Re: SQL report

Hi Rob,

I have default B-Tree indexes created for each of the indexed columes and
primary key columes. (No multiple columes indexe or NULL FIRST or
DESC/ASC). I am using PostgreSQL 8.3 with the auto vacuum daemon on. I
assume analyse will be automatically run to collect statistics for use by
the planner and there is no maintainance for B-tree indexes once it is
created. (Please point me out if I am wrong about this)

I will probably try to partition the status table to group more recent
status records together to minimize the dataset I am querying.

Thx
John

On Jul 31, 2009 1:16am, Rob Sargent <robjsargent(at)gmail(dot)com> wrote:
> 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(at)gmail(dot)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

> 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
> 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