Tom Lane wrote:
ITAGAKI Takahiro <[EMAIL PROTECTED]> writes:
This is a stand-alone patch for aggressive freezing. I'll propose
to use OldestXmin instead of FreezeLimit as the freeze threshold
in the circumstances below:

I think it's a really bad idea to freeze that aggressively under any
circumstances except being told to (ie, VACUUM FREEZE).  When you
freeze, you lose history information that might be needed later --- for
forensic purposes if nothing else.  You need to show a fairly amazing
performance gain to justify that, and I don't think you can.

There could be a GUC vacuum_freeze_limit, and the actual FreezeLimit would be calculated as
GetOldestXmin() - vacuum_freeze_limit

The default for vacuum_freeze_limit would be MaxTransactionId/2, just
as it is now.

greetings, Florian Pflug

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