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diff --git a/contrib/xml/TODO b/contrib/xml/TODO deleted file mode 100644 index 5ddd62a658..0000000000 --- a/contrib/xml/TODO +++ /dev/null @@ -1,78 +0,0 @@ -PGXML TODO List -=============== - -Some of these items still require much more thought! Since the first -release, the XPath support has improved (because I'm no longer using a -homemade algorithm!). - -1. Performance considerations - -At present each document is parsed to produce the DOM tree on every query. - -Pros: - Easy - No persistent memory or storage allocation for parsed trees - (libxml docs suggest representation of a document might - be 4 times the size of the text) - -Cons: - Slow/ CPU intensive to parse. - Makes it difficult for PLs to apply libxml manipulations to create - new documents or amend existing ones. - - -2. XQuery - -I'm not sure if the addition of XQuery would be best as a function or -as a new front-end parser. This is one to think about, but with a -decent implementation of XPath, one of the prerequisites is covered. - -3. DOM Interfaces - -Expose more aspects of the DOM to user functions/ PLs. This would -allow a procedure in a PL to run some queries and then use exposed -interfaces to libxml to create an XML document out of the query -results. I accept the argument that this might be more properly -performed on the client side. - -4. Returning sets of documents from XPath queries. - -Although the current implementation allows you to amalgamate the -returned results into a single document, it's quite possible that -you'd like to use the returned set of nodes as a source for FROM. - -Is there a good way to optimise/index the results of certain XPath -operations to make them faster?: - -select docid, pgxml_xpath(document,'//site/location/text()','','') as location -where pgxml_xpath(document,'//site/name/text()','','') = 'Church Farm'; - -and with multiple element occurences in a document? - -select d.docid, pgxml_xpath(d.document,'//site/location/text()','','') -from docstore d, -pgxml_xpaths('docstore','document','//feature/type/text()','docid') ft -where ft.key = d.docid and ft.value ='Limekiln'; - -pgxml_xpaths params are relname, attrname, xpath, returnkey. It would -return a set of two-element tuples (key,value) consisting of the value of -returnkey, and the cdata value of the xpath. The XML document would be -defined by relname and attrname. - -The pgxml_xpaths function could be the basis of a functional index, -which could speed up the above query very substantially, working -through the normal query planner mechanism. - -5. Return type support. - -Better support for returning e.g. numeric or boolean values. I need to -get to grips with the returned data from libxml first. - - -John Gray <jgray@azuli.co.uk> 16 August 2001 - - - - - - |