On 2023-09-20 19:16 +0530, Rajesh Kumar wrote: > Why unique index is used over unique constraints? Is the question why someone might want to use a unique index instead of a unique constraint? The index can be functional, e.g. CREATE TABLE account (username text NOT NULL); CREATE UNIQUE INDEX account_lower_username_idx ON account (lower(username)); will make the username unique and case-insensitive (depending on the collation and locale). -- Erik
