On Thu, Apr 2, 2015 at 6:33 AM, Pietro Pugni pietro.pu...@gmail.com wrote:
*T420*
work_mem = 512MB
*MacMini*
work_mem = 32MB
So that is why the T420 does memory sorts and the mini does disk sorts.
I'd start looking at why memory sorts on the T420 is so slow. Check your
numa settings,
On Thu, Apr 2, 2015 at 9:23 AM, Pietro Pugni pietro.pu...@gmail.com wrote:
the command
dmesg | grep -i numa
doesn’t display me anything. I think T420 hasn’t NUMA on it. Is there a
way to enable it from Ubuntu? I don’t have immediate access to BIOS (server
is in another location).
NUMA
On Wed, Apr 1, 2015 at 9:56 AM, Pietro Pugni pietro.pu...@gmail.com wrote:
*Now let’s propose some query profiling times.*
B type set are transactions, so it's impossible for me to post EXPLAIN
ANALYZE results. I've extracted two querys from a single transactions and
executed the twos on
record, seeks somewhere else to read something, etc.
Or, if you put WAL on a journalled FS, even if it's on dedicated spindles ;-)
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wasn't 100% utilized?
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(depending on
insert/update/delete patterns coupled with query types)
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, are you getting to the point of migrating large XFS filesystems to
ext4 for production databases yet? Or at least using ext4 in new
large-scale filesystems for PG?
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the battery is failing...
of course, it's going to start screaming and send all your monitoring
alarms off (you're monitoring that, right?), but have you thought to
make sure that your FS is remounted with barriers at the first sign of
battery trouble?
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details in the
future, so keep up on the filesystem details of whatever you're
using...
So keep doing burn-ins, with real pull-the-cord tests... They can't
prove it's 100% safe, but they can quickly prove when it's not ;-)
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postgres (server and psql) using the source default of /tmp?
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for the kernel to setup the mappings is
less than the repeated syscalls of a simple write().
All those things seem like something that somebody could synthetically
benchmark to prove value before even trying to bolt into PostgreSQL.
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responses since
the fsync/barreir hasn't completed.
Or have I missed another subtle interaction?
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as data, on a RAID5, even with BBU is worse than WAL on a
dedicated set of RAID1 spindles with it's own BBU.
Wow!
;-)
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of not having to wait for all the dirty
ext3 pages from your whole database FS to be flushed before the WAL write
can complete on it's own FS.
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* Greg Smith g...@2ndquadrant.com [100121 09:49]:
Aidan Van Dyk wrote:
Sure, if your WAL is on the same FS as your data, you're going to get
hit, and *especially* on ext3...
But, I think that's one of the reasons people usually recommend putting
WAL separate.
Separate disks can actually
to completely chop your 43MB/s rate...
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it as a dedicated DB-only machine. Go
figure :) doing other stuff the cache tends to turn over pretty quickly.
All the more reason to find a way to use it all as shared buffers and
lock it into ram...
Oh, sorry, you expect the DB to play nice with everything else?
;-)
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on
the OS and the disks. If you access a table via index scan though, all its
pages will go through shared_buffers.
In older version too, or only since synchronized scans got in?
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it ;-)
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that scares me about raid-5 is the write-hole, and the
possible delayed inconsistency that brings...
Again, hopefully mitigated by a dependable controller w/ BBU...
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% improvement? The
forking isn't the expensive part, the per-database setup that happens is
the expensive setup... All pre-forking would save us is a tiny part of
the initial setup, and in turn make our robust postmaster controller no
longer have control.
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for
small simple queries where all the data is in shared buffers or the cache.
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... as long as you don't ever have a disk or system crash ...
... or can afford to rebuild if you do ...
... etc ...
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* Joshua D. Drake [EMAIL PROTECTED] [081209 11:01]:
Yes the SmartArray series is quite common and actually know to perform
reasonably well, in RAID 10. You still appear to be trying RAID 5.
*boggle*
Are people *still* using raid5?
/me gives up!
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it's poor performance is...
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Seems like this didn't make it through to the list the first time...
* Aidan Van Dyk [EMAIL PROTECTED] [081106 22:19]:
* David Rees [EMAIL PROTECTED] [081106 21:22]:
2. A write barrier instructs the lower level hardware that commands
issued before the barrier must be written to disk
But the documents don't mention anything about cluster being unsafe.
AFAIK, Vacuum full doesn't suffer the same MVCC issues that cluster
does. Is this correct?
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