15.4.5.Using XML and Free Text

Virtuoso integrates classic free text retrieval and XML semi-structured query features to offer a smart, scalable XML repository. When a column is declared as indexed XML with the CREATE TEXT XML INDEX statement the text is checked for well-formedness at time of storage. The specific XML structure of the text is also considered when making the free text index entries. This XML-aware free text index is used for processing XPath queries in the xcontains SQL predicate. This predicate is only applicable to columns for which there is an XML free text index.

Arbitrary free text criteria can appear inside the XPath expression of xcontains . These are introduced by the XPath extension function text-contains() , which may only be used within xcontains as it relies on the underlying free text index.

[Note] Note

xpath_contains() does not require the existence of a free text index and can thus apply to any well-formed XML content.