Horton

Re: Parallel bitmap heap scan

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Dilip Kumar <dilipbalaut@gmail.com>
Cc: Thomas Munro <thomas.munro@enterprisedb.com>, Haribabu Kommi <kommi.haribabu@gmail.com>, Rafia Sabih <rafia.sabih@enterprisedb.com>, tushar <tushar.ahuja@enterprisedb.com>, Amit Khandekar <amitdkhan.pg@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, Andres Freund <andres@anarazel.de>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-03-07T16:04:04Z
Lists: pgsql-hackers 
On Mon, Mar 6, 2017 at 12:35 AM, Dilip Kumar <dilipbalaut@gmail.com> wrote:
> On Thu, Mar 2, 2017 at 6:52 PM, Robert Haas <robertmhaas@gmail.com> wrote:
>> 0002 wasn't quite careful enough about the placement of #ifdef
>> USE_PREFETCH, but otherwise looks OK.  Committed after changing that
>> and getting rid of the local variable prefetch_iterator, which seemed
>> to be adding rather than removing complexity after this refactoring.
>
> 0003 is rebased after this commit.

You've still got this:

+               if (DsaPointerIsValid(node->pstate->tbmiterator))
+                       tbm_free_shared_area(dsa, node->pstate->tbmiterator);
+
+               if (DsaPointerIsValid(node->pstate->prefetch_iterator))
+                       dsa_free(dsa, node->pstate->prefetch_iterator);

I'm trying to get to a point where both calls use
tbm_free_shared_area() - i.e. no peeking behind the abstraction layer.

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

Commits

  1. Pass DSA_ALLOC_HUGE when allocating a shared TIDBitmap.

  2. Support parallel bitmap heap scans.

  3. tidbitmap: Support shared iteration.

  4. Shut down Gather's children before shutting down Gather itself.

  5. Revise the way the element allocator for a simplehash is specified.

  6. Refactor bitmap heap scan estimation of heap pages fetched.

  7. Use more efficient hashtable for tidbitmap.c to speed up bitmap scans.