Update of /cvsroot/monetdb/java/src/nl/cwi/monetdb/jdbc
In directory
sc8-pr-cvs16.sourceforge.net:/tmp/cvs-serv12362/src/nl/cwi/monetdb/jdbc
Modified Files:
MonetConnection.java
Log Message:
Fix for bug #1886326:
MonetDB JDBC driver exception for XQuery with no results
2 and a half hour later ...
Due to missing history (cvs moves) and missing documentation (on my
end) it took quite some while to figure out what was the "correct" way
to solve this bug. In the end it al boiled down on the limitation of
the XQuery backend to only support full-results-at-once, which means the
resource allocation of JDBC needs to allocate the entire result at once.
If the result is 0 rows big, however, then things went wrong when
calculating the current cache block. Anyway, for the future we now know
why we did this cache block calulation thing like this again...
Index: MonetConnection.java
===================================================================
RCS file: /cvsroot/monetdb/java/src/nl/cwi/monetdb/jdbc/MonetConnection.java,v
retrieving revision 1.2
retrieving revision 1.3
diff -u -d -r1.2 -r1.3
--- MonetConnection.java 11 Jan 2008 10:36:16 -0000 1.2
+++ MonetConnection.java 20 Feb 2008 19:50:24 -0000 1.3
@@ -1164,7 +1164,17 @@
isSet = new boolean[7];
this.parent = parent;
if (parent.cachesize == 0) {
- cacheSize = lang == LANG_SQL ?
MonetConnection.DEF_FETCHSIZE : tuplecount;
+ /* Below we have to calculate how many "chunks"
we need
+ * to allocate to store the entire result.
However, if
+ * the user didn't set a cache size, as in this
case, we
+ * need to stick to our defaults. So far, so
good. Now
+ * the problem with XQuery is, that it doesn't
support
+ * any block fetching, so we need to always
fetch
+ * everything at once. For that reason, the
cache size
+ * is here set to the tuplecount, such that we
do a full
+ * fetch at once. To avoid a division by zero
lateron,
+ * we make sure the cache size is not 0 */
+ cacheSize = lang == LANG_SQL ?
MonetConnection.DEF_FETCHSIZE : (tuplecount + 1);
cacheSizeSetExplicitly = false;
} else {
cacheSize = parent.cachesize;
-------------------------------------------------------------------------
This SF.net email is sponsored by: Microsoft
Defy all challenges. Microsoft(R) Visual Studio 2008.
http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/
_______________________________________________
Monetdb-checkins mailing list
[email protected]
https://lists.sourceforge.net/lists/listinfo/monetdb-checkins
