pg pg_prewarm用法

按照插件

> create extension pg_prewarm ;

缓存表

> test=# select pg_prewarm('weather','buffer' ) ;  pg_prewarm
> ------------
>           1

缓存表部分内容

test=# select pg_prewarm('weather','buffer','main',0,0) ;
 pg_prewarm
------------
          1
(1 row)

表大小只有0号页，只能缓存这么大

缓存索引

test=# \d+ weather
                                                  Table "public.weather"
  Column   |         Type          | Collation | Nullable | Default | Storage  | Compression | Stats target | Description
-----------+-----------------------+-----------+----------+---------+----------+-------------+--------------+-------------
 city      | character varying(80) |           |          |         | extended |             |              |
 temp_low  | integer               |           |          |         | plain    |             |              |
 temp_high | integer               |           |          |         | plain    |             |              |
 prcp      | real                  |           |          |         | plain    |             |              |
 date      | date                  |           |          |         | plain    |             |              |
Indexes:
    "idx_city" btree (city)
Access method: heap

test=# select pg_prewarm('idx_city','buffer' ) ;
 pg_prewarm
------------
          2

影响：