Put.java

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// Put stored procedure
//
//   Puts the given Key-Value pair


package voltkvqa.procedures;

import org.voltdb.*;
import java.nio.ByteBuffer;

public class Put extends VoltProcedure
{
    // Checks if key exists
    public final SQLStmt checkStmt = new SQLStmt("SELECT key,value FROM store WHERE key = ?;");

    // Updates a key/value pair
    public final SQLStmt updateStmt = new SQLStmt("UPDATE store SET value = ? WHERE key = ?;");

    // Inserts a key/value pair
    public final SQLStmt insertStmt = new SQLStmt("INSERT INTO store (key, value) VALUES (?, ?);");

    public VoltTable[] run(String key, byte[] value)
    {
        long putCounter = 0;

        // Check whether the pair exists
        voltQueueSQL(checkStmt, key);
        VoltTable[] queryresults = voltExecuteSQL();

        //Stuff an incrementing putCounter into the 1st long of the payload
        //This is clearly going to mess up compressed data.

        // Insert new or update existing key depending on result
        if (queryresults[0].getRowCount() == 0) {
            //New key gets putCounter  set to 0
            for (int i = 0; i < 8; i++) {
                value[i] = 0;
            }
            voltQueueSQL(insertStmt, key, value);
        }
        else {
            // Get the old count from 1st 8 bytes, increment it, stuff it
            // back in
            queryresults[0].advanceRow();
            ByteBuffer bb = ByteBuffer.wrap(queryresults[0].getVarbinary(1));
            putCounter = bb.getLong(0);
            putCounter++;
            bb.putLong(0, putCounter);
            voltQueueSQL(updateStmt, bb.array(), key);
        }
        voltExecuteSQL(true);
        VoltTable t[] = new VoltTable[1];
        t[0] = new VoltTable(new VoltTable.ColumnInfo("counter",VoltType.BIGINT));
        t[0].addRow(putCounter);
        return t ;
    }
}