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From "Kristian Waagan (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (DERBY-5090) Retrieving BLOB fields sometimes fails
Date Thu, 18 Aug 2011 07:30:27 GMT

     [ https://issues.apache.org/jira/browse/DERBY-5090?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Kristian Waagan resolved DERBY-5090.
------------------------------------

          Resolution: Fixed
       Fix Version/s: 10.9.0.0
    Issue & fix info: [Newcomer, Release Note Needed, Repro attached, Workaround attached]
 (was: [Workaround attached, Repro attached, Release Note Needed, Patch Available, Newcomer])

Since the incorporated issue and this issue have been marked as unsuitable for backport, there
is no more work to be done.

Note that the fix isn't required for proper operation. The fix makes Derby balk if someone
tries to do something that's not in accordance with the JDBC specification.

> 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
>            Assignee: Kristian Waagan
>              Labels: BLOB, derby_backport_reject_10_8, exception, null, read
>             Fix For: 10.9.0.0
>
>         Attachments: Derby5090.java, Derby5090_2.java, Derby5090_3.java, derby-5090-1a-fix.diff,
derby-5090-1a-fix.stat, derby-5090-1b-fix.diff, derby-5090-2a-test.diff, derby-5090-2a-test.stat,
derby-5090-3a-change_messages.diff, releaseNote.html
>
>
> 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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