Question

Using Oracle Ref Cursors in Java: Performance Issue

Asked by: chetsk

Hi Experts,
               Desperately seeking answer to this question. Any help would be, needless to say, highly appreciated:

The following is the scenario we have:
1. We have a database schema dedicated to our app.
2. We have another schema (residing on another box) for the Data Warehouse.

We need to query the Data Warehouse. For this we are:

1. creating a database link from the local database schema to the Data Warehouse schema.
2. Executing the queries on the Data Warehouse using the Data base link.

When I get the result of the queries I am storing it in a Ref cursor that is the out parameter of my Stored Procedure. I read that Ref cursor in Java and write the contents to a flat file.

The issue we are facing are:
1. One of the functionality we have should allow us to select a subset of the records from the refcursor. For this, I am inserting the " and rownum < 11" condition while getting my ref cursor.  I expect that this would also be returned to java immediately as I have requested only a subset of the records. However, this is not happening, the Stored Proc runs in 2 mins, however the resulset is obtained in java only after 40 mins.

My question:
1. Is the approach we are using above correct? If no, what is the better approach?

Regards,
Chet

This Question has been solved and asker verified All Experts Exchange premium technology solutions are available to subscription members.

Subscribe now for full access to Experts Exchange and get

Instant Access to this Solution

  • Plus...
  • 30 Day FREE access, no risk, no obligation
  • Collaborate with the world's top tech experts
  • Unlimited access to our exclusive solution database
  • Never be left without tech help again

Subscribe Now

Asked On
2006-01-23 at 22:12:13ID21707676
Tags

java

,

oracle

,

cursor

,

ref

,

performance

Topic

Java Programming Language

Participating Experts
3
Points
300
Comments
7

Trusted by hundreds of thousands everyday for fast, accurate and reliable tech support.

  • "The time we save is the biggest benefit of Experts Exchange to Warner Bros. What could take multiple guys 2 hours or more each to find is accessed in around 15 minutes on Experts Exchange." Mike Kapnisakis, Warner Bros.
  • "Our team likes having a resource that is more secure than just using Google and most experts using this service really know their stuff. It's nice to look here first versus using Google." Dayna Sellner, Lockheed Martin
  • "Anytime that I've been stumped with a problem, 9 out of 10 times Experts Exchange has either the accepted solution or an open discussion of the potential solution to the problem." Kenny Red, eBay Inc.

See what Experts Exchange can do for you.

Got a question?

We've got the answer.

Experts Exchange has been collecting answers to technology questions since 1996…3 million and counting! If you have a question, chances are we already have your answer.

Screenshot of Experts Exchange Knowledgebase

Need individual assistance?

Our experts are ready to help.

If you can't find the exact answer you're looking for, ask our exclusive community of 50,000 experts. You’ll get a personalized answer from a trusted professional.

Screenshot of Experts Exchange Knowledgebase

Want to learn from the best?

Read articles from industry experts.

Thousands of free tech tips, tricks, how-to’s and tutorials are available in our peer reviewed articles section. See for yourself how smart our experts are, no login required.

Screenshot of an Article

Working on a long term project?

Store your work and research.

Save solutions to your questions, answers you’ve discovered through searching plus helpful articles in your personal knowledgebase for easy future access.

Screenshot of Experts Exchange Knowledgebase

Access the answers to your technology questions today.

Subscribe Now

30-day free trial. Register in 60 seconds.

What Makes Experts Exchange Unique?

Members of the expert community talk about why the experience at Experts Exchange is different than what you will find anywhere else.

Trusted by the world's most respected brands.

image of each brand's logo

Faithfully serving IT professionals since 1996.

Experts Exchange Logo

Try it out and discover for yourself.

Subscribe Now

30-day free trial. Register in 60 seconds.

Related Solutions

  1. RowNum
    I want to select 100 rows. What is the syntex of the select query (like rownum<=100 in Oracle)? thank,
  2. RowNum with SQLServer
    Hi, How can I get the 50 to 100 records of a select query (something like "rownum > 50 and rownum < 100" in Oracle)? Thanks
  3. returning a subset of a query result
    We have a web page that needs to display a subset from the returned recordset, i.e. records 1 to 50, then records 50 - 100..... Is this possible in Oracle?
  4. Rownum
    Is there an equivalent of 'rownum' (Oracle) when retrieving data from a table in SQL Server?
  5. Rownum
    select * from table where rownum = 4 no rows. select * from table where rownum <= 4 4 rows returned select * from table where rownum = 1 1 row returned select * from table where rownum = 2 no rows returned. ?
  6. REF Cursors
    Look at this: PACKAGE TEST1 IS type abc is ref cursor; FUNCTION function_name ( table_id IN number) RETURN abc; END; PACKAGE BODY TEST1 IS FUNCTION function_name ( table_id IN number) RETURN abc IS lv_table_name p...

Free Tech Articles

  1. WARNING: 5 Reasons why you should NEVER fix a computer for free.
    It is in our nature to love the puzzle. We are obsessed. The lot of us. We love puzzles. We love the challenge. We thrive on finding the answer. We hate disarray. It bothers us deep in our soul. W...
  2. SCCM OSD Basic troubleshooting
    SCCM 2007 OSD is a fantastic way to deploy operating systems, however, like most things SCCM issues can sometimes be difficult to resolve due to the sheer volume of logs to sift through and the dispe...
  3. Migrate Small Business Server 2003 to Exchange 2010 and Windows 2008 R2
    This guide is intended to provide step by step instructions on how to migrate from Small Business Server 2003 to Windows 2008 R2 with Exchange 2010. For this migration to work you will need the fo...
  4. Create a Win7 Gadget
    This article shows you how to create a simple "Gadget" -- a sort of mini-application supported by Windows 7 and Vista. Gadgets can be dropped anywhere on the desktop to provide instant information, ...
  5. Outlook continually prompting for username and password
    There have been a lot of questions recently regarding Outlook prompting for a username and password whilst using Exchange 2007. There are a few reasons why this would happen and I will try to cover t...
  6. Backup Exchange 2010 Information Store using Windows Backup
    There seems to be quite a lot of confusion around the ability to backup Exchange 2010 using the built in Windows Backup feature. This stems from the omission of this feature prior to Exchange 2007 s...

Cloud Class Webinars

  1. Avoiding Bugs in Microsoft Access
    Alison Balter takes and in-depth look at avoiding bugs in Access. In this webinar you will learn about using the immediate window to debug your applications, invoking the debugger, using breakpoints to troubleshoot, stepping through code, setting the next statement to execute, ...
  2. Top 10 Best New Features in Visio 2010
    Scott Helmers gives live demonstrations of the top 10 new features in Visio 2010. This webinar will teach you how to create compelling diagrams by adding shapes to the page with a single click, linking the shapes in a diagram to data in Excel (or SQL Server, or SharePoint), ...
  3. IT Consultant Business Secrets Revealed
    Michael Munger, Experts Exchange tech pro and IT consultant, pulls back the curtain on his very successful businesses and answers question on every IT consultant and business owner should know about. He shares secrets on what he did to solve the 5 most common problems in IT, ...
  4. Disaster Recovery and Business Continuity
    Quest CTO, Mike Billon, gives an overview of the steps involved in building a dunamic disaster recovery plan. Through case studies and an examination of software/hardware tooles for monitoring and testing, you'll gain a better understandin of where you are, where you want ...
  5. Organize Your Visio Diagrams with Containers and Lists
    Scott Helmers uses cross functional flowcharts, wireframe diagrams, data graphic legends and seating charts to teach you: how to ustilize all three new structured diagram components in Visio 2010, the best practices for organizeing shapes in previous version of Visio, how to organize ...
  6. How to Us Objects, Properties, Events and Methods in Microsoft Access
    Alison Dalter gives an in-depbth look at objects, properties, events and methods in Microsoft Access. In this webinar you will learn about using the object browser, referring to objects, working with properties and methods, working with object variables, understanding the ...

Join the Community

Give a Little. Get a Lot.

Join the community of experts here and help other tech pros by answering question in your area of expertise. You can earn FREE access to all Experts Exchange's premium features and resources.

Join the Community

Answers

 

by: CEHJPosted on 2006-01-24 at 00:00:13ID: 15773745

>>One of the functionality we have should allow us to select a subset of the records from the refcursor

Why do you want to do this btw?

 

by: Giant2Posted on 2006-01-24 at 02:29:42ID: 15774266

Instead of this I did:
create a user could see both DB.
In the views of this user create one doing the things done by Cursor.
In java code you only make query over ths view.

Hope this could help you.
Bye, Giant.

 

by: oraelbisPosted on 2006-01-24 at 09:05:48ID: 15777493

Hello:

Seems, that problem on selecting large queries on remote server and populating them to local server over network. Only after that result set is cut by local select statement.

I think, that best way to do your task:
-  Create package or stored procedures on the Data Warehouse level.
-  Make them parameterized according your filter criteria and return cursors. You have to transmit only needed results over network.
- Local selects have to get records from remote procedures according criteria.

Best regards,
  Siarhei Berdachuk

 

by: chetskPosted on 2006-01-29 at 10:42:34ID: 15818315

Hi Siarhei,
              Thank you for your reply. Here is my problem in detail:
1. I cannot create packages or stored procedures at the Data Warehouse level. Also, the Data Warehouse is sitting on a different box as compared to my local database schema.

I need to return around 1 million + rows from querying the datawarehouse. I am, as I have described above, using a database link to query the datawarehouse. In addition to the 1 million + records I also have a preview mode in my application in which case only 10 records from the million need to be returned back from the stored procedure.

    I am currently using a ref cursor to pass data back from the stored procedure. The query takes around 1/2 hour to run for the million records. However, in the preview mode i put in the additonal conditon:: { and rownum < 11 } , this does return back the 10 records quickly however java still takes the same time to retrieve the ref cursor i.e. 1/2 hour.

I have been exploring other options to send back the rows retrieved.

1. Return using a table type
2. Return XML

Kindly provide your opinion on which option would be best for me. It would be great if you could also give a small example. Revert back in case of any clarifications.

Thanks and Regards,
Chet

 

by: CEHJPosted on 2006-01-29 at 10:49:12ID: 15818364

Counting rows is expensive. Try to use an index

AND pkcolumn < n

 

by: oraelbisPosted on 2006-01-29 at 23:17:20ID: 15821643

Hello Chet,
May be this solution can help you:
http://www.experts-exchange.com/Programming/Programming_Languages/Delphi/Q_21619698.html

I mean some job to retrive you query results from external database to internal temp table, and then requery from this table.

 

by: oraelbisPosted on 2006-01-29 at 23:45:24ID: 15821706

You can do same task without job with using session temporary tables and retriving external data to it in your procedure as first step. Script for creating temp table have to be look like:

create global temporary table MY_TEMP_DATA
(  
  MY_ID   NUMBER(10) not null,
  MY_NAME VARCHAR2(255)
)
on commit preserve rows;


Your result select have to be look like:

select rnum, my_id, my_name
  from (select rownum as rnum, s.*
          from (select my_id, my_name
                  from my_data
                union
                select my_id, my_name from
                  my_temp_data) s
         where rownum <= :end_row)
 where rnum between :first_row and :end_row

Where you retrive data page to page and calculate rows interval by formula:

first_row := (nvl(p_page_num, 1) - 1) * nvl(p_rows_on_page, 10) + 1;
end_row   := least(nvl(p_page_num, 1) * nvl(p_rows_on_page, 10),
                         p_tot_rows);





 

20120131-EE-VQP-002

3 Ways to Join

30-Day Free Trial

The Experts

98% positive feedback on 31,087 answers since March 2000. angeliii is a Microsoft Most Valuable Professional for his work with MS SQL Server & Develoment.

He has also proven his knowledge of Visual Basic Programming, PHP Scripting and Oracle Databases.

The Experts

97% positive feedback on 10,752 answers since July 2000. lrmoore has more than 18 years experience in the networking industry.

The six-time Mircosoft MVPs specialties include firewalls, virtual private networking, and network management.

Testimonials

"...and excellent source for support... Kind of like having your very own IT dept." Electriciansnet

Testimonials

"I was apprehensive at signing up at first. However... it has already made my life as an IT administrator much easier." JaCrews

Testimonials

"WOW! You guys have great, active, and knowledgeable people on here." moore50

Business Clients

Business Clients

In the Press

"If you’ve got a question... Experts Exchange can supply an answer.”

In the Press

"...an invaluable aid for both IT professionals and those who require tech support."

In the Press

"where IT professionals provide quick answers on just about any topic"

Business Account Plans

Loading Advertisement...