The Teradata Database channel includes discussions around advanced Teradata features such as high-performance parallel database technology, the optimizer, mixed workload management solutions, and other related technologies.
Hi, what is the reason for not joining into a union all? For example: A view containing a union all of 2 storesalestables (key of both tables a store_id). This view is joined to a storelocationtable via the store_id. The wherecondition is something like “where storelocationtable.village = 'Berndorf'“. Instead of eliminating almost all records by joining the locationtable to both storesalestables, Teradata first spools the two storesalestables together (million of records) and then joins to the storelocationtable. Only a few records qualify for this join. Yes, if you create foreign key constraints, Teradata does this join first. But what is the reason that Teradata does not join into such a Union All without constraints? Bye Martin