How do I delete an enum type value that I created in postgresql?
create type admin_level1 as enum('classifier', 'moderator', 'god');
E.g. I want to remove moderator from the list.
I can't seem to find anything on the docs.
I'm using Postgresql 9.3.4.
You delete (drop) enum types like any other type, with DROP TYPE:
DROP TYPE admin_level1;
Is it possible you're actually asking about how to remove an individual value from an enum type? If so, you can't. It's not supported:
Although
enumtypes are primarily intended for static sets of values, there is support for adding new values to an existing enum type, and for renaming values (seeALTER TYPE). Existing values cannot be removed from an enum type, nor can the sort ordering of such values be changed, short of dropping and re-creating the enum type.
You must create a new type without the value, convert all existing uses of the old type to use the new type, then drop the old type.
E.g.
CREATE TYPE admin_level1 AS ENUM ('classifier', 'moderator');
CREATE TABLE blah (
user_id integer primary key,
power admin_level1 not null
);
INSERT INTO blah(user_id, power) VALUES (1, 'moderator'), (10, 'classifier');
ALTER TYPE admin_level1 ADD VALUE 'god';
INSERT INTO blah(user_id, power) VALUES (42, 'god');
-- .... oops, maybe that was a bad idea
CREATE TYPE admin_level1_new AS ENUM ('classifier', 'moderator');
-- Remove values that won't be compatible with new definition
-- You don't have to delete, you might update instead
DELETE FROM blah WHERE power = 'god';
-- Convert to new type, casting via text representation
ALTER TABLE blah
ALTER COLUMN power TYPE admin_level1_new
USING (power::text::admin_level1_new);
-- and swap the types
DROP TYPE admin_level1;
ALTER TYPE admin_level1_new RENAME TO admin_level1;
Very well written here:
http://blog.yo1.dog/updating-enum-values-in-postgresql-the-safe-and-easy-way/
rename the existing type
ALTER TYPE status_enum RENAME TO status_enum_old;
create the new type
CREATE TYPE status_enum AS ENUM('queued', 'running', 'done');
update the columns to use the new type
ALTER TABLE job ALTER COLUMN job_status TYPE status_enum USING job_status::text::status_enum;
remove the old type
DROP TYPE status_enum_old;
Possible Errors and Troubleshooting:
invalid input value for enum {enum name}: "{some value}" - One or more rows have a value ("{some value}") that is not in your new type. You must handle these rows before you can update the column type.default for column "{column_name}" cannot be cast automatically to type {enum_name} - The default value for the column is not in your new type. You must change or remove the default value for the column before you can update the column type. Thanks to Philipp for this addition.cannot alter type of a column used by a view or rule - All views and rules using the column have to be dropped before the ALTER can be executed and then recreated afterwards. There are ways to do that automatically.
This is a very dangerous operation. You must make sure no table is using the enum value you want to remove. If you don't, you will badly break all tables that reference the enum value
If you want delete item of enum type, you must operate on system table of PostgreSQL.
With this command, you can display all the items enum type
SELECT * FROM pg_enum;
Then check that searched the value is unique. To increase the uniqueness during the removal of rekoru must be passed 'enumtypid' in addition to 'enumlabel'.
This command removes the entry in enum type, where 'unique' is your value.
DELETE FROM pg_enum en WHERE en.enumtypid=124 AND en.enumlabel='unique';
Note: This command must not be used if 'unique' is used anywhere in the database.
For those who wish to modify the enum values, recreating it seems to be the only viable and safe solution.
It consists in temporarely convert the enum column to a string format, recreate the enum and then reconverting the string column back to the enum type.
Here is an example:
ALTER TABLE your_schema.your_table ALTER COLUMN your_column TYPE varchar(255);
ALTER TABLE your_schema.your_table ALTER COLUMN your_column SET DEFAULT('your_default_enum_value');
DROP TYPE your_schema.your_enum_name;
CREATE TYPE your_schema.your_enum_name AS ENUM ('enum1', 'enum2', 'enum3');
ALTER TABLE your_schema.your_table ALTER your_column DROP DEFAULT;
ALTER TABLE your_schema.your_table ALTER COLUMN your_column TYPE your_schema.your_enum_name USING your_enum_name::your_schema.your_column;
ALTER TABLE your_schema.your_table ALTER COLUMN your_column SET DEFAULT('your_default_enum_value');
Use following query to Delete ENUM value from Postgresql type
DELETE FROM pg_enum
WHERE enumlabel = 'moderator'
AND enumtypid = ( SELECT oid FROM pg_type WHERE typname = 'admin_level1');
Just info for what's type and what's value
DELETE FROM pg_enum
WHERE enumlabel = 'ENUM_VALUE'
AND enumtypid = ( SELECT oid FROM pg_type WHERE typname = 'ENUM_TYPE')
You should change existing values to other. For that if you need to add new value, then use:
ALTER TYPE **ENUM_TYPE** ADD VALUE '**ENUM_VALUE2**';
Before deleting, update type value to new type value or existing value.
The programmatic way to do this is as follows. The same general steps as given
in https://stackoverflow.com/a/47305844/629272 are appropriate, but those are
more manual than made sense for my purposes (writing an alembic down migration). my_type, my_type_old, and value_to_delete, should, of course, be changed as appropriate.
Rename your type.
ALTER TYPE my_type RENAME TO my_type_old;
Create a new type with the values from your old type, excluding the one you want to delete.
DO $$
BEGIN
EXECUTE format(
'CREATE TYPE my_type AS ENUM (%s)',
(
SELECT string_agg(quote_literal(value), ',')
FROM unnest(enum_range(NULL::my_type_old)) value
WHERE value <> 'value_to_delete'
)
);
END $$;
Change all existing columns which use the old type to use the new one.
DO $$
DECLARE
column_data record;
table_name varchar(255);
column_name varchar(255);
BEGIN
FOR column_data IN
SELECT cols.table_name, cols.column_name
FROM information_schema.columns cols
WHERE udt_name = 'my_type_old'
LOOP
table_name := column_data.table_name;
column_name := column_data.column_name;
EXECUTE format(
'
ALTER TABLE %s
ALTER COLUMN %s
TYPE my_type
USING %s::text::my_type;
',
table_name, column_name, column_name
);
END LOOP;
END $$;
Delete the old type.
DROP TYPE my_type_old;
It's not possible to delete individual value from ENUM, the only possible solution is to DROP and recreate ENUM with needed values.
My solution starts from the fact that I don't have permissions in my scenario to perform DELETE FROM pg_enum as I'm getting a permissions error.
Starting from other replies, I created a generic function that can be used to remove a single value from a enum, supporting the update value to release the use of given value
-- https://stackoverflow.com/a/62444685
-- https://stackoverflow.com/a/51073579
create or replace function remove_enum_value(
type_name text, -- Name of the type where you need to remove a value from
value_to_delete text, -- Specific value of the given type you want to remove
value_fallback text, -- Which new value columns will have instead of the value deleted
column_default text -- DEFAULT value for the column after type alteration (DEFAULT need to be disabled before changing type, https://stackoverflow.com/a/41149789)
)
RETURNS VOID AS $body$
declare
-- Used as temporary type
_type_name_tmp text := type_name || '_tmp_' || floor(extract(epoch from now()) * 1000);
-- Used to store statements to execute
_sql text;
-- Used to loop tables and switch type from current to temporary
_column_data record;
_table_name varchar(255);
_column_name varchar(255);
begin
--------------------------------------------------------------------------------------------------------------
-- Check: required inputs
if type_name is null
then
raise exception 'Parameter type_name is null';
end if;
if value_to_delete is null
then
raise exception 'Parameter value_to_delete is null';
end if;
-- Check: type exists
IF not EXISTS (SELECT 1 FROM pg_type WHERE typname = type_name) THEN
raise info 'Type %s does not exists', type_name;
return;
END IF;
-- Check: value to delete exists
if not exists(
select *
FROM pg_enum -- check existing of value to delete
WHERE enumtypid = (select oid from pg_type where typName=cast(type_name as varchar) limit 1) and enumlabel=cast(value_to_delete as varchar)
)
then
raise info 'Value to delete % does not exists in type %s', value_to_delete, type_name;
return;
end if;
-- Check: fallback value is provided and exists
if value_fallback is not null and not exists(
select *
FROM pg_enum -- check existing of value to delete
where
enumtypid = (select oid from pg_type where typName=cast(type_name as varchar) limit 1)
and enumlabel=cast(value_fallback as varchar)
)
then
raise info 'Fallback value % does not exists in type %s', value_fallback, type_name;
return;
end if;
-- Check values are different
if value_fallback = value_to_delete
then
raise info 'Value to delete %s is the same as fallback value %', value_to_delete, value_fallback;
return;
end if;
raise info 'Checks passed, ready to process!';
--------------------------------------------------------------------------------------------------------------
-- Retrieve current values of type
_sql := format('
SELECT string_agg(quote_literal(value), '','')
FROM unnest(enum_range(NULL::%s)) value
WHERE value <> ''%s''
', type_name, value_to_delete);
raise info '%', _sql;
execute _sql into _sql;
-- Create temporary enum
_sql := format(
'CREATE TYPE %s AS ENUM (%s)',
_type_name_tmp,
_sql
);
raise info '%', _sql;
execute _sql;
-- Rename all values from value that need to be deleted to new value (selecting all tables with schemas which has column with enum relation)
for _column_data in (
select
concat(c.table_schema,'.',c.table_name ) as table_name,
c.column_name
FROM information_schema.columns c
where
c.udt_name = cast(type_name as varchar)
and c.table_schema=c.udt_schema
and data_type = 'USER-DEFINED'
)
LOOP
_sql:= format('UPDATE %1$s set %2$s = %3$L where %2$s=%4$L', _column_data.table_name, _column_data.column_name, value_fallback, value_to_delete);
raise info 'Update by looping: %', _sql;
EXECUTE _sql;
END LOOP;
-- Switch type from current to temporary
FOR _column_data in (
SELECT cols.table_name, cols.column_name
FROM information_schema.columns cols
WHERE udt_name = type_name
)
LOOP
_table_name := _column_data.table_name;
_column_name := _column_data.column_name;
_sql := format(
'
ALTER TABLE %s
ALTER COLUMN %s DROP DEFAULT,
ALTER COLUMN %s TYPE %s USING %s::text::%s,
ALTER COLUMN %s SET DEFAULT %s;
',
_table_name,
_column_name,
_column_name, _type_name_tmp, _column_name, _type_name_tmp,
_column_name, (case when column_default is null then null else '''' || column_default || '''::' || _type_name_tmp end)
);
raise info '%', _sql;
execute _sql;
END LOOP;
-- Drop previous type
_sql := format('DROP TYPE %s;', type_name);
raise info '%', _sql;
execute _sql;
-- Rename type to previous name
_sql := format('ALTER TYPE %s RENAME TO %s;', _type_name_tmp, type_name);
raise info '%', _sql;
execute _sql;
END $body$
LANGUAGE plpgsql;
Had the same problem in v.10. postgres. Deletion requires certain procedures, and if the sequence is not correct, then there will even be a chance of the table being locked for reading.
Wrote a convenient script to delete. Already proven several times its performance. However, this procedure involves replacing the deleted value with a new one (it can be NULL if the table field allows this).
To use, you just need to fill in 3 values.
DO $$
DECLARE
enumTypeName VARCHAR := 'enum_name'; -- VALUE #1, set yor value!
enumOldFieldValue varchar := 'old_enum_value'; -- VALUE #2, enum value which have to be deleted
enumNewFieldValue varchar := null; -- VALUE #3, which new value must be instead of deleted
sql varchar:='';
rec record;
BEGIN
raise info 'Check on old and new enum values.';
IF exists(select * FROM pg_enum -- check existing of OLD enum value
WHERE enumtypid = (select oid from pg_type where typName=cast(enumTypeName as varchar) limit 1) and enumlabel=cast(enumOldFieldValue as varchar))
AND
(exists(select *
FROM pg_enum -- check existing of NEW enum value
WHERE enumtypid = (select oid from pg_type where typName = cast(enumTypeName as varchar) limit 1)
and enumlabel = cast(enumNewFieldValue as varchar))
OR
enumNewFieldValue IS NULL)
THEN
raise info 'Check passed!';
-- selecting all tables with schemas which has column with enum relation
create temporary table tmp_table_names
as SELECT concat(c.table_schema,'.',c.table_name ) as table_name, c.column_name
FROM information_schema.columns c
WHERE c.udt_name = cast(enumTypeName as varchar)
and c.table_schema=c.udt_schema and data_type = 'USER-DEFINED';
-- if we have table(s) that uses such enum
if exists(select * from tmp_table_names)
then
FOR rec in (select table_name, column_name from tmp_table_names) LOOP
sql:= format('UPDATE %1$s set %2$s = %3$L where %2$s=%4$L',rec.table_name, rec.column_name, enumNewFieldValue, enumOldFieldValue);
raise info 'Update by looping: %', sql;
EXECUTE sql;
END LOOP;
end if;
-- just after changing all old values in all tables we can delete old enum value
sql := format('DELETE FROM pg_enum WHERE enumtypid = (select oid from pg_type where typName=%1$L limit 1) and enumlabel=%2$L',enumTypeName,enumOldFieldValue);
raise info 'Delete enum value: %', sql;
EXECUTE sql;
drop table tmp_table_names;
ELSE
raise info 'Old or new enum values is missing.';
end if;
END $$;
if your dataset is not so big you can dump with --column-inserts edit the dump with a text editor, remove the value and re-import the dump
