Horton

Re: libpq debug log

Yugo Nagata <nagata@sraoss.co.jp>

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From: Yugo Nagata <nagata@sraoss.co.jp>
To: "Iwata, Aya" <iwata.aya@jp.fujitsu.com>
Cc: "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2018-08-27T12:51:24Z
Lists: pgsql-hackers 
On Fri, 24 Aug 2018 04:38:22 +0000
"Iwata, Aya" <iwata.aya@jp.fujitsu.com> wrote:

> Hi,
> 
> 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. 

Do you mean you want to monitor the protocol message exchange at
the client side to analyze performance issues, right?  Actually,
this might be useful to determin where is the problem, for example,
the client application, the backend PostgreSQL, or somewhere in the
network.

Such logging can be implemented in the application, but if libpq
provides the standard way, it would be helpful to resolve a problem
without modifying the application code.

> 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. 

I couldn't image how this is like. Could you show us a sample of log lines
in your head?

> To collect the log, set the connection string or environment variable.
> - logdir or PGLOGDIR : directory where log file written
> - logsize or PGLOGSIZE : maximum log size

How we can specify the log file name?  What should happen if a file size
exceeds to PGLOGSIZE?

Regards,
-- 
Yugo Nagata <nagata@sraoss.co.jp>

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.