Horton

Re: Patch: Write Amplification Reduction Method (WARM)

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Pavan Deolasee <pavan.deolasee@gmail.com>
Cc: Alvaro Herrera <alvherre@2ndquadrant.com>, Robert Haas <robertmhaas@gmail.com>, Bruce Momjian <bruce@momjian.us>, Jaime Casanova <jaime.casanova@2ndquadrant.com>, Haribabu Kommi <kommi.haribabu@gmail.com>, Tomas Vondra <tomas.vondra@2ndquadrant.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-03-27T11:15:40Z
Lists: pgsql-hackers 
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

Commits

  1. Implement SortSupport for macaddr data type

  2. Simplify check of modified attributes in heap_update

  3. Remove direct uses of ItemPointer.{ip_blkid,ip_posid}

  4. Fix CatalogTupleInsert/Update abstraction for case of shared indstate.

  5. Provide CatalogTupleDelete() as a wrapper around simple_heap_delete().

  6. Band-aid fix for incorrect use of view options as StdRdOptions.

  7. Update visibility map in the second phase of vacuum.

  8. Avoid having two copies of the HOT-chain search logic.

  9. Postgres95 1.01 Distribution - Virgin Sources