| From: | Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> |
|---|---|
| To: | Gavin Flower <GavinFlower(at)archidevsys(dot)co(dot)nz> |
| Cc: | Jeff Davis <pgsql(at)j-davis(dot)com>, Robert Haas <robertmhaas(at)gmail(dot)com>, Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>, Andres Freund <andres(at)2ndquadrant(dot)com>, Kouhei Kaigai <kaigai(at)ak(dot)jp(dot)nec(dot)com>, Amit Langote <amitlangote09(at)gmail(dot)com>, Amit Langote <Langote_Amit_f8(at)lab(dot)ntt(dot)co(dot)jp>, Fabrízio Mello <fabriziomello(at)gmail(dot)com>, Thom Brown <thom(at)linux(dot)com>, Stephen Frost <sfrost(at)snowman(dot)net>, pgsql-hackers <pgsql-hackers(at)postgresql(dot)org> |
| Subject: | Re: Parallel Seq Scan |
| Date: | 2015-07-03 12:05:43 |
| Message-ID: | CAA4eK1KqTrUW0+g8pb27_wveA74MtGLRnGxmNNev2cjj2fWX-A@mail.gmail.com |
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| Lists: | pgsql-hackers |
On Thu, Jul 2, 2015 at 1:47 AM, Gavin Flower <GavinFlower(at)archidevsys(dot)co(dot)nz>
wrote:
>
> On 01/07/15 17:37, Amit Kapila wrote:
>>
>> Yes, you are right and we have done quite some testing (on the hardware
>> available) with this patch (with different approaches) to see how much
>> difference it creates for IO and CPU, with respect to IO we have found
>> that it doesn't help much [1], though it helps when the data is cached
>> and there are really good benefits in terms of CPU [2].
>>
> [...]
>
> I assume your answer refers to a table on one spindle of spinning rust.
>
>
> QUESTIONS:
>
> 1. what about I/O using an SSD?
>
> 2. what if the table is in a RAID array (of various types), would
> having the table spread over multiple spindles help?
>
I think it will be helpful if we could get the numbers on more type of
m/c's,
please feel free to test and share the data if you have access to such
m/c's.
Attached, find the rebased version of patch.
Note - You need to first apply the assess-parallel-safety patch which you
can find at:
http://www.postgresql.org/message-id/CAA4eK1JjsfE_dOsHTr_z1P_cBKi_X4C4X3d7Nv=VWX9fs7qdJA@mail.gmail.com
With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com
| Attachment | Content-Type | Size |
|---|---|---|
| parallel_seqscan_v16.patch | application/octet-stream | 155.8 KB |
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