Here's the answer for you from the jdbc list:
Alvin Hung wrote:
Currently, 8.0.2 / JDBC 8.0-310, log_min_duration_statement does not
work with JDBC. Nothing will get logged. This makes it very
difficult to tune a java application. Can you tell me when will this
be fixed? Thanks.
This is a server limitation: it does not handle logging of the V3
extended query protocol very well. There's gradual progress being made
on it; you might want to search the pgsql-hackers and pgsql-patches
archives for details.
==========================================================================================
We are using prepared statements, but we are using the 7.4 driver with
the 8.0.3 server. I think it comes down to locally (on the client)
prepared statements vs using server side prepared statments. I never
got past this issue (changing the code is in our todo list, but pretty
far down it) so I never noticed the logging issues.)
I had a problem with prepared statements with the 8.x drivers -- here's
what I got from the jdbc list when I asked the question:
1. What changed between the driver versions that generate this error?
The driver started to use server-side prepared statements for
parameterization of queries (i.e. the driver translates ? to $n in the
main query string, and sends the actual parameter values out-of-band
from the query itself). One sideeffect of this is that parameters are
more strongly typed than in the 7.4.x versions where the driver would do
literal parameter substitution into the query string before sending it
to the backend. Also, you can use parameters in fewer places (they must
fit the backend's idea of where parameterizable expressions are allowed)
-- e.g. see the recent thread about "ORDER BY ?" changing behaviour with
the newer driver.
2. What is the downside of continuing to use the 7.x version of the
driver -- or are there better alternatives (patch, new version, etc). I
am using build 311 of the driver.
Most active development happens on the 8.0 version; 7.4.x is maintained
for bugfixes but that's about it, you won't get the benefit of any
performance improvements or added features that go into 8.0. Also, the
7.4.x driver won't necessarily work with servers >= 8.0.
In the longer term, the 7.4.x version will eventually become unmaintained.
So for the short term, you could downgrade your driver.
Brent Henry wrote:
We are running Postgres 8.0.2 with the 8.0.2 jdbc
driver. And yes we are using prepared statements.
I've spent hours trying to get the
'log_min_duration_statement' and 'log_duration'
options to work with no luck. I never get any
duration from the statement. I also never see 'begin'
or 'commit' in the log so I can't tell how long my
batch commands are taking to commit to the DB.
Is there a different kind of 'prepared' statements
that we should be using in the driver to get logging
to work properly? What is the 'new' protocol?
Tom, what version are you using? Are you using
prepared statements in JDBC?
-Brent
--- Christopher Kings-Lynne
<[EMAIL PROTECTED]> wrote:
we are using jdbc -- the
"log_min_duration_statement = 3000 "
statement works fine for me. Looks like there's
no other work around
for the bug(?). Not sure since I have no
interest in logging a
million statements a day, I only want to see the
poorly performing hits.
Doesn't it depend on what jdbc driver you are
using?
It depends if he's using new-protocol prepared
queries which don't get
logged properly. Wasn't that fixed for 8.1 or
something?
Chris
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