| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Konstantin Knizhnik <k(dot)knizhnik(at)postgrespro(dot)ru> |
| Cc: | Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com>, 曾文旌(义从) <wenjing(dot)zwj(at)alibaba-inc(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org>, 蔡松露(子嘉) <zijia(at)taobao(dot)com>, "Cai, Le" <le(dot)cai(at)alibaba-inc(dot)com>, 张广舟(明虚) <guangzhou(dot)zgz(at)alibaba-inc(dot)com>, 赵殿奎 <diankui(dot)zdk(at)alibaba-inc(dot)com>, 萧少聪(铁庵) <shaocong(dot)xsc(at)alibaba-inc(dot)com> |
| Subject: | Re: [Proposal] Global temporary tables |
| Date: | 2019-11-01 15:26:40 |
| Message-ID: | CA+TgmoZFWaND4PpT_CJbeu6VZGZKi2rrTuSTL-Ykd97fexTN-w@mail.gmail.com |
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On Fri, Nov 1, 2019 at 11:15 AM Konstantin Knizhnik
<k(dot)knizhnik(at)postgrespro(dot)ru> wrote:
> It seems to me that I have found quite elegant solution for per-backend statistic for GTT: I just inserting it in backend's catalog cache, but not in pg_statistic table itself.
> To do it I have to add InsertSysCache/InsertCatCache functions which insert pinned entry in the correspondent cache.
> I wonder if there are some pitfalls of such approach?
That sounds pretty hackish. You'd have to be very careful, for
example, that if the tables were dropped or re-analyzed, all of the
old entries got removed -- and then it would still fail if any code
tried to access the statistics directly from the table, rather than
via the caches. My assumption is that the statistics ought to be
stored in some backend-private data structure designed for that
purpose, and that the code that needs the data should be taught to
look for it there when the table is a GTT.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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