Show IDLE backends in citus_dist_stat_activity (#5700)

* Break the dependency to CitusInitiatedBackend infrastructure

With this change, we start to show non-distributed backends as well
in citus_dist_stat_activity. I think that
  (a) it is essential for making citus_lock_waits to work for blocked
      on DDL commands.
  (b) it is more expected from the user's perspective. The name of
      the view is a little inconsistent now (e.g., citus_dist_stat_activity)
      but we are already planning to improve the names with followup
      PRs.

Also, we have global pids assigned, the CitusInitiatedBackend
becomes obsolete.

src/backend/distributed/transaction/citus_dist_stat_activity.c

@@ -155,7 +155,12 @@ FROM \
 	get_all_active_transactions() AS dist_txs(database_id, process_id, initiator_node_identifier, worker_query, transaction_number, transaction_stamp, global_pid) \
 	ON pg_stat_activity.pid = dist_txs.process_id \
 WHERE \
-	dist_txs.worker_query = false;"
+	backend_type = 'client backend' \
+	AND \
+	pg_stat_activity.query NOT ILIKE '%stat_activity%' \
+	AND \
+	pg_stat_activity.application_name NOT SIMILAR TO 'citus_internal gpid=\\d+'; \
+"
 
 #define CITUS_WORKER_STAT_ACTIVITY_QUERY \
 	"\
@@ -186,7 +191,7 @@ SELECT \
 	dist_txs.global_id \
 FROM \
 	pg_stat_activity \
-	LEFT JOIN \
+	JOIN \
 	get_all_active_transactions() AS dist_txs(database_id, process_id, initiator_node_identifier, worker_query, transaction_number, transaction_stamp, global_id) \
 	ON pg_stat_activity.pid = dist_txs.process_id \
 WHERE \

src/test/regress/expected/isolation_citus_dist_activity.out

@@ -32,7 +32,7 @@ pg_sleep
 (1 row)
 
 step s2-view-dist:
- SELECT query, query_hostname, query_hostport, distributed_query_host_name, distributed_query_host_port, state, wait_event_type, wait_event, usename, datname FROM citus_dist_stat_activity WHERE query NOT ILIKE '%pg_prepared_xacts%' AND query NOT ILIKE '%COMMIT%' ORDER BY query DESC;
+	SELECT query, query_hostname, query_hostport, distributed_query_host_name, distributed_query_host_port, state, wait_event_type, wait_event, usename, datname FROM citus_dist_stat_activity WHERE query NOT ILIKE '%pg_prepared_xacts%' AND query NOT ILIKE '%COMMIT%' and query not ILIKE '%BEGIN%' and query NOT ILIKE '%pg_catalog.pg_isolation_test_session_is_blocked%' ORDER BY query DESC;
 
 query                                         |query_hostname  |query_hostport|distributed_query_host_name|distributed_query_host_port|state              |wait_event_type|wait_event|usename |datname
 ---------------------------------------------------------------------
@@ -102,7 +102,7 @@ pg_sleep
 (1 row)
 
 step s2-view-dist:
- SELECT query, query_hostname, query_hostport, distributed_query_host_name, distributed_query_host_port, state, wait_event_type, wait_event, usename, datname FROM citus_dist_stat_activity WHERE query NOT ILIKE '%pg_prepared_xacts%' AND query NOT ILIKE '%COMMIT%' ORDER BY query DESC;
+	SELECT query, query_hostname, query_hostport, distributed_query_host_name, distributed_query_host_port, state, wait_event_type, wait_event, usename, datname FROM citus_dist_stat_activity WHERE query NOT ILIKE '%pg_prepared_xacts%' AND query NOT ILIKE '%COMMIT%' and query not ILIKE '%BEGIN%' and query NOT ILIKE '%pg_catalog.pg_isolation_test_session_is_blocked%' ORDER BY query DESC;
 
 query                                        |query_hostname  |query_hostport|distributed_query_host_name|distributed_query_host_port|state              |wait_event_type|wait_event|usename |datname
 ---------------------------------------------------------------------
@@ -166,7 +166,7 @@ pg_sleep
 (1 row)
 
 step s2-view-dist:
- SELECT query, query_hostname, query_hostport, distributed_query_host_name, distributed_query_host_port, state, wait_event_type, wait_event, usename, datname FROM citus_dist_stat_activity WHERE query NOT ILIKE '%pg_prepared_xacts%' AND query NOT ILIKE '%COMMIT%' ORDER BY query DESC;
+	SELECT query, query_hostname, query_hostport, distributed_query_host_name, distributed_query_host_port, state, wait_event_type, wait_event, usename, datname FROM citus_dist_stat_activity WHERE query NOT ILIKE '%pg_prepared_xacts%' AND query NOT ILIKE '%COMMIT%' and query not ILIKE '%BEGIN%' and query NOT ILIKE '%pg_catalog.pg_isolation_test_session_is_blocked%' ORDER BY query DESC;
 
 query                                |query_hostname  |query_hostport|distributed_query_host_name|distributed_query_host_port|state              |wait_event_type|wait_event|usename |datname
 ---------------------------------------------------------------------
@@ -233,7 +233,7 @@ pg_sleep
 (1 row)
 
 step s2-view-dist:
- SELECT query, query_hostname, query_hostport, distributed_query_host_name, distributed_query_host_port, state, wait_event_type, wait_event, usename, datname FROM citus_dist_stat_activity WHERE query NOT ILIKE '%pg_prepared_xacts%' AND query NOT ILIKE '%COMMIT%' ORDER BY query DESC;
+	SELECT query, query_hostname, query_hostport, distributed_query_host_name, distributed_query_host_port, state, wait_event_type, wait_event, usename, datname FROM citus_dist_stat_activity WHERE query NOT ILIKE '%pg_prepared_xacts%' AND query NOT ILIKE '%COMMIT%' and query not ILIKE '%BEGIN%' and query NOT ILIKE '%pg_catalog.pg_isolation_test_session_is_blocked%' ORDER BY query DESC;
 
 query                                                   |query_hostname  |query_hostport|distributed_query_host_name|distributed_query_host_port|state              |wait_event_type|wait_event|usename |datname
 ---------------------------------------------------------------------

src/test/regress/expected/isolation_global_pid.out

@@ -31,7 +31,7 @@ run_commands_on_session_level_connection_to_node
 (1 row)
 
 step s2-coordinator-citus_dist_stat_activity:
-    SELECT global_pid != 0 FROM citus_dist_stat_activity() WHERE query LIKE '%SELECT * FROM dist\_table%';
+    SELECT global_pid != 0 FROM citus_dist_stat_activity() WHERE query LIKE '%SELECT * FROM dist\_table%' and query NOT ILIKE '%run_commands_on_session_level_connection_to_node%';
 
 ?column?
 ---------------------------------------------------------------------
@@ -93,7 +93,7 @@ a|b
 (0 rows)
 
 step s2-coordinator-citus_dist_stat_activity:
-    SELECT global_pid != 0 FROM citus_dist_stat_activity() WHERE query LIKE '%SELECT * FROM dist\_table%';
+    SELECT global_pid != 0 FROM citus_dist_stat_activity() WHERE query LIKE '%SELECT * FROM dist\_table%' and query NOT ILIKE '%run_commands_on_session_level_connection_to_node%';
 
 ?column?
 ---------------------------------------------------------------------

src/test/regress/expected/isolation_replicate_reference_tables_to_coordinator.out

@@ -83,14 +83,17 @@ pg_sleep
 (1 row)
 
 step s2-view-dist:
-	SELECT query, query_hostname, query_hostport, distributed_query_host_name, distributed_query_host_port, state, wait_event_type, wait_event, usename, datname FROM citus_dist_stat_activity WHERE query NOT ILIKE '%pg_prepared_xacts%' AND query NOT ILIKE '%COMMIT%' ORDER BY query DESC;
+        SELECT query, query_hostname, query_hostport, distributed_query_host_name, distributed_query_host_port, state, wait_event_type, wait_event, usename, datname FROM citus_dist_stat_activity WHERE query NOT ILIKE '%pg_prepared_xacts%' AND query NOT ILIKE '%COMMIT%' AND query NOT ILIKE '%pg_isolation_test_session_is_blocked%' AND query NOT ILIKE '%BEGIN%' ORDER BY query DESC;
 
 query                                    |query_hostname  |query_hostport|distributed_query_host_name|distributed_query_host_port|state              |wait_event_type|wait_event|usename |datname
 ---------------------------------------------------------------------
 
+  SELECT check_distributed_deadlocks();
+|coordinator_host|         57636|                           |                          0|idle               |Client         |ClientRead|postgres|regression
+
     update ref_table set a = a + 1;
     |coordinator_host|         57636|coordinator_host           |                      57636|idle in transaction|Client         |ClientRead|postgres|regression
-(1 row)
+(2 rows)
 
 step s2-view-worker:
 	SELECT query, query_hostname, query_hostport, distributed_query_host_name,

src/test/regress/spec/isolation_citus_dist_activity.spec

@@ -71,7 +71,7 @@ step "s2-sleep"
 
 step "s2-view-dist"
 {
-	SELECT query, query_hostname, query_hostport, distributed_query_host_name, distributed_query_host_port, state, wait_event_type, wait_event, usename, datname FROM citus_dist_stat_activity WHERE query NOT ILIKE '%pg_prepared_xacts%' AND query NOT ILIKE '%COMMIT%' ORDER BY query DESC;
+	SELECT query, query_hostname, query_hostport, distributed_query_host_name, distributed_query_host_port, state, wait_event_type, wait_event, usename, datname FROM citus_dist_stat_activity WHERE query NOT ILIKE '%pg_prepared_xacts%' AND query NOT ILIKE '%COMMIT%' and query not ILIKE '%BEGIN%' and query NOT ILIKE '%pg_catalog.pg_isolation_test_session_is_blocked%' ORDER BY query DESC;
 
 }
 

src/test/regress/spec/isolation_global_pid.spec

@@ -62,7 +62,7 @@ session "s2"
 
 step "s2-coordinator-citus_dist_stat_activity"
 {
-    SELECT global_pid != 0 FROM citus_dist_stat_activity() WHERE query LIKE '%SELECT * FROM dist\_table%';
+    SELECT global_pid != 0 FROM citus_dist_stat_activity() WHERE query LIKE '%SELECT * FROM dist\_table%' and query NOT ILIKE '%run_commands_on_session_level_connection_to_node%';
 }
 
 step "s2-coordinator-citus_worker_stat_activity"

src/test/regress/spec/isolation_replicate_reference_tables_to_coordinator.spec

@@ -83,7 +83,7 @@ step "s2-lock-ref-table-placement-on-coordinator"
 
 step "s2-view-dist"
 {
-	SELECT query, query_hostname, query_hostport, distributed_query_host_name, distributed_query_host_port, state, wait_event_type, wait_event, usename, datname FROM citus_dist_stat_activity WHERE query NOT ILIKE '%pg_prepared_xacts%' AND query NOT ILIKE '%COMMIT%' ORDER BY query DESC;
+        SELECT query, query_hostname, query_hostport, distributed_query_host_name, distributed_query_host_port, state, wait_event_type, wait_event, usename, datname FROM citus_dist_stat_activity WHERE query NOT ILIKE '%pg_prepared_xacts%' AND query NOT ILIKE '%COMMIT%' AND query NOT ILIKE '%pg_isolation_test_session_is_blocked%' AND query NOT ILIKE '%BEGIN%' ORDER BY query DESC;
 }
 
 step "s2-view-worker"
@@ -114,6 +114,7 @@ step "s2-active-transactions"
 // thus we manually issue the deadlock detection
 session "deadlock-checker"
 
+
 // we issue the checker not only when there are deadlocks to ensure that we never cancel
 // backend inappropriately
 step "deadlock-checker-call"