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

Anvesh Patel — Sat, 20 Aug 2016 13:05:07 +0000

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:

CREATE TABLE tbl_Students
(
    StudID INTEGER
    ,StudName CHARACTER VARYING 
    ,Duration TSRANGE    
    ,EXCLUDE USING GIST (StudName WITH=, Duration WITH &&) 
);

While creating above table with EXCLUDE Range constraint,I was getting below error .

ERROR:  data type character varying has no default operator class for access method "gist"
HINT:  You must specify an operator class for the index or define a default operator class for the data

The solution is to create btree_gist EXTENSION.

CREATE EXTENSION btree_gist;

Insert few valid sample records:

INSERT INTO tbl_Students 
VALUES 
(1,'Anvesh','[2000-01-01, 2005-01-01)')
,(2,'Roy','[2001-01-01, 2006-01-01)')
,(3,'Eric','[2002-01-01, 2007-01-01)')
,(4,'Jenny','[2000-01-01, 2005-01-01)');

Try to Insert Same Student Name with same range:

INSERT INTO tbl_Students 
VALUES 
(5,'Anvesh','[2000-01-01, 2005-01-01)');

You will get an error like, because we have added constraint like, no duplicate range with the same Student Name.

ERROR:  conflicting key value violates exclusion constraint "tbl_students_studname_duration_excl"

btree_gist – Database Research & Development

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