我们注意到性能读数严重下降 MS Windows 10计算机上的PostgreSQL 12中的pg_Catalog.pg_settings表与早期版本的比较。

explain (analyze, buffers, timing)
SELECT * from pg_catalog.pg_settings where name =
'standard_conforming_strings';

在PostgreSQL 12.5上，由Visual C++Build 1914编译，64位：

Function Scan on pg_show_all_settings a  (cost=0.00..12.50 rows=5
width=485) (actual time=343.350..343.356 rows=1 loops=1)
  Filter: (name = 'standard_conforming_strings'::text)
  Rows Removed by Filter: 313
Planning Time: 0.079 ms
Execution Time: 343.397 ms

对比PostgreSQL 11.13，由Visual C++Build 1914编译，64位：

Function Scan on pg_show_all_settings a  (cost=0.00..12.50 rows=5
width=485) (actual time=0.723..0.728 rows=1 loops=1)
  Filter: (name = 'standard_conforming_strings'::text)
  Rows Removed by Filter: 289
Planning Time: 0.125 ms
Execution Time: 0.796 ms

这是标准安装，更改的参数为：