Hi Eric,
Ferrer, Eric wrote:
Thanks for the reply, Can the OJB developers reply with their thoughts
on this.
I would have figured the load by persistence object calls we make and we
do them when we only want 1 record a lot would do the same job as the
SQL select statement.
For a while I thought maybe our driver was an issue.
This may be major for us since we auto generate a lot of our OR mapping
using Velocity so as to not expose the data model. From what you just
told me we have to analyze table growth and convert our Persistence Load
Query to SQL calls.
First, I'm not a sql/database expert and only do marginal work on the
query-engine of OJB - so please bear with me ;-)
I think it would be possible to add support for l"imiting row numbers"
in OJB 1.0.x branch. As far as I know to "limit the number of rows
returned" is not SQL standard and depends on the DB vendor:
DB2: select * from table fetch first 5 rows only
MySQL and PostgreSQL: select * from table limit 5
Oracle: select * from table rownum <= 5
SQL Server: select top 5 * from table
Here is my train of thoughts:
I don't know if we can use method Query.set(Start/End)AtIndex(...) to
add "row limit" support. Maybe we have to add a new method
Query.setRowLimit(...).
Before a Query object is executed in OJB method query.preprocess(broker)
is called. With the PB instance we can access the Platform class were we
have to locate the different "row limit" information.
Now the "only thing" to do is to integrate the limit expression string
in the query string. Think we can add the "limit expression string"
while the query string is created in SqlSelectStatement#buildSqlString().
What do you think?
regards,
Armin
-Eric
-----Original Message-----
From: Janssen, Roger [mailto:[EMAIL PROTECTED]
Sent: Friday, February 02, 2007 1:29 AM
To: OJB Users List
Subject: RE: Performance Issue on lookup on a table
Hi,
We have the same problem. This is because OJB does not (yet?) implement
paging based on RDBMS native paging/limiting syntax. A query, hitting
the complete resultset is executed and cursors are used to fetch the
requested page. Large resultsets, will take a lot of time.
We have been experiencing more and more problems over the last few years
with this.
I am wating for the OJB 1.1 release (For over 2 years now!) and hoping
that it will implemented this feature. Right now, I have to expose the
datamodel within my application code, bypassing our domain model and OJB
as OR mapper, and that really hurts.
Greetings,
Roger Janssen
iBanx
-----Original Message-----
From: Ferrer, Eric [mailto:[EMAIL PROTECTED]
Sent: vrijdag 2 februari 2007 3:54
To: OJB Users List
Subject: RE: Performance Issue on lookup on a table
Just to add it appears to work when passing a straight SQL query versus
using the persistable method.
-Eric
-----Original Message-----
From: Ferrer, Eric [mailto:[EMAIL PROTECTED]
Sent: Thursday, February 01, 2007 4:57 PM
To: OJB Users List
Subject: RE: Performance Issue on lookup on a table
Sorry
Accidently hit send.
What I was saying the query generate looks like this
SELECT TOP 1
A0.SERIAL_NUMBER,A0.AD_ID,A0.LIC_NUM,A0.RECEIVED_DTIME,A0.LIC_ST,A0.LIC_
TYPE
FROM MY_LIC_TLB A0
WHERE ((A0.LIC_NUM = '1236713' ) AND A0.LIC_ST = 'DD' ) AND
A0.LIC_TYPE = 'NORMAL'
When I run it in the sql management tool it comes back in less than 20
seconds, however via ojb it varies between 5 and 7 minutes.
The table has 3 gigs of data.
Any ideas what can be the difference?
We do lots of similar calls and this is the first one we ever
experienced this with.
Thanks
-Eric
-----Original Message-----
From: Ferrer, Eric [mailto:[EMAIL PROTECTED]
Sent: Thursday, February 01, 2007 4:52 PM
To: OJB Users List
Subject: Performance Issue on lookup on a table
I am experience an issue with an OJB query using a persistable object.
Basically its taking 7 minutes to return on the call getObjectByQuery.
When I run the query
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