Retrieving BLOB fields sometimes fails
--------------------------------------
Key: DERBY-5090
URL: https://issues.apache.org/jira/browse/DERBY-5090
Project: Derby
Issue Type: Bug
Components: JDBC
Affects Versions: 10.7.1.1
Environment: JDBC derby embedded driver
Reporter: Unai Vivi
Priority: Minor
This is my first issue report, so please be understanding if I'm posting the
wrong thing, in the wrong place or in the wrong way. I just want to help. :)
While iterating through a ResultSet, when accessing a BLOB field to read its
contents via an InputStream, I noticed that:
- if the current ResultSet's has been "warmed up" by retrieving another column
first, everything it's fine;
- if, on the other hand, you first-thing access the BLOB (and read other
columns later), then upon reading the first byte out the InputStream bound to
the BLOB field (ResultSet.getBinaryStream("col_name")) an IOException is thrown
(and IOException's getMessage() method returns null).
Following is an example, taken from a real application. The two code segments
only differ in the fact that a SMALLINT & VARCHAR read is done before/after the
BLOB read.
--Working snippet--
[...]
icRelPath[i] = "imm" + File.separator + "ic" + "_" +
rs.getShort("setIcone") + "_" + i + "." + rs.getString("estensione");
AutoCloseInputStream acis = new
AutoCloseInputStream(rs.getBinaryStream("ic" + i));
if (rs.wasNull())
icRelPath[i] = null;
else
{
//icRelPath[i] = "imm" + File.separator + "ic" + "_" +
rs.getShort("setIcone") + "_" + i + "." + rs.getString("estensione");
BufferedInputStream bis = new BufferedInputStream(acis);
int b = bis.read();//READS FINE
[...]
--Broken snippet--
[...]
//icRelPath[i] = "imm" + File.separator + "ic" + "_" +
rs.getShort("setIcone") + "_" + i + "." + rs.getString("estensione");
AutoCloseInputStream acis = new
AutoCloseInputStream(rs.getBinaryStream("ic" + i));
if (rs.wasNull())
icRelPath[i] = null;
else
{
icRelPath[i] = "imm" + File.separator + "ic" + "_" +
rs.getShort("setIcone") + "_" + i + "." + rs.getString("estensione");
BufferedInputStream bis = new BufferedInputStream(acis);
int b = bis.read();//THROWS IOException WITH A null
ERROR MESSAGE STRING
[...]
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