Re: Pluggable Storage - Andres's take

On Thu, Oct 18, 2018 at 1:04 PM Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>
wrote:

> On Tue, Oct 9, 2018 at 1:46 PM Haribabu Kommi <kommi(dot)haribabu(at)gmail(dot)com>
> wrote:
>
>>
>> I also observed the failure of aggregates.sql, will look into it.
>>
>
> The random failure of aggregates.sql is as follows
>
> SELECT avg(a) AS avg_32 FROM aggtest WHERE a < 100;
> ! avg_32
> ! ---------------------
> ! 32.6666666666666667
> (1 row)
>
> -- In 7.1, avg(float4) is computed using float8 arithmetic.
> --- 8,16 ----
> (1 row)
>
> SELECT avg(a) AS avg_32 FROM aggtest WHERE a < 100;
> ! avg_32
> ! --------
> !
> (1 row)
>
> Same NULL result for another aggregate query on column b.
>
> The aggtest table is accessed by two tests that are running in parallel.
> i.e aggregates.sql and transactions.sql, In transactions.sql, inside a
> transaction
> all the records in the aggtest table are deleted and aborted the
> transaction,
> I suspect that some visibility checks are having some race conditions that
> leads
> to no records on the table aggtest, thus it returns NULL result.
>
> If I try the scenario manually by opening a transaction and deleting the
> records, the
> issue is not occurring.
>
> I am yet to find the cause for this problem.
>

I am not yet able to generate a test case where the above issue can occur
easily for
debugging, it is happening randomly. I will try to add some logs to find
out the problem.

During the checking for the above problem, I found some corrections,
1. Remove of the tableam_common.c file as it is not used.
2. Remove the extra heaptuple visibile check in heapgettup_pagemode function
3. New API for init fork.

Regards,
Haribabu Kommi
Fujitsu Australia