/* This file is part of VoltDB.
* Copyright (C) 2008-2017 VoltDB Inc.
*
* Permission is hereby granted, free of charge, to any person obtaining
* a copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sublicense, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
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* OTHER DEALINGS IN THE SOFTWARE.
*/
package uniquedevices;
import java.io.IOException;
import org.voltdb.SQLStmt;
import org.voltdb.VoltProcedure;
import org.voltdb.VoltTable;
public class CountDeviceExact extends VoltProcedure {
final static SQLStmt estimatesSelect = new SQLStmt("select devicecount from estimates where appid = ?;");
final static SQLStmt estimatesUpsert = new SQLStmt("upsert into estimates (appid, devicecount) values (?, ?);");
final static SQLStmt exactUpsert = new SQLStmt("upsert into exact (appid, deviceid) values (?, ?);");
final static SQLStmt exactCardinality = new SQLStmt("select count(*) from exact where appid = ?;");
public VoltTable[] run(long appId, long hashedDeviceId) throws IOException {
// get the current cardinality
voltQueueSQL(estimatesSelect, EXPECT_ZERO_OR_ONE_ROW, appId);
// upsert this appid,deviceid pair into the "exact" table
voltQueueSQL(exactUpsert, EXPECT_ZERO_OR_ONE_ROW, appId, hashedDeviceId);
// count rows in the "exact" table for this appId
voltQueueSQL(exactCardinality, EXPECT_SCALAR_LONG, appId);
VoltTable[] results = voltExecuteSQL();
// get the previous cardinality (if any)
long current = 0;
VoltTable estimatesTable = results[0];
if (estimatesTable.advanceRow()) {
current = estimatesTable.getLong("devicecount");
}
// get the new cardinality
long newCardinality = results[2].asScalarLong();
// if the estimates row needs updating, upsert it
if (newCardinality != current) {
voltQueueSQL(estimatesUpsert, EXPECT_SCALAR_MATCH(1), appId, newCardinality);
voltExecuteSQL(true);
}
return null;
}
}