On Mon, Aug 29, 2016 at 5:22 PM, maksim <m.milyu...@postgrespro.ru
<mailto:m.milyu...@postgrespro.ru>> wrote:
Hi, hackers!
Now I complete extension that provides facility to see the current
state of query execution working on external session in form of
EXPLAIN ANALYZE output. This extension works on 9.5 version, for 9.6
and later it doesn't support detailed statistics for parallel nodes yet.
I want to present patches to the latest version of PostgreSQL core
to enable this extension.
Hello,
Did you publish the extension itself yet?
Hello, extension for version 9.5 is available in repository
https://github.com/postgrespro/pg_query_state/tree/master.
Last year (actually, exactly one year ago) I was trying to do something
very similar, and it quickly turned out that signals are not the best
way to make this sort of inspection. You can find the discussion
here:
https://www.postgresql.org/message-id/CACACo5Sz7G0MFauC082iM=xx_hq7qq5ndr4jpo+h-o5vp6i...@mail.gmail.com
Thanks for link!
My patch *custom_signal.patch* resolves the problem of «heavy» signal
handlers. In essence, I follow the course offered in *procsignal.c*
file. They define *ProcSignalReason* values on which the SUGUSR1 is
multiplexed. Signal recent causes setting flags for *ProcessInterrupt*
actuating, i.e. procsignal_sigusr1_handler() only sets specific flags.
When CHECK_FOR_INTERRUPTS appears later on query execution
*ProcessInterrupt* is called. Then triggered user defined signal handler
is executed.
As a result, we have a deferred signal handling.
Patch *runtime_explain.patch* releases the problem with error from
InstrEndLoop(). I catch all places where this unlucky function is called
and wrap in checks on *runtime* flag. This flag indicates whether
*ExplainQuery* is called for running query. Also I complement explain
output, you can see details in README.md in repository.
--
Maksim Milyutin
Postgres Professional: http://www.postgrespro.com
Russian Postgres Company
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