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: 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: 2017-02-14T03:45:56Z
Lists: pgsql-hackers 
On Mon, Feb 13, 2017 at 8:48 AM, Dilip Kumar <dilipbalaut@gmail.com> wrote:
> On Mon, Feb 13, 2017 at 6:24 PM, Robert Haas <robertmhaas@gmail.com> wrote:
>> I don't think it's acceptable (or necessary) to move the DSA
>> definitions into postgres.h.  Why do you think you need to do that,
>> vs. just including dsa.h in a few more places?
>
> I need to access dsa_pointer in tidbitmap.h, which is included from
> FRONTEND as well. Now, problem is that dsa.h is including #include
> "port/atomics.h", but atomic.h can not be included if FRONTEND is
> defined.
>
> #ifndef ATOMICS_H
> #define ATOMICS_H
> #ifdef FRONTEND
> #error "atomics.h may not be included from frontend code"
> #endif
>
> Is there any other solution to this ?

Well, any problem like this generally has a bunch of solutions, so
I'll say yes.  I spent a good chunk of today studying the issue and
started a new thread devoted specifically to it:

https://www.postgresql.org/message-id/CA%2BTgmoZ%3DF%3DGkxV0YEv-A8tb%2BAEGy_Qa7GSiJ8deBKFATnzfEug%40mail.gmail.com

-- 
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.