On 2015-04-15 17:58:54 +0300, Heikki Linnakangas wrote: > When the speculative insertion is finished, write a new kind of a WAL record > for that. The record only needs to contain the ctid of the tuple. Replaying > that record will clear the flag on the heap tuple that said that it was a > speculative insertion. > > In logical decoding, decode speculative insertions like any other insertion. > To decode a super-deletion record, scan the reorder buffer for the > transaction to find the corresponding speculative insertion record for the > tuple, and remove it. > > BTW, that'd work just as well without the new WAL record to finish a > speculative insertion. Am I missing something?
I'm, completely independent of logical decoding, of the *VERY* strong opinion that 'speculative insertions' should never be visible when looking with normal snapshots. For one it allows to simplify considerations around wraparound (which has proven to be a very good idea, c.f. multixacts + vacuum causing data corruption years after it was thought to be harmless). For another it allows to reclaim/redefine the bit after a database restart/upgrade. Given how complex this is and how scarce flags are that seems like a really good property. And avoiding those flags to be visible to the outside requires a WAL record, otherwise it won't be correct on the standby. Andres -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
