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https://issues.apache.org/jira/browse/DERBY-3243?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12563132#action_12563132
]
Knut Anders Hatlen commented on DERBY-3243:
-------------------------------------------
Does the DRDA spec require that locators are two-byte integers, or could we use
four bytes? Seems like we at least should make EmbedConnection.lobHMKey wrap
around on the max value we are able to send over DRDA, and ensure that it
doesn't go negative.
I don't think resetting the lob key on commit/rollback works, as the client
does not expect the keys to be reused. Old Clob/Blob objects on the client will
then start returning data for the queries performed in the new transaction. I
ran the code below to test it.
-----8<-----
import java.sql.*;
public class ResetCounter {
public static void main(String[] args) throws Exception {
Class.forName("org.apache.derby.jdbc.ClientDriver");
Connection c = DriverManager.getConnection(
"jdbc:derby://localhost/db;create=true");
Statement s1 = c.createStatement();
ResultSet rs1 = s1.executeQuery("values cast('first' as clob)");
rs1.next();
Clob first = rs1.getClob(1);
rs1.close(); // auto-commit happens here
Statement s2 = c.createStatement();
ResultSet rs2 = s2.executeQuery("values cast('second' as clob)");
rs2.next();
Clob second = rs2.getClob(1);
System.out.println("1: " + first.getSubString(1, 100)); // should fail
System.out.println("2: " + second.getSubString(1, 100));
rs2.close();
}
}
----->8-----
Without the patch, first.getSubString(1, 100) failed (correctly) because the
transaction in which the Clob was created, had been committed. With the patch
applied, it instead returned the data that the second transaction had retrieved.
> (jdbc net client) exception during normal iteration through "ResultSet" of
> "select * from t"
> --------------------------------------------------------------------------------------------
>
> Key: DERBY-3243
> URL: https://issues.apache.org/jira/browse/DERBY-3243
> Project: Derby
> Issue Type: Bug
> Components: JDBC
> Affects Versions: 10.3.2.1
> Environment: ------------------ Java Information ------------------
> Java Version: 1.4.2_03
> Java Vendor: Sun Microsystems Inc.
> Java home: C:\Programme\Java\j2re1.4.2_03
> Java classpath: derbyclient.jar
> OS name: Windows XP
> OS architecture: x86
> OS version: 5.1
> Java user name: cbdqok
> Java user home: C:\Dokumente und Einstellungen\cbdqok
> Java user dir: D:\users\cbdqok\privat\osj\lib_derby_net\lib
> java.specification.name: Java Platform API Specification
> java.specification.version: 1.4
> --------- Derby Information --------
> JRE - JDBC: J2SE 1.4.2 - JDBC 3.0
> [D:\users\cbdqok\privat\osj\lib_derby_net\lib\derbyclient.jar] 10.3.1.4 -
> (561794)
> ------------------------------------------------------
> ----------------- Locale Information -----------------
> ------------------------------------------------------
> Reporter: Oliver Seidel
> Priority: Critical
> Attachments: derby-3243_fix_double_hashmap_entry_diff.txt,
> derby-3243_fix_double_hashmap_entry_stat.txt
>
>
> Thanks again to the DERBY developers.
> For my convenience I use the client/server variant of DERBY. This is where
> the error occurs. I have temporarily alleviated the problem for my case by
> using the embedded version.
> I'm forced to use outlook and have built a program which siphons the messages
> into a derby database (phase 1 -- table has two varchar fields and a clob).
> When reading them back (phase 2 -- simple select of all records in no
> particular order, all 3 attributes), it has developed an exception. This is
> a result of data volume. I have reduced the problem to a single
> demonstration program.
> This behaviour, and the fact that the error is not a "DERBY Exception", but a
> proper exception coming back from the JDBC call, leads me to the diagnosis
> that it is a derby network client jdbc problem.
> The problem has been reproduced once by Bryan Pendleton:
> http://www.nabble.com/IndexOutOfBoundsException-t4926228.html
> I'll try to attach the code "error.java"; it can also be found on:
> http://www.os10000.net/error.java
> Please use as follows:
> javac -classpath derby.jar:derbynet.jar error.java
> java -cp .:derby.jar:derbynet.jar error
> It will create a directory "test_db" and fill it with approx 120mb data.
> Then you will observe the failure.
> /* -*- Mode:Java; c-basic-offset:8 -*- */
> //
> --------------------------------------------------------------------------------
> public class error {
> //
> ------------------------------------------------------------------------
> public static final int port = 1527;
> public static final String host = "127.0.0.1";
> //
> ------------------------------------------------------------------------
> public static void log(String x) { System.out.println(x); };
> //
> ------------------------------------------------------------------------
> public static void log_stacktrace(Exception e) {
> java.io.StringWriter sw = new java.io.StringWriter();
> java.io.PrintWriter pw = new java.io.PrintWriter(sw);
> e.printStackTrace(pw);
> log(sw.toString());
> };
> //
> ------------------------------------------------------------------------
> public static void start_server() {
> try {
> org.apache.derby.drda.NetworkServerControl server =
> new
> org.apache.derby.drda.NetworkServerControl(java.net.InetAddress.getByName(host),port);
> server.start(null);
> try { java.lang.Thread.sleep(5000); } catch (Exception
> e) { };
> log("started DERBY on host "+host+" port
> "+Integer.toString(port)+".");
> } catch (Exception e) {
> log_stacktrace(e);
> };
> };
> //
> ------------------------------------------------------------------------
> public static java.sql.Connection con()
> throws java.sql.SQLException, java.lang.ClassNotFoundException {
> Class.forName("org.apache.derby.jdbc.ClientDriver");
> String x_dbse = "test_db";
> String x_user = ";user=os10000";
> String x_pass = ";password=ding";
> String x_crte = ";create=true";
> String x_msgs = ";retrieveMessagesFromServerOnGetMessage=true";
> String connect =
> "jdbc:derby://"+host+":"+port+"/"+x_dbse+x_user+x_crte+x_msgs;
> return java.sql.DriverManager.getConnection(connect);
> };
> //
> ----------------------------------------------------------------------
> public static String getclob(java.sql.Clob b) {
> java.io.CharArrayWriter caw = new java.io.CharArrayWriter();
> try {
> java.io.Reader rd = b.getCharacterStream();
> char cb[] = new char[4096];
> int off=0, bts = rd.read(cb);
> while (bts>0) { caw.write(cb,off,bts); off+=bts;
> bts=rd.read(cb); };
> rd.close();
> } catch(Exception e) {};
> String res = caw.toString();
> caw.close();
> return res;
> };
> //
> ----------------------------------------------------------------------
> public static class myclob implements java.sql.Clob {
> String v;
> public myclob(String z) { v=z; };
> public java.io.InputStream getAsciiStream() { return new
> java.io.ByteArrayInputStream(v.getBytes()); };
> public java.io.Reader getCharacterStream() { return new
> java.io.CharArrayReader(v.toCharArray()); };
> public String getSubString(long pos, int length) { return
> v.substring((int)pos,(int)(pos+length)); };
> public long length() { return v.length(); };
> public long position(java.sql.Clob pattern, long start) {
> return 0; };
> public long position(String pattern, long start) { return 0; };
> public java.io.OutputStream setAsciiStream(long pos) {
> new java.sql.SQLException("setAsciiStream not
> implemented."); return null; };
> public java.io.Writer setCharacterStream(long pos) {
> new java.sql.SQLException("setCharacterStream not
> implemented."); return null; };
> public int setString(long pos, String s) {
> new java.sql.SQLException("setString not
> implemented."); return -1; };
> public int setString(long pos, String s, int offset, int len) {
> new java.sql.SQLException("setString not
> implemented."); return -1; };
> public void truncate(long len) {
> new java.sql.SQLException("truncate not implemented.");
> };
> };
> public static java.sql.Clob putclob(String x) { return new myclob(x); };
>
> //
> ------------------------------------------------------------------------
> public static String getLob(java.sql.ResultSet rs, int arg)
> throws java.sql.SQLException { return getclob(rs.getClob(arg));
> };
> public static void setLob(java.sql.PreparedStatement ps, int arg,
> String val)
> throws java.sql.SQLException { ps.setClob(arg,putclob(val)); };
> //
> ------------------------------------------------------------------------
> public static String clean_string(String x) {
> return
> x.replaceAll("[\0\r\\\\]","").replaceAll("'","\\\"").replaceAll(",+",",");
> };
> //
> ------------------------------------------------------------------------
> public static String make_string(int digits) {
> double dl = (Math.random()) *
> (Math.pow(10.0,digits*Math.random()));
> int len = (int) dl;
> byte buf[] = new byte[len];
> while (len>0) {
> double db = 256*Math.random();
> buf[--len] = (byte)db;
> };
> return clean_string(new String(buf));
> };
> //
> ------------------------------------------------------------------------
> public static void update(java.sql.Connection c, String cmd)
> throws java.sql.SQLException {
> c.createStatement().execute(cmd);
> };
> //
> ------------------------------------------------------------------------
> public static final int entries=100000;
> public static void fill_db(java.sql.Connection c)
> throws java.sql.SQLException {
> try { update(c,"drop table mail_raw"); } catch (Exception e) {};
> try { update(c,"create table mail_raw ( msg varchar(999), att
> varchar(100), val clob )"); }
> catch (Exception e) { log_stacktrace(e); };
> java.sql.PreparedStatement pstmt = null;
> try { pstmt = c.prepareStatement("insert into mail_raw values (
> ?, ?, ? )"); }
> catch (Exception e) { log_stacktrace(e); };
> for (int i=0; i<entries; i++) {
> pstmt.setString(1,make_string(3));
> pstmt.setString(2,"5 body");
> setLob(pstmt,3,make_string(4));
> pstmt.executeUpdate();
> if (i%100==0) log("step "+i+"/"+entries);
> };
> };
> //
> ------------------------------------------------------------------------
> public static void dump_db(java.sql.Connection c)
> throws java.sql.SQLException {
> log("performing dump.");
> java.sql.ResultSet rs =
> c.createStatement().executeQuery("select * from mail_raw");
> while (rs.next()) {
> String msg = rs.getString(1);
> String att = rs.getString(2);
> String val = getLob(rs,3);
> };
> };
> //
> ------------------------------------------------------------------------
> public static void main(String args[]) {
> start_server();
> try {
> java.sql.Connection c = con();
> fill_db(c);
> dump_db(c);
> } catch (Exception e) { log_stacktrace(e); };
> };
> //
> ------------------------------------------------------------------------
> };
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