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https://issues.apache.org/jira/browse/DERBY-6788?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14287887#comment-14287887
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ASF subversion and git services commented on DERBY-6788:
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Commit 1653986 from [~mamtas] in branch 'code/trunk'
[ https://svn.apache.org/r1653986 ]
DERBY-6788(Wrong value inserted by INSERT INTO with multiple subselects)
Adding a junit test case for DERBY-6788. This bug might be related to
DERBY-6786(NullPointerException in INSERT INTO statement with multiple
subselects)
> Wrong value inserted by INSERT INTO with multiple subselects
> ------------------------------------------------------------
>
> Key: DERBY-6788
> URL: https://issues.apache.org/jira/browse/DERBY-6788
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.1.1.0, 10.2.2.0, 10.3.3.0, 10.4.2.0, 10.5.3.0,
> 10.6.2.1, 10.7.1.1, 10.8.2.2, 10.9.1.0, 10.10.2.0, 10.11.1.1
> Environment: not relevant, tested under Windows 7 32bit
> Reporter: Manfred Steinsiek
> Priority: Critical
>
> Certain INSERT INTO statements with multiple subselects insert wrong values,
> i.e. may lead to data corruption.
> Here is a very simple example how to reproduce this bug: Start with a new
> (empty) Derby database, create 3 tiny tables, and insert two records:
> create table m1 (k varchar(64), s decimal);
> create table m2 (k varchar(64), s decimal);
> create table v (s decimal);
> insert into m1 values ('Bug', 2015);
> insert into m2 values ('Bug', 1957);
> Now, the following (likewise simple) select
> select res.* from (select d2.s from m1
> left join (select k,s from m2) as d2 on m1.k=d2.k) as res
> yields 1957, of course. - Of course? Not entirely: If I add an INSERT INTO to
> that select, i.e.
> insert into v (select res.* from (select d2.s from m1
> left join (select k,s from m2) as d2 on m1.k=d2.k) as res)
> then table v contains 1 row (as it should), but in this row s=4,355,431. This
> value is interesting, because 4355431 = Hex 427567 and 'B' = X42, 'u'=X75,
> 'g'=X67.
> Finally, if I slightly modify the INSERT INTO above as
> insert into v (select res.* from (select d2.s*1 from m1
> left join (select k,s from m2) as d2 on m1.k=d2.k) as res)
> then it works correct.
> This phenomenon arose with every Derby version 10.x I tried (see list above).
> Possibly this bug is related to DERBY-6786, where similar INSERT INTOs with
> subselects appear.
> Addendum: There is indeed a close relationship between DERBY-6786 and this
> one: Let's denote by SQL1 the first INSERT INTO above, by SQL2 the second
> one, i.e.
> SQL1 = insert into v (select res.* from (select d2.s from m1 left join
> (select k,s from m2) as d2 on m1.k=d2.k) as res)
> SQL2 = insert into v (select res.* from (select d2.s*1 from m1 left join
> (select k,s from m2) as d2 on m1.k=d2.k) as res)
> We further assume that there are exactly 1 record R1 in table M1 and exactly
> 1 record R2 in table M2, both without NULL-values. Then:
> If R1.k is equal to R2.k, then SQL1 -> data corruption, SQL2 -> correct.
> If R1.k is not equal to R2.k, then SQL1 -> correct, SQL2 ->
> NullPointerException.
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