| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Peter Geoghegan <pg(at)heroku(dot)com> |
| Cc: | Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, Pg Hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: WIP: [[Parallel] Shared] Hash |
| Date: | 2017-01-11 18:57:42 |
| Message-ID: | CA+TgmobLTcQRpEmPF2sZHWwyKP=c-5EmxTf+-84987PA4F-tdg@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Jan 10, 2017 at 8:56 PM, Peter Geoghegan <pg(at)heroku(dot)com> wrote:
> Instead of all this, I suggest copying some of my changes to fd.c, so
> that resource ownership within fd.c differentiates between a vfd that
> is owned by the backend in the conventional sense, including having a
> need to delete at eoxact, as well as a lesser form of ownership where
> deletion should not happen.
If multiple processes are using the same file via the BufFile
interface, I think that it is absolutely necessary that there should
be a provision to track the "attach count" of the BufFile. Each
process that reaches EOXact decrements the attach count and when it
reaches 0, the process that reduced it to 0 removes the BufFile. I
think anything that's based on the notion that leaders will remove
files and workers won't is going to be fragile and limiting, and I am
going to push hard against any such proposal.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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