On Mon, Oct 22, 2018 at 6:16 PM Haribabu Kommi <kommi.harib...@gmail.com> wrote:
> On Thu, Oct 18, 2018 at 1:04 PM Haribabu Kommi <kommi.harib...@gmail.com> > wrote: > >> On Tue, Oct 9, 2018 at 1:46 PM Haribabu Kommi <kommi.harib...@gmail.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. > I am able to generate the simple test and found the problem. The issue with the following SQL. SELECT * INTO TABLE xacttest FROM aggtest; During the processing of the above query, the tuple that is selected from the aggtest is sent to the intorel_receive() function, and the same tuple is used for the insert, because of this reason, the tuple xmin is updated and it leads to failure of selecting the data from another query. I fixed this issue by materializing the slot. During the above test run, I found another issue during analyze, that is trying to access the invalid offset data. Attached a fix patch. Regards, Haribabu Kommi Fujitsu Australia
0001-scan-start-offset-fix-during-analyze.patch
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0002-Materialize-all-the-slots-before-they-are-processed-.patch
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