From: PFC <lists@peufeu.com>
To: Carlos Henrique Reimer <carlosreimer@yahoo.com.br>
To: Andre Felipe Machado <andremachado@techforce.com.br>
To: pgsql-performance@postgresql.org
Subject: Re: firebird X postgresql 8.1.2 windows, performance comparison
Date: Thu, 09 Mar 2006 13:05:07 +0100
Message-ID: <op.s55ait13cigqcu@apollo13> (raw)
In-Reply-To: <20060309104131.27381.qmail@web53209.mail.yahoo.com>
References: <20060309104131.27381.qmail@web53209.mail.yahoo.com>
> I hope tomorrow execute explain with the bitmapscan and seqscan enabled.
> bitmapscans are almost always faster?
Like all the rest, they're just a tool, which works great when used in
its intended purpose :
- Fetching just a few percent of the rows from a table is better served
by an index scan
- Fetching a lot of rows (>30-50%) from a table is better served by a seq
scan
- Bitmap scan comes in between and it's a very welcome addition.
Also Bitmap scan will save your life if you have complex searches, like
if you run a dating site and have an index on blondes and an index on boob
size, because it can use several indexes in complex AND/OR queries.
Common wisdom says simpler databases can be faster than postgres on
simple queries.
Reality check with pg 8.1 driven by PHP :
- SELECT 1
mysql 5 ~ 42 us
postgres ~ 70 us
- SELECT * FROM users WHERE id=1
mysql 5 ~ 180 us
postgres ~ 160 us
Of course people doing stupid things, like using the database to keep a
hit counter on their website which is updated on every hit, will say that
postgres is slow.
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To: pgsql-performance@postgresql.org
Cc: lists@peufeu.com, carlosreimer@yahoo.com.br, andremachado@techforce.com.br
Subject: Re: firebird X postgresql 8.1.2 windows, performance comparison
In-Reply-To: <op.s55ait13cigqcu@apollo13>
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