From: Bruce Momjian <pgman@candle.pha.pa.us>
Message-Id: <200506290122.j5T1Mt721527@candle.pha.pa.us>
Subject: Re: log_min_duration_statement versus log_statement
In-Reply-To: <20050621181832.GR17728@www.async.com.br>
To: Christian Robottom Reis <kiko@async.com.br>
Date: Tue, 28 Jun 2005 21:22:55 -0400 (EDT)
Cc: pgsql-docs@postgresql.org,
	Guilherme Salgado <salgado@async.com.br>
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OK, what if we change the documentaiton to be:

	log_min_duration_statement = 1000 # Log all statements whose
	                 # execution time exceeds the value, in
	                 # milliseconds.  -1 disables. Zero logs
	                 # all statements and their durations.

I think you are confused because log_min_duration_statement is really
about _when_ to log (duration > ? ms), and what to log (the statement).

Also, if you set log_min_duration_statement = 1000, it will print every
statement which takes over 1 second, and its duration.  Are you not
seeing that happen?

---------------------------------------------------------------------------

Christian Robottom Reis wrote:
> 
> Hello there,
> 
>     I've just discovered that our postgresql.conf and the related
> documentation are a bit unclear when explaining how log_min_duration_statement
> works. From the wording 
> 
>     log_min_duration_statement = 1000 # Log all statements whose
>                  # execution time exceeds the value, in
>                  # milliseconds.  -1 disables. Zero logs
>                  # all statements.
> 
> I would think that if I enabled it, it would override/control the statements
> being logged. However, that's not how it behaves (at least in 
> 
>     kiko@anthem:~$ psql -V
>     psql (PostgreSQL) 7.4.7
> 
> ) -- if I enable it /and/ log_statement is enabled as well, I get all
> statements logged. In other words, the trailing sentence:
> 
>     # Zero logs all statements.
> 
> is confusing because it seems to imply that to log all statements you should
> set log_min_duration_statement to zero.
> 
> I'd much prefer a behaviour change here (it would make it more obvious and
> useful for log_min_duration_statement, which appears under "When to Log", to
> control /when/ to log, and "What to log" to control /what/ to log :-), but I
> think I'd have been less confused with a documentation change that explicitly
> said that if log_statement or log_duration are on, then /all/ statements will
> be logged, regardless of log_min_duration_statement.
> 
> Below is a snippet of that I have now (which is exactly what I want) in
> my postgresql.conf. From visual inspection only, it would appear that
> this configuration would print nothing (since nothing is defined under
> "What to Log"). However, it does exactly what I want (only log
> statements that run over 1s).
> 
> ----------------------------------------------------------------------
> # - When to Log -
> 
> #client_min_messages = notice   # Values, in order of decreasing detail:
>                 #   debug5, debug4, debug3, debug2, debug1,
>                 #   log, info, notice, warning, error
>                 
> #log_min_messages = notice  # Values, in order of decreasing detail:
>                 #   debug5, debug4, debug3, debug2, debug1,
>                 #   info, notice, warning, error, log, fatal,
>                 #   panic
> 
> #log_error_verbosity = default   # terse, default, or verbose messages
> 
> #log_min_error_statement = panic # Values in order of increasing severity:
>                  #   debug5, debug4, debug3, debug2, debug1,
>                  #   info, notice, warning, error, panic(off)
> 
> log_min_duration_statement = 1000 # Log all statements whose
>                  # execution time exceeds the value, in
>                  # milliseconds.  -1 disables. Zero logs
>                  # all statements.
> 
> silent_mode = false          # DO NOT USE without Syslog!
> 
> # - What to Log -
> 
> #debug_print_parse = false
> #debug_print_rewritten = false
> #debug_print_plan = false
> #debug_pretty_print = false
> #log_connections = false
> #log_duration = false
> #log_pid = false
> #log_statement = false
> #log_timestamp = false
> #log_hostname = false
> #log_source_port = false
> ----------------------------------------------------------------------
> 
> Opinions? Am I confused? Thanks for listening. 
> 
> Take care,
> --
> Christian Robottom Reis | http://async.com.br/~kiko/ | [+55 16] 3376 0125
> 
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