primary key and unique index

[Thomas Poty <thomas.poty@xxxxxxxxx>]

Hi all,

I am migrating fromMySQL to Postgresql 9.6.

In MySQL a  "show create table" gives me :
 ...
  PRIMARY KEY (`ID`,`CountryCode`,`LanguageCode`),
  UNIQUE KEY `unique_my table_4` (`ID`,`CountryCode`,`LanguageCode`),
...

So, In PostgreSQL, does it make sense to create a primary key AND a unique index based on the same columns?

Is PostgreSQL smart enough to use the unique index created for the primary key.

I know PostgreSQL can be based on a unique index to create a primary key but I also know it is possible to create several indexes on the same columns with the same order.

Thanks

Thomas