On Wed, Apr 21, 2010 at 10:41 AM, Robert Haas <robertmhaas@xxxxxxxxx> wrote:
On Tue, Apr 20, 2010 at 5:05 PM, Kris Jurka <books@xxxxxxxxxx> wrote:Hmm. I didn't think this was possible. How are you doing this?
> The reason this is not done is that the mechanism used for fetching a piece
> of the results at a time can change the query plan used if using a
> PreparedStatement. There are three ways to plan a PreparedStatement:
>
> a) Using the exact parameter values by substituting them directly into the
> query. This isn't really "planned" as you can't re-use it at all. This is
> only available using the V2 protocol.
>
> b) Using the parameter values for statistics, but not making any stronger
> guarantees about them. So the parameters will be used for evaluating the
> selectivity, but not to perform other optimizations like contraint_exclusion
> or transforming a LIKE operation to a range query. This is the default plan
> type the JDBC driver uses.
More to the point is there some option that can shift you into method a? I'm thinking of warehousing type applications where you want to re-plan a good portion of your queries.
