Jeff Janes writes:
> So my conclusions are:
> 2) Heavy-weight locks are called that for a reason, they use a lot of
> CPU even without contention.
> 3) The CPU usage of the hash-index code proper is quite small, with
> more time being spent in heavy-weight PageLocks (specific to hash
> indexes,
On Sun, Oct 4, 2009 at 7:13 PM, Tom Lane wrote:
> Jeff Janes writes:
>> I see that the docs were recently changed from discouraging hash
>> indexes both because they were no known uses in which they were
>> meaningfully better than btree, and because they aren't recoverable;
>> to now just discou
On Mon, Oct 5, 2009 at 6:49 AM, Tom Lane wrote:
> Jeff Janes writes:
>> Do you know why that should be? I've done some work with gprof, and
>> the results are pretty suspect, because the total gprof time adds up
>> to only about 1/3 of the total time the backend spends on CPU
>> (according to "t
Jeff Janes writes:
> Do you know why that should be? I've done some work with gprof, and
> the results are pretty suspect, because the total gprof time adds up
> to only about 1/3 of the total time the backend spends on CPU
> (according to "top"), and I don't know where the unaccounted for time
>
On Sun, Oct 4, 2009 at 7:13 PM, Tom Lane wrote:
> Jeff Janes writes:
>
>> I've played around a bit with hash indexes, and it seems to me that
>> making them generally worthwhile will take (at least) reducing or
>> entirely doing away with the heavy-wait locks.
>
> Concurrency is really the least
Jeff Janes writes:
> I see that the docs were recently changed from discouraging hash
> indexes both because they were no known uses in which they were
> meaningfully better than btree, and because they aren't recoverable;
> to now just discouraging them because they are not recoverable. Does
> t
I see that the docs were recently changed from discouraging hash
indexes both because they were no known uses in which they were
meaningfully better than btree, and because they aren't recoverable;
to now just discouraging them because they are not recoverable. Does
that mean there are now uses in
