pypgsql overuses server-side cursors resulting in large performance penalty

[Jeremy Kemper <jeremy@…>]

Most trac + postgres installs are using pyscopg2 which pulls full result sets for cursor.execute by default.

pypgsql, on the other hand, uses server-side cursors by default, leading to incredibly inefficient queries: rather than fetch e.g. select ... limit 20 all at once, it does declare cursor; fetch 1; fetch 1; ...

Fortunately, server-side cursors can be turned off with great results. I imagine some of pypgsql's widespread perception of slowness with Trac is due to this strange default behavior.

[Jeremy Kemper <jeremy@…>]

disable server-side cursors when using pypgsql

[cboos]

Thanks for the investigation and the fix!

[cboos]

Applied in r4754 (trunk) and r4756 (0.10-stable).