> 2020年1月6日 下午8:17，Dean Rasheed <dean.a.rash...@gmail.com> 写道： > > On Mon, 6 Jan 2020 at 11:01, Tomas Vondra <tomas.von...@2ndquadrant.com> > wrote: >> >> On Mon, Jan 06, 2020 at 01:04:15PM +0800, 曾文旌(义从) wrote: >> >>> 2 We feel that gtt needs to maintain statistics, but there is no >>> agreement on what it will be done. >>> >> >> I certainly agree GTT needs to maintain statistics, otherwise it'll lead >> to poor query plans. > > +1 > >> AFAIK the current patch stores the info in a hash >> table in a backend private memory, and I don't see how else to do that >> (e.g. storing it in a catalog would cause catalog bloat). >> > > It sounds like it needs a pair of system GTTs to hold the table and > column statistics for other GTTs. One would probably have the same > columns as pg_statistic, and the other just the relevant columns from > pg_class. I can see it being useful for the user to be able to see > these stats, so perhaps they could be UNIONed into the existing stats > view. The current patch provides several functions as extension(pg_gtt) for read gtt statistics. Next I can move them to the kernel and let the view pg_stats can see gtt’s statistics.
> Regards, > Dean
