| From: | Robert Haas <robertmhaas(at)gmail(dot)com> | 
|---|---|
| To: | Vlad Arkhipov <arhipov(at)dc(dot)baikal(dot)ru> | 
| Cc: | Cédric Villemain <cedric(dot)villemain(dot)debian(at)gmail(dot)com>, pgsql-performance(at)postgresql(dot)org | 
| Subject: | Re: Optimization idea | 
| Date: | 2010-04-29 03:17:25 | 
| Message-ID: | AANLkTikqfvY_tCJbxg_lE0ccqvxecKmowpId5_YF3zog@mail.gmail.com | 
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| Lists: | pgsql-performance | 
On Wed, Apr 28, 2010 at 5:37 AM, Vlad Arkhipov <arhipov(at)dc(dot)baikal(dot)ru> wrote:
> Even if it will be done it does not solve the original issue. If I
> understood you right there is now no any decent way of speeding up the query
>
> select *
> from t2
> join t1 on t1.t = t2.t
> where t1.id = X;
>
> except of the propagating the t1.id value to the table t2 and createing and
> index for this column?
No, what I'm saying is that if X is any ANY() expression, you can get
a faster plan in this case by writing:
SELECT * FROM t2 JOIN t1 ON t1.t = t2.t WHERE t2.id = X;
For me this is about 8x faster.
...Robert
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