From: Rob Sargent <robjsargent@gmail.com>
To: wkipjohn@gmail.com
Cc: pgsql-sql@postgresql.org
Subject: Re: SQL report
Date: Thu, 30 Jul 2009 09:16:35 -0600
Message-ID: <4A71B953.4070208@gmail.com> (raw)
In-Reply-To: <0016e64f68205aab0d046fe35882@google.com>
References: <0016e64f68205aab0d046fe35882@google.com>
I would be curious to know the performance curve for let's say 20K, 40K
, 60K, 80K, 100K records. And what sort of indexing you have, whether
or not it's clustered, re-built and so on.
One could envision partitioning the status table such that recent
records were grouped together (on the assumption that they will be most
frequently "reported").
wkipjohn@gmail.com wrote:
> I have the following senario.
>
> I have a tracking system. The system will record the status of an
> object regularly, all the status records are stored in one table. And
> it will keep a history of maximum 1000 status record for each object
> it tracks. The maximum objects the system will track is 100,000. Which
> means I will potentially have a table size of 100 million records.
>
> I have to generate a report on the latest status of all objects being
> tracked at a particular point in time, and also I have to allow user
> to sort and filter on different columes in the status record displayed
> in the report.
>
> The following is a brief description in the status record (they are
> not actual code)
>
> ObjectRecord(
> objectId bigint PrimaryKey
> desc varchar
> )
>
> StatusRecord (
> id bigint PrimaryKey
> objectId bigint indexed
> datetime bigint indexed
> capacity double
> reliability double
> efficiency double
> )
>
> I have tried to do the following, it works very well with around
> 20,000 objects. (The query return in less than 10s) But when I have
> 100,000 objects it becomes very very slow. (I don't even have patience
> to wait for it to return.... I kill it after 30 mins)
>
> select * from statusrecord s1 INNER JOIN ( SELECT objectId ,
> MAX(datetime) AS msdt FROM statusrecord WHERE startDatetime <=
> 1233897527657 GROUP BY objectId ) AS s2 ON ( s1.objectId = s2.objectId
> AND s1.datetime = s2.msdt ) where ( capacity < 10.0 ) order by
> s1.datetime DESC, s1.objectId DESC;
>
> I did try to write a store procedure like below, for 100,000 objects
> and 1000 status records / object, it returns in around 30 mins.
>
> CREATE OR REPLACE FUNCTION getStatus(pitvalue BIGINT) RETURNS SETOF
> statusrecord AS $BODY$
> DECLARE
> id VARCHAR;
> status statusrecord%ROWTYPE;
> BEGIN
> FOR object IN SELECT * FROM objectRecord
> LOOP
> EXECUTE 'SELECT * FROM statusrecord WHERE objectId = ' ||
> quote_literal(object.objectId) ||
> ' AND datetime <= ' || quote_literal(pitvalue) || ' ORDER BY datetime
> DESC'
> INTO status;
> IF FOUND THEN
> RETURN NEXT status;
> END IF;
> END LOOP;
> RETURN;
> END
> $BODY$ LANGUAGE plpgsql;
>
> Just wanna to know if anyone have a different approach to my senario.
> Thanks alot.
>
> John
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To: pgsql-sql@postgresql.org
Cc: robjsargent@gmail.com, wkipjohn@gmail.com
Subject: Re: SQL report
In-Reply-To: <4A71B953.4070208@gmail.com>
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