[*] make sample scripts idempotent

samples/Autonomous.sql

@@ -21,6 +21,8 @@ END;
 $$
 LANGUAGE PLPGSQL;
 
+DELETE FROM timetable.chain WHERE chain_name = 'call_proc_every_10s';
+
 WITH
     cte_chain (v_chain_id) AS (
         INSERT INTO timetable.chain (chain_name, run_at, max_instances, live, self_destruct) 

samples/Basic.sql

@@ -1,3 +1,5 @@
+DELETE FROM timetable.chain WHERE chain_name = 'notify_every_minute';
+
 SELECT timetable.add_job(
     job_name            => 'notify_every_minute',
     job_schedule        => '* * * * *',

samples/Chain.sql

@@ -10,6 +10,9 @@ DECLARE
     v_task_id          bigint;
     v_chain_id   bigint;
 BEGIN
+    -- Remove existing chain to make this script idempotent
+    DELETE FROM timetable.chain WHERE chain_name = 'chain_operation';
+
     -- In order to implement chain pperation, we will create a table
     CREATE TABLE IF NOT EXISTS timetable.chain_log (
         chain_log BIGSERIAL,

samples/ClientMessages.sql

@@ -9,6 +9,8 @@ BEGIN
 END; 
 $BODY$;
 
+DELETE FROM timetable.chain WHERE chain_name = 'raise_client_message_every_minute';
+
 SELECT timetable.add_job(
     job_name            => 'raise_client_message_every_minute',
     job_schedule        => '* * * * *',

samples/CronStyle.sql

@@ -17,6 +17,8 @@ CREATE TABLE IF NOT EXISTS timetable.dummy_log (
 -- │ └────────── hour (0 - 23)
 -- └──────────── minute (0 - 59)
 
+DELETE FROM timetable.chain WHERE chain_name = 'cron_insert_every_2h_on_27th';
+
 SELECT timetable.add_job (
     job_name     => 'cron_insert_every_2h_on_27th',
     job_schedule => '40 */2 27 * *',

samples/DelayedRetry.sql

@@ -31,6 +31,8 @@ BEGIN
 END
 $$;
 
+DELETE FROM timetable.chain WHERE chain_name = 'retry_on_fail_delayed';
+
 SELECT timetable.add_job(
         job_name            => 'retry_on_fail_delayed',
         job_schedule        => '@every 10 minutes',
@@ -39,8 +41,8 @@ SELECT timetable.add_job(
         job_live            => TRUE,
         job_ignore_errors   => FALSE,
         job_on_error        => $$SELECT retry_chain_on_error(
-            worker_name => 'worker001', 
+            worker_name => 'demo_worker', 
             maximum_retry_count => 3, 
             minimum_retry_timeout => interval '10 seconds', 
             maximum_retry_duration => interval '5 minutes')$$
-    )
+    );

samples/ErrorHandling.sql

@@ -1,3 +1,5 @@
+DELETE FROM timetable.chain WHERE chain_name = 'fail_with_on_error_notify';
+
 SELECT timetable.add_job(
         job_name            => 'fail_with_on_error_notify',
         job_schedule        => '* * * * *',
@@ -8,4 +10,4 @@ SELECT timetable.add_job(
         job_on_error        => $$SELECT pg_notify('monitoring', 
             format('{"ConfigID": %s, "Message": "Something bad happened"}', 
                 current_setting('pg_timetable.current_chain_id')::bigint))$$
-    )
+    );

samples/Exclusive.sql

@@ -8,6 +8,8 @@ BEGIN
 END; 
 $BODY$;
 
+DELETE FROM timetable.chain WHERE chain_name IN ('exclusive_sleep_every_10s', 'exclusive_sleep_after_10s');
+
 SELECT timetable.add_job(
     job_name            => 'exclusive_sleep_every_10s',
     job_schedule        => '@every 10 seconds',

samples/Log.sql

@@ -1,3 +1,5 @@
+DELETE FROM timetable.chain WHERE chain_name = 'builtin_log_every_minute';
+
 SELECT timetable.add_job(
     job_name            => 'builtin_log_every_minute',
     job_schedule        => NULL, -- same as '* * * * *'

samples/NoOp.sql

@@ -1,3 +1,5 @@
+DELETE FROM timetable.chain WHERE chain_name = 'noop_every_minute';
+
 SELECT timetable.add_job(
     job_name            => 'noop_every_minute',
     job_schedule        => '* * * * *',

samples/SelfDestruct.sql

@@ -1,15 +1,17 @@
-CREATE OR REPLACE FUNCTION raise_func(text)
+CREATE OR REPLACE FUNCTION raise_notice_func(text)
   RETURNS void LANGUAGE plpgsql AS
 $BODY$ 
 BEGIN 
    RAISE NOTICE '%', $1; 
 END; 
 $BODY$;
 
+DELETE FROM timetable.chain WHERE chain_name = 'notify_then_destruct';
+
 SELECT timetable.add_job(
     job_name            => 'notify_then_destruct',
     job_schedule        => '* * * * *',
-    job_command         => 'SELECT raise_func($1)',
+    job_command         => 'SELECT raise_notice_func($1)',
     job_parameters      => '[ "Ahoj from self destruct task" ]' :: jsonb,
     job_kind            => 'SQL'::timetable.command_kind,
     job_live            => TRUE,

samples/Sleep.sql

@@ -1,3 +1,5 @@
+DELETE FROM timetable.chain WHERE chain_name = 'sleep_every_10s';
+
 SELECT timetable.add_job(
     job_name            => 'sleep_every_10s',
     job_schedule        => '@every 10 seconds',