[
http://issues.apache.org/jira/browse/DERBY-1486?page=comments#action_12420608 ]
David Heath commented on DERBY-1486:
------------------------------------
Please could someone validate my assumptions from the previous post?
Firstly, from the previous post my understanding is the JDBS standards say, if
one uses interleaved ResultSets, then a Blob should not be extracted from the
ResultSet after a call to acquire a second ResultSet is made (given the
ResultSet is forward-only and holdable).
Thus the following should always fail
if (rs.next()) {
rs.getInt(1);
readTable1(con, id); <-- ---causes transaction commit,
InputStream stream = rs.getBinaryStream(2);
ObjectInputStream objStream = new ObjectInputStream(stream);
Object obj = objStream.readObject();
double[] array = (double[]) obj;
System.out.println(array.length);
}
Where as the following should always work:
while (rs.next()) {
rs.getInt(1);
InputStream stream = rs.getBinaryStream(2);
ObjectInputStream objStream = new ObjectInputStream(stream);
Object obj = objStream.readObject();
double[] array = (double[]) obj;
System.out.println(array.length);
readTable1(con, id); <------- transaction commit
}
If this is true I will change my code (I would then assume MySQL does not
strictly adhere to the standards (which I have seen in other areas), as the
first example also works using it).
Secondly, the fact the second example only works within derby, if the select
statement is changed from: SELECT * FROM TABLE_2 to SELECT * FROM TABLE_2 WHERE
ID>0 implies there is a bug somewhere in derby?
> ERROR 40XD0 - When exracting Blob from a database
> --------------------------------------------------
>
> Key: DERBY-1486
> URL: http://issues.apache.org/jira/browse/DERBY-1486
> Project: Derby
> Type: Bug
> Components: Miscellaneous
> Versions: 10.1.2.1
> Environment: Windows XP
> Reporter: David Heath
>
> An exception occurs when extracting a Blob from a database.
> The following code, will ALWAYS fail with the Exception:
> java.io.IOException: ERROR 40XD0: Container has been closed
> at
> org.apache.derby.impl.store.raw.data.OverflowInputStream.fillByteHolder(Unknown
> Source)
> at
> org.apache.derby.impl.store.raw.data.BufferedByteHolderInputStream.read(Unknown
> Source)
> at java.io.DataInputStream.read(Unknown Source)
> at java.io.FilterInputStream.read(Unknown Source)
> at java.io.ObjectInputStream$PeekInputStream.read(Unknown Source)
> at java.io.ObjectInputStream$PeekInputStream.readFully(Unknown Source)
> at java.io.ObjectInputStream$BlockDataInputStream.readDoubles(Unknown
> Source)
> at java.io.ObjectInputStream.readArray(Unknown Source)
> at java.io.ObjectInputStream.readObject0(Unknown Source)
> at java.io.ObjectInputStream.readObject(Unknown Source)
> at BlobTest.readRows(BlobTest.java:81)
> at BlobTest.main(BlobTest.java:23)
> CODE:
> import java.io.*;
> import java.sql.*;
> import java.util.*;
> public class BlobTest
> {
> private static final String TABLE1 = "CREATE TABLE TABLE_1 ( "
> + "ID INTEGER NOT NULL, "
> + "COL_2 INTEGER NOT NULL, "
> + "PRIMARY KEY (ID) )";
> private static final String TABLE2 = "CREATE TABLE TABLE_2 ( "
> + "ID INTEGER NOT NULL, "
> + "COL_BLOB BLOB, "
> + "PRIMARY KEY (ID) )";
> public static void main(String... args) {
> try {
> createDBandTables();
> Connection con = getConnection();
> addRows(con, 10000, 1);
> readRows(con, 1);
> con.close();
> }
> catch(Exception exp) {
> exp.printStackTrace();
> }
> }
> private static void addRows(Connection con, int size, int id)
> throws Exception
> {
> String sql = "INSERT INTO TABLE_1 VALUES(?, ?)";
> PreparedStatement pstmt = con.prepareStatement(sql);
> pstmt.setInt(1, id);
> pstmt.setInt(2, 2);
> pstmt.executeUpdate();
> pstmt.close();
> double[] array = new double[size];
> array[size-1] = 1.23;
> sql = "INSERT INTO TABLE_2 VALUES(?, ?)";
> pstmt = con.prepareStatement(sql);
> pstmt.setInt(1, id);
> ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
> ObjectOutputStream objStream = new ObjectOutputStream(byteStream);
> objStream.writeObject(array); // Convert object to byte stream
> byte[] bytes = byteStream.toByteArray();
> ByteArrayInputStream inStream = new ByteArrayInputStream(bytes);
> pstmt.setBinaryStream(2, inStream, bytes.length);
> pstmt.executeUpdate();
> pstmt.close();
> }
> private static void readRows(Connection con, int id) throws Exception
> {
> String sql = "SELECT * FROM TABLE_2";
> Statement stmt = con.createStatement();
> ResultSet rs = stmt.executeQuery(sql);
> if (rs.next()) {
> rs.getInt(1);
> readTable1(con, id);
> InputStream stream = rs.getBinaryStream(2);
> ObjectInputStream objStream = new ObjectInputStream(stream);
> Object obj = objStream.readObject(); // FAILS HERE
> double[] array = (double[]) obj;
> System.out.println(array.length);
> }
> rs.close();
> stmt.close();
> }
> private static void readTable1(Connection con, int id) throws Exception {
> String sql = "SELECT ID FROM TABLE_1 WHERE ID=" + id;
> Statement stmt = con.createStatement();
> ResultSet rs = stmt.executeQuery(sql);
> if (rs.next()) {
> }
> rs.close();
> stmt.close();
> }
>
> private static Connection getConnection() throws Exception {
> String driver="org.apache.derby.jdbc.EmbeddedDriver";
> Properties p = System.getProperties();
> p.put("derby.system.home", "C:\\databases\\sample");
>
> Class.forName(driver);
> String url = "jdbc:derby:derbyBlob";
> Connection con = DriverManager.getConnection(url);
> return con;
> }
> private static void createDBandTables() throws Exception {
> String driver="org.apache.derby.jdbc.EmbeddedDriver";
> Properties p = System.getProperties();
> p.put("derby.system.home", "C:\\databases\\sample");
>
> Class.forName(driver);
> String url = "jdbc:derby:derbyBlob;create=true";
> Connection con = DriverManager.getConnection(url);
> Statement stmt = con.createStatement();
> stmt.execute(TABLE1);
> stmt.execute(TABLE2);
> stmt.close();
> con.close();
> }
> }
> The Exception DOES NOT occur if call to readTable1() is not made.
> The Exception DOES NOT occur if the size of the Blob is reduced - for example
> calling:
> addRows(con, 1000, 1);
> This is a show stopper.
> Output from: java org.apache.derby.tools.sysinfo
> ------------------ Java Information ------------------
> Java Version: 1.5.0_05
> Java Vendor: Sun Microsystems Inc.
> Java home: C:\Program Files\Java\jre1.5.0_05
> Java classpath:
> C:\tools\derby\db-derby-10.1.2.1-bin\lib\derby.jar;C:\tools\der
> by\db-derby-10.1.2.1-bin\lib\derbytools.jar;
> OS name: Windows XP
> OS architecture: x86
> OS version: 5.1
> Java user name: David
> Java user home: C:\Documents and Settings\David
> Java user dir: C:\david\novice\derby
> java.specification.name: Java Platform API Specification
> java.specification.version: 1.5
> --------- Derby Information --------
> JRE - JDBC: J2SE 5.0 - JDBC 3.0
> [C:\tools\derby\db-derby-10.1.2.1-bin\lib\derby.jar] 10.1.2.1 - (330608)
> [C:\tools\derby\db-derby-10.1.2.1-bin\lib\derbytools.jar] 10.1.2.1 - (330608)
> ------------------------------------------------------
> ----------------- Locale Information -----------------
> ------------------------------------------------------
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