[basex-talk] following::* is 100x slower than preceding::*

[Gioele Barabucci]

Hello,

I have noticed that this query using the "following" axes
    //*[@xml:id = "lemma-aMSa"]
            /following::*[self::tei:entry or self::tei:re]
                         [position() <= 3]

is much slower than the same query with the "preceding" axes

    //*[@xml:id = "lemma-aMSa"]
            /preceding::*[self::tei:entry or self::tei:re]
                         [position() <= 3]

The query that uses "preceding" takes about 2.5 ms to execute, while the 
one using "following" takes about 250 ms: it is 100 times slower.

Why this discrepancy between these two queries?

I can provide the base XML file (19MB) on request.

Also, I also get a warning about «'following::*[(self::tei:entry or 
self::tei:re)][(fn:position() <= 3)]' will never yield results.» but 
that is obviously false, as it yields exactly the 3 results I expect.

Regards,

--
Gioele Barabucci <gio...@svario.it>