Content Comparison

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Now, the updated query does not look for a list data node for a given xpath (representing a list Ex: /bookstore/categories). Instead, it looks for all the fragments in the table which have a similar xpath to that of the list followed by opening square bracket starting with "[" and any attribute identified in the query by special symbol "%"

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and ending with ] using pattern matching.

To make it work we use a combination of LIKE and NOT LIKE keywords.

For this we make use of the LIKE keyword along with % wildcard to make use of pattern matching.

But the above query would also return fragments for xpaths like /bookstore/categories[@code='1']/books[@name="Hello"]

To avoid this scenario, we make use of NOT LIKE keyword along with the same % wildcard. and hence we have [%[% to exclude multiple opening brackets.

"SELECT * FROM fragment WHERE anchor_id = :anchorId "
+ " 
   AND (xpath = ANY (:xpaths) OR xpath LIKE ANY (array(SELECT concat(t, '[%') FROM unnest(:xpaths) as t)))

So as seen in the above segment of the query, we have "AND (xpath = ANY (:xpaths) OR xpath LIKE ANY (array(SELECT concat(t, '[%') FROM unnest(:xpaths) as t)))".

Any given xpath for a list (Ex: /bookstore/categories) would become like so:

(xpath = '/bookstore/categories' OR xpath LIKE '/bookstore/categories[%') + "AND xpath LIKE :escapedXpath||'[@%]' ESCAPE '\\' "
            + "AND xpath NOT LIKE :escapedXpath||'[@%[%' ESCAPE '\\'"

And this would return 2 fragments as follows.

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