On Tue, Nov 5, 2019 at 10:34 AM Tomas Vondra <tomas.von...@2ndquadrant.com> wrote: > 2) This adds another hashtable maintenance to BufferAlloc etc. but > you've only done tests / benchmark for the case this optimizes. I > think we need to see a benchmark for workload that allocates and > invalidates lot of buffers. A pgbench with a workload that fits into > RAM but not into shared buffers would be interesting.
Yeah, it seems pretty hard to believe that this won't be bad for some workloads. Not only do you have the overhead of the hash table operations, but you also have locking overhead around that. A whole new set of LWLocks where you have to take and release one of them every time you allocate or invalidate a buffer seems likely to cause a pretty substantial contention problem. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
