On 22.10.2013 19:12, Andres Freund wrote:
On 2013-10-18 20:26:16 +0200, Andres Freund wrote:
4) Store both (cmin, cmax) for catalog tuples.


BTW: That would have the nice side-effect of delivering the basis of
what you need to do parallel sort in a transaction that previously has
performed DDL.

Currently you cannot do anything in parallel after DDL, even if you only
scan the table in one backend, because operators et al. have to do
catalog lookups which you can't do consistently since cmin/cmax aren't
available in both.

Parallel workers will need cmin/cmax for user tables too, to know which tuples are visible to the snapshot.

- Heikki


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