Richard Neill wrote:
The key issue for short,fast transactions seems to be
how fast an fdatasync() call can run, forcing the commit to disk, and
allowing the transaction to return to userspace.
Attached is a short C program which may be of use.
Right. I call this the "commit rate" of the storage, and on traditional
spinning disks it's slightly below the rotation speed of the media (i.e.
7200RPM = 120 commits/second). If you've got a battery-backed cache
in front of standard disks, you can easily clear 10K commits/second.
I normally test that out with sysbench, because I use that for some
other tests anyway:
sysbench --test=fileio --file-fsync-freq=1 --file-num=1
--file-total-size=16384 --file-test-mode=rndwr run | grep "Requests/sec"
--
Greg Smith 2ndQuadrant Baltimore, MD
PostgreSQL Training, Services and Support
greg@xxxxxxxxxxxxxxx www.2ndQuadrant.com
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