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: Rafia Sabih <rafia.sabih@enterprisedb.com>, Tom Lane <tgl@sss.pgh.pa.us>, Jeff Janes <jeff.janes@gmail.com>, Thomas Munro <thomas.munro@enterprisedb.com>, Haribabu Kommi <kommi.haribabu@gmail.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: 2017-03-27T12:28:07Z
Lists: pgsql-hackers 
On Mon, Mar 27, 2017 at 5:02 AM, Dilip Kumar <dilipbalaut@gmail.com> wrote:
> On Mon, Mar 27, 2017 at 12:53 PM, Rafia Sabih
> <rafia.sabih@enterprisedb.com> wrote:
>> Recently, on testing TPC-H 300 scale factor I stumbled on to a error
>> for Q6, the test environment is as follows,
>> work_mem = 1GB,
>> shared_buffers = 10 GB,
>> Effective_cache_size = 10GB
>> random_page_cost = seq+page_cost =0.1
>>
>> The error message is, ERROR:  invalid DSA memory alloc request size 1610612740
>> In case required, stack trace is as follows,
>
> Thanks for reporting.  In pagetable_allocate, DSA_ALLOC_HUGE flag were
> missing while allocating the memory from the DSA.  I have also handled
> the NULL pointer return from dsa_get_address.
>
> Please verify with the attached patch.

Failing to pass DSA_ALLOC_HUGE is an obvious oversight, but I think
the ptbase == NULL check shouldn't be needed, because we're not
passing DSA_ALLOC_NO_OOM.  And that's good, because this is going to
be called from SH_CREATE, which isn't prepared for a NULL return
anyway.

Am I all wet?

-- 
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.