Fire the event trigger for DROP SCHEMA and DROP OWNED

HISTORY.asc

@@ -6,6 +6,14 @@ extension_drop depends on cat_tools, which already requires PostgreSQL
 too (a cat_tools function it calls needs PG11+ internally) -- this
 just makes the declared floor honest.
 
+== Run drop commands when `DROP SCHEMA ... CASCADE` or `DROP OWNED BY` drops an extension
+The event trigger now fires for `DROP SCHEMA` and `DROP OWNED` as well as
+`DROP EXTENSION`, and returns immediately unless an extension is among the
+dropped objects, so other drops are unaffected. Previously the other two
+commands skipped the registered SQL and left a stale registration that made
+every later `DROP EXTENSION` fail with `XD001`; remove any existing stale
+registration with `extension_drop__repair()`.
+
 == Remove redundant client_min_messages handling from install script
 `CREATE EXTENSION` already raises `client_min_messages` to `WARNING` for
 the install script (only-raising, so a stricter caller is respected) and

README.md

@@ -42,6 +42,8 @@ arbitrary SQL to run later. Grant them to specific roles as needed.
 ## How it works
 
 An event trigger (`extension_drop`, on `sql_drop`) fires whenever an
-extension is dropped, runs any SQL registered for it via
+extension is dropped -- by `DROP EXTENSION`, `DROP SCHEMA ... CASCADE` or
+`DROP OWNED BY` -- runs any SQL registered for it via
 `extension_drop__add`/`extension_drop__update`, and removes the registration
-afterward.
+afterward. Those commands fire the trigger for every drop, but it returns
+immediately unless an extension is among the dropped objects.

sql/extension_drop--0.1.1--stable.sql

@@ -2,9 +2,17 @@ CREATE OR REPLACE FUNCTION extension_drop__event_trigger(
 ) RETURNS event_trigger LANGUAGE plpgsql SET search_path FROM CURRENT AS
 $body$
 DECLARE
-  r extension_drop__commands;
+  r record; -- Not extension_drop__commands: the type must not resolve before the early return
 BEGIN
   RAISE DEBUG 'extension_drop event trigger entry: tg_event %, tg_tag %', tg_event, tg_tag;
+
+  -- Most drops involve no extension; don't touch our table (or assert) for them.
+  IF NOT EXISTS(
+    SELECT 1 FROM pg_catalog.pg_event_trigger_dropped_objects() WHERE object_type = 'extension'
+  ) THEN
+    RETURN;
+  END IF;
+
   FOR r IN
     SELECT c.*
       FROM extension_drop__commands c
@@ -25,4 +33,12 @@ BEGIN
 END
 $body$;
 
+-- ALTER EVENT TRIGGER can't change WHEN
+DROP EVENT TRIGGER extension_drop;
+CREATE EVENT TRIGGER extension_drop
+  ON sql_drop
+  WHEN tag IN( 'DROP EXTENSION', 'DROP SCHEMA', 'DROP OWNED' ) -- NOTE! This MUST be IN
+  EXECUTE PROCEDURE extension_drop__event_trigger()
+;
+
 -- vim: sw=2 ts=2 expandtab

sql/extension_drop.sql

@@ -264,9 +264,17 @@ SELECT __extension_drop.create_function(
   , 'event_trigger LANGUAGE plpgsql'
   , $body$
 DECLARE
-  r extension_drop__commands;
+  r record; -- Not extension_drop__commands: the type must not resolve before the early return
 BEGIN
   RAISE DEBUG 'extension_drop event trigger entry: tg_event %, tg_tag %', tg_event, tg_tag;
+
+  -- Most drops involve no extension; don't touch our table (or assert) for them.
+  IF NOT EXISTS(
+    SELECT 1 FROM pg_catalog.pg_event_trigger_dropped_objects() WHERE object_type = 'extension'
+  ) THEN
+    RETURN;
+  END IF;
+
   FOR r IN
     SELECT c.*
       FROM extension_drop__commands c
@@ -291,7 +299,8 @@ $body$
 
 CREATE EVENT TRIGGER extension_drop
   ON sql_drop
-  WHEN tag IN( 'DROP EXTENSION' ) -- NOTE! This MUST be IN
+  -- DROP SCHEMA CASCADE and DROP OWNED BY also drop extensions.
+  WHEN tag IN( 'DROP EXTENSION', 'DROP SCHEMA', 'DROP OWNED' ) -- NOTE! This MUST be IN
   EXECUTE PROCEDURE extension_drop__event_trigger()
 ;
 

test/expected/drop_owned.out

@@ -0,0 +1,16 @@
+\set ECHO none
+1..13
+ok 1 - Insert into extension_drop_test_table
+ok 2 - Create role
+ok 3 - Create test extension as role
+ok 4 - Verify extension_drop__get()
+ok 5 - Drop owned
+ok 6 - Test extension does not exist
+ok 7 - extension_drop_test_table is empty
+ok 8 - No stale registration
+ok 9 - Create test extension
+ok 10 - Test extension exists
+ok 11 - Drop test extension
+ok 12 - Test extension does not exist
+ok 13 - extension_drop's schema should not be reachable via search_path
+# TRANSACTION INTENTIONALLY LEFT OPEN!

test/expected/drop_owned_1.out

@@ -0,0 +1,16 @@
+\set ECHO none
+1..13
+ok 1 - Insert into extension_drop_test_table
+ok 2 - Create role
+ok 3 - Create test extension as role
+ok 4 - Verify extension_drop__get()
+ok 5 - Drop owned
+ok 6 - Test extension does not exist
+ok 7 - extension_drop_test_table is empty
+ok 8 - No stale registration
+ok 9 - Create test extension
+ok 10 - Test extension exists
+ok 11 - Drop test extension
+ok 12 - Test extension does not exist
+ok 13 # SKIP existing mode: extension_drop's placement is outside this suite's control
+# TRANSACTION INTENTIONALLY LEFT OPEN!

test/expected/drop_schema_cascade.out

@@ -0,0 +1,16 @@
+\set ECHO none
+1..13
+ok 1 - Insert into extension_drop_test_table
+ok 2 - Create schema
+ok 3 - Create test extension in schema
+ok 4 - Verify extension_drop__get()
+ok 5 - Drop schema cascade
+ok 6 - Test extension does not exist
+ok 7 - extension_drop_test_table is empty
+ok 8 - No stale registration
+ok 9 - Create test extension
+ok 10 - Test extension exists
+ok 11 - Drop test extension
+ok 12 - Test extension does not exist
+ok 13 - extension_drop's schema should not be reachable via search_path
+# TRANSACTION INTENTIONALLY LEFT OPEN!

test/expected/drop_schema_cascade_1.out

@@ -0,0 +1,16 @@
+\set ECHO none
+1..13
+ok 1 - Insert into extension_drop_test_table
+ok 2 - Create schema
+ok 3 - Create test extension in schema
+ok 4 - Verify extension_drop__get()
+ok 5 - Drop schema cascade
+ok 6 - Test extension does not exist
+ok 7 - extension_drop_test_table is empty
+ok 8 - No stale registration
+ok 9 - Create test extension
+ok 10 - Test extension exists
+ok 11 - Drop test extension
+ok 12 - Test extension does not exist
+ok 13 # SKIP existing mode: extension_drop's placement is outside this suite's control
+# TRANSACTION INTENTIONALLY LEFT OPEN!

test/expected/unrelated_drops.out

@@ -0,0 +1,11 @@
+\set ECHO none
+1..8
+ok 1 - Create non-superuser role
+ok 2 - Grant CREATE on database
+ok 3 - Non-superuser DROP SCHEMA CASCADE
+ok 4 - Non-superuser DROP OWNED BY
+ok 5 - Insert stale registration
+ok 6 - Stale registration is present
+ok 7 - Superuser DROP SCHEMA with stale registration
+ok 8 - extension_drop's schema should not be reachable via search_path
+# TRANSACTION INTENTIONALLY LEFT OPEN!

test/expected/unrelated_drops_1.out

@@ -0,0 +1,11 @@
+\set ECHO none
+1..8
+ok 1 - Create non-superuser role
+ok 2 - Grant CREATE on database
+ok 3 - Non-superuser DROP SCHEMA CASCADE
+ok 4 - Non-superuser DROP OWNED BY
+ok 5 - Insert stale registration
+ok 6 - Stale registration is present
+ok 7 - Superuser DROP SCHEMA with stale registration
+ok 8 # SKIP existing mode: extension_drop's placement is outside this suite's control
+# TRANSACTION INTENTIONALLY LEFT OPEN!

test/helpers/test_ext__verify_dropped.sql

@@ -0,0 +1,11 @@
+SELECT hasnt_extension('extension_drop_test', 'Test extension does not exist');
+SELECT is_empty(
+  $$SELECT * FROM $$ || :'TT'
+  , :'TT' || ' is empty'
+);
+SELECT is_empty(
+  format($$SELECT unnest(%I.extension_drop__sanity_check())$$, :'extension_drop_schema')
+  , 'No stale registration'
+);
+
+-- vi: expandtab sw=2 ts=2

test/sql/drop_owned.sql

@@ -0,0 +1,56 @@
+\set ECHO none
+\i test/pgxntool/setup.sql
+
+/*
+ * DROP OWNED BY can drop an extension; its registered command must run and
+ * the registration must go away, or the stale row makes every later DROP
+ * EXTENSION fail.
+ */
+SELECT plan(
+  0
+
+  + 1 -- Insert into test table
+
+  + 1 -- Create role
+  + 1 -- Create test extension as role
+  + 1 -- Verify extension_drop__get()
+  + 1 -- Drop owned
+  + 3 -- Verify extension is gone, table is empty, no stale registration (test/helpers/test_ext__verify_dropped.sql)
+
+  + 4 -- Create and drop test extension again (test/helpers/test_ext__create_drop.sql)
+
+  + 1 -- extension_drop's schema should not be on search_path (test/finish.sql)
+);
+
+\i test/helpers/test_ext__insert.sql
+
+SELECT lives_ok(
+  'CREATE ROLE extension_drop_test_owner SUPERUSER'
+  , 'Create role'
+);
+-- ALTER EXTENSION can't change the owner, so create it as that role
+SELECT lives_ok(
+  $q$DO $$ BEGIN
+    SET LOCAL ROLE extension_drop_test_owner;
+    CREATE EXTENSION extension_drop_test;
+    RESET ROLE;
+  END $$$q$
+  , 'Create test extension as role'
+);
+SELECT bag_eq(
+  format($$SELECT * FROM %I.extension_drop__get('extension_drop_test')$$, :'extension_drop_schema')
+  , $$SELECT 'extension_drop_test'::name, 'DELETE FROM extension_drop_test_table'::text$$
+  , 'Verify extension_drop__get()'
+);
+
+SELECT lives_ok(
+  'DROP OWNED BY extension_drop_test_owner'
+  , 'Drop owned'
+);
+\i test/helpers/test_ext__verify_dropped.sql
+
+\i test/helpers/test_ext__create_drop.sql
+
+\i test/finish.sql
+
+-- vi: expandtab sw=2 ts=2

test/sql/drop_schema_cascade.sql

@@ -0,0 +1,54 @@
+\set ECHO none
+\i test/pgxntool/setup.sql
+
+/*
+ * DROP SCHEMA ... CASCADE can drop an extension; its registered command must
+ * run and the registration must go away, or the stale row makes every later
+ * DROP EXTENSION fail.
+ */
+SELECT plan(
+  0
+
+  + 1 -- Insert into test table
+
+  + 1 -- Create schema
+  + 1 -- Create test extension in it
+  + 1 -- Verify extension_drop__get()
+  + 1 -- Drop schema cascade
+  + 3 -- Verify extension is gone, table is empty, no stale registration (test/helpers/test_ext__verify_dropped.sql)
+
+  + 4 -- Create and drop test extension again (test/helpers/test_ext__create_drop.sql)
+
+  + 1 -- extension_drop's schema should not be on search_path (test/finish.sql)
+);
+
+-- Hide the version-specific "drop cascades to" NOTICE
+SET client_min_messages = WARNING;
+
+\i test/helpers/test_ext__insert.sql
+
+SELECT lives_ok(
+  'CREATE SCHEMA extension_drop_test_schema'
+  , 'Create schema'
+);
+SELECT lives_ok(
+  'CREATE EXTENSION extension_drop_test SCHEMA extension_drop_test_schema'
+  , 'Create test extension in schema'
+);
+SELECT bag_eq(
+  format($$SELECT * FROM %I.extension_drop__get('extension_drop_test')$$, :'extension_drop_schema')
+  , $$SELECT 'extension_drop_test'::name, 'DELETE FROM extension_drop_test_table'::text$$
+  , 'Verify extension_drop__get()'
+);
+
+SELECT lives_ok(
+  'DROP SCHEMA extension_drop_test_schema CASCADE'
+  , 'Drop schema cascade'
+);
+\i test/helpers/test_ext__verify_dropped.sql
+
+\i test/helpers/test_ext__create_drop.sql
+
+\i test/finish.sql
+
+-- vi: expandtab sw=2 ts=2

test/sql/unrelated_drops.sql

@@ -0,0 +1,73 @@
+\set ECHO none
+\i test/pgxntool/setup.sql
+
+/*
+ * DROP SCHEMA and DROP OWNED fire extension_drop's event trigger, so drops
+ * that involve no extension must not depend on the caller's privileges or on
+ * the state of extension_drop__commands.
+ */
+SELECT plan(
+  0
+
+  + 1 -- Create non-superuser role
+  + 1 -- Grant it CREATE on the database
+  + 1 -- Non-superuser DROP SCHEMA CASCADE
+  + 1 -- Non-superuser DROP OWNED BY
+
+  + 1 -- Insert stale registration
+  + 1 -- Stale registration is present
+  + 1 -- Superuser DROP SCHEMA with stale registration
+
+  + 1 -- extension_drop's schema should not be on search_path (test/finish.sql)
+);
+
+-- Hide version- and database-specific NOTICE/WARNING text from the drops
+SET client_min_messages = ERROR;
+
+SELECT lives_ok(
+  'CREATE ROLE extension_drop_test_plain'
+  , 'Create non-superuser role'
+);
+SELECT lives_ok(
+  format('GRANT CREATE ON DATABASE %I TO extension_drop_test_plain', current_database())
+  , 'Grant CREATE on database'
+);
+
+SELECT lives_ok(
+  $q$DO $$ BEGIN
+    SET LOCAL ROLE extension_drop_test_plain;
+    CREATE SCHEMA extension_drop_test_plain_schema;
+    CREATE TABLE extension_drop_test_plain_schema.t(i int);
+    DROP SCHEMA extension_drop_test_plain_schema CASCADE;
+    RESET ROLE;
+  END $$$q$
+  , 'Non-superuser DROP SCHEMA CASCADE'
+);
+SELECT lives_ok(
+  $q$DO $$ BEGIN
+    SET LOCAL ROLE extension_drop_test_plain;
+    CREATE SCHEMA extension_drop_test_plain_schema;
+    CREATE TABLE extension_drop_test_plain_schema.t(i int);
+    DROP OWNED BY extension_drop_test_plain;
+    RESET ROLE;
+  END $$$q$
+  , 'Non-superuser DROP OWNED BY'
+);
+
+SELECT lives_ok(
+  format($$INSERT INTO %I.extension_drop__commands VALUES('extension_drop_test_stale', 'SELECT 1')$$, :'extension_drop_schema')
+  , 'Insert stale registration'
+);
+SELECT results_eq(
+  format($$SELECT %I.extension_drop__sanity_check()$$, :'extension_drop_schema')
+  , $$SELECT '{extension_drop_test_stale}'::name[]$$
+  , 'Stale registration is present'
+);
+SELECT lives_ok(
+  $$CREATE SCHEMA extension_drop_test_su_schema; DROP SCHEMA extension_drop_test_su_schema$$
+  , 'Superuser DROP SCHEMA with stale registration'
+);
+
+\i test/finish.sql
+
+-- vi: expandtab sw=2 ts=2