Hmmm...I would've thought copy would cache the file...learned something new
(again)....but at least you've identified the problem as caching vs disk i/o.
#1 Are you using the same database file on both Windows and Linux or are you
creating it independently on each? I'm wondering if your Windows system is
fragmented (much more likely than your Linux system is to frag). How full is
the disk that your database is on and have you defragged that disk?
#2 How long does your fread program take to run? If must be much less then 40
seconds I would imagine.
#3 How long does "select * from mytable" take when it's the first thing you run
on both Linux and Windows?
#4 Have you tried changing your caching to "System Cache" instead of "Programs"
jsut to see what happens?
People with gigabyte-sized+ files are frequently out of luck if they have to
actually query the whole database (this is where indexes can come in real handy
to minimize how much reading goes on). But if you walk through all the data
caching the whole database isn't an option if it's bigger than available memory.
Michael D. Black
Senior Scientist
Advanced Analytics Directorate
Northrop Grumman Information Systems
________________________________
From: sqlite-users-boun...@sqlite.org on behalf of Samet YASLAN
Sent: Fri 7/23/2010 3:05 AM
To: sqlite-users@sqlite.org
Subject: EXTERNAL:Re: [sqlite] Very Slow DB Access After Reboot on Windows
I have tried changing the extension and also "copy my.db nul:". The
result does not change a bit. Still 40sec.
I also tried reading the file with fread before openning db connection like;
FILE* fp = fopen(fileName.c_str(), "rb");
if ( fp ) {
char pBuffer[1024*32];
while ( fread(pBuffer, 1024, 32, fp) > 0 )
{
}
fclose(fp);
}
This is very helpful and really decreases the total read performance
including this operation.
But if the file size is too big than this may lead to some problems again.
Anyway there must be some users reaching gigabytes of DB size and I am
not sure they are waiting one hour after restarting their PCs.
There must be a way to solve this problem. As I said before Linux is
just fine. I wish to see Linux on every PC one day.
*Samet YASLAN*
On 22.07.2010 22:51, Kees Nuyt wrote:
> On Thu, 22 Jul 2010 10:44:50 -0500, "Black, Michael (IS)"
> <michael.bla...@ngc.com> wrote:
>
>
>> Wrong....read the docs...if copy didn't do binary by default there would so
>> many screwed up computers in the world....
>>
>>
>> http://www.microsoft.com/resources/documentation/windows/xp/all/proddocs/en-us/copy.mspx?mfr=true
>>
>> Using /b
>>
> I stand corrected, thanks for the research.
>
_______________________________________________
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
_______________________________________________
sqlite-users mailing list
sqlite-users@sqlite.org
http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
