| From: | Dilip Kumar <dilipbalaut(at)gmail(dot)com> |
|---|---|
| To: | Robert Haas <robertmhaas(at)gmail(dot)com> |
| Cc: | Thomas Munro <thomas(dot)munro(at)enterprisedb(dot)com>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, Rafia Sabih <rafia(dot)sabih(at)enterprisedb(dot)com>, tushar <tushar(dot)ahuja(at)enterprisedb(dot)com>, Amit Khandekar <amitdkhan(dot)pg(at)gmail(dot)com>, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com>, Andres Freund <andres(at)anarazel(dot)de>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Parallel bitmap heap scan |
| Date: | 2017-03-07 16:27:36 |
| Message-ID: | CAFiTN-sPtFUqahAKymqFp-zBLTP8d-W+=pjr64RFLy2nor58HA@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Tue, Mar 7, 2017 at 9:44 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
> I mean, IIUC, the call to PrefetchBuffer() is not done under any lock.
> And that's the slow part. The tiny amount of time we spend updating
> the prefetch information under the mutex should be insignificant
> compared to the cost of actually reading the buffer. Unless I'm
> missing something.
Okay, but IIUC, the PrefetchBuffer is an async call to load the buffer
if it's not already in shared buffer? so If instead of one process is
making multiple async calls to PrefetchBuffer, if we make it by
multiple processes will it be any faster? Or you are thinking that at
least we can make BufTableLookup call parallel because that is not an
async call.
--
Regards,
Dilip Kumar
EnterpriseDB: http://www.enterprisedb.com
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