Horton

Re: Parallel bitmap heap scan

Dilip Kumar <dilipbalaut@gmail.com>

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From: Dilip Kumar <dilipbalaut@gmail.com>
To: Robert Haas <robertmhaas@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: 2017-03-07T16:40:21Z
Lists: pgsql-hackers 
On Tue, Mar 7, 2017 at 10:07 PM, Robert Haas <robertmhaas@gmail.com> wrote:
> It's not about speed.  It's about not forgetting to prefetch.  Suppose
> that worker 1 becomes the prefetch worker but then doesn't return to
> the Bitmap Heap Scan node for a long time because it's busy in some
> other part of the plan tree.  Now you just stop prefetching; that's
> bad.  You want prefetching to continue regardless of which workers are
> busy doing what; as long as SOME worker is executing the parallel
> bitmap heap scan, prefetching should continue as needed.

Right, I missed this part. I will fix this.


-- 
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.