Enable PGMQ to run without installing an extension (#379)

* Enable PGMQ to run without installing an extension * Additional guard to avoid "An extension may only use CREATE ... IF NOT EXISTS to skip object creation if the conflicting object is one that it already owns." * Adjusted line number
tembo-io · Feb 17, 2025 · 87530ed · 87530ed
1 parent 58fdf5e
commit 87530ed
Show file tree

Hide file tree

Showing 2 changed files with 104 additions and 80 deletions.
diff --git a/pgmq-extension/sql/pgmq.sql b/pgmq-extension/sql/pgmq.sql
@@ -1,8 +1,17 @@
 ------------------------------------------------------------
 -- Schema, tables, records, privileges, indexes, etc
 ------------------------------------------------------------
--- We don't need to create the `pgmq` schema because it is automatically
--- created by postgres due to being declared in extension control file
+-- When installed as an extension, we don't need to create the `pgmq` schema
+-- because it is automatically created by postgres due to being declared in
+-- the extension control file
+DO
+$$
+BEGIN
+    IF (SELECT NOT EXISTS( SELECT 1 FROM pg_extension WHERE extname = 'pgmq')) THEN
+      CREATE SCHEMA IF NOT EXISTS pgmq;
+    END IF;
+END
+$$;
 
 -- Table where queues and metadata about them is stored
 CREATE TABLE pgmq.meta (
@@ -268,6 +277,29 @@ BEGIN
 END;
 $$ LANGUAGE plpgsql;
 
+-- send: actual implementation
+CREATE FUNCTION pgmq.send(
+    queue_name TEXT,
+    msg JSONB,
+    headers JSONB,
+    delay TIMESTAMP WITH TIME ZONE
+) RETURNS SETOF BIGINT AS $$
+DECLARE
+    sql TEXT;
+    qtable TEXT := pgmq.format_table_name(queue_name, 'q');
+BEGIN
+    sql := FORMAT(
+            $QUERY$
+        INSERT INTO pgmq.%I (vt, message, headers)
+        VALUES ($2, $1, $3)
+        RETURNING msg_id;
+        $QUERY$,
+            qtable
+           );
+    RETURN QUERY EXECUTE sql USING msg, delay, headers;
+END;
+$$ LANGUAGE plpgsql;
+
 -- send: 2 args, no delay or headers
 CREATE FUNCTION pgmq.send(
     queue_name TEXT,
@@ -313,26 +345,26 @@ CREATE FUNCTION pgmq.send(
     SELECT * FROM pgmq.send(queue_name, msg, headers, clock_timestamp() + make_interval(secs => delay));
 $$ LANGUAGE sql;
 
--- send: actual implementation
-CREATE FUNCTION pgmq.send(
+-- send_batch: actual implementation
+CREATE FUNCTION pgmq.send_batch(
     queue_name TEXT,
-    msg JSONB,
-    headers JSONB,
+    msgs JSONB[],
+    headers JSONB[],
     delay TIMESTAMP WITH TIME ZONE
 ) RETURNS SETOF BIGINT AS $$
 DECLARE
     sql TEXT;
     qtable TEXT := pgmq.format_table_name(queue_name, 'q');
 BEGIN
     sql := FORMAT(
-        $QUERY$
+            $QUERY$
         INSERT INTO pgmq.%I (vt, message, headers)
-        VALUES ($2, $1, $3)
+        SELECT $2, unnest($1), unnest(coalesce($3, ARRAY[]::jsonb[]))
         RETURNING msg_id;
         $QUERY$,
-        qtable
-    );
-    RETURN QUERY EXECUTE sql USING msg, delay, headers;
+            qtable
+           );
+    RETURN QUERY EXECUTE sql USING msgs, delay, headers;
 END;
 $$ LANGUAGE plpgsql;
 
@@ -381,29 +413,6 @@ CREATE FUNCTION pgmq.send_batch(
     SELECT * FROM pgmq.send_batch(queue_name, msgs, headers, clock_timestamp() + make_interval(secs => delay));
 $$ LANGUAGE sql;
 
--- send_batch: actual implementation
-CREATE FUNCTION pgmq.send_batch(
-    queue_name TEXT,
-    msgs JSONB[],
-    headers JSONB[],
-    delay TIMESTAMP WITH TIME ZONE
-) RETURNS SETOF BIGINT AS $$
-DECLARE
-    sql TEXT;
-    qtable TEXT := pgmq.format_table_name(queue_name, 'q');
-BEGIN
-    sql := FORMAT(
-        $QUERY$
-        INSERT INTO pgmq.%I (vt, message, headers)
-        SELECT $2, unnest($1), unnest(coalesce($3, ARRAY[]::jsonb[]))
-        RETURNING msg_id;
-        $QUERY$,
-        qtable
-    );
-    RETURN QUERY EXECUTE sql USING msgs, delay, headers;
-END;
-$$ LANGUAGE plpgsql;
-
 -- returned by pgmq.metrics() and pgmq.metrics_all
 CREATE TYPE pgmq.metrics_result AS (
     queue_name text,
@@ -504,7 +513,9 @@ RETURNS VOID AS $$
 DECLARE
   atable TEXT := pgmq.format_table_name(queue_name, 'a');
 BEGIN
-  EXECUTE format('ALTER EXTENSION pgmq DROP TABLE pgmq.%I', atable);
+  IF pgmq._extension_exists('pgmq') THEN
+    EXECUTE format('ALTER EXTENSION pgmq DROP TABLE pgmq.%I', atable);
+  END IF;
 END
 $$ LANGUAGE plpgsql;
 
@@ -601,26 +612,28 @@ BEGIN
         queue_name
     ) INTO partitioned;
 
-    EXECUTE FORMAT(
-        $QUERY$
-        ALTER EXTENSION pgmq DROP TABLE pgmq.%I
-        $QUERY$,
-        qtable
-    );
+    IF pgmq._extension_exists('pgmq') THEN
+        EXECUTE FORMAT(
+            $QUERY$
+            ALTER EXTENSION pgmq DROP TABLE pgmq.%I
+            $QUERY$,
+            qtable
+        );
 
-    EXECUTE FORMAT(
-        $QUERY$
-        ALTER EXTENSION pgmq DROP SEQUENCE pgmq.%I
-        $QUERY$,
-        qtable_seq
-    );
+        EXECUTE FORMAT(
+            $QUERY$
+            ALTER EXTENSION pgmq DROP SEQUENCE pgmq.%I
+            $QUERY$,
+            qtable_seq
+        );
 
-    EXECUTE FORMAT(
-        $QUERY$
-        ALTER EXTENSION pgmq DROP TABLE pgmq.%I
-        $QUERY$,
-        atable
-    );
+        EXECUTE FORMAT(
+            $QUERY$
+            ALTER EXTENSION pgmq DROP TABLE pgmq.%I
+            $QUERY$,
+            atable
+        );
+    END IF;
 
     EXECUTE FORMAT(
         $QUERY$
@@ -729,13 +742,15 @@ BEGIN
     atable
   );
 
-  IF NOT pgmq._belongs_to_pgmq(qtable) THEN
-      EXECUTE FORMAT('ALTER EXTENSION pgmq ADD TABLE pgmq.%I', qtable);
-      EXECUTE FORMAT('ALTER EXTENSION pgmq ADD SEQUENCE pgmq.%I', qtable_seq);
-  END IF;
+  IF pgmq._extension_exists('pgmq') THEN
+      IF NOT pgmq._belongs_to_pgmq(qtable) THEN
+          EXECUTE FORMAT('ALTER EXTENSION pgmq ADD TABLE pgmq.%I', qtable);
+          EXECUTE FORMAT('ALTER EXTENSION pgmq ADD SEQUENCE pgmq.%I', qtable_seq);
+      END IF;
 
-  IF NOT pgmq._belongs_to_pgmq(atable) THEN
-      EXECUTE FORMAT('ALTER EXTENSION pgmq ADD TABLE pgmq.%I', atable);
+      IF NOT pgmq._belongs_to_pgmq(atable) THEN
+          EXECUTE FORMAT('ALTER EXTENSION pgmq ADD TABLE pgmq.%I', atable);
+      END IF;
   END IF;
 
   EXECUTE FORMAT(
@@ -801,13 +816,15 @@ BEGIN
     atable
   );
 
-  IF NOT pgmq._belongs_to_pgmq(qtable) THEN
-      EXECUTE FORMAT('ALTER EXTENSION pgmq ADD TABLE pgmq.%I', qtable);
-      EXECUTE FORMAT('ALTER EXTENSION pgmq ADD SEQUENCE pgmq.%I', qtable_seq);
-  END IF;
+  IF pgmq._extension_exists('pgmq') THEN
+      IF NOT pgmq._belongs_to_pgmq(qtable) THEN
+          EXECUTE FORMAT('ALTER EXTENSION pgmq ADD TABLE pgmq.%I', qtable);
+          EXECUTE FORMAT('ALTER EXTENSION pgmq ADD SEQUENCE pgmq.%I', qtable_seq);
+      END IF;
 
-  IF NOT pgmq._belongs_to_pgmq(atable) THEN
-      EXECUTE FORMAT('ALTER EXTENSION pgmq ADD TABLE pgmq.%I', atable);
+      IF NOT pgmq._belongs_to_pgmq(atable) THEN
+          EXECUTE FORMAT('ALTER EXTENSION pgmq ADD TABLE pgmq.%I', atable);
+      END IF;
   END IF;
 
   EXECUTE FORMAT(
@@ -851,18 +868,21 @@ BEGIN
 END;
 $$ LANGUAGE plpgsql;
 
-CREATE FUNCTION pgmq._ensure_pg_partman_installed()
-RETURNS void AS $$
-DECLARE
-  extension_exists BOOLEAN;
-BEGIN
-  SELECT EXISTS (
+CREATE FUNCTION pgmq._extension_exists(extension_name TEXT)
+    RETURNS BOOLEAN
+    LANGUAGE SQL
+AS $$
+SELECT EXISTS (
     SELECT 1
     FROM pg_extension
-    WHERE extname = 'pg_partman'
-  ) INTO extension_exists;
+    WHERE extname = extension_name
+)
+$$;
 
-  IF NOT extension_exists THEN
+CREATE FUNCTION pgmq._ensure_pg_partman_installed()
+RETURNS void AS $$
+BEGIN
+  IF NOT pgmq._extension_exists('pg_partman') THEN
     RAISE EXCEPTION 'pg_partman is required for partitioned queues';
   END IF;
 END;
@@ -910,9 +930,11 @@ BEGIN
     qtable, partition_col
   );
 
-  IF NOT pgmq._belongs_to_pgmq(qtable) THEN
-      EXECUTE FORMAT('ALTER EXTENSION pgmq ADD TABLE pgmq.%I', qtable);
-      EXECUTE FORMAT('ALTER EXTENSION pgmq ADD SEQUENCE pgmq.%I', qtable_seq);
+  IF pgmq._extension_exists('pgmq') THEN
+      IF NOT pgmq._belongs_to_pgmq(qtable) THEN
+          EXECUTE FORMAT('ALTER EXTENSION pgmq ADD TABLE pgmq.%I', qtable);
+          EXECUTE FORMAT('ALTER EXTENSION pgmq ADD SEQUENCE pgmq.%I', qtable_seq);
+      END IF;
   END IF;
 
   -- https://github.com/pgpartman/pg_partman/blob/master/doc/pg_partman.md
@@ -988,8 +1010,10 @@ BEGIN
     atable, a_partition_col
   );
 
-  IF NOT pgmq._belongs_to_pgmq(atable) THEN
-      EXECUTE FORMAT('ALTER EXTENSION pgmq ADD TABLE pgmq.%I', atable);
+  IF pgmq._extension_exists('pgmq') THEN
+      IF NOT pgmq._belongs_to_pgmq(atable) THEN
+          EXECUTE FORMAT('ALTER EXTENSION pgmq ADD TABLE pgmq.%I', atable);
+      END IF;
   END IF;
 
   -- https://github.com/pgpartman/pg_partman/blob/master/doc/pg_partman.md

diff --git a/pgmq-extension/test/expected/base.out b/pgmq-extension/test/expected/base.out
@@ -595,7 +595,7 @@ SELECT * FROM pgmq.create_partitioned(
     :'retention_interval'
 );
 ERROR:  pg_partman is required for partitioned queues
-CONTEXT:  PL/pgSQL function pgmq._ensure_pg_partman_installed() line 12 at RAISE
+CONTEXT:  PL/pgSQL function pgmq._ensure_pg_partman_installed() line 4 at RAISE
 SQL statement "SELECT pgmq._ensure_pg_partman_installed()"
 PL/pgSQL function pgmq.create_partitioned(text,text,text) line 12 at PERFORM
 -- With the extension existing, the queue is created successfully