Daniel Barclay (Drill) created DRILL-2420:
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Summary: Identify and fix DatabaseMetaData.getColumns() bugs
[umbrella/tracking bug]
Key: DRILL-2420
URL: https://issues.apache.org/jira/browse/DRILL-2420
Project: Apache Drill
Issue Type: Bug
Components: Client - JDBC, Metadata
Reporter: Daniel Barclay (Drill)
Assignee: Daniel Barclay (Drill)
Drill's implementation of {{DatabaseMetaData.getColumns(...)}} (currently at
{{org.apache.drill.jdbc.MetaImpl.getColumns()}}) doesn't match the JDBC
specification (the Javadoc documentation for
{{DatabaseMetaData.getColumns(...)}} (as of Java 7)). In the returned
{{ResultSet}}:
1. Column {{DATA_TYPE}} is of type {{VARCHAR}} (containing the type name)
rather than being of type {{INTEGER}} (containing values per
{{java.sql.Types.*}}).
2. Column {{TYPE_NAME}} is missing.
3. Column {{COLUMN_SIZE}} is missing.
4. (Columns after {{DATA_TYPE}} are at incorrect indexes.)
5. Column {{DECIMAL_DIGITS}} is misnamed {{DECIMAL_PRECISION}}.
6. Column {{REMARKS}} is an empty string, but probably should be {{NULL}}.
7. Column {{COLUMN_DEF}} is an empty string, but probably should be {{NULL}}.
8. Column {{CHAR_OCTET_LENGTH}} is always {{4}}, but should be "the maximum
number of bytes in the _column_" for character types .
9. Column {{ORDINAL_POSITION}} is always {{1}}, but should be the index of the
specific column.
10. Column {{IS_NULLABLE}} is {{'YES'}}, which doesn't seem to correspond to
the value for {{NULLABLE}} ({{DatabaseMetaData.columnNullableUnknown}}).
11. Column {{SCOPE_CATALOG}} is an empty string, but should be {{NULL}}.
12. Column {{SCOPE_SCHEMA}} is an empty string, but should be {{NULL}}.
13. Column {{SCOPE_TABLE}} is an empty string, but should be {{NULL}}.
14. Column {{SOURCE_DATA_TYPE}} is an empty string, but should be {{NULL}}.
(Other columns to check:
Re {{BUFFER_LENGTH}}, {{SQL_DATA_TYPE}}, and {{SQL_DATETIME_SUB}}: When JDBC
says a column is not used, are there any requirements on the values (e.g.,
being {{NULL}})?
Re {{IS_AUTOINCREMENT}}: Do we know that a column is not auto-incremented? If
so, the value could be {{'NO'}} rather than an empty string.
Re {{IS_GENERATEDCOLUMN}}: Do we know that a column is not generated? If so,
the value could be {{'NO'}} rather than an empty string.
Re {{NULLABLE}} (and {{IS_NULLABLE}}): Do know whether a column is nullable or
not? If so, we could return the specific answer rather that just saying that
it's unknown.
)
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