Hi all,
Does the BaseX GUI open a Database via embedded mode, locking the Database it in the process?
It surely locks it, but I don't know how.
Note that I know I should not use the GUI to open the same database when the database server is running too, but I don't know if it's the only error that is not propagated? (I do get other errors, such as "XQJFOS021 - FORWARD_ONLY_SEQUENCE: Cursor is not positioned on an XQItem" in my Java code. Good. Also, if I try a non-existing database, I get "[FODC0002]: Resource "[...]/basex/bin/xxxx-factbook" not found." in my Java code. Good too.)
I know of two ways to mess up: the GUI, and the standalone command line utility. It took me some time to realize that "bin/basex" is not some TCP/IP client that connects to a running database server (as started with "bin/basexserver"), but rather opens the database files itself. The GUI does the same. So, I know I should use "bin/basexclient" instead, to connect to the server, to ensure the server can still correctly handle requests from my Java code.
In the unit test I attached earlier, I described some steps I forgot in the message itself:
When the database is somehow in use, the Java code fails silently. Like:
- Start the server, using: $ basexserver -S Server was started.
- Import Factbook, using: $ basex BaseX 7.3 [Standalone] Try help to get more information.
create db factbook ../mondial-3.0.xml
Database 'factbook' created in 592.53 ms.
show databases
1 opened database(s): - factbook (1x)
- Leave the standalone tool open, hence make the database unavailable for updates by the server.
- Run this very unit test; though the log in data/.logs does show the BXDB0007 error, the Java code just silently ignores that.
(As an aside: in the GUI, menu Database, Server Administration warns: "Warning: The client/server architecture and the GUI are not synchronized. The same database should not be opened from clients and the GUI.")
Regards, Arjan.
On Thu, Aug 23, 2012 at 10:30 AM, Charles Foster charles@cfoster.netwrote:
Does the BaseX GUI open a Database via embedded mode, locking the Database it in the process?
Please could you give me a couple more steps to go on Arjan? If there is a problem with the XQJ Driver I would like to fix it.
Regards,
Charles
On 23 August 2012 03:53, Christian Grün christian.gruen@gmail.com wrote:
Hi Arjan,
thanks for your report. I managed to reproduce the issue. I assume that this behavior is due to XQJ, which is why I’m forwarding your mail to Charles.
Hope this helps, Christian
@Charles: if you have more questions, or if you believe that the bug is on our side.. Your feedback is welcome! ___________________________
On Wed, Aug 22, 2012 at 5:44 PM, Arjan van Bentem arjan.vanbentem@bidnetwork.org wrote:
Hi all,
Maybe this is related to http://xqj.net/basex/ instead of BaseX
itself, but
as I don't know allow me to ask here first.
Whenever I have somehow locked a BaseX database, like by using the standalone command line utility or the GUI, then I get something like
the
following in the BaseX log files:
QUERY(1) for $c in
collection('factbook')//country[name='Albania']return(
replace value of node $c/@population with xs:integer($c/@population +
1)) OK
39.92 ms QUERY(1) OK 0.62 ms FULL(1) Error: [BXDB0007] Database 'factbook' is opened by another
process.
CLOSE(1) OK 39.68 ms
Good.
However, I don't see that error in my Java code. The Java code just continues like all was fine.
Can I somehow make the Java code fail when this happens?
See example below, and the same thing in the attachment.
Thanks, Arjan.
private static final String DRIVER = "net.xqj.basex.BaseXXQDataSource";
private static final String SELECT =
"xs:long(collection('factbook')//country[name='Albania']/@population[1]/data(.))";
private static final String UPDATE = "for $c in collection('factbook')//country[name='Albania']"
- "return("
- " replace value of node $c/@population with
xs:integer($c/@population +
1)"
- ")";
@Test public void testUpdate() { try {
XQDataSource xqd = (XQDataSource) Class.forName(DRIVER) .newInstance(); XQConnection xqc = xqd.getConnection("admin", "admin"); XQExpression xqe = xqc.createExpression();
XQSequence xqs = xqe.executeQuery(SELECT); xqs.next(); long before = xqs.getLong(); System.out.println("Initial value: " + before);
System.out.println("Updating..."); xqs = xqe.executeQuery(UPDATE);
xqs = xqe.executeQuery(SELECT); xqs.next(); long after = xqs.getLong(); System.out.println("Resulting value: " + after);
xqc.close();
Assert.assertEquals("Update should have succeeded or failed", before + 1, after);
} catch (Exception e) { e.printStackTrace(); }
}
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