Thanks for the reply Mr. Tom. So, I think that the function ExecSetParamPlan (as the code suggests too) is called _once_ in any plan/expression and that should be mostly for a sub-select query.
Kindly correct me if I am wrong. Since I am not able to understand this usecase completely, a sample query which is capable of calling this function (ExecSetParamPlan) could show some light. It would be really kind of you / anyone to show me a query executable through psql which can actually call ExecSetParamPlan and involves the use of a on-disk relation. The reason I am asking for a query which I could run on psql is that I am using gdb to debug (and notice the steps taken by) PG. Regards, Vaibhav On Fri, 2011-03-25 at 14:37 -0400, Tom Lane wrote: > Vaibhav Kaushal <vaibhavkaushal...@gmail.com> writes: > > Hello all, > > I was going through the Expression Evaluator and was trying to > > understand how the expressions are formed and evaluated. I was informed > > on the IRC channel that the PARAM nodes are quite important and many > > well written client applications use PARAMs for sending query to the > > backend. I found while looking at the ExecEvalParam function that a call > > is made to the ExecSetParamPlan for the first time when the PARAM is > > caught in the ExprState tree. > > > I am confused about how many times the call is made to the > > ExecSetParamPlan funtion. > > Indeed ... ExecSetParamPlan has nothing at all to do with Params > representing values coming from a client (PARAM_EXTERN parameters). > It's used in connection with PARAM_EXEC parameters that represent > the outputs of InitPlan subplans (that is, execute-only-once subplans). > > regards, tom lane -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
