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: Andres Freund <andres@anarazel.de>, 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>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2017-02-08T09:20:16Z
Lists: pgsql-hackers 
On Wed, Feb 8, 2017 at 3:44 AM, Robert Haas <robertmhaas@gmail.com> wrote:
>>> +#ifndef SH_USE_NONDEFAULT_ALLOCATOR
>>> +
>>
>> That should probably be documented in the file header.
>
> Right.  OK, did that and a few other cleanups, and committed.

The new SH_CREATE(MemoryContext ctx, uint32 nelements) don't have any
option to supply arguments to it. Our callback functions need access
to TBM.

Is it expected that if the user of SH_CREATE who doesn't want to pass
a "MemoryContext" then we can pass arguments instead of ctx?

something like this ?
if (!tbm->dsa)
       tbm->pagetable = pagetable_create(tbm->mcxt, 128);
else
       tbm->pagetable = pagetable_create((MemoryContext)tbm, 128);

And, In allocation function, we can access this context and typecast to tbm?

As shown below.
static void *
pagetable_allocate(pagetable_hash *pagetable, Size size)
{
    TIDBitmap  *tbm = pagetable->ctx;


So Is it expected to do like I explained above, or we missed to have
an arg parameter to SH_CREATE as well as in SH_TYPE structure or there
is some other way you have in mind?

-- 
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.