What is meant by "unstructured Join"? Thanks, Gourav
On 12 October 2017 at 22:47, Gourav Kumar <gourav1...@gmail.com> wrote: > My objective is to construct join graph from a given query. > A join graph, has a node for each relation involved in a join, and an edge > between two relations if they share a join predicate among them. > > To do this I first tried to use the make_join_rel() function > - There I checked if they root->join->cur->level is 2, just write the > relation names to a file. > - But this strategy failed, because if there is somewhere a Cartesian > product among two relations, then they can't have an edge in the join graph. > - So, along with writing the relation name, I need to know if they > share a join predicate among them or not. > > > On 12 October 2017 at 22:08, Tom Lane <t...@sss.pgh.pa.us> wrote: > >> Gourav Kumar <gourav1...@gmail.com> writes: >> > I have the RelOptInfo data structure for the relations which are to be >> > joined but when I check their joininfo, it is empty. >> >> You aren't telling us anything much about the case you're studying, >> but if the join clauses have the form of equality comparisons, they >> likely got converted into EquivalenceClass data structures instead. >> These days the joininfo lists only contain "unstructured" join >> conditions. >> >> regards, tom lane >> > > > > -- > Thanks, > Gourav Kumar > Computer Science and Automation > Indian Institute of Science > -- Thanks, Gourav Kumar Computer Science and Automation Indian Institute of Science
