Press Summary
Large SGA on 32-bit Redhat Linux
June 10th, 2010
Written by Centroid
Many DBAs are familiar with the SGA size limitations on 32-bit platforms.  This post shows how to allocate a 3Gb buffer cache on 32-bit RHAS 3. Step 1: Mount /dev/shm to as type ramfs.  Edit /etc/fstab and add an entry like this: none                    /dev/shm                ramfs defaults,size=4G 0 0 Step 2: do a "mount -a" to mount /dev/shm.  I use ramfs instead of tmpfs because it doesn't use swap; tmpfs does.  With ramfs memory allocation will also grow dynamically, whereas when...
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Using DBMS_SQLDIAG
March 3rd, 2010
Written by Centroid
As a DBA, have you ever had an issue you suspected may be a bug and have been asked to generate "test data" for Oracle development?  We ran into this at a client recently and found a cool 11g utility (at least I *think* it's new :)) to get Oracle Support the data they need to reproduce the issue in-house. The situation had to do with optimizer_features_enable being set to 11.1.0.7 in a database recently upgraded form 9.2.0.5 in an Oracle eBusiness Suite environment (11.5.10.2) that utilized...
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Connecting an Oracle Database with a DB2 Database
January 30th, 2010
Written by Centroid
On a recent project we had a business and technology reason to connect Oracle EBS running 11g to a DB2 database.  After a few weeks of researching for the best practice and approach we decided on the following implementation steps. Download a DB2 driver, such as from DataTek, and download to your application server in any storage directory. Create a directory called "YM" under your custom application top.  example: $CUSTOM_TOP/java/YM.  (Assumes you have already created a $CUSTOM_TOP and it...
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What you can do with ASH: Top Resource Consuming SQL
April 10th, 2009
Written by Centroid
 The following SQL shows you the top resource-consuming pieces of SQL in your instance: select ash.SQL_ID ,      sum(decode(ash.session_state,'ON CPU',1,0))     "CPU",      sum(decode(ash.session_state,'WAITING',1,0))    -      sum(decode(ash.session_state,'WAITING', decode(en.wait_class, 'User I/O',1,0),0))    "WAIT" ,      sum(decode(ash.session_state,'WAITING', decode(en.wait_class, 'User I/O',1,0),0))    "IO" ,      sum(decode(ash.session_state,'ON CPU',1,1))     "TOTAL...
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"Oracle is slow, can you see if anything is going on?"
April 10th, 2009
Written by Centroid
As DBAs, we're faced with this question all the time.  In order to quickly supply an accurate answer to this question, an experienced Oracle DBA needs to have a few tools in his belt - and I'm not talking about any special software or monitoring solutions, I'm talking simply SQL*Plus scripts and access to a database account with access to the V$ views. Here's what I do when someone asks me this question: Step #1: Take a look at V$SESSION_WAIT.  This will show you details about sessions...
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