Add a function plpy.cursor that is similar to plpy.execute but uses an
SPI cursor to avoid fetching the entire result set into memory.
Jan Urbański, reviewed by Steve Singer
This provides a separate exception class for each error code that the
backend defines, as well as the ability to get the SQLSTATE from the
exception object.
Jan Urbański, reviewed by Steve Singer
Adds a context manager, obtainable by plpy.subtransaction(), to run a
group of statements in a subtransaction.
Jan Urbański, reviewed by Steve Singer, additional scribbling by me
