Patrick TJ McPhee wrote:
% Patrick TJ McPhee wrote:
[...]
[the query is "select 1"]
% > But if I turn on duration logging, I get timings like
% > LOG: duration: 91.480 ms
The logs and data are all one file system, which seems to be on a logical
volume with a single disk sitting under it.
Florian Pflug reports that he had a similar problem due to a slow RAID
controller driver, to which I have no comment.
You could try doing:
begin;
select 1;
select 1;
...
rollback;
If this is faster, than it's committing a transaction which is slow -
remember that a statement not wrapped in begin/commit will cause
postgres to start a transaction, execute the statement, and commit
afterwards.
If this is slow too, then I'd suggest playing with postgresql.conf
parameters - e.g. try turning any logging, and the statistics collector
off. If that doesn't reveal a possible cause, then I'd suggest that
you strace the backend you're connected to, and try to see where it's
spending it's time. Since 100ms for a simple "select 1;" is way out
of bounds, I bet that it's some syscall that's taking up all the time -
probably either network or disk related.
greetings, Florian Pflug
Thanks for your comments.
