Re: Parallel Sequence Scan doubts

On Thu, Aug 21, 2014 at 2:47 AM, Haribabu Kommi
<kommi(dot)haribabu(at)gmail(dot)com> wrote:
> Implementation of "Parallel Sequence Scan"
>
> Approach:
>
> 1."Parallel Sequence Scan" can achieved by using the background
> workers doing the job of actual sequence scan including the
> qualification check also.
>
> 2. Planner generates the parallel scan plan by checking the possible
> criteria of the table to do a parallel scan and generates the tasks
> (range of blocks).
>
> 3. In the executor Init phase, Try to copy the necessary data required
> by the workers and start the workers.
>
> 4. In the executor run phase, just get the tuples which are sent by
> the workers and process them further in the plan node execution.

Well, this is something I've thought quite a bit about already. Many
of my thoughts on parallelism are here:

https://wiki.postgresql.org/wiki/Parallel_Sort

Although the page title is parallel sort, many of the concerns are
applicable to parallelism of any sort.

I posted some patches containing some of the necessary infrastructure here:

http://archives.postgresql.org/message-id/CA+Tgmoam66dTzCP8N2cRcS6S6dBMFX+JMba+mDf68H=KAkNjPQ@mail.gmail.com

I seem to have forgotten to add that message to the CommitFest. Crap.

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company