| From: | Robert Haas <robertmhaas(at)gmail(dot)com> |
|---|---|
| To: | Florian Pflug <fgp(at)phlo(dot)org> |
| Cc: | Merlin Moncure <mmoncure(at)gmail(dot)com>, Sergey Koposov <koposov(at)ast(dot)cam(dot)ac(dot)uk>, Jeff Janes <jeff(dot)janes(at)gmail(dot)com>, pgsql-hackers(at)postgresql(dot)org, Stephen Frost <sfrost(at)snowman(dot)net> |
| Subject: | Re: 9.2beta1, parallel queries, ReleasePredicateLocks, CheckForSerializableConflictIn in the oprofile |
| Date: | 2012-06-01 17:51:11 |
| Message-ID: | CA+TgmobzgZ6We+cnxToM7FypFN+WQpAOnSjbrNzoOaiPuE7rfg@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Fri, Jun 1, 2012 at 8:47 AM, Florian Pflug <fgp(at)phlo(dot)org> wrote:
> A simpler idea would be to collapse UnpinBuffer() / PinBuffer() pairs
> by queing UnpinBuffer() requests for a while before actually updating
> shared state.
So, what happens when somebody wants a cleanup lock on the buffer
you've decided to keep pinned? We have this problem already; I'm wary
of making it worse.
> We'd drain the unpin queue whenever we don't expect a PinBuffer() request
> to happen for a while. Returning to the main loop is an obvious such place,
> but there might be others.
However, on a workload like pgbench -S, dropping the pin when you
return to the main loop would render the optimization useless.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
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