Horton

Re: libpq debug log

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: "Iwata, Aya" <iwata.aya@jp.fujitsu.com>
Cc: "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2018-08-24T13:48:34Z
Lists: pgsql-hackers 
"Iwata, Aya" <iwata.aya@jp.fujitsu.com> writes:
> I'm going to propose libpq debug log for analysis of queries on the application side.
> I think that it is useful to determine whether the cause is on the application side or the server side when a slow query occurs. 

Hm, how will you tell that really?  And what's the advantage over the
existing server-side query logging capability?

> The provided information is "date and time" at which execution of processing is started, "query", "application side processing", which is picked up information from PQtrace(), and "connection id", which is for uniquely identifying the connection. 

PQtrace() is utterly useless for anything except debugging libpq
internals, and it's not tremendously useful even for that.  Don't
bother with that part.

Where will you get a "unique connection id" from?

How will you deal with asynchronously-executed queries --- either
the PQgetResult style, or the single-row-at-a-time style?

			regards, tom lane

Commits

  1. Rename PQtraceSetFlags() to PQsetTraceFlags().

  2. Suppress length of Notice/Error msgs in PQtrace regress mode

  3. Strip file names reported in error messages on Windows, too.

  4. Fix setvbuf()-induced crash in libpq_pipeline

  5. libpq_pipeline: Must strdup(optarg) to avoid crash

  6. Remove setvbuf() call from PQtrace()

  7. Initialize conn->Pfdebug to NULL when creating a connection

  8. Disable force_parallel_mode in libpq_pipeline

  9. libpq_pipeline: add PQtrace() support and tests

  10. Improve PQtrace() output format

  11. Re-simplify management of inStart in pqParseInput3's subroutines.