Re: 'Index Full Scan' for Index Scan without Index Cond

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Simon Riggs <simon(at)2ndquadrant(dot)com>
Cc: ITAGAKI Takahiro <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp>, pgsql-patches(at)postgresql(dot)org
Subject: Re: 'Index Full Scan' for Index Scan without Index Cond
Date: 2006-06-06 15:26:49
Message-ID: 17609.1149607609@sss.pgh.pa.us
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Simon Riggs <simon(at)2ndquadrant(dot)com> writes:
> On Tue, 2006-06-06 at 10:31 -0400, Tom Lane wrote:
>> This discussion is also overlooking
>> the possibility that a partial index is being used for its predicate

> Assuming its possible, of course.

Sure:

regression=# create index tenk1p on tenk1(unique1) where unique2 % 100 = 0;
CREATE INDEX
regression=# explain select * from tenk1 where unique2 % 100 = 0;
QUERY PLAN
----------------------------------------------------------------------
Bitmap Heap Scan on tenk1 (cost=2.10..139.14 rows=50 width=244)
Recheck Cond: ((unique2 % 100) = 0)
-> Bitmap Index Scan on tenk1p (cost=0.00..2.10 rows=50 width=0)
(3 rows)

regards, tom lane

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