Re: rewrite HeapSatisfiesHOTAndKey

On Sat, Jan 7, 2017 at 11:27 AM, Mithun Cy <mithun(dot)cy(at)enterprisedb(dot)com> wrote:
> On Thu, Jan 5, 2017 at 6:15 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>>
>> Your test and results look good, what kind of m/c you have used to
>> test this. Let me see if I or one of my colleague can do this and
>> similar test on some high-end m/c.
>
> As discussed with Amit, I have tried to run the same tests with below
> modification,
> 1. Increased the total rows to 10milion.
> 2. Set fsync off;
> 3. Changed tests as below. Updated all rows at a time.
>
> VACUUM FULL;
> BEGIN;
> UPDATE testtab SET col2 = md5(random()::text);
> ROLLBACK;
>
> I have run these tests on IBM power2 which have sufficient ram. I have
> set shared_buffer=32GB.
>
> My results show after this patch there is a slight increase in
> response time (psql \timing was used) for the above update statement.
> Which is around 5 to 10% delay.
>

I would like to add here, that the intention of the test was to stress
the changes of the patch to see the overhead patch can incur. Now,
surely this is a synthetic test prepared to test this patch, but I
think it indicates that the changes have some overhead which might or
might not be ignorable depending on how important is to get this
patch. I think if Warm tuples or indirect indexes need this patch and
they can't do without this, then it is worth considering this patch
along with those patches. OTOH, if we can reduce the overhead, then
it might be okay proceed with this patch on the basis of simplicity it
can bring.

--
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com