From: Premsun Choltanwanich <Premsun@nsasia.co.th>
To: pgsql-sql@postgresql.org
Subject: Slow Query problem
Date: Mon, 28 Jan 2008 14:18:24 +0700
Message-ID: <479DE418.C5F7.004C.0@nsasia.co.th> (raw)
Dear All,
I am currently using PostgreSQL database version 8.0.13. My problem relates to a slow result when a query using a defined view joins to another table for a result.
Background: I have 7 tables of invoice transactions. The tables are slightly different in that they record different data (some different columns in each table). There are about 250,000 records when a union view is created. A simply query on this union performs satisfactorily.
The invoice table union view is then joined with a table of receipts (which have a total of about 150,000 records).
It takes around 3.5 seconds for "select * from view_transaction where member_id = 999 and receipt_no is null" (which returns unpaid invoices).
By hard coding I created a single table from the 7 invoice tables (instead of creating a union) and then used it with receipt table. This time for the same query improved to 1.8 seconds.
To further improve things I tried to code the selection rather than to use a view, and so "select * from temp_transaction where member_id = 999 and receipt_no is null" provided the result in .5 second. (2 records returned containing the details of receipt_no, transaction_no, transaction_type, transaction_amount, member_id).
I would prefer to be able to have completed the above by using unions and views. Is it possible to do this, or am I better creating a permanent table of invoices and writing the query as I did above?
Any comments on this and suggestions would be appreciated. If there is documentation where I can read up please let me have a link.
Thank You,
Premsun
NETsolutions Asia Limited
+66 (2) 237 7247
http://www.nsasia.co.thAttachments:IMAGE.jpg (image/jpg, 6.3K) downloadview image
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To: pgsql-sql@postgresql.org
Cc: Premsun@nsasia.co.th
Subject: Re: Slow Query problem
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