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From "Tomohito Nakayama (JIRA)" <derby-...@db.apache.org>
Subject [jira] Commented: (DERBY-721) State of InputStream retrieved from resultset is not clean , if there exists previous InputStream .
Date Wed, 23 Nov 2005 07:06:36 GMT
    [ http://issues.apache.org/jira/browse/DERBY-721?page=comments#action_12358338 ] 

Tomohito Nakayama commented on DERBY-721:
-----------------------------------------

I found that BinaryToRawStream is subclass of java.io.FilteredInputStream and 
would just close source InputStream when close method was called.

However, source InputStream was shared between bunch of destination InputStream.
Then, just closing source InputStream may be not correct.

I found when this phenomena was found , substantial class of source InputStream object implements
Resetable .

I will call method to reset source InputStream object ,if it was Resetable object , in BinaryToRawSteream.

> State of InputStream retrieved from resultset is not clean , if there exists previous
InputStream .
> ---------------------------------------------------------------------------------------------------
>
>          Key: DERBY-721
>          URL: http://issues.apache.org/jira/browse/DERBY-721
>      Project: Derby
>         Type: Bug
>   Components: Unknown
>  Environment: naka@rufelza:~/derby/dev/trunk$ cat /proc/version 
> Linux version 2.6.12-1-386 (horms@tabatha.lab.ultramonkey.org) (gcc version 4.0.2 20050917
(prerelease) (Debian 4.0.1-8)) #1 Tue Sep 27 12:41:08 JST 2005
> naka@rufelza:~/derby/dev/trunk$ java -version
> java version "1.4.2_10"
> Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.2_10-b03)
> Java HotSpot(TM) Client VM (build 1.4.2_10-b03, mixed mode)
>     Reporter: Tomohito Nakayama
>     Assignee: Tomohito Nakayama
>  Attachments: testLob.java, testResult.txt
>
> State of InputStream retrieved from ResultSet was not clean , if there exists previous
InputStream retrieved from ResultSet .
> Test code ...
> 	PreparedStatement pst = conn.prepareStatement("insert into a(b) values(?)");
> 	byte[] data = new byte[1024 * 1024];
> 	for(int i = 0;
> 	    i < 1024 * 1024;
> 	    i  ++){
> 	    data[i] = (byte)(i % 256);
> 	}
> 	pst.setBinaryStream(1,new ByteArrayInputStream(data),data.length);
> 	pst.executeUpdate();
> 	pst.close();
> 	
> 	
> 	st = conn.createStatement();
> 	ResultSet rs = st.executeQuery("select b from a");
> 	rs.next();
> 	
> 	InputStream is = rs.getBinaryStream(1);
> 	System.out.println("Here goes first stream");
> 	System.out.println(is.read());
> 	System.out.println(is.read());
> 	System.out.println(is.read());
> 	
> 	is = rs.getBinaryStream(1);
> 	System.out.println("Here goes 2nd stream");
> 	System.out.println(is.read());
> 	System.out.println(is.read());
> 	System.out.println(is.read());
> Result ....
> naka@rufelza:~/derby/test/20051121$ java testLob
> Here goes first stream
> 0
> 1
> 2
> Here goes 2nd stream
> 7
> 8
> 9
> It is expected that result printed from first stream is as same as result printed from
2nd.

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