Re: Missing update of all_hasnulls in BRIN opclasses

On 4/24/23 17:36, Alvaro Herrera wrote:
> On 2023-Apr-23, Tomas Vondra wrote:
>
>> here's an updated version of the patch, including a backport version. I
>> ended up making the code yet a bit closer to master by introducing
>> add_values_to_range(). The current pre-14 code has the loop adding data
>> to the BRIN tuple in two places, but with the "fixed" logic handling
>> NULLs and the empty_range flag the amount of duplicated code got too
>> high, so this seem reasonable.
>
> In backbranches, the new field to BrinMemTuple needs to be at the end of
> the struct, to avoid ABI breakage.
>

Good point.

> There's a comment in add_values_to_range with a typo "If the range was had".
> Also, "So we should not see empty range that was not modified" should
> perhaps be "should not see an empty range".
>

OK, I'll check the wording of the comments.

> (As for your FIXME comment in brin_memtuple_initialize, I think you're
> correct: we definitely need to reset bt_placeholder. Otherwise, we risk
> places that call it in a loop using a BrinMemTuple with one range with
> the flag set, in a range where that doesn't hold. It might be
> impossible for this to happen, given how narrow the conditions are on
> which bt_placeholder is used; but it seems safer to reset it anyway.)
>

Yeah. But isn't that a separate preexisting issue, strictly speaking?

> Some pgindent noise would be induced by this patch. I think it's worth
> cleaning up ahead of time.
>

True. Will do.

> I did a quick experiment of turning the patches over -- applying test
> first, code fix after (requires some conflict fixing). With that I
> verified that the behavior of 'hasnulls' indeed changes with the code
> fix.
>

Thanks. Could you do some testing of the union_tuples stuff too? It's a
bit tricky part - the behavior is timing sensitive, so testing it
requires gdb breakpoints breakpoints or something like that. I think
it's correct, but it'd be nice to check that.

regards

--
Tomas Vondra
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company