Horton

Re: [POC] hash partitioning

Robert Haas <robertmhaas@gmail.com>

View thread View on postgr.es
From: Robert Haas <robertmhaas@gmail.com>
To: amul sul <sulamul@gmail.com>
Cc: 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: 2017-11-02T08:05:48Z
Lists: pgsql-hackers 
On Wed, Nov 1, 2017 at 3:46 PM, amul sul <sulamul@gmail.com> wrote:
> Although partition constraints become more simple, there isn't any performance
> gain with 0005 patch. Also I am little skeptic about logic in 0005 where we
> copied extended hash function info from the partition key, what if parent is
> changed while we are using it? Do we need to keep lock on parent until commit in
> satisfies_hash_partition?

I don't think it should be possible for the parent to be changed.  I
mean, the partition key is altogether immutable -- it can't be changed
after creation time.  The partition bounds can be changed for
individual partitions but that would require a lock on the partition.

Can you give an example of the kind of scenario about which you are concerned?

-- 
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.