linux+large database question

Manfred Spraul (manfreds@colorfullife.com)
Tue, 10 Aug 1999 01:32:10 +0200


I read that you/SGI made benchmarks with Oracle and 4 MB page tables, so
I hope that you can aswer some of these question:

What's the typical file layout for a large database, and how is the
database accessed?
i.e.
* mostly mmap, or normal read/write calls?
* one huge file, or many independant files?

* do you know if some UNIXes support multiple outstanding read/write
operations per file handle? Under Win32, I can store the file pointer in
an OVERLAPPED structure and send multiple parallel operations to the
same handle. AFAIK, Linux doesn't support that.
* how many parallel read/write operation are attempted per file?
Just one operation, or multiple operations [using multiple filp's?]?

I ask these questions because I try to find an acceptable synchonization
for sys_read()/ sys_write()/ sys_ftruncate()/ O_APPEND. Currently
[2.3.13], this is completely missing, and I'm not sure that i_sem is the
correct sync object.

Regards,
Manfred

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