On Tue, Oct 18, 2016 at 8:27 PM, Amit Kapila <amit.kapil...@gmail.com> wrote: > By this problem, I mean to say deadlocks for suspended scans, that can > happen in btree for non-Mvcc or other type of scans where we don't > release pin during scan. In my mind, we have below options: > > a. problem of deadlocks for suspended scans should be tackled as a > separate patch as it exists for other indexes (at least for some type > of scans). > b. Implement page-scan mode and then we won't have deadlock problem > for MVCC scans. > c. Let's not care for non-MVCC scans unless we have some way to hit > those for hash indexes and proceed with Dead tuple marking idea. I > think even if we don't care for non-MVCC scans, we might hit this > problem (deadlocks) when the index relation is unlogged. > > Here, even if we want to go with (b), I think we can handle it in a > separate patch, unless you think otherwise.
After some off-list discussion with Amit, I think I get his point here: the deadlock hazard which is introduced by this patch already exists for btree and has for a long time, and nobody's gotten around to fixing it (although 2ed5b87f96d473962ec5230fd820abfeaccb2069 improved things). So it's probably OK for hash indexes to have the same issue. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
