Examples of VoltTable

org.voltdb.VoltTable

Summary

The primary representation of a result set (of tuples) or a temporary table in VoltDB. VoltTable has arbitrary schema, is serializable, and is used from within Stored Procedures and from the client library.

Accessing Rows by Index

Given a VoltTable, individual rows can be accessed via the {@link #fetchRow(int)}method. This method returns a {@link VoltTableRow} instance with position set tothe specified row. See VoltTableRow for further information on accessing individual column data within a row.

A VoltTable is also a VoltTableRow

Like a {@link VoltTableRow}, a VoltTable has a current position within its rows. This is because VoltTable is a subclass of VoltTableRow. This allows for easy sequential access of data. Example:

 while (table.advanceRow()) {
     System.out.println(table.getLong(7));
 }

Building a Table Dynamically

VoltTables can be constructed on the fly. This can help generate cleaner result sets from stored procedures, or more manageable parameters to them. Example:

 VoltTable t = new VoltTable(
     new VoltTable.ColumnInfo("col1", VoltType.BIGINT),
     new VoltTable.ColumnInfo("col2", VoltType.STRING));
 t.addRow(15, "sampleString");
 t.addRow(-9, "moreData");

     * from V group by V.V_D1_PKEY
     * @throws InterruptedException
     */
    public void testDistributedSumAndGroup() throws NoConnectionsException,
    ProcCallException, IOException, InterruptedException {
        VoltTable vt;
        Client client = getClient();
        loadF(client, 0);


        // FIXME String qs = "select V.V_D1_PKEY, sum(V.SUM_V1), sum(V.SUM_V2), sum(V.SUM_V3) "
//            + "from V group by V.V_D1_PKEY";
        String qs = "select V.V_D1_PKEY, sum(V.SUM_V1), sum(V.SUM_V2) "
                + "from V group by V.V_D1_PKEY";
        


        vt = client.callProcedure("@AdHoc", qs).getResults()[0];
        System.out.println("testDistributedSumAndJoin result: " + vt);
        assert (vt.getRowCount() == 10); // 10 unique values for dim1 which is
        // the grouping col


        int found[] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
        while (vt.advanceRow()) {
            Integer d1 = (Integer) vt.get(0, VoltType.INTEGER);
            Integer s1 = (Integer) vt.get(1, VoltType.INTEGER);
            Integer s2 = (Integer) vt.get(2, VoltType.INTEGER);
            // FIXME Integer s3 = (Integer) vt.get(3, VoltType.INTEGER);


            // track that 10 dim1s are in the final group
            found[d1.intValue()] += 1;
            // sum1 is const 2. 100 dim1 instances / group

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