Re: Reviewing freeze map code

On Wed, Jun 8, 2016 at 12:19 PM, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
> On Tue, Jun 7, 2016 at 10:10 PM, Masahiko Sawada <sawada(dot)mshk(at)gmail(dot)com>
> wrote:
>>
>> Thank you for implementing the patch.
>>
>> I've not test it deeply but here are some comments.
>> This check tool only checks if the frozen page has live-unfrozen tuple.
>> That is, it doesn't care in case where the all-frozen page mistakenly
>> has dead-frozen tuple.
>>
>
> Do you mean to say that we should have a check for ItemIdIsDead() and then
> if item is found to be dead, then add it to array of non_frozen items?

Yes.

> If so, earlier I thought we might not need this check as we are already using
> heap_tuple_needs_eventual_freeze(),

You're right. Sorry, I had misunderstood.

> but now again looking at it, it seems
> wise to check for dead items separately as those won't be covered by other
> check.

Sounds good.

>>
>> + /* Clean up. */
>> + if (vmbuffer != InvalidBuffer)
>> + ReleaseBuffer(vmbuffer);
>>
>> I think that we should use BufferIsValid() here.
>>
>
> We can use BufferIsValid() as well, but I am trying to be consistent with
> nearby code, refer collect_visibility_data(). We can change at all places
> together if people prefer that way.
>

In vacuumlazy.c we use it like BufferisValid(vmbuffer), so I think we
can replace all these thing to be more safety if there is not specific
reason.

Regards,

--
Masahiko Sawada