Re: Block level parallel vacuum WIP

On Tue, Aug 23, 2016 at 11:17 AM, Alvaro Herrera
<alvherre(at)2ndquadrant(dot)com> wrote:
> Robert Haas wrote:
>> 2. When you finish the heap scan, or when the array of dead tuple IDs
>> is full (or very nearly full?), perform a cycle of index vacuuming.
>> For now, have each worker process a separate index; extra workers just
>> wait. Perhaps use the condition variable patch that I posted
>> previously to make the workers wait. Then resume the parallel heap
>> scan, if not yet done.
>
> At least btrees should easily be scannable in parallel, given that we
> process them in physical order rather than logically walk the tree. So
> if there are more workers than indexes, it's possible to put more than
> one worker on the same index by carefully indicating each to stop at a
> predetermined index page number.

Well that's fine if we figure it out, but I wouldn't try to include it
in the first patch. Let's make VACUUM parallel one step at a time.

--
Robert Haas
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