Extension exists but uuid_generate_v4 fails

Question

At amazon ec2 RDS Postgresql:

=> SHOW rds.extensions;

rds.extensions                                                                                                                                 
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
 btree_gin,btree_gist,chkpass,citext,cube,dblink,dict_int,dict_xsyn,earthdistance,fuzzystrmatch,hstore,intagg,intarray,isn,ltree,pgcrypto,pgrowlocks,pg_trgm,plperl,plpgsql,pltcl,postgis,postgis_tiger_geocoder,postgis_topology,sslinfo,tablefunc,tsearch2,unaccent,uuid-ossp
(1 row)

As you can see, uuid-ossp extension does exist. However, when I'm calling the function for generation uuid_v4, it fails:

CREATE TABLE my_table (
    id uuid DEFAULT uuid_generate_v4() NOT NULL,
    name character varying(32) NOT NULL,

);

What's wrong with this?

Answer 1

The extension is available but not installed in this database.

CREATE EXTENSION IF NOT EXISTS "uuid-ossp";

Answer 2

If the extension is already there but you don't see the uuid_generate_v4() function when you do a describe functions \df command then all you need to do is drop the extension and re-add it so that the functions are also added. Here is the issue replication:

db=# \df
                       List of functions
 Schema | Name | Result data type | Argument data types | Type
--------+------+------------------+---------------------+------
(0 rows)
CREATE EXTENSION "uuid-ossp";
ERROR:  extension "uuid-ossp" already exists
DROP EXTENSION "uuid-ossp";
CREATE EXTENSION "uuid-ossp";
db=# \df
                                  List of functions
 Schema |        Name        | Result data type |    Argument data types    |  Type
--------+--------------------+------------------+---------------------------+--------
 public | uuid_generate_v1   | uuid             |                           | normal
 public | uuid_generate_v1mc | uuid             |                           | normal
 public | uuid_generate_v3   | uuid             | namespace uuid, name text | normal
 public | uuid_generate_v4   | uuid             |                           | normal

db=# select uuid_generate_v4();
           uuid_generate_v4
--------------------------------------
 b19d597c-8f54-41ba-ba73-02299c1adf92
(1 row)

What probably happened is that the extension was originally added to the cluster at some point in the past and then you probably created a new database within that cluster afterward. If that was the case then the new database will only be "aware" of the extension but it will not have the uuid functions added which happens when you add the extension. Therefore you must re-add it.

Answer 3

Looks like the extension is not installed in the particular database you require it.

You should connect to this particular database with

 \CONNECT my_database

Then install the extension in this database

 CREATE EXTENSION "uuid-ossp";

Answer 4

Step #1: re-install uuid-ossp extention into the exact schema:

If this is a fresh installation you can skip SET and DROP. Credits to @atomCode (details)

SET search_path TO public;
DROP EXTENSION IF EXISTS "uuid-ossp";

CREATE EXTENSION "uuid-ossp" SCHEMA public;

After this, you should see uuid_generate_v4() function IN THE RIGHT SCHEMA (when execute \df query in psql command-line prompt).

Step #2: use fully-qualified names (with schemaname. qualifier):

For example:

CREATE TABLE public.my_table (
    id uuid DEFAULT public.uuid_generate_v4() NOT NULL,

Answer 5

If you've changed the search_path, specify the public schema in the function call:

public.uuid_generate_v4()

Answer 6

This worked for me.

create extension IF NOT EXISTS "uuid-ossp" schema pg_catalog version "1.1"; 

make sure the extension should by on pg_catalog and not in your schema...

Answer 7

Just add this code to the Beginning of your script

DROP EXTENSION IF EXISTS "uuid-ossp";
CREATE EXTENSION IF NOT EXISTS "uuid-ossp";

Answer 8

Maybe It was the same I was facing. The uuid_generate_v4 was from the public schema and I was trying to run it in a specific schema, so to fix it I did:

SET search_path TO specific_schema;

INSERTO INTO my_table VALUES public.uuid_generate_v4();

You can check the schema where your function is running:

\df uuid_generate_v4

Or

SELECT n.nspname, p.probin, p.proname
FROM
    pg_proc p
    LEFT JOIN pg_namespace n ON p.pronamespace = n.oid
WHERE p.proname like 'uuid_generate_v4';

You can check info related to the extension of the uuid-ossp like this:

SELECT * FROM pg_extension WHERE extname LIKE 'uuid-ossp';

You can add this extension case you don't have it already:

CREATE EXTENSION IF NOT EXISTS "uuid-ossp";

Answer 9

if you do it from unix command (apart from PGAdmin) dont forget to pass the DB as a parameter. otherwise this extension will not be enabled when executing requests on this DB

psql -d -c "create EXTENSION pgcrypto;"

Answer 10

in my case were 3 steps. Create the database, connect to the database and create the extension. The important step is the second one, "connect to the database", and you can notice the line without ";" cause is a command and not a SQL sentence.

CREATE DATABASE database_name_here;
\connect database_name_here 
CREATE EXTENSION IF NOT EXISTS "uuid-ossp";

Answer 11

I'm leaving this here incase it might help. I was working on a nestjs app which uses typeorm. When I tried running migrations I got the error below:

error: function uuid_generate_v4() does not exist

After reading through all responses and trying different things, I ran this block of code to install the extention if it does not exist:

CREATE EXTENSION IF NOT EXISTS "uuid-ossp";

Then I ran SELECT uuid_generate_v4(); which returned a positive response. But I tried running the migrations again and it still failed. Then I ran this code below:

CREATE OR REPLACE FUNCTION uuid_generate_v4() RETURNS uuid AS $$ SELECT uuid_generate_v4(); $$ LANGUAGE sql VOLATILE;

The above step creates a uuid_generate_v4() function that simply calls the real postgres function under the hood.

Then I ran this also

GRANT EXECUTE ON FUNCTION uuid_generate_v4() TO username;

Replace username with your postgres username

Then when I tried the migrations again, it worked.

Answer 12

It seems that the uuid-ossp extension is installed in your PostgreSQL database1. However, the error you are getting suggests that the function uuid_generate_v4() is not available. This could be because the extension is not enabled or installed correctly.

You can try running the following command to enable the extension:

CREATE EXTENSION IF NOT EXISTS "uuid-ossp";

After enabling the extension, you can try running the following command to create your table:

CREATE TABLE my_table (
    id uuid DEFAULT uuid_generate_v4() NOT NULL,
    name character varying(32) NOT NULL
);