Re: Block level parallel vacuum WIP

On Tue, Aug 23, 2016 at 9:40 PM, Alexander Korotkov
<a(dot)korotkov(at)postgrespro(dot)ru> wrote:
> On Tue, Aug 23, 2016 at 3:32 PM, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>
>> Claudio Freire <klaussfreire(at)gmail(dot)com> writes:
>> > Not only that, but from your description (I haven't read the patch,
>> > sorry), you'd be scanning the whole index multiple times (one per
>> > worker).
>>
>> What about pointing each worker at a separate index? Obviously the
>> degree of concurrency during index cleanup is then limited by the
>> number of indexes, but that doesn't seem like a fatal problem.
>
>
> +1
> We could eventually need some effective way of parallelizing vacuum of
> single index.
> But pointing each worker at separate index seems to be fair enough for
> majority of cases.
>

Or we can improve vacuum of single index by changing data
representation of dead tuple to bitmap.
It can reduce the number of index whole scan during vacuum and make
comparing the index item to the dead tuples faster.
This is a listed on Todo list and I've implemented it.

Regards,

--
Masahiko Sawada