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Tracker SPARQL Library Reference Manual | ![]() |
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There are a number of environment variables which affect the way that the libtracker-sparql library will do its work. Those environment variables are described here.
Backends for libtracker-sparql are dynamically loaded at
run time. Currently there are only two backends which are
As explained in the last paragraph, the backends are dynamically loaded at run time. The location for these backends is usually in a set place: $prefix/lib/tracker-$version/sparql-modules. This environment variable is mostly useful for the unit tests and general debugging to override this location.
Tracker caches database statements which occur frequently to make subsequent repeat queries much faster. The cache size is set to 100 by default for each type (select and update queries). This must be at least 2 as a minimum, any less and a value of 3 is used instead. The number represents the number of cached statements to keep around. This environment variable is used mainly for testing purposes.
Tracker's store also has environment variables to control this behavior, see the manual pages for tracker-store regarding TRACKER_STORE_SELECT_CACHE_SIZE and TRACKER_STORE_UPDATE_CACHE_SIZE.
Historically, all queries would go through tracker-store and all requests would be logged according to the verbosity set in tracker-store.cfg (see manual pages for tracker-store.cfg). Since libtracker-sparql may circumvent tracker-store if using the direct access backend, this environment variable was added to let clients choose the log level. The same values apply to all other processes which have logging and a configuration to control it. Values range from 0 to 3, 0=errors, 1=minimal, 2=detailed, 3=debug. By default it is 0.