Hi all:
I am new in pgsql, I am even new in using mailing list. I send this email
just to give a suggestion on performance.
I found that if primary key or a colume which has an unique index, is in a
select sql，the distinct sometimes is Unnecessary.
Actually, the SQL with DISTINCT will runs more sl
On 5 November 2017 at 04:20, 刘瑞 wrote:
> CREATE TABLE test_tbl ( k INT PRIMARY KEY, col text)
> INSERT into test_tbl select generate_series(1,1000), 'test';
>
> SQL with DISTINCT:
> test=# explain analyze select distinct col, k from test_tbl order by k limit
> 1000;
>
