Re: pg_waldump stucks with options --follow or -f and --stats or -z

From: Michael Paquier <michael(at)paquier(dot)xyz>
To: Bharath Rupireddy <bharath(dot)rupireddyforpostgres(at)gmail(dot)com>
Cc: Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org>, PostgreSQL Hackers <pgsql-hackers(at)lists(dot)postgresql(dot)org>
Subject: Re: pg_waldump stucks with options --follow or -f and --stats or -z
Date: 2021-11-26 06:20:08
Message-ID: YaB8mLRRyA0DWnzY@paquier.xyz
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On Sat, Nov 20, 2021 at 11:46:35AM +0530, Bharath Rupireddy wrote:
> Thanks. Here's the v3 patch, a much simpler one. Please review it.

+ pqsignal(SIGINT, SignalHandlerForTermination);
+ pqsignal(SIGTERM, SignalHandlerForTermination);
+ pqsignal(SIGQUIT, SignalHandlerForTermination);
FWIW, I think that we should do this stuff only on SIGINT. I would
imagine that this behavior becomes handy mainly when one wishes to
Ctrl+C the terminal running pg_waldump but still get some
information.

XLogDumpCountRecord(&config, &stats, xlogreader_state);
+ stats.endptr = xlogreader_state->currRecPtr;
Isn't what you are looking for here EndRecPtr rather than currRecPtr,
to track the end of the last record read?

+ When <option>--follow</option> is used with <option>--stats</option> and
+ the <application>pg_waldump</application> is terminated or interrupted
+ with signal <systemitem>SIGINT</systemitem> or <systemitem>SIGTERM</systemitem>
+ or <systemitem>SIGQUIT</systemitem>, the summary statistics computed
+ as of the termination will be displayed.
This description is not completely correct, as the set of stats would
show up only by using --stats, in non-quiet mode. Rather than
describing this behavior at the end of the docs, I think that it would
be better to add a new paragraph in the description of --stats.
--
Michael

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