Possible premature SNAPBUILD_CONSISTENT with DB-specific running_xacts - Mailing list pgsql-hackers

A cluster-wide decoder must never have its snapshot-builder state changed
by a database-specific running_xacts record. Adding a check to return it early.

I think otherwise a cluster wide decoder can potentially go to 

SNAPSHOT_CONSISTENT state immediately even though transactions older

than nextXid are still in progress on a different DB (not tracked by running_xact

record). This race is now possible with cluster wide decoders and Repack

concurrently run.

Attached a patch to fix this. Thoughts?

Thanks

Satya