Hi,
I have a table with the following structure:
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FIELD TYPE COMMENTS
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id serial primary key
m1 integer id of record in another table
m2 integer id of record in another table
So, "m1" and "m2" are foreign keys.
I have read that it is a good practice to define an index for each foreign key so "m1" and "m2" are also regular and independent indexes.
Now, the combination of "m1" and "m2" together cannot be duplicated. So for example, the following entries
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id m1 m2 COMMENTS
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1 2 10
2 8 3
3 18 1
4 2 10 This is invalid.
5 13 8 This is invalid.
6 18 18 This is invalid.