Currently we save every URI ever qname'd forever in here: https://github.com/RDFLib/rdflib/blob/master/rdflib/namespace.py#L289

If you serialize a big graph in a store that is off disk, we may run out of memory.

Either:

• Add a lru_cache (from py3 functools + this 2.7 implementation
• Depend on

Self-explanatory.

The handling of binding substitution fails for queries of the form select (func(?x) as ?y). For a binding x=foo the output is select (func('foo' as ?x) as ?y) when it should be select (func('foo') as ?y). The current code only works for select ?x ?y ?z type queries. Regex needs to be modified to ignore patterns that are preceeded by 'as'.