[redland-dev] Reducing query time variance with cost based planner

[Andrew Reslan]

Are there any mechanisms in redland/rasqal for reducing query time variance depending on statement order in a SPARQL query.

For example a query that contains an exact literal match as the first statement, may take a few ms to execute and return a single result.

But if the statement order is changed so that the first statement returns 1000's of potential matches then the query time may increases to tens of seconds to return the same single result.

I'm trying to find where in the code the execution engine walks the syntax tree, and I'm wondering of this could be modified to use a cost based planner that could modify the execution order of statements?

Andy