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https://issues.apache.org/jira/browse/DERBY-6017?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13537829#comment-13537829
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Knut Anders Hatlen commented on DERBY-6017:
-------------------------------------------
For the problem fixed by the 1a patch, I didn't find any problematic
combinations except BIGINT/DOUBLE. As far as I can see REAL/DOUBLE doesn't have
the problem because the conversion from REAL to DOUBLE never loses precision.
And mixing INT and REAL is not a problem either, as the problem only affects IN
lists that consists entirely of literals, and Derby's grammar doesn't have any
way to express REAL literals (all approximate number literals get the type
DOUBLE). You can of course cast a DOUBLE literal to a REAL, but then it's no
longer a ConstantNode, and the problematic optimization is not applied.
However, mixing REAL and INT seems to have similar problems as DOUBLE and
BIGINT when using non-constant expressions in the IN list. Here's one example:
ij> select * from tt where r1 in (i1, r2);
I1 |R1 |R2
---------------------------------------
2147483645 |2.14748365E9 |2.14748365E9
2147483645 |2.14748365E9 |0.0
2 rows selected
ij> select * from tt where r1 in (values i1, r2);
I1 |R1 |R2
---------------------------------------
2147483645 |2.14748365E9 |2.14748365E9
1 row selected
The two queries are supposed to be equivalent, but they return different
results.
I think the former query performs both of the comparisons (r1=i1, r1=r2) using
REAL semantics, whereas the latter query uses DOUBLE semantics because the
(values i1,r2) sub-query has DOUBLE as its row type.
> IN lists with mixed types may return wrong results
> --------------------------------------------------
>
> Key: DERBY-6017
> URL: https://issues.apache.org/jira/browse/DERBY-6017
> Project: Derby
> Issue Type: Bug
> Components: SQL
> Affects Versions: 10.9.1.0
> Reporter: Knut Anders Hatlen
> Assignee: Knut Anders Hatlen
> Attachments: d6017-1a-duplicates.diff
>
>
> Given this table:
> ij> connect 'jdbc:derby:memory:db;create=true';
> ij> create table t(x bigint);
> 0 rows inserted/updated/deleted
> ij> insert into t values 9223372036854775805, 9223372036854775806,
> 9223372036854775807;
> 3 rows inserted/updated/deleted
> A query that uses an IN list that contains all the three values actually
> stored in the table, returns all three rows as expected:
> ij> select * from t where x in (9223372036854775805, 9223372036854775806,
> 9223372036854775807);
> X
> --------------------
> 9223372036854775805
> 9223372036854775806
> 9223372036854775807
> 3 rows selected
> However, if we add a value whose type precedence is higher, like a DOUBLE
> value, and that value happens to be equal to the approximation of the other
> values in the IN list when they are cast from BIGINT to DOUBLE, only one row
> is returned:
> ij> select * from t where x in (9223372036854775805, 9223372036854775806,
> 9223372036854775807, 9.223372036854776E18);
> X
> --------------------
> 9223372036854775805
> 1 row selected
> I believe this query should return all three rows too.
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