Re: pgsql 10: hash indexes testing

On Fri, Aug 4, 2017 at 10:59 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> On Fri, Aug 4, 2017 at 6:22 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>> I have increased the number of hash bitmap pages as a separate patch.
>> I am not completely sure if it is a good idea to directly increase it
>> to 1024 as that will increase the size of hashmetapagedata from 960
>> bytes to 4544 bytes. Shall we increase it to 512?
>
> I don't quite see what the problem is with increasing it to 4544
> bytes. What's your concern?
>

Nothing as such. It is just that the previous code might have some
reason to keep it at 128, probably if there are that many overflow
bucket pages, then it is better to reindex the index otherwise the
performance might suck while traversing the long overflow chains. In
general, I see your point that if we can provide user to have that big
overflow space, then let's do it.

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