On Thu, Sep 17, 2020 at 10:06:07AM -0400, Tom Lane <tgl@xxxxxxxxxxxxx> wrote: > =?UTF-8?Q?=C3=98ystein_Kolsrud?= <kolsrud@xxxxxxxxx> writes: > > So my question is: When does a postgres process forked for a connection use > > private memory instead of shared, and what can I do to avoid this? > > The only significant long-term consumption of private memory is for > caches. There are catalog caches, which can get large if the session > accesses a whole lot of database objects (e.g., thousands of different > tables). Some of the PLs maintain caches with parsed versions of any > function that's been executed. (An ex-employer of mine had a lot of > trouble in that regard, because they had hundreds of thousands of lines > worth of plpgsql functions.) There isn't any user-accessible knob for > limiting the size of those caches. If you have a problem of that sort, > about the only way to mitigate it is to use fewer backends so that the > total memory consumption stays in bounds, or redesign your application. > In some cases it might help to restart your sessions when they get too > big, but that seems like at best a band-aid. > > regards, tom lane For what it's worth, I have 171305 lines of plpgsql/sql functions and it hasn't caused any problem on a server with 4GB RAM. With a small number of long-lived connections. cheers, raf
