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: 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: 2017-02-20T07:46:49Z
Lists: pgsql-hackers 
On Sun, Feb 19, 2017 at 10:34 PM, Robert Haas <robertmhaas@gmail.com> wrote:
> Yeah, but it looks like ExecReScanGather gets rid of the workers, but
> reuses the existing DSM.  I'm not quite sure what happens to the DSA.
> It looks like it probably just hangs around from the previous
> iteration, which means that any allocations will also hang around.

Yes right, they hang around. But, during rescan
(ExecReScanBitmapHeapScan) we can free all these DSA pointers ? That
mean before reallocating the DSA pointers we would have already got
rid of the old ones.


-- 
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.