Armin, Its nice to know that you are thinking about the web, but my issues dont revolve around the web at this point. When I do a persistable query, if I get a collection, I set the max to what ever configurable param, display 20 records or more per page, and I already have another struts/jsf solution to handle the user interaction from paging x pages with out going back to the database. In fact I dont think we need this since on the pages we access for these types of queries, I believe its all in a collection or cached result set. What I want is for the select top query to be native supported since in most case we simply expect 1 record from a database table or a 1:n relationship (i.e. 1 customer can have numerous contact). The table in question is populated monthly, outside of my controll and our lookups should only return 1 record always due to the referential integrity constraint. Actually we set our persistable object with the keys that are only indexed as for performance reason. At first I thought we was doing a full table scan. Now I know better. Hopefully there can be some short term solution to prevent the disclosing of our data model layer. Does this behavior we are talking about occur on any other RDMS function calls we perform? I know its SQL Server and I had no choice, but I think i get page locks when I do logical persisted calls to update a set of tables per our business work flow processes (5 table prior to commit). Lets keep this discussion going, perhaps there are some other Object Relational Bridge tools we can bench off for this solution? Hibernate? EJB3? POJO ? -Eric
________________________________ From: Armin Waibel [mailto:[EMAIL PROTECTED] Sent: Mon 2/5/2007 7:38 PM To: OJB Users List Subject: Re: Performance Issue on lookup on a table Hi Roger, Janssen, Roger wrote: > Hi, > > Hearing that the pagination might be implemented using native SQL > limiting syntax puts a smile on my face. It might be a bit more complex > though then suggested by Armin. All beginnings are difficult ;-) The limit support can't substitute the real "native based" pagination. My thought was to combine current OJB-pagination with new limit support and fetch-size - e.g set limit to 300, Query.setStartAtIndex(150), Query.setEndAtIndex(300) to get results 150...300 and fetch-size=30 set to web-page result number size. This isn't perfect, but I think this will be much more effective on large result sets as current behavior (without limit). > We do not only want to limit the amount > of records, but also want to be able to define an offset, aka request a > specific page. Since every RDBMS has its own logic, it is not > straightforward. A re-write of the quey might even be necessary, instead > of just adding a limit-clause: > > MSSQL: > > SELECT * FROM ( > SELECT TOP n * FROM ( > SELECT TOP z columns -- (z=n+skip) > FROM tablename > ORDER BY key ASC > ) AS FOO ORDER BY key DESC -- ('FOO' may be anything) > ) AS BAR ORDER BY key ASC -- ('BAR' may be anything) > > MYSQL: > > SELECT columns > FROM tablename > ORDER BY key ASC > LIMIT n OFFSET skip > > ORACLE: > > SELECT * FROM ( > SELECT > ROW_NUMBER() OVER (ORDER BY key ASC) AS rn, > columns > FROM tablename > ) > WHERE rn > skip AND rn <= (n+skip) > > (I think the oracle example can be simplified though.) > > And of course, there are many other platforms as well. > You are right, native pagination support will be much more complex to implement than limit support (your examples point out the problem). But isn't it in most cases a simple sql-string split to integrate the paging query string? > [ I got this info from > http://troels.arvin.dk/db/rdbms/#select-limit-offset ] > Excellent link! > And to complicate it even more, if the platform will not be supported by > OJB, I think it would be nice if OJB falls back on it's current > implementation. But the buildup of the resultsets is of course completey > different using native pagination and the current OJB implementation, > can they co-exist? In the current implementation OJB simply use a RsIterator wrapper class to "simulate" paging. Thus if native paging is supported by OJB it has to use the default RsIterator and as fall back OJB can use the current wrapper class. Give me time to think more about it (seems it could be possible to implement native paging without changing too many classes and internal interfaces - I could be fatally wrong ;-)). By the way, it seems that someone started with paging support some time ago (see Platform class methods) but never implement it. regards, Armin > > Roger Janssen > iBanx > > -----Original Message----- > From: Armin Waibel [mailto:[EMAIL PROTECTED] > Sent: zaterdag 3 februari 2007 3:05 > To: OJB Users List > Subject: Re: Performance Issue on lookup on a table > > 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.LI >> C_ >> 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 >> >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: [EMAIL PROTECTED] >> For additional commands, e-mail: [EMAIL PROTECTED] >> >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: [EMAIL PROTECTED] >> For additional commands, e-mail: [EMAIL PROTECTED] >> >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: [EMAIL PROTECTED] >> For additional commands, e-mail: [EMAIL PROTECTED] >> ********************************************************************** >> ** >> * >> The information contained in this communication is confidential and is > >> intended solely for the use of the individual or entity to whom it is > >> addressed.You should not copy, disclose or distribute this >> communication without the authority of iBanx bv. iBanx bv is neither >> liable for the proper and complete transmission of the information has > >> been maintained nor that the communication is free of viruses, >> interceptions or interference. >> >> If you are not the intended recipient of this communication please >> return the communication to the sender and delete and destroy all >> copies. >> >> >> >> >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: [EMAIL PROTECTED] >> For additional commands, e-mail: [EMAIL PROTECTED] >> >> >> --------------------------------------------------------------------- >> To unsubscribe, e-mail: [EMAIL PROTECTED] >> For additional commands, e-mail: [EMAIL PROTECTED] >> >> > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: [EMAIL PROTECTED] > For additional commands, e-mail: [EMAIL PROTECTED] > > --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
