I have analysis the cause of the performance drop.
My first statement is wrong, the performance drop is not from 7.2 to 7.3 but from 7.2 to 7.2.1.
BaseX v7.2 executes the query in sequence. First the flwor which extracts data and stores them in a map. Second the flwor which test if values are contains in the map.
BaseX v7.2.1 optimises the query and the two sequentials flwor are merge in a main flwor with an embed flwor. The maps seems to be constructed again and again for each value of the second flwor.
Hope it will help,
Regards,
Nicolas
On Mon, Jun 25, 2012 at 10:21 AM, Nicolas Labrot nithril@gmail.com wrote:
Hello,
I have upgraded BaseX from 7.2 to 7.3 but I have a severe performance drop on my query.
My query is in 2 parts :
- The first part extracts values from an xpath and store them in a map
(the map contains 40000 entries)
- The second part extracts values from an xpath and test if they are
contains in the map (xpath return around 30000 entries).
On 7.2 a typical query run on 2s and on 7.3 I have no result after 10 minutes
Is there modification on BaseX 7.3 which can explain this performance drop ?
Thanks for your help,
Regards,
Nicolas