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.