Search Postgresql Archives

Re: Postgres 11, partitioning with a custom hash function

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On 4 October 2018 at 16:22, Harry B <harrysungod@xxxxxxxxx> wrote:
> I am still having trouble reconciling what happens under the HASH
> partitioning!. If I have text column forming the basis of PARTITIONED BY
> HASH, the HASH value used in the partitioning setup does not seem to match
> to `hashtext()` of that value

It won't match. The hash partition hash is seeded with a special const
(HASH_PARTITION_SEED) see [1].

You could likely roll your own hash ops. See [2] for an example. This
can then be used to create a hash partitioned table like [3].

[1] https://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/backend/partitioning/partbounds.c#l2056
[2] https://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/test/regress/sql/insert.sql#l241
[3] https://git.postgresql.org/gitweb/?p=postgresql.git;a=blob;f=src/test/regress/sql/hash_part.sql#l10

-- 
 David Rowley                   http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services




[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Index of Archives]     [Postgresql Jobs]     [Postgresql Admin]     [Postgresql Performance]     [Linux Clusters]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Postgresql & PHP]     [Yosemite]

  Powered by Linux