Re: ? Very large tables vs unioning smaller tables

Why are the 2 emp tables separate? If they have the same columns in them, are the emps qualitatively different? Was this a design consideration? The UNION makes sense, but the 2nd query (select * from emp,dept where...) will do a cartesian product if the join condition is absent. That means that EVERY rtow of the emp table is joined to EVERY row of the dept table, even if that makes no sense. With the join, the indexes on emp and dept will resolve the query without the cartesian product. Am I missing something?????

HTH

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