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From: Zdenek Kotala <Zdenek.Kotala@Sun.COM>
To: Alex Hunsaker <badalex@gmail.com>
Cc: Xiao Meng <mx.cogito@gmail.com>
Cc: pgsql-patches@postgresql.org, "Jonah H. Harris" <jonah.harris@gmail.com>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Subject: Re: hash index improving v3
Date: Mon, 08 Sep 2008 10:58:09 +0200
Message-ID: <48C4E921.20606@sun.com> (raw)
In-Reply-To: <34d269d40809051321w2ed16037od0373a4a29c311f1@mail.gmail.com>
References: <ded849dd0808171846g2c6c65adub942bd2510a6c94f@mail.gmail.com>
	<29987.1220560114@sss.pgh.pa.us>
	<7627.1220569888@sss.pgh.pa.us>
	<34d269d40809041742r6a0703dbgfbdd012f7f19de2e@mail.gmail.com>
	<10995.1220577198@sss.pgh.pa.us>
	<11525.1220579153@sss.pgh.pa.us>
	<34d269d40809041854g355a8f68ga3a037a69e3d9fcb@mail.gmail.com>
	<11962.1220581027@sss.pgh.pa.us>
	<34d269d40809042048m3b532a5ej7a9588f63a788d0c@mail.gmail.com>
	<34d269d40809050912u33f2afc8mb90e316bc465136e@mail.gmail.com>
	<34d269d40809051321w2ed16037od0373a4a29c311f1@mail.gmail.com>

It is nice test case. It should be part of hash index regression test.

	Zdenek


Alex Hunsaker napsal(a):
> Ok now that I made it so it actually *test* collisions, with the patch
> it always returns all rows that matched the hashed "key".  For example
> (non lobotomized inthash8, I just brute forced some collisions for 0
> so that anyone can try this)
> 
> create table test_hash (num int8);
> insert into test_hash (num) values (0), (1805671691), (3294821164),
> (4294967297);
> create index test_hash_num_idx on test_hash using hash (num);
> select * from test_hash where num = 0;
>     num
> ------------
>           0
>  1805671691
>  3294821164
>  4294967297
> 
> set enable_bitmapscan to off;
> 
> select * from test_hash where num = 0;
>  num
> -----
>    0
> 
> CVS HEAD, 8_3_STABLE obviously work if I force the index scan


-- 
Zdenek Kotala              Sun Microsystems
Prague, Czech Republic     http://sun.com/postgresql




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