From: Tom Lane <tgl@sss.pgh.pa.us>
To: arnaulist@andromeiberica.com
Cc: PostgreSQL Performance <pgsql-performance@postgresql.org>
Subject: Re: Performace comparison of indexes over timestamp fields
Date: Tue, 22 May 2007 10:11:28 -0400
Message-ID: <12213.1179843088@sss.pgh.pa.us> (raw)
In-Reply-To: <4652C846.4020801@andromeiberica.com>
References: <4652C846.4020801@andromeiberica.com>
Arnau <arnaulist@andromeiberica.com> writes:
> As you can see the time difference are very big
> Timestamp: 318.328 ms
> int8 index: 120.804 ms
> double precision: 57.065 ms
As already suggested elsewhere, you probably weren't sufficiently
careful in taking your measurements.
A look at the code says that int8 comparison ought to be the fastest
of these. If timestamps are implemented as floats (which you didn't
say) their comparison speed ought to be *exactly* the same as floats,
because the comparison functions are line-for-line the same. If
timestamps are implemented as int8 then they should be similar to
int8 comparisons, maybe a tad slower due to an extra level of function
call. But in any case it seems likely that the actual comparison
function calls would be just a small fraction of the runtime.
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, arnaulist@andromeiberica.com
Subject: Re: Performace comparison of indexes over timestamp fields
In-Reply-To: <12213.1179843088@sss.pgh.pa.us>
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