From: Rural Hunter <ruralhunter@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-performance@postgresql.org
Subject: Re: how to change the index chosen in plan?
Date: Fri, 08 Jun 2012 22:23:12 +0800
Message-ID: <4FD20AD0.3040902@gmail.com> (raw)
In-Reply-To: <11881.1339164658@sss.pgh.pa.us>
References: <4FD1FF14.9060303@gmail.com>
<11881.1339164658@sss.pgh.pa.us>
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@gmail.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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To: pgsql-performance@postgresql.org
Cc: ruralhunter@gmail.com, tgl@sss.pgh.pa.us
Subject: Re: how to change the index chosen in plan?
In-Reply-To: <4FD20AD0.3040902@gmail.com>
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