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https://issues.apache.org/jira/browse/DRILL-2420?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14355712#comment-14355712
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Daniel Barclay (Drill) commented on DRILL-2420:
-----------------------------------------------
The expected result set table is described at
[http://docs.oracle.com/javase/8/docs/api/java/sql/DatabaseMetaData.html#getColumns-java.lang.String-java.lang.String-java.lang.String-java.lang.String-].
> 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}}.
> Additional bugs or suspect behavior:
> - {{DECIMAL_DIGITS}}/{{DECIMAL_PRECISION}} is {{-1}} when it should be
> {{NULL}} (when not applicable).
> - {{NUM_PREC_RADIX}} is {{-1}} when it probably should be {{NULL}} (when not
> applicable).
> (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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