A full table scan of 16 million rows and 55 columns on Vista with
FILE_FLAG_RANDOM_ACCESS finished in 600 seconds (cold) and 499 seconds
(warm) and turned Vista into a brick. The same test with the flag removed
ran in 119 seconds (cold) and 99 seconds (warm), and caused no adverse
problems with the OS.

Not even Sql Server could do a full table scan of the same data that fast!
Same test on Sql Server 2005 on the same machine ran in a minimum of 180
seconds, and averaged 220 seconds!  Oh and Sql Server's memory usage shot to
3gb as well.  Fun stuff.

I ran the same tests with SQLite on an XP laptop.  I got 618 seconds with
FILE_FLAG_RANDOM_ACCESS, and 599 seconds without the flag.  Not so dramatic
of a difference, but still in the right direction.

So I'd agree that the hint should only be used for CE, and no other
platforms.  Roger quoted the CE compression blurb from this MSDN page:
http://msdn.microsoft.com/en-us/library/ms923949.aspx

Robert


-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Roger Binns
Sent: Wednesday, September 17, 2008 4:24 PM
To: General Discussion of SQLite Database
Subject: Re: [sqlite] Vista frustrations

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Robert Simpson wrote:
> Ideally, at least on non-CE platforms, I'd like see SQLite not give the OS
> any hints about caching.  However, I'm not sure what kind of performance
hit
> (if any) that would have on Windows.  It's already been proven that
> providing the hint on WinCE is beneficial.

I agree.  Open a ticket and include measurements in it.

With Windows CE, setting the flag prevents compression:

  Using the FILE_FLAG_RANDOM_ACCESS flag in the RAM file
  system, which places files in the object store, will
  prevent a file from being compressed. If performance is
  an issue, this could be the correct solution. Read and
  write operations to a compressed file are slower than
  read and write operations to an uncompressed file.

Roger
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