Обсуждение: JDBC Performance

I am having some performance problems with postgresql and JDBC when it
comes to updates.  If I try and update a record it seems to be taking 1.7
seconds for 100 records or 14 seconds for 500 records.  An insert is only
taking between 3-5 ms/record.  Performance on the updates continue to
decrease until I vacuum analyze the database again.  Is this normal?

Mike

Doesn't sound normal! Can you post the schema for the table you are
updating

 pg_dump -s -t tablename dbname

One thing you can try if you are doing bulk updates is to drop the index
before the update, and create it again afterwards

Dave

-----Original Message-----
From: pgsql-jdbc-owner@postgresql.org
[mailto:pgsql-jdbc-owner@postgresql.org] On Behalf Of mike@mwcs.mb.ca
Sent: July 31, 2001 4:01 PM
To: pgsql-jdbc@postgresql.org
Subject: [JDBC] JDBC Performance



I am having some performance problems with postgresql and JDBC when it
comes to updates.  If I try and update a record it seems to be taking
1.7 seconds for 100 records or 14 seconds for 500 records.  An insert is
only taking between 3-5 ms/record.  Performance on the updates continue
to decrease until I vacuum analyze the database again.  Is this normal?

Mike



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This is typical.  Until you do a vacuum the old versions of a row are
still in the db, so an update has to do an index query on an index to
get to the row that needs indexing, which returns a lot of pointers to
old entries, that then have to be tranversed until the valid one in
found.  Then the update makes one more invalid row.

mike@mwcs.mb.ca wrote:
> I am having some performance problems with postgresql and JDBC when it
> comes to updates.  If I try and update a record it seems to be taking 1.7
> seconds for 100 records or 14 seconds for 500 records.  An insert is only
> taking between 3-5 ms/record.  Performance on the updates continue to
> decrease until I vacuum analyze the database again.  Is this normal?
>
> Mike
>
>
>

>


--
Joseph Shraibman
jks@selectacast.net
Increase signal to noise ratio.  http://www.targabot.com