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Re: slow join on postgresql6.5

From: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
To: Hiroshi Inoue <Inoue(at)tpf(dot)co(dot)jp>
Cc: Don Baccus <dhogaza(at)pacifier(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Wenjin Zheng <wenjin(dot)zheng(at)lsbc(dot)com>, pgsql-hackers(at)postgresql(dot)org
Subject: Re: slow join on postgresql6.5
Date: 2000-04-02 16:36:58
Message-ID: 200004021636.MAA04853@candle.pha.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
> > >As for NULL,it seems possible to look up NULL keys in a btree index
> > >because NULL == NULL for btree indexes.
> > >I've wondered why PostgreSQL's planner/executor never looks up
> > >indexes for queries using 'IS NULL'.
> >
> > Unfortunately for the RI MATCH PARTIAL case, NULL is a "wildcard".
> >
> 
> Oops I misunderstood NULL.
> 
> Hmm,is the following TODO worth the work ?
> * Use index to restrict rows returned by multi-key index when used with
>   non-consecutive keys or OR clauses, so fewer heap accesses.

This is a Vadim item.


-- 
  Bruce Momjian                        |  http://www.op.net/~candle
  pgman(at)candle(dot)pha(dot)pa(dot)us               |  (610) 853-3000
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  +  Christ can be your backup.        |  Drexel Hill, Pennsylvania 19026

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