Обсуждение: Use case for enabling log_duration other than benchmarking
Do you know any use case for enabling log_duration? Like 3rd party tools for instance.I find this parameter pretty much useless (in opposite to log_min_duration_statement) as it does not show the query text, so besides having just the timing logged it is of no use in troubleshooting and often causes huge overhead. Am I missing something?
https://www.postgresql.org/docs/current/runtime-config-logging.html
Note
The difference between enabling log_duration and setting log_min_duration_statement to zero is that exceeding log_min_duration_statement forces the text of the query to be logged, but this option doesn't. Thus, if log_duration is on and log_min_duration_statement has a positive value, all durations are logged but the query text is included only for statements exceeding the threshold. This behavior can be useful for gathering statistics in high-load installations.
Born in Arizona, moved to Babylonia.
On 1/10/23 07:14, Alicja Kucharczyk wrote:Do you know any use case for enabling log_duration? Like 3rd party tools for instance.I find this parameter pretty much useless (in opposite to log_min_duration_statement) as it does not show the query text, so besides having just the timing logged it is of no use in troubleshooting and often causes huge overhead. Am I missing something?
https://www.postgresql.org/docs/current/runtime-config-logging.htmlNote
The difference between enabling
log_durationand setting log_min_duration_statement to zero is that exceedinglog_min_duration_statementforces the text of the query to be logged, but this option doesn't. Thus, iflog_durationisonandlog_min_duration_statementhas a positive value, all durations are logged but the query text is included only for statements exceeding the threshold. This behavior can be useful for gathering statistics in high-load installations.
wt., 10 sty 2023 o 14:57 Ron <ronljohnsonjr@gmail.com> napisał(a):On 1/10/23 07:14, Alicja Kucharczyk wrote:Do you know any use case for enabling log_duration? Like 3rd party tools for instance.I find this parameter pretty much useless (in opposite to log_min_duration_statement) as it does not show the query text, so besides having just the timing logged it is of no use in troubleshooting and often causes huge overhead. Am I missing something?
https://www.postgresql.org/docs/current/runtime-config-logging.htmlNote
The difference between enabling
log_durationand setting log_min_duration_statement to zero is that exceedinglog_min_duration_statementforces the text of the query to be logged, but this option doesn't. Thus, iflog_durationisonandlog_min_duration_statementhas a positive value, all durations are logged but the query text is included only for statements exceeding the threshold. This behavior can be useful for gathering statistics in high-load installations.thank you Ron.My question is a bit more practical - Does anyone really find it useful?What value brings the info that 20% of my query are under 1ms and 10% over 1 minute
If your application requires subsecond response, and you're only getting subsecond response some of the time, then you obviously want to know why. Part of that is checking to see if the database and queries are doing their job.
- If just checked once and then turned off - I can understand to have more visibility into the overall characteristics. But let say someone have it enabled on a production system all the time - what could be the reason for that?
Born in Arizona, moved to Babylonia.
If your application requires subsecond response, and you're only getting subsecond response some of the time, then you obviously want to know why. Part of that is checking to see if the database and queries are doing their job.
On Tue, Jan 10, 2023 at 04:57:11PM +0100, Alicja Kucharczyk wrote: > thank you Ron. > My question is a bit more practical - Does anyone really find it useful? > What value brings the info that 20% of my query are under 1ms and 10% over 1 > minute - If just checked once and then turned off - I can understand to have > more visibility into the overall characteristics. But let say someone have it > enabled on a production system all the time - what could be the reason for > that? I think the big value is that enabling log_statement and log_duration prints the statement text when it _starts, while enabling only log_min_duration_statement prints the statement and duration when it _ends_. -- Bruce Momjian <bruce@momjian.us> https://momjian.us EDB https://enterprisedb.com Embrace your flaws. They make you human, rather than perfect, which you will never be.