| From: | Rural Hunter <ruralhunter(at)gmail(dot)com> |
|---|---|
| To: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
| Cc: | pgsql-performance(at)postgresql(dot)org |
| Subject: | Re: how to change the index chosen in plan? |
| Date: | 2012-06-08 14:23:12 |
| Message-ID: | 4FD20AD0.3040902@gmail.com |
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| Lists: | pgsql-performance |
No, it's not the analyze problem. For some other values on b.bid such
as 9, 10, the plan is fine since there a a lot of rows in table b for
them. But for some specific values such as 8 I want the plan changed.
于2012年6月8日 22:10:58,Tom Lane写到:
> Rural Hunter <ruralhunter(at)gmail(dot)com> writes:
>> I have a query like this:
>> select a.* from a inner join b on a.aid=b.aid where a.col1=33 a.col2=44
>> and b.bid=8
>> postgresql selected the index on a.col1 then selected the index on
>> b.bid. But in my situation, I know that the query will be faster if it
>> chose the index on b.bid first since there are only a few rows with
>> value 8.
>
> If you know that and the planner doesn't, maybe ANALYZE is called for.
>
> regards, tom lane
>
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