[jira] Issue Comment Edited: (DERBY-4172) You can open a read-write connection to a database which was originally opened by another thread using the classpath subprotocol

["Dag H. Wanvik (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DERBY-4172?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12701269#action_12701269 ] 

Dag H. Wanvik edited comment on DERBY-4172 at 4/21/09 2:16 PM:
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If the file name is simple, Derby handles it (current directory is on classpath here):

ij> connect 'jdbc:derby:classpath:wombat';
ij> insert into t values 1;
ERROR 25502: An SQL data change is not permitted for a read-only connection, user or database.
ij> connect 'jdbc:derby:wombat';
ij(CONNECTION1)> insert into t values 1;
ERROR 25502: An SQL data change is not permitted for a read-only connection, user or database.
ij(CONNECTION1)> 

The second connect uses the normal file based URL. If I used an absolute path Derby fails to match them:

ij(CONNECTION1)> connect 'jdbc:derby:/export/home/dag/java/sb/tests/foo/wombat';
ij(CONNECTION2)> insert into t values 1;
1 row inserted/updated/deleted

although this is the same "wombat":

ij(CONNECTION2)> exit;
dag@T61pOS:~/java/sb/tests/foo$ pwd
/export/home/dag/java/sb/tests/foo

derby.log shows two booted instances, corresponding to connect 1 and 3 above,

      was (Author: dagw):
    If the file name is simple, Derby handles it (current directory is on classpath here):

ij> connect 'jdbc:derby:classpath:wombat';
ij> insert into t values 1;
ERROR 25502: An SQL data change is not permitted for a read-only connection, user or database.
ij> connect 'jdbc:derby:wombat';
ij(CONNECTION1)> insert into t values 1;
ERROR 25502: An SQL data change is not permitted for a read-only connection, user or database.
ij(CONNECTION1)> 

The second connect uses the normal file based URL. If I used an absolute path is fails to match them:

ij(CONNECTION1)> connect 'jdbc:derby:/export/home/dag/java/sb/tests/foo/wombat';
ij(CONNECTION2)> insert into t values 1;
1 row inserted/updated/deleted

although this is the same "wombat":

ij(CONNECTION2)> exit;
dag@T61pOS:~/java/sb/tests/foo$ pwd
/export/home/dag/java/sb/tests/foo

derby.log shows two booted instances, corresponding to connect 1 and 3 above,
  
> You can open a read-write connection to a database which was originally opened by another thread using the classpath subprotocol
> --------------------------------------------------------------------------------------------------------------------------------
>
>                 Key: DERBY-4172
>                 URL: https://issues.apache.org/jira/browse/DERBY-4172
>             Project: Derby
>          Issue Type: Bug
>          Components: JDBC
>    Affects Versions: 10.6.0.0
>            Reporter: Rick Hillegas
>
> The original connection, using the classpath subprotocol, was supposed to open the DATABASE (not the connection) as read-only, according to the Developer's Guide section titled "Database connection examples". However, I am able to write to this database in another connection which opens the database using the default, file-based protocol.
> At a minimum, the documentation is wrong. But the documentation may be trying to impose a consistent, easily described model on the behavior of our subprotocols. It may be that the behavior of our subprotocols cannot be described by a simple set of rules that users can grasp easily.
> To show this problem, I created a database and then moved it into a directory on my classpath (in this case, trunk/classes). Here is a script which shows this behavior:
> connect 'jdbc:derby:classpath:derby10.6' as conn1;
> -- fails because a database which is opened on the classpath is supposed to be marked as read-only
> insert into t( a ) values 1;
> connect 'jdbc:derby:trunk/classes/derby10.6' as conn2;
> -- this succeeds even though the database is supposed to be read-only
> -- according to the Developer's Guide section "Database connection examples"
> insert into t( a ) values 2;
> select * from t;
> delete from t;

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