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From "Sunitha Kambhampati (JIRA)" <derby-...@db.apache.org>
Subject [jira] Updated: (DERBY-500) Update/Select failure when BLOB/CLOB fields updated in several rows by PreparedStatement using setBinaryStream and setCharacterStream
Date Tue, 18 Oct 2005 07:36:48 GMT
     [ http://issues.apache.org/jira/browse/DERBY-500?page=all ]

Sunitha Kambhampati updated DERBY-500:

    Attachment: Derby500.diff.txt

Background :
In Derby, when a stream is set as a parameter value, the wrapper stream object used for character
data is ReaderToUTF8Stream 
and for binary data it is RawToBinaryFormatStream.Both these stream objects on read() return
data in a format that is used to store the respective datatype value. E.g in case of char,
the characters read from the user stream are converted using utf-8 derby specific encoding
and read calls return 
the data as expected by store layer. Beginning 2 bytes either have the utflen or has zeroes,
or if it is a long string, then the value is ended with the special marker 0xE0 , 0x00, 0x00.
For binary data, the stream data is prepended with 4 zeroes. 

once,the stream has been read fully and end of file reached, further read() returns a -1.
 If a stream is re-read, it returns a -1 which is incorrect data.  E.g.in the repro for DERBY-500,
the update statement has multiple rows that qualify and since the stream parameter is used;
the first row gets updated with the correct value and the stream is drained. For the subsequent
rows, the read from the stream parameter value returns -1 and thus is updated with incorrect
data.When retrieving the row back, the format of the fields is incorrect and thus the exception.

This patch

1. adds changes to RawToBinaryFormatStream and ReaderToUTF8Stream to throw an EOFException
if stream is re-read.
If a stream value has been fully read and end of file reached, any further reads on the stream
object  will result in an EOFException. This seems reasonable and more correct than using
incorrect values.  
Adds a new error message - 'Stream has already been read and end-of-file reached and cannot
be re-used.'

2. changes to RememberBytesInputStream to keep track of the stream state and not call read
on the stream objects once eof is reached.

3. Fix a bug in StoredPage.logColumn related to streams. In one particular scenario, column
was not being set to RememberBytesInputStream object and thus losing the data that would be
read from stream into RememberBytesInputStream.

4. adds testcases to store/streamingColumn.java and lang/forbitdata.java 

Also note
- This fix affects cases when a stream is re-used in which case an exception will be thrown.

So code that reads the stream once and materializes it will not be affected. E.g.  Currently
in case of char,varchar,long varchar, streams are materialized and this will work fine as

Ran tests ok on jdk142/win2k (using classes directory)

svn stat
M      java\engine\org\apache\derby\impl\jdbc\RawToBinaryFormatStream.java
M      java\engine\org\apache\derby\impl\jdbc\ReaderToUTF8Stream.java
M      java\engine\org\apache\derby\impl\store\raw\data\RememberBytesInputStream.java
M      java\engine\org\apache\derby\impl\store\raw\data\StoredPage.java
M      java\engine\org\apache\derby\iapi\reference\SQLState.java
M      java\engine\org\apache\derby\loc\messages_en.properties
M      java\testing\org\apache\derbyTesting\functionTests\tests\lang\forbitdata.java
M      java\testing\org\apache\derbyTesting\functionTests\tests\store\streamingColumn.java
M      java\testing\org\apache\derbyTesting\functionTests\master\streamingColumn.out
M      java\testing\org\apache\derbyTesting\functionTests\master\forbitdata.out

I'll add clarifications to the paper - JDBCImplementation.html and attach it as another patch
to this jira entry.

Can someone please review it. Thanks.

> Update/Select failure when BLOB/CLOB fields updated in several rows by PreparedStatement
using setBinaryStream and setCharacterStream
> -------------------------------------------------------------------------------------------------------------------------------------
>          Key: DERBY-500
>          URL: http://issues.apache.org/jira/browse/DERBY-500
>      Project: Derby
>         Type: Bug
>   Components: JDBC
>     Versions:
>  Environment: Windows 2000, java SDK 1.4
>     Reporter: Peter Kovgan
>     Assignee: Sunitha Kambhampati
>      Fix For:
>  Attachments: Derby500.diff.txt, Derby500.stat.txt
> I have table contained BLOB and CLOB fields:
> Create table string is:
> private static final String CREATE = "CREATE TABLE ta (" +
>             "ta_id INTEGER NOT NULL," +
>             "mname VARCHAR( 254 ) NOT NULL," +
>             "mvalue INT NOT NULL," +
>             "mdate DATE NOT NULL," +
>             "bytedata BLOB NOT NULL," +
>             "chardata CLOB NOT NULL," +
>             "PRIMARY KEY ( ta_id ))";
> Then I insert 2000 rows in the table.
> Then I update all 2000 rows by command:
> private static final String UPDATE  =  "UPDATE ta " +
>     		"SET bytedata=? ,chardata=? " +
>     		"WHERE mvalue=?";
> /**create blob and clob arrays**/
>         int len1 = 10000;//for blob length data
>         int len2 = 15000;//for clob length data
>         byte buf [] = new byte[len1];
>         for(int i=0;i<len1;i++){
>         	buf [i] = (byte)45;
>         }
>         ByteArrayInputStream bais = new ByteArrayInputStream(buf);
>         char[] bufc = new char[len2];
>         for (int i = 0; i < bufc.length; i++) {
>         	bufc[i] = (char)'b';
> 		}
>         CharArrayReader car = new CharArrayReader(bufc);
> /***/
> PreparedStatement pstmt = connection.prepareStatement(UPDATE);
> pstmt.setBinaryStream(1,bais, len1);
> pstmt.setCharacterStream(2,car, len2);
> pstmt.setInt(3,5000);
> int updated =  pstmt.executeUpdate();
> pstmt.close();
> System.out.printlen("updated ="+updated );
> all 2000 rows updated , because I receive output : updated =2000
> But If I run select (SELECT bytedata ,chardata  FROM ta)  after update, select failed
with error:
> ERROR XSDA7: Restore of a serializable or SQLData object of class , attempted to
>  read more data than was originally stored
>         at org.apache.derby.iapi.error.StandardException.newException(StandardEx
> ception.java)
>         at org.apache.derby.impl.store.raw.data.StoredPage.readRecordFromArray(S
> toredPage.java)
>         at org.apache.derby.impl.store.raw.data.StoredPage.restoreRecordFromSlot
> (StoredPage.java)
>         at org.apache.derby.impl.store.raw.data.BasePage.fetchFromSlot(BasePage.
> java)
>         at org.apache.derby.impl.store.access.conglomerate.GenericScanController
> .fetchRows(GenericScanController.java)
>         at org.apache.derby.impl.store.access.heap.HeapScan.fetchNextGroup(HeapS
> can.java)
>         at org.apache.derby.impl.sql.execute.BulkTableScanResultSet.reloadArray(
> BulkTableScanResultSet.java)
>         at org.apache.derby.impl.sql.execute.BulkTableScanResultSet.getNextRowCo
> re(BulkTableScanResultSet.java)
>         at org.apache.derby.impl.sql.execute.NestedLoopJoinResultSet.getNextRowC
> ore(NestedLoopJoinResultSet.java)
>         at org.apache.derby.impl.sql.execute.NestedLoopLeftOuterJoinResultSet.ge
> tNextRowCore(NestedLoopLeftOuterJoinResultSet.java)
>         at org.apache.derby.impl.sql.execute.ProjectRestrictResultSet.getNextRow
> Core(ProjectRestrictResultSet.java)
>         at org.apache.derby.impl.sql.execute.SortResultSet.getRowFromResultSet(S
> ortResultSet.java)
>         at org.apache.derby.impl.sql.execute.SortResultSet.getNextRowFromRS(Sort
> ResultSet.java)
>         at org.apache.derby.impl.sql.execute.SortResultSet.loadSorter(SortResult
> Set.java)
>         at org.apache.derby.impl.sql.execute.SortResultSet.openCore(SortResultSe
> t.java)
>         at org.apache.derby.impl.sql.execute.BasicNoPutResultSetImpl.open(BasicN
> oPutResultSetImpl.java)
>         at org.apache.derby.impl.sql.GenericPreparedStatement.execute(GenericPre
> paredStatement.java)
>         at org.apache.derby.impl.jdbc.EmbedStatement.executeStatement(EmbedState
> ment.java)
>         at org.apache.derby.impl.jdbc.EmbedPreparedStatement.executeStatement(Em
> bedPreparedStatement.java)
>         at org.apache.derby.impl.jdbc.EmbedPreparedStatement.execute(EmbedPrepar
> edStatement.java)
>         at com.beep_beep.dbtest.complex.Benchmark.testSelect(Unknown Source)
>         at com.beep_beep.dbtest.complex.Benchmark.executeSimplestBigTable(Unknown Sour
> ce)
>         at com.beep_beep.dbtest.complex.Benchmark.testBigTable(Unknown Source)
>         at com.beep_beep.dbtest.complex.Benchmark.executeDegradationBenchmark(Unknown
> Source)
>         at com.beep_beep.dbtest.complex.Benchmark.main(Unknown Source)
> From the stack trace and from console I see that Update passed, but error was raised
in Select after Update.
> When I try the same update, but with difference(I changed WHERE clause, causing update
only 1 row):
> private static final String UPDATE  =  "UPDATE ta " +
>     		"SET bytedata=? ,chardata=? " +
>     		"WHERE mname=?";
> PreparedStatement pstmt = connection.prepareStatement(UPDATE);
> pstmt.setBinaryStream(1,bais, len1);
> pstmt.setCharacterStream(2,car, len2);
> pstmt.setInt(3,"PETER");
> int updated =  pstmt.executeUpdate();
> pstmt.close();
> System.out.printlen("updated ="+updated );
> Only 1 row updated , because I receive output : updated =1
> In this case I have NO errors in select(the same as previous) .
> My assumption:
> It seems that Update receives ByteArrayInputStream and updates correctly only 1 row,
then all rows updated by some
> incorrect value(may be because ByteArrayInputStream reached its end in first update),
causing select failure.
> I tested PointBase by the same test and PointBase passed this stage without errors, no
matter how many rows was updated.
> So I think it is a bug.
> Thank you.

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