Closes #289: same periodic tasks on different queues can coexist

docs/howto/cron.rst

@@ -78,6 +78,20 @@ plan to have the same value for every job::
     def run_healthchecks(timestamp: int):
         ...
 
+The value of those parameters is static, but you could put different values on different
+workers. If the same task is periodically deferred to different queues, each job will be
+independent::
+
+    @app.periodic(cron="*/5 * * * *")
+    @app.task(
+        queue=f"healthchecks_{my_worker_id}",
+    )
+    def run_healthchecks(timestamp: int):
+        ...
+
+In this setup, each worker (with differing values of ``my_worker_id``) would defer their
+own healthcheck jobs, independently from other workers.
+
 Using cron
 ----------
 

procrastinate/sql/migrations/delta_0.14.0_001_add_locks_to_periodic_defer.sql

@@ -1,3 +1,15 @@
+ALTER TABLE procrastinate_periodic_defers
+    ADD COLUMN queue_name character varying(128) NOT NULL DEFAULT 'undefined';
+
+ALTER TABLE procrastinate_periodic_defers
+    ALTER COLUMN queue_name DROP DEFAULT;
+
+ALTER TABLE procrastinate_periodic_defers
+    DROP CONSTRAINT procrastinate_periodic_defers_task_name_defer_timestamp_key;
+
+ALTER TABLE procrastinate_periodic_defers
+    ADD CONSTRAINT procrastinate_periodic_defers_unique UNIQUE (task_name, queue_name, defer_timestamp);
+
 DROP FUNCTION IF EXISTS procrastinate_defer_periodic_job;
 CREATE FUNCTION procrastinate_defer_periodic_job(
     _queue_name character varying,
@@ -14,8 +26,8 @@ DECLARE
 BEGIN
 
     INSERT
-        INTO procrastinate_periodic_defers (task_name, defer_timestamp)
-        VALUES (_task_name, _defer_timestamp)
+        INTO procrastinate_periodic_defers (task_name, queue_name, defer_timestamp)
+        VALUES (_task_name, _queue_name, _defer_timestamp)
         ON CONFLICT DO NOTHING
         RETURNING id into _defer_id;
 

procrastinate/sql/schema.sql

@@ -40,7 +40,8 @@ CREATE TABLE procrastinate_periodic_defers (
     task_name character varying(128) NOT NULL,
     defer_timestamp bigint,
     job_id bigint REFERENCES procrastinate_jobs(id) NULL,
-    UNIQUE (task_name, defer_timestamp)
+    queue_name character varying(128) NOT NULL,
+    CONSTRAINT procrastinate_periodic_defers_unique UNIQUE (task_name, queue_name, defer_timestamp)
 );
 
 CREATE TABLE procrastinate_events (
@@ -100,8 +101,8 @@ DECLARE
 BEGIN
 
     INSERT
-        INTO procrastinate_periodic_defers (task_name, defer_timestamp)
-        VALUES (_task_name, _defer_timestamp)
+        INTO procrastinate_periodic_defers (task_name, queue_name, defer_timestamp)
+        VALUES (_task_name, _queue_name, _defer_timestamp)
         ON CONFLICT DO NOTHING
         RETURNING id into _defer_id;