Re: Hash Indexes

On Wed, Nov 9, 2016 at 11:41 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> On Wed, Nov 9, 2016 at 9:10 PM, Robert Haas <robertmhaas(at)gmail(dot)com> wrote:
>> On Wed, Nov 9, 2016 at 9:04 AM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>> I think we can give a brief explanation right in the code comment. I
>> referred to "decreasing the TIDs"; you are referring to "moving tuples
>> around". But I think that moving the tuples to different locations is
>> not the problem. I think the problem is that a tuple might be
>> assigned a lower spot in the item pointer array
>
> I think we both understand the problem and it is just matter of using
> different words. I will go with your suggestion and will try to
> slightly adjust the README as well so that both places use same
> terminology.

Yes, I think we're on the same page.

> Right, but we don't need that guarantee (there is no pending scan that
> has seen the flag after it is cleared) to clear the flags. It was
> written in one of the previous patches where I was exploring the idea
> of using cleanup lock to clear the flags and then don't use the same
> during vacuum. However, there were some problems in that design and I
> have changed the code, but forgot to update the comment.

OK, got it, thanks.

--
Robert Haas
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