Upgrade to 5.0.3.
- It is now possible to use a custom array cast function by changing
  the type caster for the 'anyarray' type.  For instance, by calling
  set_typecast('anyarray', lambda v, c: v) you can have arrays returned
  as strings instead of lists.  Note that in the pg module, you can also
  call set_array(False) in order to return arrays as strings.
- The namedtuple classes used for the rows of query results are now cached
  and reused internally, since creating namedtuples classes in Python is a
  somewhat expensive operation.  By default the cache has a size of 1024
  entries, but this can be changed with the set_row_factory_size() function.
  In certain cases this change can notably improve the performance.

(darcy)