perfsonar development work

[Szymon Trocha <>]

Hi all,

testing gLS we found out that eXist resources are sometimes consumed up 
to the limit by a query. This resulted in failures of LS operations on 
eXist database.

Here is a description and solution for a problem which may help somebody:

http://article.gmane.org/gmane.text.xml.exist/3996

> after a heavy query ,  eXist complains:
>
> WARN  (XQueryWatchDog.java [proceed]:122) - Query exceeded predefined
> limit for document fragments:
>
> What is and can I set this limit?

The purpose of the watchdog is to limit the time and the memory consumed
by a single query. Otherwise, users might be able (by mistake or
intention) to formulate queries that consume all available resources and
finally kill the server.

The memory limit is currently defined in terms of the number of
in-memory nodes a single query can construct during query execution. The
default limit is 10 000 nodes, which is a bit low for most applications.

Both limits can either be changed or disabled in the configuration file
or through an XQuery pragma:

1) Change conf.xml:

<watchdog query-timeout="-1" output-size-limit="10000"/>

and set output-size-limit="-1".

2) Add a pragma to the start of your query:

(::pragma exist:output-size-limit -1 ::)

--
Szymon Trocha

Poznan Supercomputing & Ntw. Center ::: NETWORK OPERATION CENTER
Tel. (+48 61) 8582022
http://noc.man.poznan.pl  ::: http://noc.pionier.gov.pl