From: | Simon Riggs <simon(at)2ndQuadrant(dot)com> |
---|---|
To: | Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> |
Cc: | Stephen Frost <sfrost(at)snowman(dot)net>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>, PostgreSQL Hackers <pgsql-hackers(at)postgresql(dot)org> |
Subject: | Re: ToDo: log plans of cancelled queries |
Date: | 2013-01-11 20:50:57 |
Message-ID: | CA+U5nMJvqFLJvADPJ7dnL_VgiT2eDivs6BjxLADHGqMbwg3AzQ@mail.gmail.com |
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Lists: | pgsql-hackers |
On 11 January 2013 16:52, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
> We already overload the signals, so its just a new type for the signal
> handler to cope with.
>
> See procsignal_sigusr1_handler()
I roughed up something to help you here... this is like 50% of a patch.
pg_explain_backend() calls a SIGUSR1 variant which then allows a call
to RunDynamicExplain() during any call to CHECK_FOR_INTERRUPTS()
That only works when something in the executor has called
SetDynamicExplain(), which later needs to be Unset...
So that's all you need to invoke a dynamic EXPLAIN via a sysadmin
function. All you need to do is generate an EXPLAIN and dump it
somewhere useful, like the server log. Over to you Pavel. There's a
patch somewhere by Greg Stark that generated a plan from a running
server for progress bar stuff, but that was like 5 years ago nearly.
But the explain invocation stuff from that might be useful as a guide.
--
Simon Riggs http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
Attachment | Content-Type | Size |
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signal_dynamic_explain.v1.patch | application/octet-stream | 6.5 KB |
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