Re: [PERFORM] Tryint to match Solaris-Oracle performance with directio?

2004-09-18 Thread Shachar Shemesh
Mischa Sandberg wrote:
In the meantime, what I gather from browsing mail archives is that 
postgresql on Solaris seems to get hung up on IO rather than CPU.
Well, people more knowledgeable in the secrets of postgres seem 
confident that this is not your problem. Fortunetly, however, there is a 
simple way to find out.

Just download the utinyint var type from pgfoundry 
(http://pgfoundry.org/projects/sql2pg/). There are some stuff there you 
will need to compile yourself from CVS. I'm sorry, but I haven't done a 
proper release just yet. In any case, the utinyint type should provide 
you with the data type you seek, and thus allow you to find out whether 
this is, indeed, the problem.

--
Shachar Shemesh
Lingnu Open Source Consulting ltd.
http://www.lingnu.com/
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Re: [PERFORM] PostgreSQL on VMWare vs Windows vs CoLinux

2004-06-02 Thread Shachar Shemesh
Greg Stark wrote:
That said, I'm curious why the emulated servers performed better than the
Native Windows port. My first thought is that they probably aren't syncing
every write to disk so effectively they're defeating the fsyncs, allowing the
host OS to buffer disk writes.
 

I havn't tested it, and it's certanly possible. However, please bear in 
mind that it is also possible that it just gives better performance.

The reason this may be possible is that the emulation layer gets the CPU 
(and other resources) from the OS in bulk, and decides on it's own how 
to allocate it to the various processes running within the emulation. 
Inparticular, this on it's own is done using the stock Linux kernel. 
As Postgresql works sufficiently better on Linux than on Windows, this 
yields better performance.

Again - speculation only. Someone should defenitely make sure that no 
caching takes place where it shouldn't.

As a side note, I have had a chance to talk to Dan Aloni (coLinux 
maintainer) about running PostgreSQL on coLinux. He said that he knows 
that this particular use is high on people's priority list, but he feels 
it is totally unsafe to run a production database on alpha grade 
software. Then again, free software projects being what they are, this 
is usually what a maintainer would say.

Shachar
--
Shachar Shemesh
Lingnu Open Source Consulting
http://www.lingnu.com/
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