Re: ITL mechanism

From: John Hurley <hurleyjohnb_at_yahoo.com>
Date: Fri, 12 Aug 2011 16:51:32 -0700 (PDT)
Message-ID: <a429e430-fb10-43bd-828c-21cb8596814a_at_bl1g2000vbb.googlegroups.com>

VSE: # I was reading about ITL mechanism and it was mentioned that Oracle creates ITL entry for *every* updated row in a block.

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Looks like you are getting information on that question.

Think about a select for update operation that locks a whole bunch of rows in a bunch of different blocks.

Lots of work maintaining the ITL information in all those blocks eh?

Tom Kyte talks about locking is free in oracle but the cpu costs and latching costs can be quite significant if one does not have a good key to do the locking with. Plus redo entries to support it etc. Received on Fri Aug 12 2011 - 18:51:32 CDT