lambdai/mapred_jobs

Join

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lambdai commented

There are 3 kinds of natural join-like grammar: on and using

  • The NATURAL JOIN is the common one.
  • USING is a natural join with constraint that natural join only using limit columns, rather than all the columns have the same name.
  • ON is the fundamental of theta-join. While the expression uses Operator=, the result is kind of natural join.

On the first step, we only support the first kind of natural join.

lambdai commented

Support Natural join now but not "on"