Re: Hot standby, RestoreBkpBlocks and cleanup locks

Simon Riggs wrote:
> The idea outlined before didn't deal with all call points for
> RecordIsCleanupRecord(), so doesn't actually work.

Hmm, grep finds two call points for that:

> !             case RECOVERY_TARGET_PAUSE_CLEANUP:
> !                     /*
> !                      * Advance until we see a cleanup record, then pause.
> !                      */
> !                     if (RecordIsCleanupRecord(record))
> !                         pauseHere = true;
> !                     break;
> ! 


and

> +                     /*
> +                      * Wait, kill or otherwise resolve any conflicts between
> +                      * incoming cleanup records and user queries. This is the
> +                      * main barrier that allows MVCC to work correctly when 
> +                      * running standby servers. Only need to do this if there
> +                      * is a possibility that users may be active.
> +                      */
> +                     if (reachedSafeStartPoint && RecordIsCleanupRecord(record))
> +                         ResolveRedoVisibilityConflicts(EndRecPtr, record);

The second we can easily handle by getting rid of 
ResolveRedoVisibilityConflicts functions and making the redo-functions 
call XactResolveRecoveryConflicts when necessary.

Is the first really useful? I would understand "advance until next 
cleanup record *that would block/kill queries*", but why would you want 
to advance until the next cleanup record? Anyway, if it is useful, you 
could do the pausing in XactResolveRecoveryConflicts, too.

--   Heikki Linnakangas  EnterpriseDB   http://www.enterprisedb.com