[PHOENIX-947] Zero length strings are incorrectly treated as NULL

• Type: New Feature
• Status: Resolved
• Priority: Major
• Resolution: Not A Problem
• Affects Version/s: 3.0.0
• Assignee: Unassigned
• Reporter: Robert Roland
• Created: 23/Apr/14 19:03
• Updated: 09/Aug/14 01:56
• Resolved: 09/Aug/14 01:56

Description

Given the following table schema, you should be able to insert an empty string into the TESTSTR column:

CREATE TABLE TEST1 (
    ID INTEGER NOT NULL PRIMARY KEY,
    TESTSTR VARCHAR(255) NOT NULL,
    TESTSTR2 VARCHAR(255)
);

UPSERT INTO TEST1 (ID, TESTSTR, TESTSTR2)
VALUES (1, '', 'foo');

Instead, you are given an error:

org.apache.phoenix.schema.ConstraintViolationException: TEST1.TESTSTR may not be null
    at org.apache.phoenix.schema.PTableImpl$PRowImpl.setValue(PTableImpl.java:618)
    at org.apache.phoenix.execute.MutationState.addRowMutations(MutationState.java:176)
    at org.apache.phoenix.execute.MutationState.commit(MutationState.java:350)
    at org.apache.phoenix.jdbc.PhoenixConnection.commit(PhoenixConnection.java:351)
    at org.apache.phoenix.jdbc.PhoenixStatement.executeMutation(PhoenixStatement.java:229)
    at org.apache.phoenix.jdbc.PhoenixStatement.execute(PhoenixStatement.java:919)
    at sqlline.SqlLine$Commands.execute(SqlLine.java:3673)
    at sqlline.SqlLine$Commands.sql(SqlLine.java:3584)
    at sqlline.SqlLine.dispatch(SqlLine.java:821)
    at sqlline.SqlLine.begin(SqlLine.java:699)
    at sqlline.SqlLine.mainWithInputRedirection(SqlLine.java:441)
    at sqlline.SqlLine.main(SqlLine.java:424)

SQL92 specifies that zero-length strings are not NULL. SQL99 changes this a bit:

"In SQL-92, if the value of a character value expression was a zero-length string or if a zero-length character string was assigned to a target, there were no exception conditions permitted. In SQL:1999, it is implementation-defined whether in these circumstances an exception condition is raised: data-exception--zero-length character string. (This rule provides support for some SQL implementations that do not distinguish between zero-length character strings and the null value.)"

• p 777, SQL:1999 - Understanding Relational Language Components, Jim Melton, Alan R. Simpson

While SQL99 relaxed this restriction, it would be ideal to be able to represent a zero length string as NOT NULL.