new file mode 100644
--- /dev/null
+++ b/tests/Bug_LargeQueries_6571_6693.java
@@ -0,0 +1,161 @@
+/*
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0.  If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * Copyright 1997 - July 2008 CWI, August 2008 - 2019 MonetDB B.V.
+ */
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.ResultSet;
+import java.sql.Statement;
+import java.sql.SQLException;
+
+public class Bug_LargeQueries_6571_6693 {
+	final static String tbl_nm = "tbl6693";
+	final static String largedata = createLargedata(98765);
+
+	private static String createLargedata(int num) {
+		String repeatValue = "*";
+		StringBuilder sb = new StringBuilder(num * repeatValue.length());
+		for (int i = 0; i < num; i++)
+			sb.append(repeatValue);
+		String largedata = sb.toString();
+		if (largedata.length() <= 8192)
+			System.out.println("Length (" + largedata.length() + ") of largedata value is too small! Should be larger than 8192!");
+		return largedata;
+	}
+
+	// To execute this test program: start a local MonetDB server (mserver5 process) and next execute command:
+	// java -cp monetdb-jdbc-2.29.jar:. Bug_LargeQueries_6571_6693 "jdbc:monetdb://localhost:50000/demo?user=monetdb&password=monetdb"
+
+	public static void main(String[] args) throws SQLException {
+		int script_iterations = 10;
+		String conURL = args.length > 0 ? args[0] : "";
+
+		if (args.length > 1) {
+			try {
+				script_iterations = Integer.parseInt(args[1]);
+			} catch (NumberFormatException nfe) {
+				System.err.println("Cannot convert 2nd argumnent to an integer. Ignoring it.");
+			}
+		}
+
+		try (Connection con = DriverManager.getConnection(conURL)) {
+			try (Statement stmt = con.createStatement()) {
+				// create a test table.
+				stmt.executeUpdate("CREATE TABLE IF NOT EXISTS " + tbl_nm + " (attribute CLOB, value CLOB);");
+				System.out.print("Created table: " + tbl_nm);
+				System.out.print(" Inserting rows. ");
+				String insertCmd = "INSERT INTO " + tbl_nm + " VALUES ('activeset_default_fiets', '" + largedata + "');";
+				int ins = stmt.executeUpdate(insertCmd);
+				ins += stmt.executeUpdate(insertCmd);
+				ins += stmt.executeUpdate(insertCmd);
+				System.out.println(ins + " rows inserted");
+			}
+
+			run_tests(conURL, script_iterations);
+
+			try (Statement stmt = con.createStatement()) {
+				System.out.println("Cleanup TABLE " + tbl_nm);
+				stmt.executeUpdate("DROP TABLE IF EXISTS " + tbl_nm);
+			}
+		}
+
+		System.out.println("Test completed without hanging");
+	}
+
+	private static void run_tests(String conURL, int iterations) throws SQLException {
+		String script =
+			  "delete from " + tbl_nm + " where attribute='activeset_default_fiets';\n"
+			+ "insert into " + tbl_nm + " values ('activeset_default_fiets', '" + largedata + "');\n"
+			+ "insert into " + tbl_nm + " values ('activeset_default_fiets', '" + largedata + "');\n"
+			+ "insert into " + tbl_nm + " values ('activeset_default_fiets', '" + largedata + "');\n"
+			+ "select value from " + tbl_nm + " where attribute='activeset_default_fiets';\n";
+		System.out.println("Script size is " + script.length());
+
+		// first try to make the execution hang after many iterations of sending large data queries within one connection
+		System.out.println("First test repeat " + iterations + " times");
+		try (Connection con = DriverManager.getConnection(conURL)) {
+			System.out.print("Iteration: ");
+			for (int i = 1; i <= iterations; i++) {
+				System.out.print(i + " ");
+				try (Statement stmt = con.createStatement()) {
+					process_script(stmt, script, 1, 3, 6);
+				}
+			}
+			System.out.println();
+		}
+		System.out.println("Completed first test");
+
+		// also try to make the execution hang after many iterations of making connections (each their own socket) and sending large scripts
+		System.out.println("Second test repeat " + iterations + " times");
+		System.out.print("Iteration: ");
+		for (int i = 1; i <= iterations; i++) {
+			try (Connection con = DriverManager.getConnection(conURL)) {
+				System.out.print(i + " ");
+				try (Statement stmt = con.createStatement()) {
+					process_script(stmt, script, 1, 3, 6);
+					process_script(stmt, script, 1, 3, 6);
+					process_script(stmt, script, 1, 3, 6);
+					process_script(stmt, script, 1, 3, 6);
+				}
+			}
+		}
+		System.out.println();
+		System.out.println("Completed second test");
+
+		// next try to make the execution hang by sending very many queries combined in 1 large script
+		final int queries = 8765;
+		StringBuilder sb = new StringBuilder(queries * 13);
+		for (int i = 1; i <= queries; i++)
+			sb.append(" SELECT ").append(i).append(';');
+		script = sb.toString();
+		System.out.println("Script size is " + script.length());
+		iterations = 3;
+		System.out.println("Third test repeat " + iterations + " times");
+		try (Connection con = DriverManager.getConnection(conURL)) {
+			System.out.print("Iteration: ");
+			for (int i = 1; i <= iterations; i++) {
+				System.out.print(i + " ");
+				try (Statement stmt = con.createStatement()) {
+					process_script(stmt, script, queries, queries, 0);
+				}
+			}
+			System.out.println();
+		}
+		System.out.println("Completed third test");
+	}
+
+	private static void process_script(Statement stmt, String script,
+				int expectedResults, int expectedTotalRows, int expectedUpdates) throws SQLException {
+		int results = 0;
+		int rows = 0;
+		int updates = 0;
+		stmt.execute(script);
+		do {
+			ResultSet rs = stmt.getResultSet();
+			if (rs != null) {
+				results++;
+				while(rs.next()) {
+					String val = rs.getString(1);
+					rows++;
+				}
+				rs.close();
+			} else {
+				int uc = stmt.getUpdateCount();
+				if (uc > 0)
+					updates += uc;
+			}
+		} while (stmt.getMoreResults() || stmt.getUpdateCount() != -1);
+
+		/* verify nr of processed resultsets and retrieved rows are as expected */
+		if (results != expectedResults)
+			System.out.print(results + "!=" + expectedResults + " ");
+		if (rows != expectedTotalRows)
+			System.out.print(rows + "!=" + expectedTotalRows + " ");
+		if (updates != expectedUpdates)
+			System.out.print(updates + "!=" + expectedUpdates + " ");
+	}
+}

--- a/tests/build.xml
+++ b/tests/build.xml
@@ -140,6 +140,7 @@ Copyright 1997 - July 2008 CWI, August 2
     <antcall target="Bug_PrepStmtSetObject_CLOB_6349" />
     <antcall target="Bug_Connect_as_voc_getMetaData_Failure_Bug_6388" />
     <antcall target="Bug_PrepStmtSetString_6382" />
+    <antcall target="Bug_LargeQueries_6571_6693" />
   </target>
 
   <target name="test_class" depends="compile,jdbc">
@@ -419,4 +420,10 @@ Copyright 1997 - July 2008 CWI, August 2
     </antcall>
   </target>
 
+  <target name="Bug_LargeQueries_6571_6693">
+    <antcall target="test_class">
+      <param name="test.class" value="Bug_LargeQueries_6571_6693" />
+    </antcall>
+  </target>
+
 </project>