使用JDBC从Hive表中选择数组字段

Question

I have a Hive table which has column with array data type. I am using JDBC to select rows from the table.

SELECT col1 FROM hive_table WHERE condition = 'condition'

After receiving the resultset, I am using res.getArray() method for the specific array field while looping through resultset.

Array arrayCol = res.getArray(1);

This is throwing a "Method not supported" error. Is it valid to use getArray() method for such queries executed on Hive table?

Answer 1

Unfortunately, no. You can see getArray() method is not implemented in ResultSet class for Hive JDBC. The actual class name is HiveBaseResultSet and the source code is located here .

Depends on what type of values the array holds, a client program need to decode its value by itself. For example, a column of type array<string> is encoded as a single String object like `["VALUE1","VALUE2",...,"VALUEN"]'. And we can use getString() method and freely re-construct any object of type Array<String> or List<String>.

Answer 2

You can loop though the result set and add the column values to arraylist in java. See example below assuming that your table column is of String type.

List<String> list = new ArrayList<String>();

     while (res.next()) {
                      list.add( res.getString(1));
                    }