Re: Fwd: Snapshot too old from READ-ONLY table (data pump export)

  • From: Ron Chennells <ron.chennells@xxxxxxxxxxxxxx>
  • To: oracle-l@xxxxxxxxxxxxx
  • Date: Tue, 19 Jul 2011 09:58:28 +0100

Some details here


Quoting Laimutis.Nedzinskas@xxxxxx:

Since the question was raised again, does anyone know the latest,
up-do-date explanation on how oracle multi versioning works.

ITL's, commit SCN's, row lock byte all put together and explained :)

The problem is that many very clever people reverse engineered one or
another aspect of the process but one can hardly find an all-out
I dare to claim that some statements one finds on internet made by even
experienced oracle gurus are doubtful to say the least.
Actually, oracle's own metalink is known to provide hmmm.. strange
statements. That happens.
The whole multi versioning is easy to explain at a high level but
implementation is quite tricky.

Why is implementation that important? Because knowing how it works one can
answer some questions right away how fast oracle can perform in particular
It's less of a black box approach and more of algorithm analysis then.

Thank you in advance,
Laimis N



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