From: Csaba Nagy <nagy@ecircle-ag.com>
To: Joost Kraaijeveld <J.Kraaijeveld@Askesis.nl>
Cc: Pgsql-Performance <pgsql-performance@postgresql.org>
Subject: Re: Can this query go faster???
Date: Tue, 06 Dec 2005 10:52:57 +0100
Message-ID: <1133862777.4779.185.camel@coppola.muc.ecircle.de> (raw)
In-Reply-To: <1133862229.8837.61.camel@Panoramix>
References: <1133862229.8837.61.camel@Panoramix>
Joost,
Why do you use an offset here ? I guess you're traversing the table
somehow, in this case it would be better to remember the last zipcode +
housenumber and put an additional condition to get the next bigger than
the last one you've got... that would go for the index on
zipcode+housenumber and be very fast. The big offset forces postgres to
traverse that many entries until it's able to pick the one row for the
result...
On Tue, 2005-12-06 at 10:43, Joost Kraaijeveld wrote:
> Hi,
>
> Is it possible to get this query run faster than it does now, by adding
> indexes, changing the query?
>
> SELECT customers.objectid FROM prototype.customers, prototype.addresses
> WHERE
> customers.contactaddress = addresses.objectid
> ORDER BY zipCode asc, housenumber asc
> LIMIT 1 OFFSET 283745
>
> Explain:
>
> Limit (cost=90956.71..90956.71 rows=1 width=55)
> -> Sort (cost=90247.34..91169.63 rows=368915 width=55)
> Sort Key: addresses.zipcode, addresses.housenumber
> -> Hash Join (cost=14598.44..56135.75 rows=368915 width=55)
> Hash Cond: ("outer".contactaddress = "inner".objectid)
> -> Seq Scan on customers (cost=0.00..31392.15
> rows=368915 width=80)
> -> Hash (cost=13675.15..13675.15 rows=369315 width=55)
> -> Seq Scan on addresses (cost=0.00..13675.15
> rows=369315 width=55)
>
> The customers table has an index on contactaddress and objectid.
> The addresses table has an index on zipcode+housenumber and objectid.
>
> TIA
>
> --
> Groeten,
>
> Joost Kraaijeveld
> Askesis B.V.
> Molukkenstraat 14
> 6524NB Nijmegen
> tel: 024-3888063 / 06-51855277
> fax: 024-3608416
> e-mail: J.Kraaijeveld@Askesis.nl
> web: www.askesis.nl
>
>
>
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>
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To: pgsql-performance@postgresql.org
Cc: nagy@ecircle-ag.com, J.Kraaijeveld@Askesis.nl
Subject: Re: Can this query go faster???
In-Reply-To: <1133862777.4779.185.camel@coppola.muc.ecircle.de>
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