Re: Hash Indexes

From: Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>
To: Jesper Pedersen <jesper(dot)pedersen(at)redhat(dot)com>
Cc: Mithun Cy <mithun(dot)cy(at)enterprisedb(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Hash Indexes
Date: 2016-09-02 03:55:35
Message-ID: CAA4eK1J6b8O4PcEPqRxNYbLVbfToNMJEEm+qn0jZX31-obXrJw@mail.gmail.com
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On Thu, Sep 1, 2016 at 11:33 PM, Jesper Pedersen
<jesper(dot)pedersen(at)redhat(dot)com> wrote:
> On 08/05/2016 07:36 AM, Amit Kapila wrote:

>
> Needs a rebase.
>

Done.

>
> + if (blkno == P_NEW)
> + elog(ERROR, "hash AM does not use P_NEW");
>
> Left over ?
>

No. We need this check similar to all other _hash_*buf API's, as we
never expect caller of those API's to pass P_NEW. The new buckets
(blocks) are created during split and it uses different mechanism to
allocate blocks in bulk.

I have fixed all other issues you have raised. Updated patch is
attached with this mail.

>
> Ran some tests on a CHAR() based column which showed good results. Will have
> to compare with a run with the WAL patch applied.
>

Okay, Thanks for testing. I think WAL patch is still not ready for
performance testing, I am fixing few issues in that patch, but you can
do the design or code level review of that patch at this stage. I
think it is fine even if you share the performance numbers with this
and or Mithun's patch [1].

[1] - https://commitfest.postgresql.org/10/715/

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

Attachment Content-Type Size
concurrent_hash_index_v5.patch application/octet-stream 100.4 KB

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