I have a big performance problem in my SQL select query:
select * from event where user_id in
Hi,
I have a big performance problem in my SQL select query:
select * from event where user_id in
On Thu, 24 Sep 2009, Dan Sugalski wrote:
Is there any practical limit to the number of shared buffers PG 8.3.7 can
handle before more becomes counter-productive?
There are actually two distinct questions here you should consider,
because the popular wisdom here and what makes sense for your
Xia Qingran qingran@gmail.com writes:
I have a big performance problem in my SQL select query:
select * from event where user_id in
(500,499,498, ... ,1,0);
The above SELECT always spends 1200ms.
Your EXPLAIN ANALYZE shows that the actual runtime is only about 240ms.
So either the
Is there any practical limit to the number of shared buffers PG 8.3.7
can handle before more becomes counter-productive?
It is more efficient to have the page in shared buffers, rather than doing
a context switch to the OS, copying the entire page from the OS's cache
into shared buffers,
if you reuse that set a lot, how about storing it in a table , and doing the
join on db side ? if it is large, it sometimes makes sense to create temp
table just for single query (I use that sort of stuff for comparing with few
M records).
But temp tables in that case have to be short lived, as
On Fri, 25 Sep 2009, Jeff Janes wrote:
Does it do this even if the block was already in shared_buffers?
Usually not. The buffer ring algorithm is used to manage pages that are
read in specifically to satisfy a sequential scan (there's a slightly
different ring method used for VACUUM too).
Xia Qingran wrote:
Hi,
I have a big performance problem in my SQL select query:
select * from event where user_id in
On 26-Sep-2009, at 10:16 PM, Claus Guttesen wrote:
I have a big performance problem in my SQL select query:
select * from event where user_id in
On Sat, Sep 26, 2009 at 9:57 AM, Gerhard Wiesinger li...@wiesinger.com wrote:
On Sat, 26 Sep 2009, Greg Smith wrote:
On Fri, 25 Sep 2009, Jeff Janes wrote:
Does it do this even if the block was already in shared_buffers?
Usually not. The buffer ring algorithm is used to manage pages that
On Sat, Sep 26, 2009 at 8:19 AM, Greg Smith gsm...@gregsmith.com wrote:
Another problem spot are checkpoints. If you dirty a very large buffer
cache, that whole thing will have to get dumped to disk eventually, and on
some workloads people have found they have to reduce shared_buffers
On Sat, 26 Sep 2009, Jeff Janes wrote:
On Sat, Sep 26, 2009 at 8:19 AM, Greg Smith gsm...@gregsmith.com wrote:
Another problem spot are checkpoints. If you dirty a very large buffer
cache, that whole thing will have to get dumped to disk eventually, and on
some workloads people have found
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