Robert Haas wrote: > > A predicate can include columns from an index plus others. > > Am I missing something? > > Hmm, interesting point. In that case you couldn't use the index to > enforce predicate locking under MVCC without disabling HOT. But there > will be other cases where that wouldn't help anyway - a predicate > could also include unindexed columns exclusively. For those, the > traditional approach (not the one discussed in this paper) probably > requires locking against any heap insert, or checking each new heap > insert against the constraint, or... something.
If I understand that correctly > [...] by acquiring a shared lock on the next > row in order, as a scan is made to check whether rows match a predicate. > The scan might be through the data records or through an index I would say that in the case of a table scan, the whole table will be SILOCKed. I guess that's pretty much unavoidable if you want serializability. Yours, Laurenz Albe -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
