Message-ID: <484FAA8A.6040406@cybertec.at>
Date: Wed, 11 Jun 2008 12:35:54 +0200
From: Zoltan Boszormenyi <zb@cybertec.at>
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To: tv@fuzzy.cz
CC: PostgreSQL Performance <pgsql-performance@postgresql.org>,
	Hans-Juergen Schoenig <hs@cybertec.at>
Subject: Re: Scalability question
References: <484FA134.7030807@cybertec.at>
	<13093.217.77.161.17.1213179341.squirrel@sq.gransy.com>
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tv@fuzzy.cz írta:
>> Hi,
>>
>> I got a question about scalability in high volume insert situation
>> where the table has a primary key and several non-unique indexes
>> on other columns of the table. How does PostgreSQL behave
>> in terms of scalability? The high volume of inserts comes from
>> multiple transactions.
>>
>> Best regards,
>> Zoltán Böszörményi
>>     
>
> Well, that's a difficult question as it depends on hardware and software,
> but with a proper tunning the results may be very good. Just do the basic
> PostgreSQL tuning and then tune it for the INSERT performance if needed.
> It's difficult to give any other recommendations without a more detailed
> knowledge of the problem, but consider these hints:
>
> 1) move the pg_xlog to a separate drive (so it's linear)
> 2) move the table with large amount of inserts to a separate tablespace
> 3) minimize the amount of indexes etc.
>
> The basic rule is that each index adds some overhead to the insert, but it
> depends on datatype, etc. Just prepare some data to import, and run the
> insert with and without the indexes and compare the time.
>
> Tomas
>   

Thanks. The question is more about theoretical working.
E.g. if INSERTs add "similar" records with identical index records
(they are non-unique indexes) does it cause contention? Because
these similar records add index tuples that supposed to be near
to each other in the btree.

-- 
----------------------------------
Zoltán Böszörményi
Cybertec Schönig & Schönig GmbH
http://www.postgresql.at/