PostgreSQL: ERROR – data type character varying has no default operator class for access method “gist”

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If we want to store range of data, we have very good options RANGE DATATYPE in PostgreSQL.

PostgreSQL: Example of RANGE Data Type

In one of our reporting servers, require to store a range of date bases on unique log code.
Means, one unique code cannot be duplicated with the same range of dates.

We can store a range of dates using TSRANGE DATATYPE, but I have to also add one constraint which checks the unique combination of value and range.

Here, I have taken an example of the Student table where the combination of Stud Name and Duration should be unique.
Try to Create below Student table:

While creating above table with EXCLUDE Range constraint,I was getting below error .
The solution is to create btree_gist EXTENSION.
Insert few valid sample records:
Try to Insert Same Student Name with same range:
You will get an error like, because we have added constraint like, no duplicate range with the same Student Name.