Oracle 9i reading BLOB performance issues

Windows XP Pro SP2
JDK 1.5.0_05
Oracle 9i
Oracle Thin Driver for JDK 1.4 v.10.2.0.1.0
DBCP v.1.2.1
Spring v1.2.7 (I am using the JDBC template for convenience)
I have run into serious performance issues reading BLOBs from Oracle using oracle's JDBC thin driver. I am not sure if it a constraint/mis-configuration with oracle or a JDBC problem.
I am hoping that someone has some experience accessing multi-MB BLOBs under heavy volume.
We are considering using Oracle 8 or 9 as a document repository. It will end up storing hundreds of thousands of PDFs that can be as large as 30 MBs. We don't have access to Oracle 10.
TESTS
I am running tests against Oracle 8 and 9 to simulate single and multi-threaded document access. Out goal is to get a sense of KBps throughput and BLOB data access contention.
DATA
There is a single test table with 100 rows. Each row has a PK id and a BLOB field. The blobs range in size from a few dozen KB to 12MB. They represent a valid sample of production data. The total data size is approx. 121 MBs.
Single Threaded Test
The test selects a single blob object at a time and then reads the contents of the blob's binary input stream in 2 KB chunks. At the end of the test, it will have accessed all 100 blobs and streamed all 121 MBs. The test harness is JUnit.
8i Results: On 8i it starts and terminates successfully on a steady and reliable basis. The throughput hovers around 4.8 MBps.
9i Results: Similar reliability to 8i. The throughput is about 30% better.
Multi-Threaded Test
The multi-threaded test uses the same "blob reader" functionality used in the single threaded test. However, it spawns 8 threads each running a separate "blob reader".
8i Results: The tests successfully complete on a reliable basis. The aggregate throughput of all 8 threads is a bit more than 4.8 MBps.
9i Results: Erratic. The tests were highly erratic on 9i. Threads would intermittently lock when accessing a BLOB's output stream. Sometimes they lock accessing data from the same row, othertimes it is distinct rows. The number and the timing of the thread "locks" is indeterminate. When the test completed successfully the aggregate throughput of the 8 threads was approx. 5.4 MBps.
I would be more than happy to post code or the data model if that would help.
Carlos

Hi Murphy16,
Try investigate where are the principal issues in your RAC system.
Check:
* Expensive SQL's;
* Sorts in disks;
* Wait Events;
* Interconnect hardware issues;
* Applications doing unnecessary manual LOCKs (SQL);
* If SGA is adequatly sized (take care to not use of SWAP space "DISK");
* Backup's and unnecessary jobs running at business time (Realocate this jobs and backups to night window or a less intensive work hour at database);
* Rebuild indexes and identify tables that must be reorganized (fragmentation);
* Verify another software consuming resources on your server;
Please give us more info about your environment. The steps above are general, but you can use to guide u in basic performance issues.
Regards,
Rodrigo Mufalani
http://mufalani.blogspot.com

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No, use pure SQL, and the database and operating system will handle caching.
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No, use pure SQL
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No, use pure SQL
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No, use pure SQL
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I managed to get the AWR report within the time of the end of day process.
sql execute elapsed time is on the top of Time Model Statistics.
What I don't understand here is why is this issue happened only after 2 weeks?
I suspected that this might be because Oracle pick the wrong execution plan, and normally a wrong execution plan caused by outdated statistics on the indexes and tables, but what I cannot understand is why this is happening on Monday morning where in Friday night GATHER_DATABASE_STATS ran successfully.
Yesterday when the analyze schema was executed again, this morning I got another email saying that the performance issue occurred again.
The top most wait events are: db file sequential read, db file scattered read, log file parallel write, LNS Wait on SENDREQ, and log file sequential read.
Thank you,
Adhika

As a number of Oracle Connections created - Performance Issue

Hello,
We are using Oracle 9i as a backend and VB 6.0 as Frontend. For one client one connection will be opened in the Database Server, if 200 clients open the application then 200 connections will be opened in the Database Server, due to that performance issue is raising.
We are doing: If the frontend application is not in use for 10-minutes then the connection is closed and at the same time front-end application is also terminated or if the Client terminates the application the connection is closed in the Server.
Eventhought if 200-Clients connect the Server only 4 to 5 Clients send a request to the Server for retriving or for saving the data.
I want to Open a fixed number of connections in the DataBase Server eg., around 10-connections, and i want to use this 10 connections for 200 clients.
At First 10 Connections are opened and 10 Clients are using this 10 connections, among 10 Clients 1 released the database connection after finishing the Job and if 11'th Client opens then this released connection as to be used without opening a new connection, in the same way if some of the connections from 9 get free and if any other clients open application then this connections which are free as to be used for opening the application or else for doing any transaction. So, that the number of connection to be create can be redused.
Please give me the suggestion how to make use the released connection for doing the transaction or else for opening the application.
Thanking U with Regards,
Sravan,
Hyderabad.

As Satish mentioned, Shared Server can be a good solution, but it would also be worth telling us , how did you quantify this thing that due to the number of connections, you have a performance issue? 200 is not that big number I guess. What's the o/s , exact database version and the system details with database details? Also if you have statspack report, post that too over here.
HTH
Aman....

RedHat AS4 and Oracle 10R2 upgrade - performance issue

Hi all,
As part of our database upgrade project (from Oracle 10.2.0.1 to 10.2.0.3), we decided to upgrade our OS as well (RedHat AS4 from Update 2 to Update 4, 64-bit). We are in testing phase now and having some serious performance issues.
These below are steps that we have performed:
1. Ran db load testing plus Application Regression testing in order to get a baseline
2. Upgraded RH AS4 from Update 2 to Update 4
3. Ran db load testing plus Application Regression testing
4. Database load testing (including massive parallel processes, like 'insert into ...', 'create indexes ...parallel',etc ...) showed significant slowdown compared to our 'baseline' test (Update 2): 70-80%. The database is still Oracle 10.2.0.1, only RH was updated at this point
5. We upgraded Oracle 10.2.0.1 to 10.2.0.3, latest CPU , etc ...(Update 4 on OS side) still same slowdown in performances ...
6. Our Application Regression Testing has showed performance degradation also but not in same extent as db load test (10-20 % on different application modules)
7. We also did one more thing : went back and upgraded Oracle with Update 2 (some 'workarounds' were required but that's another story). Performances were OK. So it seems our problem is not (directly) related to Oracle version.
Now we are going to install Update 6 (the latest update for AS4) and see how it goes.
If anybody have any experience or idea about this case and want to share it with us, it would be highly appreciated.
Thanks in advance,
Milan N.

Just a quick update for those who follow this thread ...
Everything worked fine with 'Update 6' kernel (both Oracle 10.2.0.1 and 10.2.0.3). We have also applied all available security packages.
Milan N.

Oracle 9i reading BLOB performance issues

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