From: | Bruce Momjian <bruce(at)momjian(dot)us> |
---|---|
To: | Itagaki Takahiro <itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp> |
Cc: | pgsql-hackers(at)postgresql(dot)org, Merlin Moncure <mmoncure(at)gmail(dot)com> |
Subject: | Re: query cancel issues in contrib/dblink |
Date: | 2010-02-24 19:33:37 |
Message-ID: | 201002241933.o1OJXbP09970@momjian.us |
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Thread: | |
Lists: | pgsql-hackers |
What happened to this patch?
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Itagaki Takahiro wrote:
>
> Merlin Moncure <mmoncure(at)gmail(dot)com> wrote:
>
> > Takahiro<itagaki(dot)takahiro(at)oss(dot)ntt(dot)co(dot)jp> wrote:
> > > contrib/dblink seems to have no treatments for query cancels.
> > > (1) Users need to wait for completion of remote query.
> > > (2) PGresult objects will be memory leak.
>
> Here is a patch to fix the issues. I hope the fixes will be ported
> to older versions if possible.
>
> (1) is fixed by using non-blocking APIs in libpq. I think we should
> always use non-blocking APIs even if the dblink function itself is
> a blocking-function.
>
> (2) is fixed by RegisterXactCallback(AtEOXact_dblink). However, there
> might be any better solutions -- for example, ResourceOwner framework.
>
>
> > > For (1), asynchronous libpq functions should be used instead of blocking
> > > ones, and wait for the remote query using a loop with CHECK_FOR_INTERRUPTS().
> >
> > How would you structure this loop exactly?
>
> Please check execute_query() and wait_for_result() in the patch.
>
> Regards,
> ---
> ITAGAKI Takahiro
> NTT Open Source Software Center
>
[ Attachment, skipping... ]
>
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--
Bruce Momjian <bruce(at)momjian(dot)us> http://momjian.us
EnterpriseDB http://enterprisedb.com
PG East: http://www.enterprisedb.com/community/nav-pg-east-2010.do
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