Internal server error for UNION ALL with constants in IN-subselect

Detail name	Value
Changelog Number	7964
Type	Bug
Status	Resolved
Affected Versions	Exasol 6.1.0, Exasol 6.2.0, Exasol 7.0.0, Exasol 7.0.1, Exasol 7.0.2
Fix Versions	Exasol 7.0.3
Resolution Date	2020-10-15

Description

An internal server error may be reported under the following circumstances:

• The query contains an IN-subselect-clause
• That IN-subselect-clause directly contains an UNION ALL
• The UNION ALL only selects constants, no tables columns or similar

Example

SELECT * FROM (SELECT 1 v UNION ALL SELECT 2 v)
WHERE v IN (SELECT 1 UNION ALL SELECT 2);

Workaround

You can simply put a subselect around the UNION ALL within the IN clause:

SELECT 1 FROM (SELECT 1 v UNION ALL SELECT 2 v)
WHERE v IN (SELECT * FROM (SELECT 1 UNION ALL SELECT 2));

Fix

The query will run successfully.