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From "Knut Anders Hatlen (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DERBY-5425) Updateable holdable ResultSet terminates early after 65638 updates
Date Fri, 29 Jun 2012 13:21:43 GMT

     [ https://issues.apache.org/jira/browse/DERBY-5425?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Knut Anders Hatlen updated DERBY-5425:
--------------------------------------

    Attachment: holdable-row-holders.diff.txt

After some more debugging, it turned out this issue happens because the temporary conglomerates
are not holdable over commits, as suggested above. When the temporary row holder spills to
disk, all rows are written to it, but they are lost on commit, so that the scan is emptied
and too few rows are returned.

I mentioned in my previous comment that I had tried making TemporaryRowHolder's conglomerate
holdable over commit with no luck. However, with the attached patch (holdable-row-holders.diff.txt)
the repro successfully returns 100000 rows. That patch also makes the scans in TemporaryRowHolderResultSet
holdable.

This patch is not intended for commit, since it unconditionally changes the holdability of
all temporary row holders, but at least it shows that the lack of holdability is what's causing
this bug.
                
> Updateable holdable ResultSet terminates early after 65638 updates
> ------------------------------------------------------------------
>
>                 Key: DERBY-5425
>                 URL: https://issues.apache.org/jira/browse/DERBY-5425
>             Project: Derby
>          Issue Type: Bug
>          Components: JDBC
>    Affects Versions: 10.7.1.1
>         Environment: ------------------ Java Information ------------------
> Java Version:    1.6.0_26
> Java Vendor:     Sun Microsystems Inc.
> Java home:       D:\Program Files (x86)\Java\jre6
> Java classpath:  .;..\derby.jar
> OS name:         Windows 7
> OS architecture: x86
> OS version:      6.1
> Java user name:  Andrew
> Java user home:  D:\Users\Andrew
> Java user dir:   E:\workspace\DerbyBug\bin
> java.specification.name: Java Platform API Specification
> java.specification.version: 1.6
> java.runtime.version: 1.6.0_26-b03
> --------- Derby Information --------
> JRE - JDBC: Java SE 6 - JDBC 4.0
> [E:\workspace\DerbyBug\derby.jar] 10.7.1.1 - (1040133)
> ------------------------------------------------------
> ----------------- Locale Information -----------------
> ------------------------------------------------------
>            Reporter: Andrew Johnson
>              Labels: derby_triage10_9
>         Attachments: DerbyBug.java, holdable-row-holders.diff.txt
>
>
> After at least 65638 updates to an indexed column have been done via an updateable holdable
resultset and the transaction is committed ResultSet.next() returns false even if more rows
exist to be returned.
> The following program should output "Total: 100000" but instead outputs "Total: 65638".
> import java.sql.Connection;
> import java.sql.DriverManager;
> import java.sql.PreparedStatement;
> import java.sql.ResultSet;
> import java.sql.SQLException;
> import java.sql.Statement;
> public class DerbyBug {
> 	public static void main(String[] args) throws ClassNotFoundException, SQLException {
> 		Class.forName("org.apache.derby.jdbc.EmbeddedDriver");
> 		Connection conn = DriverManager.getConnection("jdbc:derby:TestDB;create=true");
> 		conn.setAutoCommit(false);
> 		
> 		Statement createStmt = conn.createStatement();
> 		createStmt.executeUpdate("CREATE TABLE test (a INT)");
> 		createStmt.executeUpdate("CREATE INDEX idxa ON test(a)");
> 		createStmt.close();
> 		
> 		PreparedStatement insertStmt = conn.prepareStatement("INSERT INTO test(a) VALUES (?)");
> 		
> 		for (int i = 0; i < 100000; ++i) {
> 			insertStmt.setInt(1, i);
> 			insertStmt.executeUpdate();
> 		}
> 		insertStmt.close();
> 		
> 		conn.commit();
> 		
> 		Statement selectStmt = conn.createStatement(ResultSet.TYPE_FORWARD_ONLY, ResultSet.CONCUR_UPDATABLE,
ResultSet.HOLD_CURSORS_OVER_COMMIT);
> 		ResultSet rs = selectStmt.executeQuery("SELECT a FROM test FOR UPDATE");
> 		
> 		int count = 0;
> 		while (rs.next()) {
> 			rs.updateInt(1, count);
> 			rs.updateRow();
> 			count++;
> 			
> 			conn.commit();
> 		}
> 		
> 		rs.close();
> 		selectStmt.close();
> 		conn.commit();
> 		conn.close();
> 		System.out.println("Total: " + count);
> 		
> 		try {
> 			DriverManager.getConnection("jdbc:derby:;shutdown=true");
> 		} catch (SQLException e) {
> 			if (!e.getSQLState().equals("XJ015")) {
> 				throw e;
> 			}
> 		}
> 	}
> }

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