Horton

Re: Parallel bitmap heap scan

Dilip Kumar <dilipbalaut@gmail.com>

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From: Dilip Kumar <dilipbalaut@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: Amit Kapila <amit.kapila16@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-01-04T07:02:09Z
Lists: pgsql-hackers

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On Mon, Dec 26, 2016 at 3:14 PM, Dilip Kumar <dilipbalaut@gmail.com> wrote:
> Other the another option is, that we can always make caller to provide
> an allocator. But this way every new user for simple hash need to take
> care of having allocator.
>
> What is your opinion?

Attached is the new version of the patch which implements it the way I
described.

>
>
>>This also needs docs, including a warning that just
>> using an allocator in shared memory does *NOT* allow the hash table to be
>> used in shared memory in the general case.
>
> Make sense.
Added the Warning.

I have also fixed some bug in parallel bitmap heap scan
(path.parallel_workers was not initialised before calling
cost_bitmap_heap_scan in some cases, so it was taking the
uninitialized value). Patch attached.

-- 
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com

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.