Excerpts from Tom Lane's message of jue oct 20 19:20:19 -0300 2011:
> So I've concluded that there's just no point in the GetOldestXmin
> clamping, and we should just apply the xmin value we get from the
> standby if it passes basic sanity checks (the epoch test), and hope that
> we're not too late to prevent loss of the data the standby wanted.
I am happy that the HS patch has introduced uses for the xid epoch. I
had to use them for multixact truncation in the FK locks patch, and was
nervous because I wasn't seeing any user in core code other than the
txid functions; this lack of callers, added to the comments in
GetNextXidAndEpoch ("we do not support such things"), made me feel a bit
uncomfortable about using it. I'm happy to have this problem out of my
mind now.
--
Álvaro Herrera <alvherre@commandprompt.com>
The PostgreSQL Company - Command Prompt, Inc.
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