[MonetDB-users] MonetDB/XQuery JDBC result issue
Hello, I've been having an issue with MonetDB/XQuery using the JDBC driver. Essentially, when I supply an *XPath* query such as the following: pf:collection("collection_name")//stations[date/year>=2010] ... using the mclient utility, there's no problem. The result is an <XQueryResult> root node containing all the relevant 'stations' nodes as requested by the query. However, if I issue the same query to the server from a Java application using the JDBC driver for MonetDB, the string result that is returned merely contains one 'stations' node (the first one that gets processed, I think). My guess is that the resultset (of 'stations' nodes) is not being wrapped in a root node, as is the case when querying using the mclient utility. But I'm unsure if this due to a bug, or if there's something that I'm not doing correctly. I'm also aware that this issue can be resolved by modifying the query (when using JDBC) to something such as: <result> { pf:collection("collection_name")//stations[date/year>=2010] } </result> ... but I have reasons for not wanting to do this. Any help is much appreciated. If anyone needs more information, just let me know (and if it makes any difference, I'm running a local server instance). Cheers, -Rob
Dear Rob Fynes,
You have already provided the answer in your email. XQuery specifies that a
result is actually a sequence of items. The "XQueryResult"-node has only
been added to convert the actual result sequence into a valid XML fragment.
Using XQuery over JDBC works like SQL; you can iterate over the results.
There is no artificial XQueryResult-node added.
For example:
ResultSet rs = conn.executeQuery("....");
while(rs.next()) {
.. do something with the result ..
}
With kind regards,
Wouter Alink
On Tue, Mar 1, 2011 at 10:13 PM, Rob Fynes
Hello,
I've been having an issue with MonetDB/XQuery using the JDBC driver. Essentially, when I supply an *XPath* query such as the following:
pf:collection("collection_name")//stations[date/year>=2010]
... using the mclient utility, there's no problem. The result is an <XQueryResult> root node containing all the relevant 'stations' nodes as requested by the query. However, if I issue the same query to the server from a Java application using the JDBC driver for MonetDB, the string result that is returned merely contains one 'stations' node (the first one that gets processed, I think).
My guess is that the resultset (of 'stations' nodes) is not being wrapped in a root node, as is the case when querying using the mclient utility. But I'm unsure if this due to a bug, or if there's something that I'm not doing correctly.
I'm also aware that this issue can be resolved by modifying the query (when using JDBC) to something such as:
<result> { pf:collection("collection_name")//stations[date/year>=2010] } </result>
... but I have reasons for not wanting to do this. Any help is much appreciated. If anyone needs more information, just let me know (and if it makes any difference, I'm running a local server instance).
Cheers, -Rob
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participants (2)
-
Rob Fynes -
Wouter Alink