| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Ron <rjpeace(at)earthlink(dot)net> |
| Cc: | Martijn van Oosterhout <kleptog(at)svana(dot)org>, pgsql-performance(at)postgresql(dot)org, pgsql-hackers(at)postgresql(dot)org |
| Subject: | Re: qsort again (was Re: [PERFORM] Strange Create |
| Date: | 2006-02-16 16:20:23 |
| Message-ID: | 28768.1140106823@sss.pgh.pa.us |
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| Lists: | pgsql-hackers pgsql-performance |
Ron <rjpeace(at)earthlink(dot)net> writes:
> Your cost comment basically agrees with mine regarding the cost of
> random memory accesses. The good news is that the number of datums
> to be examined during the pivot choosing process is small enough that
> the datums can fit into CPU cache while the pointers to them can be
> assigned to registers: making pivot choosing +very+ fast when done correctly.
This is more or less irrelevant given that comparing the pointers is not
the operation we need to do.
regards, tom lane
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