Re: Question about Foreign key constraint causes "costly

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).
>
>
>