From: Alex Hunsaker <badalex@gmail.com>
To: Kenneth Marshall <ktm@rice.edu>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Xiao Meng <mx.cogito@gmail.com>
Cc: Zdenek Kotala <Zdenek.Kotala@sun.com>
Cc: pgsql-patches@postgresql.org, "Jonah H. Harris" <jonah.harris@gmail.com>
Subject: Re: hash index improving v3
Date: Tue, 9 Sep 2008 19:23:03 -0600
Message-ID: <34d269d40809091823t204e252fl246443be71aed9ff@mail.gmail.com> (raw)
In-Reply-To: <20080909134839.GC6714@it.is.rice.edu>
References: <10995.1220577198@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>
<34d269d40809052249h59750f83v4b19a50d0555580@mail.gmail.com>
<22574.1220728178@sss.pgh.pa.us>
<34d269d40809061923k4c731481gf580d46d259defb0@mail.gmail.com>
<20080909134839.GC6714@it.is.rice.edu>
On Tue, Sep 9, 2008 at 7:48 AM, Kenneth Marshall <ktm@rice.edu> wrote:
> I think that the glacial speed for generating a big hash index is
> the same problem that the original code faced.
Yeah sorry, I was not saying it was a new problem with the patch. Err
at least not trying to :) *Both* of them had been running at 18+ (I
finally killed them sometime Sunday or around +32 hours...)
> It would be useful to have an equivalent test for the hash-only
> index without the modified int8 hash function, since that would
> be more representative of its performance. The collision rates
> that I was observing in my tests of the old and new mix() functions
> was about 2 * (1/10000) of what you test generated. You could just
> test against the integers between 1 and 2000000.
Sure but then its pretty much just a general test of patch vs no
patch. i.e. How do we measure how much longer collisions take when
the new patch makes things faster? That's what I was trying to
measure... Though I apologize I don't think that was clearly stated
anywhere...
Now of course it still would be interesting... And if its only to
2,000,000 I can still use the modified int8 or just use the int4
one...
Anyway Here are the numbers:
create table test_hash(num int8);
insert into test_hash (num) select generate_series(1, 2000000);
create index test_hash_num_idx on test_hash (num);
pgbench -c1 -n -t10000 -f bench_index.sql
cvs head: tps = 3161.500511
v5: tps = 7248.808839
BTW Im still planning on doing a wide vs narrow test... sometime... :)
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To: pgsql-patches@postgresql.org
Cc: badalex@gmail.com, ktm@rice.edu, tgl@sss.pgh.pa.us, mx.cogito@gmail.com, Zdenek.Kotala@sun.com, jonah.harris@gmail.com
Subject: Re: hash index improving v3
In-Reply-To: <34d269d40809091823t204e252fl246443be71aed9ff@mail.gmail.com>
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