From: | Paul Tomblin <ptomblin(at)xcski(dot)com> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: Ok, why isn't it using *this* index? |
Date: | 2001-04-01 20:10:29 |
Message-ID: | 20010401161029.B26334@allhats.xcski.com |
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Lists: | pgsql-general |
Quoting ADBAAMD (adba(dot)amdocs(at)bell(dot)ca):
> Paul Tomblin wrote:
> > I have a table with columns 'country' and 'state'. I put indexes on both
> > of them. I've done the "vacuum analyze" as per the faq. But when I ask
> > it to explain, it says it will use the index on 'state' if I do a
> > select * from waypoint where state = 'ON';
> > but it won't use the index on 'country' if I do a
> > select * from waypoint where country = 'CANADA';
>
> Maybe it's just my Oracle side, but doesn't country has a too low
> selectivity?
If I try
explain select * from waypoint where country = 'BELIZE';
a query that will only select one record out of the 8300-odd, it still
doesn't use the index.
Seq Scan on waypoint (cost=455.13 rows=6813 width=130)
--
Paul Tomblin <ptomblin(at)xcski(dot)com>, not speaking for anybody
Mommy, what does "Formatting Drive C:" mean?
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