In postgres 8.4 When running xpath() queries it seems that empty results are always returned. So if I query a table containing 1000 XML documents a 1000 rows will always be fetched even if the xpath() element of the query only matches 10 documents.
The documentation states:
The function xpath evaluates the XPath expression xpath against the XML value xml. It returns an array of XML values corresponding to the node set produced by the XPath expression.
Yet it seems that empty node sets (arrays) are also returned. So, my thought was to run a subquery to eliminate empty arrays, e.g.:
SELECT x FROM (SELECT xpath('//entry[contains(p, ''searchtext'')]/@*', docxml) AS x FROM docs) AS y WHERE x <> [test for empty array?????????]