On Wed, 30 May 2012, Merlin Moncure wrote:
hurk -- ISTM that since IOS is masikng the heap lookups, there must
be contention on the index itself? Does this working set fit in
shared memory? If so, what happens when you do a database restart and
repeat the IOS test?
The dataset fits well in shared buffers
Here are the data sizes
public.idt_photoobservation_small | 521 MB |
528756
public.idt_match_idx | 1084 MB |
528762
public.idt_match_transitid_healpixid_idx | 1522 MB |
1955140
public.idt_match | 2906 MB |
528753
And shared buffers are 10G
If I restart the db the timings do not change significantly. There is always some
variation which I don't really understand, e.g. the parallel runs sometimes
take 18s, or 25 seconds, or 30 seconds per thread. So there is something else
affecting
the runs -- I don't know, maybe that's related to which thread starts first,
or what is the starting point of the seq scan... (there is no other
activity on the machine btw).
Cheers,
S
*****************************************************
Sergey E. Koposov, PhD, Research Associate
Institute of Astronomy, University of Cambridge
Madingley road, CB3 0HA, Cambridge, UK
Tel: +44-1223-337-551 Web: http://www.ast.cam.ac.uk/~koposov/
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