[jira] [Created] (FLINK-12874) Improve the semantics of zero length character strings

[Shang Yuanchun (Jira)]

Timo Walther created FLINK-12874:
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             Summary: Improve the semantics of zero length character strings
                 Key: FLINK-12874
                 URL: https://issues.apache.org/jira/browse/FLINK-12874
             Project: Flink
          Issue Type: Sub-task
          Components: Table SQL / API
            Reporter: Timo Walther
            Assignee: Timo Walther


Zero-length character strings need special treatment as the SQL standard forbids to declare those type of character strings. For the type inference (e.g. determine the return type of a \{{TRIM('')}}) it should be possible to return zero-lengths VARCHAR types.

 

In any case, those type should not have a serializable string representation. Similar behavior is done in the Oracle system: \{{SELECT DUMP(TRIM('')) AS tt FROM dual;}} returns \{{NULL}}.



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