Re: Unique index

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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).


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