Thanks a lot for all helps. I do not have warnings anymore :-)
I'd like to setup foreign key constraint for A.col3, as the following:
CONSTRAINT Aclo3_fk FOREIGN KEY (col3) REFERENCES B(colB1)
But I got a warning msg from postgresql as:
foreign key constraint "Aclo3_fk" will require costly sequential scans
Is there not a DETAIL message following this warning? It should
explain the problem: the referring and the referred-to columns are
of different types.
Additionally, it's usually a good idea to create an index on the
referring column (A.col3) to speed up referential integrity checks
when modifying the referred-to table (B).
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TIP 6: explain analyze is your friend
