+
−/*
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− * This Source Code Form is subject to the terms of the Mozilla Public
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− * License, v. 2.0.  If a copy of the MPL was not distributed with this
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− * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
− *
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− * Copyright 1997 - July 2008 CWI, August 2008 - 2020 MonetDB B.V.
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− */
+
−
+
−import java.sql.*;
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−
+
−public class Test_Clargequery {
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−	public static void main(String[] args) throws Exception {
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−		Connection con1 = DriverManager.getConnection(args[0]);
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−		Statement stmt1 = con1.createStatement();
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−		ResultSet rs = null;
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−
+
−		// >> true: auto commit should be on by default
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−		System.out.println("0. true\t" + con1.getAutoCommit());
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−
+
−		final String query = 
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−			"-- When a query larger than the send buffer is being " +
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−			"sent, a deadlock situation can occur when the server writes " +
+
−			"data back, blocking because we as client are sending as well " +
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−			"and not reading.  Hence, to avoid this deadlock, in JDBC a " +
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−			"separate thread is started in the background such that results " +
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−			"from the server can be read, while data is still being sent to " +
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−			"the server.  To test this, we need to trigger the SendThread " +
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−			"being started, which we do with a quite large query.  We " +
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−			"construct it by repeating some stupid query plus a comment " +
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−			"a lot of times.  And as you're guessing by now, you're reading " +
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−			"this stupid comment that we use :)\n" +
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−			"select 1;\n";
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−
+
−		int size = 1000;
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−		StringBuilder bigq = new StringBuilder(query.length() * size);
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−		for (int i = 0; i < size; i++) {
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−			bigq.append(query);
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−		}
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−
+
−		// test commit by checking if a change is visible in another connection
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−		try {
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−			System.out.print("1. sending");
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−			stmt1.execute(bigq.toString());
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−			int i = 1;	// we skip the first "getResultSet()"
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−			while (stmt1.getMoreResults() != false) {
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−				i++;
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−			}
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−			if (stmt1.getUpdateCount() != -1) {
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−				System.out.println("found an update count for a SELECT query");
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−				throw new SQLException("boo");
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−			}
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−			if (i != size) {
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−				System.out.println("expecting " + size + " tuples, only got " + i);
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−				throw new SQLException("boo");
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−			}
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−		} catch (SQLException e) {
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−			// this means we failed (table not there perhaps?)
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−			System.out.println("FAILED :(");
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−			System.out.println("ABORTING TEST!!!");
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−		}
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−
+
−		if (rs != null)
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−			rs.close();
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−
+
−		con1.close();
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−	}
+
−}