MERGE with faulty ON clause crashes instead of returning proper error message

Detail name	Value
Changelog Number	7062
Type	Bug
Status	Resolved
Affected Versions	Exasol 6.1.0, EXASolution 5.0.22, Exasol 6.0.12
Fix Versions	Exasol 7.0.0
Resolution Date	2020-09-11

Problem

Within a MERGE statement, when the ON condition contains an expression that is not a predicate, the query crashes instead of returning a proper error message.
In this case, the usual error

40005: Successfully reconnected after internal server error, transaction was rolled back.

is returned.

Example

create table dst(a int, b int);
create table src(a int, b int);
insert into src values (1,1);
insert into dst values (1,1);

merge into dst
using src
    on dst.a = src.a
   and dst.b                --<-- problem
when matched then update
    set dst.b=src.b+1;

Workaround / Fix

Rewriting the problematic condition into a predicate (boolean expression) fixes the problem:

merge into dst
using src
    on dst.a = src.a
   and dst.b > 0          --> fixed it
when matched then update
    set dst.b=src.b+1;