Horton

Re: [POC] hash partitioning

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: amul sul <sulamul@gmail.com>, Ashutosh Bapat <ashutosh.bapat@enterprisedb.com>, Jesper Pedersen <jesper.pedersen@redhat.com>, Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>, Thom Brown <thom@linux.com>, Dilip Kumar <dilipbalaut@gmail.com>, Yugo Nagata <nagata@sraoss.co.jp>, David Steele <david@pgmasters.net>, Greg Stark <stark@mit.edu>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2017-10-12T20:06:11Z
Lists: pgsql-hackers 
On Thu, Oct 12, 2017 at 3:43 PM, Andres Freund <andres@anarazel.de> wrote:
> Are we going to rely on the the combine function to stay the same
> forever after?

If we change them, it will be a pg_upgrade compatibility break for
anyone using hash-partitioned tables with more than one partitioning
column.  Dump and reload will also break unless
--load-via-partition-root is used.

In other words, it's not utterly fixed in stone --- we invented
--load-via-partition-root primarily to cope with circumstances that
could change hash values --- but we sure don't want to be changing it
with any regularity, or for a less-than-excellent reason.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

Commits

  1. Add hash partitioning.

  2. Add sanity check for pg_proc.provariadic

  3. Add hash_combine64.

  4. Make RelationGetPartitionDispatchInfo expand depth-first.

  5. Introduce 64-bit hash functions with a 64-bit seed.

  6. pg_dump: Add a --load-via-partition-root option.