On Tue, Jan 22, 2019 at 2:17 PM Tomas Vondra <tomas.von...@2ndquadrant.com> wrote: > I think there are essentially two ways: > > (a) Define max amount of memory available for shared dictionarires, and > come up with an eviction algorithm. This will be tricky, because when > the frequently-used dictionaries need a bit more memory than the limit, > this will result in trashing (evict+load over and over). > > (b) Define what "unused" means for dictionaries, and unload dictionaries > that become unused. For example, we could track timestamp of the last > time each dict was used, and decide that dictionaries unused for 5 or > more minutes are unused. And evict those. > > The advantage of (b) is that it adopts automatically, more or less. When > you have a bunch of frequently used dictionaries, the amount of shared > memory increases. If you stop using them, it decreases after a while. > And rarely used dicts won't force eviction of the frequently used ones.
+1 for (b). -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
