Hello,
I recently stumbled upon on what could be a planner bug or a corner case.
If false condition OR ... is added to WHERE clause of SELECT query,
then the planner chooses a very inefficient plan. Consider a query:
SELECT count(k0.id)
FROM k0
WHERE 1 = 2
OR k0.id IN (
SELECT
2008/1/30, Tom Lane [EMAIL PROTECTED]:
Dmitry Potapov [EMAIL PROTECTED] writes:
2008/1/25, Tom Lane [EMAIL PROTECTED]:
It's hard to tell whether the planner is just being overoptimistic
about the results of ANDing the three join conditions, or if one or
more of the basic condition
Hello,
(Tom, sorry if you receive this letter twice. The first copy was
unintentionally sent with 'reply to sender only', I resend it to the
list, reply this one to keep the thread, please.)
2008/1/25, Tom Lane [EMAIL PROTECTED]:
Well, there's our problem: an estimate of 1
I've got two huge tables with one-to-many relationship with complex
key. There's also a view, which JOINs the tables, and planner chooses
unoptimal plan on SELECTs from this view.
The db schema is declared as: (from on now, I skip the unsignificant
columns for the sake of simplicity)
CREATE
Hello!
We run a large (~66Gb) web-backend database on Postgresql 8.2.4 on
Linux. The hardware is Dual Xeon 5130 with 16Gb ram, LSI Megaraid U320-2x
scsi controller w/512Mb writeback cache and a BBU. Storage setup contains 3
raid10 arrays (data, xlog, indexes, each on different
2007/8/22, Joshua D. Drake [EMAIL PROTECTED]:
We've run into an issue of IO storms on checkpoints. Once in 20min
(which is checkpoint_interval) the database becomes unresponsive for
about
4-8 seconds. Query processing is suspended, server does nothing but
writing
What are your
2007/8/22, Mark Mielke [EMAIL PROTECTED]:
Are you able to show that the dirty pages are all coming from postgres?
I don't know how to prove that, but I suspect that nothing else except
postgres writes to disk on that system, because it runs nothing except
postgresql and syslog (which I
2007/8/22, Kenneth Marshall [EMAIL PROTECTED]:
You are working at the correct level. The bgwriter performs the I/O
smoothing
function at the database level. Obviously, the OS level smoothing function
needed to be tuned and you have done that within the parameters of the OS.
You may want to
