Right now, the optimizer chooses the path with the cheapest cost. However, do we take into account the behavior of the plan in handling mis-estimated row counts? For example, if a path has a log(n) behavior for changes in the row count, and another plan that is slightly cheaper has a log(n^2) behavior, should we choose the former, knowing the the row counts are often inaccurate?
I suppose one approach would be to track not only the path costs, but the handling of mis-estimated, and account for that in the final path choice? Do we already do this by giving less stable plans higher costs? Does that have the same effect? -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + As you are, so once was I. As I am, so you will be. + + Ancient Roman grave inscription + -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
