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From "Kristian Waagan (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (DERBY-5090) Retrieving BLOB fields sometimes fails
Date Tue, 05 Jul 2011 06:57:21 GMT

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

Kristian Waagan updated DERBY-5090:
-----------------------------------

    Attachment: derby-5090-3a-change_messages.diff

Attaching patch 3a, which takes a stab at improving the message situation. I found the following
relevant messages:
6 x XCL53    LANG_STREAM_CLOSED        Stream is closed
7 x XJ012.S ALREADY_CLOSED                 '{0}' already closed.
0 x XJ094.S OBJECT_ALREADY_CLOSED  This object is already closed.
2 x J104      CONN_ALREADY_CLOSED     The object is already closed.

XCL53 doesn't carry an SQLState, so it probably belongs in MessageId. The use of XJ012.S seems
OK.
Patch 3a does the following:
 o remove unused XJ094.S
 o rename J104 to OBJECT_CLOSED.
 o replace uses of XCL53 with J104.
 o remove XCL53

Alternatively, we could do a swap - use msg/translations for XCL53 in J104 to make it more
specific (and rename it to STREAM_CLOSED).

Patch ready for review.

> 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, exception, null, read
>         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
>
>
> 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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