Re: [HACKERS] StandbyRecoverPreparedTransactions recovers subtrans links incorrectly - Mailing list pgsql-hackers

From Tom Lane
Subject Re: [HACKERS] StandbyRecoverPreparedTransactions recovers subtrans links incorrectly
Date
Msg-id 18171.1493134128@sss.pgh.pa.us
Whole thread Raw
In response to Re: [HACKERS] StandbyRecoverPreparedTransactions recovers subtranslinks incorrectly  (Simon Riggs <simon@2ndquadrant.com>)
Responses Re: [HACKERS] StandbyRecoverPreparedTransactions recovers subtranslinks incorrectly  (Simon Riggs <simon@2ndquadrant.com>)
List pgsql-hackers
Simon Riggs <simon@2ndquadrant.com> writes:
> I can't see any reason now why overwriteOK should exist at all. I'm
> guessing that the whole "overwriteOK" idea was an incorrect response
> to xids appearing where they shouldn't have done because of the
> mistake you just corrected. So I will now remove the parameter from
> the call.

Seems reasonable, but I don't like the logic change you made in
SubTransSetParent; you broke the former invariant, for non-Assert
builds, that the target pg_subtrans entry is guaranteed to have
the correct value on exit.  I do like fixing it to not dirty the
page unnecessarily, but I'd suggest that we write it like
if (*ptr != parent){    Assert(*ptr == InvalidTransactionId);    *ptr = parent;
SubTransCtl->shared->page_dirty[slotno]= true;}
 
        regards, tom lane



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