Came across the following in a paper from Oct 2010. Was wondering is this is
old news I missed in this group.
http://pdos.csail.mit.edu/papers/linux:osdi10.pdf
about Linux optimization on multi-core CPU's.
The group at MIT were exploring how some Linux apps were scaling up ---
sometimes badly, m
In a federated database engine I built in the mid-90's,
it more or less ran both plans in parallel, to implement fast-first and
min-total cost.
The index query in general started returning rows whose oids went into a filter
that discarded them from the serial query once it started to crank things
Now I'm back where I can go look at the source code :-)
Thanks.
> -Original Message-
> From: Jaime Casanova [mailto:jcasa...@systemguards.com.ec]
> Sent: Monday, July 13, 2009 8:40 PM
> To: Mischa Sandberg
> Cc: Heikki Linnakangas; PostgreSQL-development
> Subje
Does PG have an intermediate execution node to sort/batch index entries (heap
tuple ptrs) by heap page prior to lookup? Something mssql does ...
> -Original Message-
> From: pgsql-hackers-ow...@postgresql.org
> [mailto:pgsql-hackers-ow...@postgresql.org] On Behalf Of Bruce Momjian
> Sent:
Quoting Tom Lane <[EMAIL PROTECTED]>:
> Mischa Sandberg <[EMAIL PROTECTED]> writes:
> > I'm going to skip the kill(1,0) test and depend on nattch only,
> > with a function that PGSharedMemoryIsInUse() can also use.
> > (For a healthy server, nattch is never l
Quoting Stephen Frost <[EMAIL PROTECTED]>:
> * Tom Lane ([EMAIL PROTECTED]) wrote:
> > "Marc G. Fournier" <[EMAIL PROTECTED]> writes:
> > > Easiest fix: change the UID of the user running the postmaster
> (ie. pgsql) so
> > > that each runs as a distinct UID (instead of distinct PGPORT) ...
> been
Quoting Tom Lane <[EMAIL PROTECTED]>:
> Mischa Sandberg <[EMAIL PROTECTED]> writes:
> > + /* In a FreeBSD jail, you can't "kill -0" a
> postmaster
> > +* running in a different jail, so the shm seg
> might
> > +
Here (@sophos.com) we run machine cluster tests using FreeBSD jails. A
jail is halfway between a chroot and a VM. Jails blow a number of
assumptions about a unix environment: sysv ipc's are global to all
jails; but a process can only "see" other processes also running in the
jail. In fact, the quic
Tom Lane wrote:
Andrew Dunstan <[EMAIL PROTECTED]> writes:
How expensive is this going to be, especially for huge numbers of rows?
Certainly cheaper than firing a per-row trigger.
I'm curious: I've never written a MSSQL trigger that did NOT use the
INSERTED/DELETED pseudotables (aka NEW/OLD
Jim C. Nasby wrote:
On Sun, May 21, 2006 at 02:58:17PM -0700, Josh Berkus wrote:
Actually, porting TSQL to PL/pgSQL would be very hard. I speak as an expert
TSQL developer. For example, most data manipulation in TSQL is done through
updatable cursors, something we don't currently support.
Martijn van Oosterhout wrote:
For high-end MSSQL shops, a high value is being able to trace and profile
(EXPLAIN) every client SQL command from the server side ... with plenty of
options for selective trace.
This would also be highly valuable to have in PostgreSQL.
Are we talking EXPLAIN (wh
On Thursday 18 May 2006 12:38, Josh Berkus wrote:
Personally, I'd go after MSSQL before I bothered with MySQL. Sure, let's
make *migration* easier for those who wake up and smell the BS, but
migration can (and probably should) be one-way.
Somebody earlier was mentioning, why no automatic tran
[short]
This probably would be an uneasy fit into generic backend code.
Was hoping the GPUSort project might have fleeced/sorted out some issues.
[long]
Simon Riggs wrote:
On Wed, 2006-04-12 at 10:00 -0700, Mischa Sandberg wrote:
...
Long answer: we're shipping a server (appliance) pr
Greg Sabino Mullane wrote:
I wonder if it would help much just to change EXPLAIN to indent with
something other than spaces?
I like that. Maybe even decrease the indenting a little more, and compress
some of the inner whitespace (such as the 2 spaces after the operator name)
Might it be wort
Martijn van Oosterhout wrote:
On Tue, Apr 11, 2006 at 04:02:07PM -0700, Mischa Sandberg wrote:
Anybody on this list hear/opine anything pf the GPUSort project for
postgresql? I'm working on a radix-sort subcase for tuplesort, and there
are similarities.
http://www.andrew.cmu.edu/user/n
Jim C. Nasby wrote:
On Wed, Apr 12, 2006 at 04:53:20PM +0200, Thomas Hallgren wrote:
Well, the downside is that such a format means explain output is now
twice as long. But I'd love to see something like that as an option. I'd
also still like to see an SQL-parseable version as
Anybody on this list hear/opine anything pf the GPUSort project for postgresql?
I'm working on a radix-sort subcase for tuplesort, and there are similarities.
http://www.andrew.cmu.edu/user/ngm/15-823/project/
--
Engineers think that equations approximate reality.
Physicists think that reality
Are there are more possibilities for some bug in the plpgsql engine to allow an
exploit: actually changing the stack through a buffer overflow, or a bug in an
intrinsic function, or allowing an injection that crosses some privilege
boundary, via someone else's EXECUTE?
It's a lot easier to ver
I'm stuck with a web app that periodically has truly awful query
response times. The cause may be an interaction between system load,
vacuum-analyze scheduling, the occasional wild variation in join
selectivity, and stats collection. Logging the queries and running them
later doesn't create an obvi
Quoting Josh Berkus :
> Mischa,
>
> > Okay, although given the track record of page-based sampling for
> > n-distinct, it's a bit like looking for your keys under the
> streetlight,
> > rather than in the alley where you dropped them :-)
>
> Bad analogy, but funny.
Bad analogy? Page-
Quoting Markus Schaber <[EMAIL PROTECTED]>:
> Hi, Josh,
>
> Josh Berkus wrote:
>
> > Yes, actually. We need 3 different estimation methods:
> > 1 for tables where we can sample a large % of pages (say, >= 0.1)
> > 1 for tables where we sample a small % of pages but are "easily
> estimated"
> >
Just finished writing the PG rules to maintain a bunch of materialized
(aggregate) views on a ROLAP cube --- yes, I've seen Jonathan
Gardner's "matview" for postgres; didnt cover what I needed :-(. PG
happens to be pretty convenient for roll-your-own OLAP, thanks to
RULES and ARRAY datatypes. S
Quoting Josh Berkus :
> > >Perhaps I can save you some time (yes, I have a degree in Math). If I
> > >understand correctly, you're trying extrapolate from the correlation
> > >between a tiny sample and a larger sample. Introducing the tiny sample
> > >into any decision can only produce a less accu
Quoting Andrew Dunstan <[EMAIL PROTECTED]>:
> After some more experimentation, I'm wondering about some sort of
> adaptive algorithm, a bit along the lines suggested by Marko
Ristola, but limited to 2 rounds.
>
> The idea would be that we take a sample (either of fixed size, or
> some sm
Greg Stark wrote:
Mischa Sandberg <[EMAIL PROTECTED]> writes:
I take it that it is a very reasonable assumption that only a small proportion
of index records are actually invalid (else Yurk why use the index?).
That's faulty logic, the percentage of tuples that are valid is entirely
Greg Stark wrote:
Doug McNaught <[EMAIL PROTECTED]> writes:
Short answer: MVCC tuple visibility status isn't (and can't be) stored
in the index.
Well the "can't" part is false or at least unproven. From prior discussion the
only thing that would be technically challenging would be avoiding dead
Ummm time to get a 'Unix in 21 days' book,
because what you're relating indicates you are battling with
some beginner basics:
Try:
$ cd /usr/local
or:
$ cd /usr
$ cd local
not:
$ cd /usr
$ cd /local
And you can't execute a program in the current directo
http://www.cs.mcgill.ca/~kemme/papers/vldb00.html
ARC buffer replacement policy supersedes LRU.
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