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From "Kristian Waagan (JIRA)" <derby-...@db.apache.org>
Subject [jira] Created: (DERBY-1510) 'SQLBinary.readFromStream' can enter endless loop
Date Fri, 14 Jul 2006 09:30:29 GMT
'SQLBinary.readFromStream' can enter endless loop

         Key: DERBY-1510
         URL: http://issues.apache.org/jira/browse/DERBY-1510
     Project: Derby
        Type: Bug

  Components: JDBC, SQL  
    Reporter: Kristian Waagan
 Assigned to: Kristian Waagan 
    Priority: Minor

Under certain circumstances, the method 'SQLBinary.readFromStream' can enter an endless loop
while reading the stream. The following must be true for the bug to occur: 
 * There must be more data in the stream than what can fit into the initial buffer (32 K).
 * The method 'available' of the stream returns 0.

Since the default return value for 'InputStream.available' is 0, and the method reading the
stream can be used for data types CHAR FOR BIT DATA, VARCHAR FOR BIT DATA and LONG VARCHAR
FOR BIT DATA, the bug should be fixed. The maximum length is 32700 bytes.
The method will also be used by SQLBlob, but it may be better to introduce a new streaming
method for it, since the current implementation has memory-problems for large data (materializes
the whole stream). A separate issue should/will be created for this.

The symptom for this bug is a hang when calling one of the execute methods of Prepared- or
CallableStatement and maybe also certain set methods in ResultSet.
The visibility of this bug is very low, but the impact is severe/critical. When the JDBC 4
length less streaming overloads are added (DERBY-1417), visibility might increase.

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