[jira] Commented: (DERBY-4590) You can drop a file-system database from a directory named "memory"

["Kristian Waagan (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DERBY-4590?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12846931#action_12846931 ] 

Kristian Waagan commented on DERBY-4590:
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In some cases Derby uses protocol prefixes to determine the protocol. At the same time, the default protocol (which is formally 'directory:') is represented with no protocol prefix. In this case Derby is probably just checking if the string starts with "memory".
I'll have a look.

> You can drop a file-system database from a directory named "memory"
> -------------------------------------------------------------------
>
>                 Key: DERBY-4590
>                 URL: https://issues.apache.org/jira/browse/DERBY-4590
>             Project: Derby
>          Issue Type: Bug
>          Components: JDBC, Services, Store
>    Affects Versions: 10.6.0.0
>            Reporter: Kim Haase
>            Priority: Minor
>
> With both the embedded and network client drivers, it is possible to create a file-system database and drop it, if you put it in a directory named "memory". 
> I found this out by accident when I accidentally typed "memory/mydb" instead of "memory:mydb" to create an in-memory database.
> If you call the directory something other than "memory", you can't drop the db:
> ij> connect 'jdbc:derby://localhost:1527/subdir/mycdb;create=true';
> ij> create table t(c int);
> 0 rows inserted/updated/deleted
> ij> connect 'jdbc:derby://localhost:1527/subdir/mycdb;drop=true';
> ERROR XBM0I: DERBY SQL error: SQLCODE: -1, SQLSTATE: XBM0I, SQLERRMC: Directory subdir/mycdb cannot be removed.
> But if you do exactly the same thing specifying "memory", the drop succeeds:
> ij> connect 'jdbc:derby://localhost:1527/memory/mycdb;create=true';
> ij> create table t(c int);
> 0 rows inserted/updated/deleted
> ij> connect 'jdbc:derby://localhost:1527/memory/mycdb;drop=true';
> ERROR 08006: DERBY SQL error: SQLCODE: -1, SQLSTATE: 08006, SQLERRMC: Database 'memory/mycdb' dropped.
> When you do this, the "memory" directory continues to exist, but the database directory under it is removed.
> Here are similar examples using the embedded driver:
> ij>  connect 'jdbc:derby:subdir/mydb;create=true';
> ij> create table t(c int);
> 0 rows inserted/updated/deleted
> ij> connect 'jdbc:derby:subdir/mydb;drop=true';
> ERROR XBM0I: Directory subdir/mydb cannot be removed.
> ij> connect 'jdbc:derby:memory/mydb;create=true';
> ij> create table t(c int);
> 0 rows inserted/updated/deleted
> ij> connect 'jdbc:derby:memory/mydb;drop=true';
> ERROR 08006: Database 'memory/mydb' dropped.
> Some part of Derby seems to think you actually created an in-memory database, although you did not.

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