Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> Sorry to be getting in here late. Have you tried CLUSTER?
Prolly won't help much. I think what he's getting burnt by
is that the planner thinks that an indexscan based on the
LIKE 'http://www.postgresql.org/%' condition will be extremely
selective --- it has no idea that most of the URLs in his table
will match that prefix. It's ye same olde nonuniform-distribution
problem; until we have better statistics, there's not much hope
for a non-kluge solution.
regards, tom lane