Re: Patch: Write Amplification Reduction Method (WARM)

On Sat, Mar 25, 2017 at 1:24 PM, Amit Kapila <amit.kapila16@gmail.com> wrote:
> On Fri, Mar 24, 2017 at 11:49 PM, Pavan Deolasee
> <pavan.deolasee@gmail.com> wrote:
>>
>> On Fri, Mar 24, 2017 at 6:46 PM, Amit Kapila <amit.kapila16@gmail.com>
>> wrote:
>>>
>
>> While looking at this problem, it occurred to me that the assumptions made
>> for hash indexes are also wrong :-( Hash index has the same problem as
>> expression indexes have. A change in heap value may not necessarily cause a
>> change in the hash key. If we don't detect that, we will end up having two
>> hash identical hash keys with the same TID pointer. This will cause the
>> duplicate key scans problem since hashrecheck will return true for both the
>> hash entries.

Isn't it possible to detect duplicate keys in hashrecheck if we
compare both hashkey and tid stored in index tuple with the
corresponding values from heap tuple?

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