExecution time: 0.093 ms
(7 rows)

查看索引使用情况

查看索引使用的统计情况的表：

pg_stat_user_indexes

jinbo=# \d+ pg_stat_user_indexes;View "pg_catalog.pg_stat_user_indexes"Column     |  Type  | Collation | Nullable | Default | Storage | Description
---------------+--------+-----------+----------+---------+---------+-------------relid         | oid    |           |          |         | plain   | indexrelid    | oid    |           |          |         | plain   | schemaname    | name   |           |          |         | plain   | relname       | name   |           |          |         | plain   | indexrelname  | name   |           |          |         | plain   | idx_scan      | bigint |           |          |         | plain   | idx_tup_read  | bigint |           |          |         | plain   | idx_tup_fetch | bigint |           |          |         | plain   |
View definition:SELECT pg_stat_all_indexes.relid,pg_stat_all_indexes.indexrelid,pg_stat_all_indexes.schemaname,pg_stat_all_indexes.relname,pg_stat_all_indexes.indexrelname,pg_stat_all_indexes.idx_scan,pg_stat_all_indexes.idx_tup_read,pg_stat_all_indexes.idx_tup_fetchFROM pg_stat_all_indexesWHERE (pg_stat_all_indexes.schemaname <> ALL (ARRAY['pg_catalog'::name, 'information_schema'::name])) AND pg_stat_all_indexes.schemaname !~ '^pg_toast'::text;

pg_stat_all_indexes

jinbo=# \d+ pg_stat_all_indexes View "pg_catalog.pg_stat_all_indexes"Column     |  Type  | Collation | Nullable | Default | Storage | Description
---------------+--------+-----------+----------+---------+---------+-------------relid         | oid    |           |          |         | plain   | indexrelid    | oid    |           |          |         | plain   | schemaname    | name   |           |          |         | plain   | relname       | name   |           |          |         | plain   | indexrelname  | name   |           |          |         | plain   | idx_scan      | bigint |           |          |         | plain   | idx_tup_read  | bigint |           |          |         | plain   | idx_tup_fetch | bigint |           |          |         | plain   |
View definition:SELECT c.oid AS relid,i.oid AS indexrelid,n.nspname AS schemaname,c.relname,i.relname AS indexrelname,pg_stat_get_numscans(i.oid) AS idx_scan,pg_stat_get_tuples_returned(i.oid) AS idx_tup_read,pg_stat_get_tuples_fetched(i.oid) AS idx_tup_fetchFROM pg_class cJOIN pg_index x ON c.oid = x.indrelidJOIN pg_class i ON i.oid = x.indexrelidLEFT JOIN pg_namespace n ON n.oid = c.relnamespaceWHERE c.relkind = ANY (ARRAY['r'::"char", 't'::"char", 'm'::"char"]);

查看使用记录

    jinbo=# select * from pg_stat_all_indexes where schemaname = 'jinbo' and relname = 'student';relid  | indexrelid | schemaname | relname |     indexrelname      | idx_scan | idx_tup_read | idx_tup_fetch --------+------------+------------+---------+-----------------------+----------+--------------+---------------111451 |     228633 | jinbo      | student | student_score_sex_idx |        3 |            3 |             2//---------------------------------------------------分割线---------------------------------------------jinbo=# select * from pg_stat_user_indexes where schemaname = 'jinbo' and relname = 'student';relid  | indexrelid | schemaname | relname |     indexrelname      | idx_scan | idx_tup_read | idx_tup_fetch
--------+------------+------------+---------+-----------------------+----------+--------------+---------------111451 |     228633 | jinbo      | student | student_score_sex_idx |        3 |            3 |             2
(1 row)

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postgresql 查看索引是否有效及索引使用情况

查看索引是否有效

1.未使用索引前

使用索引后

查看索引使用情况

查看索引使用的统计情况的表：

查看使用记录

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