Re: Can't drop constraint?

On Mittwoch 06 Mai 2009 Tom Lane wrote:
> No.  A primary key or unique constraint is implemented by creating
> a unique index (and, for PK, also by creating NOT NULL constraints
> on the columns).  After that, the only visible difference is that
> there's an entry in pg_constraint, or not.  There are some minor
> behavioral differences --- if memory serves, you need a PK constraint
> entry to persuade a REFERENCES constraint that it should consider
> a given column as the default reference target --- but no performance
> difference.

To take it to a point: Creating an index has advantages over
constraints, without any disadvantage? So I will always only use
indices, not constraints, to have a more uniform db model.

mfg zmi
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