On 10/03/15 10:43, Rob Vesse wrote:
All
This is a gentle reminder to say please be patient when posting to any
Apache mailing lists (including this one)
People are spread geographically across a wide variety of time zones and
the person capable of answering your question may not see it for some time
as it may be sent well outside their normal waking/working hours.
Everyone who responds on this mailing list is working as a volunteer
donating their time so please don't abuse this - Re-posting the same
question only a few hours later only serves to annoy people
Rob
+1
Also, please don't cross post to dev@ and users@. If in doubt, users@
Andy
On 10/03/2015 09:55, "Rose Beck" <[email protected]> wrote:
Sorry for yet another mail. Is there some document from which I can
understand how ORDER BY and LIMIT clause are evaluated by Jena. I read
the documentation here:
http://jena.apache.org/documentation/query/arq-query-eval.html but I
am not able to understand the solution from it.
On Tue, Mar 10, 2015 at 11:24 AM, Rose Beck <[email protected]> wrote:
Hi,
I saw the following issue posted on Jena website (which has been
recently resolved):
Avoid a total sort for ORDER BY + LIMIT queries
(https://issues.apache.org/jira/browse/JENA-89).
I am very interested in understanding as to how does Jena-ARQ avoids
total sort for ORDER BY + LIMIT queries. In the post it is mentioned
that Jena-ARQ uses priority queue for avoiding a final sort, however
it is also mentioned that "ARQ's algebra package contains already a
OpTopN [3] operator. The OpExecutor [4] will need to use a new
QueryIterTopN instead of QueryIterSort + QueryIterSlice." It is not
clear now does the priority queue benefit from OpTopN operator and
QueryIterTopN as the links [3] and [4] mentioned on the website does
not work, so I am not able to understand their operation and as to how
do they help in avoiding a total sort.
Can someone please explain how does Jena-ARQ execute the queries
containing ORDER BY + LIMIT clause.
With Warm Regards,
Rose
--
With Warm Regards,
Rose
