@Override
  public TableSchema getResultSetSchema() throws HiveSQLException {
    assertState(Collections.singleton(OperationState.FINISHED));
    return RESULT_SET_SCHEMA;
  }
TABLE_CAT String => table catalog (may be null)
TABLE_SCHEM String => table schema (may be null)
TABLE_NAME String => table name
COLUMN_NAME String => column name
KEY_SEQ short => sequence number within primary key( a value of 1 represents the first column of the primary key, a value of 2 would represent the second column within the primary key).
PK_NAME String => primary key name (may be null)
service/src/java/org/apache/hive/service/cli/operation/GetPrimaryKeysOperation.java