Does LIMIT 1 still have effect on a unique column I know that adding LIMIT 1 when searching for only one record makes a lot of difference when it comes to performance. But does it still have any effect when we search a column with a unique constraint?

Let us say I store email records with a id (int) primary key column and the email field is marked as unique. Do I still need to explicitly call LIMIT 1 in my queries to speed up the returning of a result set? Or does the MySQL engine understand that as soon as one record is found the result can be returned since the field is marked as unique and is LIMIT 1 obsolete?

MySQL table definition:

CREATE TABLE Email
(
    `id` int NOT NULL,
    `email` varchar(255) NOT NULL,
    PRIMARY KEY (`id`),
    UNIQUE (`email`)
)


Does it in this case make a difference whether I do:

SELECT * WHERE `email`="john.doe@example.com";


Or

SELECT * WHERE `email`="john.doe@example.com" LIMIT 1;
if column has unique index (constraint), You do not need to use LIMIT 1

LIMIT 1 - good tools for prevent potential errors when result MUST be single and You not sure about how many rows You have