Oracle Scratchpad

May 8, 2011

Consistent Gets

Filed under: Infrastructure,Oracle,Read Consistency,Troubleshooting,undo — Jonathan Lewis @ 10:09 am BST May 8,2011

There’s an interesting question on the OTN database forum at present – why does an update of 300,000 rows take a billion buffer visits. (There are 25 indexes on the table – so you might point a finger at that initially, but only one of the indexes is going to be changed by the update so that should only account for around an extra 10 gets per row in a clean environment.)
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April 19, 2011

More CR

Filed under: Infrastructure,Oracle,Performance,Read Consistency,Troubleshooting,undo — Jonathan Lewis @ 6:32 pm BST Apr 19,2011

Following on from yesterday’s post on consistent reads, I thought I’d make the point that the way you work can make an enormous difference to the amount of work you do. Here’s a silly little demo (in 10.2.0.3):
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April 18, 2011

Consistent Reads

Filed under: Infrastructure,Oracle,Performance,Read Consistency,Troubleshooting,undo — Jonathan Lewis @ 11:08 am BST Apr 18,2011

Here’s a quick demo to make a point about consistent reads (prompted by a question on the Oracle-L mailing list):
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