Re: exposing wait events for non-backends (was: Tracking wait event for latches)

From 1e47895422410a9de9200c7dc17f767d85c29752 Mon Sep 17 00:00:00 2001
From: Kuntal Ghosh <kuntal.ghosh@enterprisedb.com>
Date: Wed, 15 Feb 2017 15:34:18 +0530
Subject: [PATCH] Infra to expose non-backend processes in pg_stat_get_activity

This patch implements the infrastructure required to expose
non-backend processes in pg_stat_activity. BackendStatusArray
is extended to store auxiliary processes as well. Backends use slots
indexed in the range from 1 to MaxBackends (inclusive), so we use
MaxBackends + AuxProcType + 1 as the index of the slot for an
auxiliary process.
---
 src/backend/postmaster/pgstat.c     | 304 ++++++++++++++++++++++++++++++------
 src/backend/storage/lmgr/proc.c     |  27 ++++
 src/backend/utils/adt/pgstatfuncs.c | 120 ++++++++------
 src/backend/utils/init/postinit.c   |   4 +-
 src/include/pgstat.h                |  35 ++++-
 src/include/storage/proc.h          |   1 +
 6 files changed, 392 insertions(+), 99 deletions(-)

diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 7176cf1..069e390 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -50,6 +50,7 @@
 #include "postmaster/autovacuum.h"
 #include "postmaster/fork_process.h"
 #include "postmaster/postmaster.h"
+#include "replication/walsender.h"
 #include "storage/backendid.h"
 #include "storage/dsm.h"
 #include "storage/fd.h"
@@ -212,7 +213,17 @@ typedef struct TwoPhasePgStatRecord
  */
 static MemoryContext pgStatLocalContext = NULL;
 static HTAB *pgStatDBHash = NULL;
-static LocalPgBackendStatus *localBackendStatusTable = NULL;
+
+/* Status for backends and auxiliary processes */
+static LocalPgBackendStatus *localProcStatusTable = NULL;
+
+/* Total number of processes including backends and auxiliary */
+static int	localNumProcs = 0;
+
+/* Index to backends in localProcStatusTable */
+static int *localBackendStatusIndex = NULL;
+
+/* Total number of backend processes */
 static int	localNumBackends = 0;
 
 /*
@@ -2404,7 +2415,29 @@ pgstat_fetch_stat_beentry(int beid)
 	if (beid < 1 || beid > localNumBackends)
 		return NULL;
 
-	return &localBackendStatusTable[beid - 1].backendStatus;
+	return &localProcStatusTable[localBackendStatusIndex[beid - 1]].backendStatus;
+}
+
+
+/* ----------
+ * pgstat_fetch_stat_procentry() -
+ *
+ *	Support function for the SQL-callable pgstat* functions. Returns
+ *	our local copy of the current-activity entry for one process.
+ *
+ *	NB: caller is responsible for a check if the user is permitted to see
+ *	this info (especially the querystring).
+ * ----------
+ */
+PgBackendStatus *
+pgstat_fetch_stat_procentry(int procid)
+{
+	pgstat_read_current_status();
+
+	if (procid < 1 || procid > localNumProcs)
+		return NULL;
+
+	return &localProcStatusTable[procid - 1].backendStatus;
 }
 
 
@@ -2426,7 +2459,29 @@ pgstat_fetch_stat_local_beentry(int beid)
 	if (beid < 1 || beid > localNumBackends)
 		return NULL;
 
-	return &localBackendStatusTable[beid - 1];
+	return &localProcStatusTable[localBackendStatusIndex[beid - 1]];
+}
+
+
+/* ----------
+ * pgstat_fetch_stat_local_procentry() -
+ *
+ *	Like pgstat_fetch_stat_procentry() but with locally computed additions (like
+ *	xid and xmin values of the backend)
+ *
+ *	NB: caller is responsible for a check if the user is permitted to see
+ *	this info (especially the querystring).
+ * ----------
+ */
+LocalPgBackendStatus *
+pgstat_fetch_stat_local_procentry(int procid)
+{
+	pgstat_read_current_status();
+
+	if (procid < 1 || procid > localNumProcs)
+		return NULL;
+
+	return &localProcStatusTable[procid - 1];
 }
 
 
@@ -2445,6 +2500,22 @@ pgstat_fetch_stat_numbackends(void)
 	return localNumBackends;
 }
 
+
+/* ----------
+ * pgstat_fetch_stat_numprocs() -
+ *
+ *	Support function for the SQL-callable pgstat* functions. Returns
+ *	the maximum current process id.
+ * ----------
+ */
+int
+pgstat_fetch_stat_numprocs(void)
+{
+	pgstat_read_current_status();
+
+	return localNumProcs;
+}
+
 /*
  * ---------
  * pgstat_fetch_stat_archiver() -
@@ -2504,20 +2575,20 @@ BackendStatusShmemSize(void)
 	Size		size;
 
 	/* BackendStatusArray: */
-	size = mul_size(sizeof(PgBackendStatus), MaxBackends);
+	size = mul_size(sizeof(PgBackendStatus), NumProcStatSlots);
 	/* BackendAppnameBuffer: */
 	size = add_size(size,
-					mul_size(NAMEDATALEN, MaxBackends));
+					mul_size(NAMEDATALEN, NumProcStatSlots));
 	/* BackendClientHostnameBuffer: */
 	size = add_size(size,
-					mul_size(NAMEDATALEN, MaxBackends));
+					mul_size(NAMEDATALEN, NumProcStatSlots));
 	/* BackendActivityBuffer: */
 	size = add_size(size,
-					mul_size(pgstat_track_activity_query_size, MaxBackends));
+				mul_size(pgstat_track_activity_query_size, NumProcStatSlots));
 #ifdef USE_SSL
 	/* BackendSslStatusBuffer: */
 	size = add_size(size,
-					mul_size(sizeof(PgBackendSSLStatus), MaxBackends));
+					mul_size(sizeof(PgBackendSSLStatus), NumProcStatSlots));
 #endif
 	return size;
 }
@@ -2535,7 +2606,7 @@ CreateSharedBackendStatus(void)
 	char	   *buffer;
 
 	/* Create or attach to the shared array */
-	size = mul_size(sizeof(PgBackendStatus), MaxBackends);
+	size = mul_size(sizeof(PgBackendStatus), NumProcStatSlots);
 	BackendStatusArray = (PgBackendStatus *)
 		ShmemInitStruct("Backend Status Array", size, &found);
 
@@ -2558,7 +2629,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_appname pointers. */
 		buffer = BackendAppnameBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumProcStatSlots; i++)
 		{
 			BackendStatusArray[i].st_appname = buffer;
 			buffer += NAMEDATALEN;
@@ -2576,7 +2647,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_clienthostname pointers. */
 		buffer = BackendClientHostnameBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumProcStatSlots; i++)
 		{
 			BackendStatusArray[i].st_clienthostname = buffer;
 			buffer += NAMEDATALEN;
@@ -2585,7 +2656,7 @@ CreateSharedBackendStatus(void)
 
 	/* Create or attach to the shared activity buffer */
 	BackendActivityBufferSize = mul_size(pgstat_track_activity_query_size,
-										 MaxBackends);
+										 NumProcStatSlots);
 	BackendActivityBuffer = (char *)
 		ShmemInitStruct("Backend Activity Buffer",
 						BackendActivityBufferSize,
@@ -2597,7 +2668,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_activity pointers. */
 		buffer = BackendActivityBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumProcStatSlots; i++)
 		{
 			BackendStatusArray[i].st_activity = buffer;
 			buffer += pgstat_track_activity_query_size;
@@ -2606,7 +2677,7 @@ CreateSharedBackendStatus(void)
 
 #ifdef USE_SSL
 	/* Create or attach to the shared SSL status buffer */
-	size = mul_size(sizeof(PgBackendSSLStatus), MaxBackends);
+	size = mul_size(sizeof(PgBackendSSLStatus), NumProcStatSlots);
 	BackendSslStatusBuffer = (PgBackendSSLStatus *)
 		ShmemInitStruct("Backend SSL Status Buffer", size, &found);
 
@@ -2618,7 +2689,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_sslstatus pointers. */
 		ptr = BackendSslStatusBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumProcStatSlots; i++)
 		{
 			BackendStatusArray[i].st_sslstatus = ptr;
 			ptr++;
@@ -2632,7 +2703,8 @@ CreateSharedBackendStatus(void)
  * pgstat_initialize() -
  *
  *	Initialize pgstats state, and set up our on-proc-exit hook.
- *	Called from InitPostgres.  MyBackendId must be set,
+ *	Called from InitPostgres and AuxiliaryProcessMain. For auxiliary process,
+ *	MyBackendId is invalid. Otherwise, MyBackendId must be set,
  *	but we must not have started any transaction yet (since the
  *	exit hook must run after the last transaction exit).
  *	NOTE: MyDatabaseId isn't set yet; so the shutdown hook has to be careful.
@@ -2642,27 +2714,47 @@ void
 pgstat_initialize(void)
 {
 	/* Initialize MyBEEntry */
-	Assert(MyBackendId >= 1 && MyBackendId <= MaxBackends);
-	MyBEEntry = &BackendStatusArray[MyBackendId - 1];
+	if (MyBackendId != InvalidBackendId)
+	{
+		/* Just a backend process */
+		Assert(MyBackendId >= 1 && MyBackendId <= MaxBackends);
+		MyBEEntry = &BackendStatusArray[MyBackendId - 1];
+	}
+	else
+	{
+		/* Must be an auxiliary process */
+		Assert(MyAuxProcType != NotAnAuxProcess);
+
+		/*
+		 * Assign the MyBEEntry for an auxiliary process.  Since it doesn't
+		 * have a BackendId, the slot is statically allocated based on the
+		 * auxiliary process type (MyAuxProcType).  Backends use slots indexed
+		 * in the range from 1 to MaxBackends (inclusive), so we use
+		 * MaxBackends + AuxProcType + 1 as the index of the slot for an
+		 * auxiliary process.
+		 */
+		MyBEEntry = &BackendStatusArray[MaxBackends + MyAuxProcType];
+	}
 
 	/* Set up a process-exit hook to clean up */
 	on_shmem_exit(pgstat_beshutdown_hook, 0);
 }
 
 /* ----------
- * pgstat_bestart() -
+ * pgstat_procstart() -
+ *
+ *	Initialize this process's entry in the PgBackendStatus array.
+ *	Called from InitPostgres and AuxiliaryProcessMain.
  *
- *	Initialize this backend's entry in the PgBackendStatus array.
- *	Called from InitPostgres.
- *	MyDatabaseId, session userid, and application_name must be set
- *	(hence, this cannot be combined with pgstat_initialize).
+ *	For a backend process, MyDatabaseId, session userid,
+ *	and application_name must be set (hence, this cannot be combined
+ *	with pgstat_initialize).
  * ----------
  */
 void
-pgstat_bestart(void)
+pgstat_procstart(void)
 {
 	TimestampTz proc_start_timestamp;
-	Oid			userid;
 	SockAddr	clientaddr;
 	volatile PgBackendStatus *beentry;
 
@@ -2677,7 +2769,6 @@ pgstat_bestart(void)
 		proc_start_timestamp = MyProcPort->SessionStartTime;
 	else
 		proc_start_timestamp = GetCurrentTimestamp();
-	userid = GetSessionUserId();
 
 	/*
 	 * We may not have a MyProcPort (eg, if this is the autovacuum process).
@@ -2696,6 +2787,55 @@ pgstat_bestart(void)
 	 * cute.
 	 */
 	beentry = MyBEEntry;
+
+	if (MyBackendId != InvalidBackendId)
+	{
+		/* Must be a backend process */
+		if (IsAutoVacuumLauncherProcess())
+		{
+			/* Autovacuum Launcher */
+			beentry->st_procType = PROC_AUTOVAC_LAUNCHER;
+		}
+		else if (am_walsender)
+		{
+			/* Wal sender */
+			beentry->st_procType = PROC_WAL_SENDER;
+		}
+		else if (IsBackgroundWorker)
+		{
+			/* bgworker */
+			beentry->st_procType = PROC_BG_WORKER;
+		}
+		else
+		{
+			/* client-backend */
+			beentry->st_procType = PROC_BACKEND;
+		}
+	}
+	else
+	{
+		/* Must be an auxiliary process */
+		Assert(MyAuxProcType != NotAnAuxProcess);
+		switch (MyAuxProcType)
+		{
+			case BgWriterProcess:
+				beentry->st_procType = PROC_BG_WRITER;
+				break;
+			case CheckpointerProcess:
+				beentry->st_procType = PROC_CHECKPOINTER;
+				break;
+			case WalWriterProcess:
+				beentry->st_procType = PROC_WAL_WRITER;
+				break;
+			case WalReceiverProcess:
+				beentry->st_procType = PROC_WAL_RECEIVER;
+				break;
+			default:
+				elog(PANIC, "unrecognized process type: %d", (int) MyAuxProcType);
+				proc_exit(1);
+		}
+	}
+
 	do
 	{
 		pgstat_increment_changecount_before(beentry);
@@ -2707,8 +2847,15 @@ pgstat_bestart(void)
 	beentry->st_state_start_timestamp = 0;
 	beentry->st_xact_start_timestamp = 0;
 	beentry->st_databaseid = MyDatabaseId;
-	beentry->st_userid = userid;
+
+	/* We have userid for client-backends and wal-sender processes */
+	if (beentry->st_procType == PROC_BACKEND || beentry->st_procType == PROC_WAL_SENDER)
+		beentry->st_userid = GetSessionUserId();
+	else
+		beentry->st_userid = InvalidOid;
+
 	beentry->st_clientaddr = clientaddr;
+
 	if (MyProcPort && MyProcPort->remote_hostname)
 		strlcpy(beentry->st_clienthostname, MyProcPort->remote_hostname,
 				NAMEDATALEN);
@@ -3027,7 +3174,7 @@ pgstat_report_xact_timestamp(TimestampTz tstamp)
 static void
 pgstat_read_current_status(void)
 {
-	volatile PgBackendStatus *beentry;
+	volatile PgBackendStatus *procentry;
 	LocalPgBackendStatus *localtable;
 	LocalPgBackendStatus *localentry;
 	char	   *localappname,
@@ -3038,31 +3185,31 @@ pgstat_read_current_status(void)
 	int			i;
 
 	Assert(!pgStatRunningInCollector);
-	if (localBackendStatusTable)
+	if (localProcStatusTable && localBackendStatusIndex)
 		return;					/* already done */
 
 	pgstat_setup_memcxt();
 
 	localtable = (LocalPgBackendStatus *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   sizeof(LocalPgBackendStatus) * MaxBackends);
+						   sizeof(LocalPgBackendStatus) * NumProcStatSlots);
 	localappname = (char *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   NAMEDATALEN * MaxBackends);
+						   NAMEDATALEN * NumProcStatSlots);
 	localactivity = (char *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   pgstat_track_activity_query_size * MaxBackends);
+					   pgstat_track_activity_query_size * NumProcStatSlots);
 #ifdef USE_SSL
 	localsslstatus = (PgBackendSSLStatus *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   sizeof(PgBackendSSLStatus) * MaxBackends);
+						   sizeof(PgBackendSSLStatus) * NumProcStatSlots);
 #endif
 
-	localNumBackends = 0;
+	localNumProcs = 0;
 
-	beentry = BackendStatusArray;
+	procentry = BackendStatusArray;
 	localentry = localtable;
-	for (i = 1; i <= MaxBackends; i++)
+	for (i = 1; i <= NumProcStatSlots; i++)
 	{
 		/*
 		 * Follow the protocol of retrying if st_changecount changes while we
@@ -3076,32 +3223,32 @@ pgstat_read_current_status(void)
 			int			before_changecount;
 			int			after_changecount;
 
-			pgstat_save_changecount_before(beentry, before_changecount);
+			pgstat_save_changecount_before(procentry, before_changecount);
 
-			localentry->backendStatus.st_procpid = beentry->st_procpid;
+			localentry->backendStatus.st_procpid = procentry->st_procpid;
 			if (localentry->backendStatus.st_procpid > 0)
 			{
-				memcpy(&localentry->backendStatus, (char *) beentry, sizeof(PgBackendStatus));
+				memcpy(&localentry->backendStatus, (char *) procentry, sizeof(PgBackendStatus));
 
 				/*
 				 * strcpy is safe even if the string is modified concurrently,
 				 * because there's always a \0 at the end of the buffer.
 				 */
-				strcpy(localappname, (char *) beentry->st_appname);
+				strcpy(localappname, (char *) procentry->st_appname);
 				localentry->backendStatus.st_appname = localappname;
-				strcpy(localactivity, (char *) beentry->st_activity);
+				strcpy(localactivity, (char *) procentry->st_activity);
 				localentry->backendStatus.st_activity = localactivity;
-				localentry->backendStatus.st_ssl = beentry->st_ssl;
+				localentry->backendStatus.st_ssl = procentry->st_ssl;
 #ifdef USE_SSL
-				if (beentry->st_ssl)
+				if (procentry->st_ssl)
 				{
-					memcpy(localsslstatus, beentry->st_sslstatus, sizeof(PgBackendSSLStatus));
+					memcpy(localsslstatus, procentry->st_sslstatus, sizeof(PgBackendSSLStatus));
 					localentry->backendStatus.st_sslstatus = localsslstatus;
 				}
 #endif
 			}
 
-			pgstat_save_changecount_after(beentry, after_changecount);
+			pgstat_save_changecount_after(procentry, after_changecount);
 			if (before_changecount == after_changecount &&
 				(before_changecount & 1) == 0)
 				break;
@@ -3110,7 +3257,7 @@ pgstat_read_current_status(void)
 			CHECK_FOR_INTERRUPTS();
 		}
 
-		beentry++;
+		procentry++;
 		/* Only valid entries get included into the local array */
 		if (localentry->backendStatus.st_procpid > 0)
 		{
@@ -3124,12 +3271,35 @@ pgstat_read_current_status(void)
 #ifdef USE_SSL
 			localsslstatus++;
 #endif
-			localNumBackends++;
+			localNumProcs++;
 		}
 	}
 
 	/* Set the pointer only after completion of a valid table */
-	localBackendStatusTable = localtable;
+	localProcStatusTable = localtable;
+
+	/*
+	 * In localBackendStatusIndex, we store the backend indices from
+	 * localProcStatusTable. We need this information since there are
+	 * user-defined functions which expects ids of backends starting from 1 to
+	 * the number of active backends. Hence, we don't want to surprise the
+	 * end-user by including auxiliary processes in the result.
+	 *
+	 * See pg_stat_get_backend_idset for further info.
+	 */
+	localBackendStatusIndex = (int *)
+		MemoryContextAlloc(pgStatLocalContext,
+						   sizeof(int) * NumProcStatSlots);
+
+	localNumBackends = 0;
+	for (i = 0; i < localNumProcs; i++)
+	{
+		if (localProcStatusTable[i].backendStatus.st_procType == PROC_BACKEND)
+		{
+			localBackendStatusIndex[localNumBackends] = i;
+			localNumBackends++;
+		}
+	}
 }
 
 /* ----------
@@ -3584,7 +3754,41 @@ pgstat_get_crashed_backend_activity(int pid, char *buffer, int buflen)
 	return NULL;
 }
 
+const char *
+pgstat_get_proctype_desc(ProcType procType)
+{
+	const char *procDesc = "unknown process type";
+
+	switch (procType)
+	{
+		case PROC_BACKEND:
+			procDesc = "client backend";
+			break;
+		case PROC_AUTOVAC_LAUNCHER:
+			procDesc = "autovacuum launcher";
+			break;
+		case PROC_WAL_SENDER:
+			procDesc = "wal sender";
+			break;
+		case PROC_BG_WORKER:
+			procDesc = "bgworker";
+			break;
+		case PROC_BG_WRITER:
+			procDesc = "writer";
+			break;
+		case PROC_CHECKPOINTER:
+			procDesc = "checkpointer";
+			break;
+		case PROC_WAL_WRITER:
+			procDesc = "wal writer";
+			break;
+		case PROC_WAL_RECEIVER:
+			procDesc = "wal receiver";
+			break;
+	}
 
+	return procDesc;
+}
 /* ------------------------------------------------------------
  * Local support functions follow
  * ------------------------------------------------------------
@@ -5048,7 +5252,9 @@ pgstat_clear_snapshot(void)
 	/* Reset variables */
 	pgStatLocalContext = NULL;
 	pgStatDBHash = NULL;
-	localBackendStatusTable = NULL;
+	localProcStatusTable = NULL;
+	localNumProcs = 0;
+	localBackendStatusIndex = NULL;
 	localNumBackends = 0;
 }
 
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 8f467be..021c9b0 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -941,6 +941,33 @@ AuxiliaryProcKill(int code, Datum arg)
 	SpinLockRelease(ProcStructLock);
 }
 
+/*
+ * AuxiliaryPidGetProc -- get PGPROC for an auxiliary process
+ * given its PID
+ *
+ * Returns NULL if not found.
+ */
+PGPROC *
+AuxiliaryPidGetProc(int pid)
+{
+	PGPROC	   *result;
+	int			index;
+
+	if (pid == 0)				/* never match dummy PGPROCs */
+		return NULL;
+
+	for (index = 0; index < NUM_AUXILIARY_PROCS; index++)
+	{
+		PGPROC	   *proc = &AuxiliaryProcs[index];
+
+		if (proc->pid == pid)
+		{
+			result = proc;
+			break;
+		}
+	}
+	return result;
+}
 
 /*
  * ProcQueue package: routines for putting processes to sleep
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index a987d0d..e858e4d 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -20,6 +20,7 @@
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "pgstat.h"
+#include "postmaster/postmaster.h"
 #include "storage/proc.h"
 #include "storage/procarray.h"
 #include "utils/acl.h"
@@ -533,14 +534,14 @@ pg_stat_get_progress_info(PG_FUNCTION_ARGS)
 }
 
 /*
- * Returns activity of PG backends.
+ * Returns activity of PG processes.
  */
 Datum
 pg_stat_get_activity(PG_FUNCTION_ARGS)
 {
 #define PG_STAT_GET_ACTIVITY_COLS	23
-	int			num_backends = pgstat_fetch_stat_numbackends();
-	int			curr_backend;
+	int			num_procs = pgstat_fetch_stat_numprocs();
+	int			curr_proc;
 	int			pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
 	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
 	TupleDesc	tupdesc;
@@ -574,13 +575,13 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 	MemoryContextSwitchTo(oldcontext);
 
 	/* 1-based index */
-	for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+	for (curr_proc = 1; curr_proc <= num_procs; curr_proc++)
 	{
 		/* for each row */
 		Datum		values[PG_STAT_GET_ACTIVITY_COLS];
 		bool		nulls[PG_STAT_GET_ACTIVITY_COLS];
-		LocalPgBackendStatus *local_beentry;
-		PgBackendStatus *beentry;
+		LocalPgBackendStatus *local_procentry;
+		PgBackendStatus *procentry;
 		PGPROC	   *proc;
 		const char *wait_event_type;
 		const char *wait_event;
@@ -589,8 +590,8 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 		MemSet(nulls, 0, sizeof(nulls));
 
 		/* Get the next one in the list */
-		local_beentry = pgstat_fetch_stat_local_beentry(curr_backend);
-		if (!local_beentry)
+		local_procentry = pgstat_fetch_stat_local_procentry(curr_proc);
+		if (!local_procentry)
 		{
 			int			i;
 
@@ -608,39 +609,48 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			continue;
 		}
 
-		beentry = &local_beentry->backendStatus;
+		procentry = &local_procentry->backendStatus;
 
 		/* If looking for specific PID, ignore all the others */
-		if (pid != -1 && beentry->st_procpid != pid)
+		if (pid != -1 && procentry->st_procpid != pid)
 			continue;
 
 		/* Values available to all callers */
-		values[0] = ObjectIdGetDatum(beentry->st_databaseid);
-		values[1] = Int32GetDatum(beentry->st_procpid);
-		values[2] = ObjectIdGetDatum(beentry->st_userid);
-		if (beentry->st_appname)
-			values[3] = CStringGetTextDatum(beentry->st_appname);
+		if (procentry->st_databaseid != InvalidOid)
+			values[0] = ObjectIdGetDatum(procentry->st_databaseid);
+		else
+			nulls[0] = true;
+
+		values[1] = Int32GetDatum(procentry->st_procpid);
+
+		if (procentry->st_userid != InvalidOid)
+			values[2] = ObjectIdGetDatum(procentry->st_userid);
+		else
+			nulls[2] = true;
+
+		if (procentry->st_appname)
+			values[3] = CStringGetTextDatum(procentry->st_appname);
 		else
 			nulls[3] = true;
 
-		if (TransactionIdIsValid(local_beentry->backend_xid))
-			values[15] = TransactionIdGetDatum(local_beentry->backend_xid);
+		if (TransactionIdIsValid(local_procentry->backend_xid))
+			values[15] = TransactionIdGetDatum(local_procentry->backend_xid);
 		else
 			nulls[15] = true;
 
-		if (TransactionIdIsValid(local_beentry->backend_xmin))
-			values[16] = TransactionIdGetDatum(local_beentry->backend_xmin);
+		if (TransactionIdIsValid(local_procentry->backend_xmin))
+			values[16] = TransactionIdGetDatum(local_procentry->backend_xmin);
 		else
 			nulls[16] = true;
 
-		if (beentry->st_ssl)
+		if (procentry->st_ssl)
 		{
 			values[17] = BoolGetDatum(true);	/* ssl */
-			values[18] = CStringGetTextDatum(beentry->st_sslstatus->ssl_version);
-			values[19] = CStringGetTextDatum(beentry->st_sslstatus->ssl_cipher);
-			values[20] = Int32GetDatum(beentry->st_sslstatus->ssl_bits);
-			values[21] = BoolGetDatum(beentry->st_sslstatus->ssl_compression);
-			values[22] = CStringGetTextDatum(beentry->st_sslstatus->ssl_clientdn);
+			values[18] = CStringGetTextDatum(procentry->st_sslstatus->ssl_version);
+			values[19] = CStringGetTextDatum(procentry->st_sslstatus->ssl_cipher);
+			values[20] = Int32GetDatum(procentry->st_sslstatus->ssl_bits);
+			values[21] = BoolGetDatum(procentry->st_sslstatus->ssl_compression);
+			values[22] = CStringGetTextDatum(procentry->st_sslstatus->ssl_clientdn);
 		}
 		else
 		{
@@ -649,11 +659,11 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 		}
 
 		/* Values only available to role member */
-		if (has_privs_of_role(GetUserId(), beentry->st_userid))
+		if (has_privs_of_role(GetUserId(), procentry->st_userid))
 		{
 			SockAddr	zero_clientaddr;
 
-			switch (beentry->st_state)
+			switch (procentry->st_state)
 			{
 				case STATE_IDLE:
 					values[4] = CStringGetTextDatum("idle");
@@ -678,9 +688,9 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 					break;
 			}
 
-			values[5] = CStringGetTextDatum(beentry->st_activity);
+			values[5] = CStringGetTextDatum(procentry->st_activity);
 
-			proc = BackendPidGetProc(beentry->st_procpid);
+			proc = BackendPidGetProc(procentry->st_procpid);
 			if (proc != NULL)
 			{
 				uint32		raw_wait_event;
@@ -690,6 +700,22 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 				wait_event = pgstat_get_wait_event(raw_wait_event);
 
 			}
+			else if (procentry->st_procType != PROC_BACKEND)
+			{
+				uint32		raw_wait_event;
+
+				/*
+				 * For auxiliary process, retrieve proc info from
+				 * AuxiliaryProcs stored in shared-mem.
+				 */
+				proc = AuxiliaryPidGetProc(procentry->st_procpid);
+
+				/* Check whether this is indeed an auxiliary process */
+				Assert(proc != NULL);
+				raw_wait_event = UINT32_ACCESS_ONCE(proc->wait_event_info);
+				wait_event_type = pgstat_get_wait_event_type(raw_wait_event);
+				wait_event = pgstat_get_wait_event(raw_wait_event);
+			}
 			else
 			{
 				wait_event_type = NULL;
@@ -706,29 +732,29 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			else
 				nulls[7] = true;
 
-			if (beentry->st_xact_start_timestamp != 0)
-				values[8] = TimestampTzGetDatum(beentry->st_xact_start_timestamp);
+			if (procentry->st_xact_start_timestamp != 0)
+				values[8] = TimestampTzGetDatum(procentry->st_xact_start_timestamp);
 			else
 				nulls[8] = true;
 
-			if (beentry->st_activity_start_timestamp != 0)
-				values[9] = TimestampTzGetDatum(beentry->st_activity_start_timestamp);
+			if (procentry->st_activity_start_timestamp != 0)
+				values[9] = TimestampTzGetDatum(procentry->st_activity_start_timestamp);
 			else
 				nulls[9] = true;
 
-			if (beentry->st_proc_start_timestamp != 0)
-				values[10] = TimestampTzGetDatum(beentry->st_proc_start_timestamp);
+			if (procentry->st_proc_start_timestamp != 0)
+				values[10] = TimestampTzGetDatum(procentry->st_proc_start_timestamp);
 			else
 				nulls[10] = true;
 
-			if (beentry->st_state_start_timestamp != 0)
-				values[11] = TimestampTzGetDatum(beentry->st_state_start_timestamp);
+			if (procentry->st_state_start_timestamp != 0)
+				values[11] = TimestampTzGetDatum(procentry->st_state_start_timestamp);
 			else
 				nulls[11] = true;
 
 			/* A zeroed client addr means we don't know */
 			memset(&zero_clientaddr, 0, sizeof(zero_clientaddr));
-			if (memcmp(&(beentry->st_clientaddr), &zero_clientaddr,
+			if (memcmp(&(procentry->st_clientaddr), &zero_clientaddr,
 					   sizeof(zero_clientaddr)) == 0)
 			{
 				nulls[12] = true;
@@ -737,9 +763,9 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			}
 			else
 			{
-				if (beentry->st_clientaddr.addr.ss_family == AF_INET
+				if (procentry->st_clientaddr.addr.ss_family == AF_INET
 #ifdef HAVE_IPV6
-					|| beentry->st_clientaddr.addr.ss_family == AF_INET6
+					|| procentry->st_clientaddr.addr.ss_family == AF_INET6
 #endif
 					)
 				{
@@ -749,19 +775,19 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 
 					remote_host[0] = '\0';
 					remote_port[0] = '\0';
-					ret = pg_getnameinfo_all(&beentry->st_clientaddr.addr,
-											 beentry->st_clientaddr.salen,
+					ret = pg_getnameinfo_all(&procentry->st_clientaddr.addr,
+											 procentry->st_clientaddr.salen,
 											 remote_host, sizeof(remote_host),
 											 remote_port, sizeof(remote_port),
 											 NI_NUMERICHOST | NI_NUMERICSERV);
 					if (ret == 0)
 					{
-						clean_ipv6_addr(beentry->st_clientaddr.addr.ss_family, remote_host);
+						clean_ipv6_addr(procentry->st_clientaddr.addr.ss_family, remote_host);
 						values[12] = DirectFunctionCall1(inet_in,
 											   CStringGetDatum(remote_host));
-						if (beentry->st_clienthostname &&
-							beentry->st_clienthostname[0])
-							values[13] = CStringGetTextDatum(beentry->st_clienthostname);
+						if (procentry->st_clienthostname &&
+							procentry->st_clienthostname[0])
+							values[13] = CStringGetTextDatum(procentry->st_clienthostname);
 						else
 							nulls[13] = true;
 						values[14] = Int32GetDatum(atoi(remote_port));
@@ -773,7 +799,7 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 						nulls[14] = true;
 					}
 				}
-				else if (beentry->st_clientaddr.addr.ss_family == AF_UNIX)
+				else if (procentry->st_clientaddr.addr.ss_family == AF_UNIX)
 				{
 					/*
 					 * Unix sockets always reports NULL for host and -1 for
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index 9f938f2..f8c36c0 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -809,7 +809,7 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 		InitializeClientEncoding();
 
 		/* report this backend in the PgBackendStatus array */
-		pgstat_bestart();
+		pgstat_procstart();
 
 		/* close the transaction we started above */
 		CommitTransactionCommand();
@@ -1021,7 +1021,7 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 
 	/* report this backend in the PgBackendStatus array */
 	if (!bootstrap)
-		pgstat_bestart();
+		pgstat_procstart();
 
 	/* close the transaction we started above */
 	if (!bootstrap)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index de8225b..80a1f36 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -41,6 +41,9 @@ typedef enum TrackFunctionsLevel
 	TRACK_FUNC_ALL
 }	TrackFunctionsLevel;
 
+/* Total number of PG processes */
+#define NumProcStatSlots	(MaxBackends + NUM_AUXPROCTYPES)
+
 /* ----------
  * The types of backend -> collector messages
  * ----------
@@ -696,6 +699,23 @@ typedef struct PgStat_GlobalStats
 
 
 /* ----------
+ * Process types
+ * ----------
+ */
+typedef enum ProcType
+{
+	PROC_BACKEND,
+	PROC_AUTOVAC_LAUNCHER,
+	PROC_WAL_SENDER,
+	PROC_BG_WORKER,
+	PROC_BG_WRITER,
+	PROC_CHECKPOINTER,
+	PROC_WAL_WRITER,
+	PROC_WAL_RECEIVER
+} ProcType;
+
+
+/* ----------
  * Backend states
  * ----------
  */
@@ -845,6 +865,12 @@ typedef struct PgBackendSSLStatus
  * showing its current activity.  (The structs are allocated according to
  * BackendId, but that is not critical.)  Note that the collector process
  * has no involvement in, or even access to, these structs.
+ *
+ * Each auxliliary process also maintains a PgBackendStatus struct in shared
+ * memory.
+ * XXX: PgBackendStatus should be renamed as PgProcStatus since it is used for
+ * backends as well as auxiliary process. But, to avoid massive code refactoring,
+ * we've kept it this way for now.
  * ----------
  */
 typedef struct PgBackendStatus
@@ -869,6 +895,9 @@ typedef struct PgBackendStatus
 	/* The entry is valid iff st_procpid > 0, unused if st_procpid == 0 */
 	int			st_procpid;
 
+	/* Type of process */
+	ProcType	st_procType;
+
 	/* Times when current backend, transaction, and activity started */
 	TimestampTz st_proc_start_timestamp;
 	TimestampTz st_xact_start_timestamp;
@@ -1056,7 +1085,7 @@ extern void pgstat_report_recovery_conflict(int reason);
 extern void pgstat_report_deadlock(void);
 
 extern void pgstat_initialize(void);
-extern void pgstat_bestart(void);
+extern void pgstat_procstart(void);
 
 extern void pgstat_report_activity(BackendState state, const char *cmd_str);
 extern void pgstat_report_tempfile(size_t filesize);
@@ -1067,6 +1096,7 @@ extern const char *pgstat_get_wait_event_type(uint32 wait_event_info);
 extern const char *pgstat_get_backend_current_activity(int pid, bool checkUser);
 extern const char *pgstat_get_crashed_backend_activity(int pid, char *buffer,
 									int buflen);
+extern const char *pgstat_get_proctype_desc(ProcType procType);
 
 extern void pgstat_progress_start_command(ProgressCommandType cmdtype,
 							  Oid relid);
@@ -1210,8 +1240,11 @@ extern PgStat_StatDBEntry *pgstat_fetch_stat_dbentry(Oid dbid);
 extern PgStat_StatTabEntry *pgstat_fetch_stat_tabentry(Oid relid);
 extern PgBackendStatus *pgstat_fetch_stat_beentry(int beid);
 extern LocalPgBackendStatus *pgstat_fetch_stat_local_beentry(int beid);
+extern PgBackendStatus *pgstat_fetch_stat_procentry(int procid);
+extern LocalPgBackendStatus *pgstat_fetch_stat_local_procentry(int procid);
 extern PgStat_StatFuncEntry *pgstat_fetch_stat_funcentry(Oid funcid);
 extern int	pgstat_fetch_stat_numbackends(void);
+extern int	pgstat_fetch_stat_numprocs(void);
 extern PgStat_ArchiverStats *pgstat_fetch_stat_archiver(void);
 extern PgStat_GlobalStats *pgstat_fetch_global(void);
 
diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h
index 5f38fa6..be3bd01 100644
--- a/src/include/storage/proc.h
+++ b/src/include/storage/proc.h
@@ -262,6 +262,7 @@ extern PGPROC *PreparedXactProcs;
  */
 #define NUM_AUXILIARY_PROCS		4
 
+extern PGPROC *AuxiliaryPidGetProc(int pid);
 
 /* configurable options */
 extern int	DeadlockTimeout;
-- 
1.8.3.1

From 231368248b0e4addc236a8e6be84148289731319 Mon Sep 17 00:00:00 2001
From: Kuntal Ghosh <kuntal.ghosh@enterprisedb.com>
Date: Wed, 15 Feb 2017 16:26:20 +0530
Subject: [PATCH] Expose stats for auxiliary processes in pg_stat_get_activity

---
 src/backend/bootstrap/bootstrap.c     |  3 +++
 src/backend/postmaster/bgwriter.c     |  6 ++++++
 src/backend/postmaster/checkpointer.c |  7 +++++++
 src/backend/postmaster/walwriter.c    |  7 +++++++
 src/backend/replication/walreceiver.c | 14 ++++++++++++++
 src/backend/replication/walsender.c   |  7 +++++++
 6 files changed, 44 insertions(+)

diff --git a/src/backend/bootstrap/bootstrap.c b/src/backend/bootstrap/bootstrap.c
index 6511c60..f56e229 100644
--- a/src/backend/bootstrap/bootstrap.c
+++ b/src/backend/bootstrap/bootstrap.c
@@ -387,6 +387,9 @@ AuxiliaryProcessMain(int argc, char *argv[])
 		/* finish setting up bufmgr.c */
 		InitBufferPoolBackend();
 
+		/* Initialize stats collection */
+		pgstat_initialize();
+
 		/* register a before-shutdown callback for LWLock cleanup */
 		before_shmem_exit(ShutdownAuxiliaryProcess, 0);
 	}
diff --git a/src/backend/postmaster/bgwriter.c b/src/backend/postmaster/bgwriter.c
index dcb4cf2..5c89444 100644
--- a/src/backend/postmaster/bgwriter.c
+++ b/src/backend/postmaster/bgwriter.c
@@ -248,6 +248,9 @@ BackgroundWriterMain(void)
 	 */
 	prev_hibernate = false;
 
+	/* report walwriter process in the PgBackendStatus array */
+	pgstat_procstart();
+
 	/*
 	 * Loop forever
 	 */
@@ -284,6 +287,7 @@ BackgroundWriterMain(void)
 		 * Send off activity statistics to the stats collector
 		 */
 		pgstat_send_bgwriter();
+		pgstat_report_activity(STATE_RUNNING, NULL);
 
 		if (FirstCallSinceLastCheckpoint())
 		{
@@ -345,6 +349,8 @@ BackgroundWriterMain(void)
 		 * down with latch events that are likely to happen frequently during
 		 * normal operation.
 		 */
+		pgstat_report_activity(STATE_IDLE, NULL);
+
 		rc = WaitLatch(MyLatch,
 					   WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
 					   BgWriterDelay /* ms */, WAIT_EVENT_BGWRITER_MAIN);
diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c
index fe9041f..62a3f7c 100644
--- a/src/backend/postmaster/checkpointer.c
+++ b/src/backend/postmaster/checkpointer.c
@@ -345,6 +345,9 @@ CheckpointerMain(void)
 	 */
 	ProcGlobal->checkpointerLatch = &MyProc->procLatch;
 
+	/* report checkpointer proc in the PgBackendStatus array */
+	pgstat_procstart();
+
 	/*
 	 * Loop forever
 	 */
@@ -365,6 +368,8 @@ CheckpointerMain(void)
 		 */
 		AbsorbFsyncRequests();
 
+		pgstat_report_activity(STATE_RUNNING, NULL);
+
 		if (got_SIGHUP)
 		{
 			got_SIGHUP = false;
@@ -556,6 +561,8 @@ CheckpointerMain(void)
 			cur_timeout = Min(cur_timeout, XLogArchiveTimeout - elapsed_secs);
 		}
 
+		pgstat_report_activity(STATE_IDLE, NULL);
+
 		rc = WaitLatch(MyLatch,
 					   WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
 					   cur_timeout * 1000L /* convert to ms */,
diff --git a/src/backend/postmaster/walwriter.c b/src/backend/postmaster/walwriter.c
index a575d8f..dfb641b 100644
--- a/src/backend/postmaster/walwriter.c
+++ b/src/backend/postmaster/walwriter.c
@@ -231,6 +231,9 @@ WalWriterMain(void)
 	 */
 	ProcGlobal->walwriterLatch = &MyProc->procLatch;
 
+	/* report walwriter proc in the PgBackendStatus array */
+	pgstat_procstart();
+
 	/*
 	 * Loop forever
 	 */
@@ -257,6 +260,8 @@ WalWriterMain(void)
 		/* Clear any already-pending wakeups */
 		ResetLatch(MyLatch);
 
+		pgstat_report_activity(STATE_RUNNING, NULL);
+
 		/*
 		 * Process any requests or signals received recently.
 		 */
@@ -290,6 +295,8 @@ WalWriterMain(void)
 		else
 			cur_timeout = WalWriterDelay * HIBERNATE_FACTOR;
 
+		pgstat_report_activity(STATE_IDLE, NULL);
+
 		rc = WaitLatch(MyLatch,
 					   WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
 					   cur_timeout,
diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index 5c2e72b..e94842e 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -316,6 +316,10 @@ WalReceiverMain(void)
 	SpinLockRelease(&walrcv->mutex);
 
 	first_stream = true;
+
+	/* report walreceiver proc in the PgBackendStatus array */
+	pgstat_procstart();
+
 	for (;;)
 	{
 		char	   *primary_sysid;
@@ -323,6 +327,8 @@ WalReceiverMain(void)
 		int			server_version;
 		WalRcvStreamOptions options;
 
+		pgstat_report_activity(STATE_RUNNING, NULL);
+
 		/*
 		 * Check that we're connected to a valid server using the
 		 * IDENTIFY_SYSTEM replication command.
@@ -423,6 +429,8 @@ WalReceiverMain(void)
 				/* Process any requests or signals received recently */
 				ProcessWalRcvInterrupts();
 
+				pgstat_report_activity(STATE_RUNNING, NULL);
+
 				if (got_SIGHUP)
 				{
 					got_SIGHUP = false;
@@ -491,6 +499,8 @@ WalReceiverMain(void)
 				 * could add and remove just the socket each time, potentially
 				 * avoiding some system calls.
 				 */
+				pgstat_report_activity(STATE_IDLE, NULL);
+
 				Assert(wait_fd != PGINVALID_SOCKET);
 				rc = WaitLatchOrSocket(walrcv->latch,
 								   WL_POSTMASTER_DEATH | WL_SOCKET_READABLE |
@@ -663,6 +673,8 @@ WalRcvWaitForStartPosition(XLogRecPtr *startpoint, TimeLineID *startpointTLI)
 	{
 		ResetLatch(walrcv->latch);
 
+		pgstat_report_activity(STATE_RUNNING, NULL);
+
 		/*
 		 * Emergency bailout if postmaster has died.  This is to avoid the
 		 * necessity for manual cleanup of all postmaster children.
@@ -696,6 +708,8 @@ WalRcvWaitForStartPosition(XLogRecPtr *startpoint, TimeLineID *startpointTLI)
 		}
 		SpinLockRelease(&walrcv->mutex);
 
+		pgstat_report_activity(STATE_IDLE, NULL);
+
 		WaitLatch(walrcv->latch, WL_LATCH_SET | WL_POSTMASTER_DEATH, 0,
 				  WAIT_EVENT_WAL_RECEIVER_WAIT_START);
 	}
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index ba506e2..3304408 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -244,6 +244,9 @@ InitWalSender(void)
 	 */
 	MarkPostmasterChildWalSender();
 	SendPostmasterSignal(PMSIGNAL_ADVANCE_STATE_MACHINE);
+
+	/* report walsender proc in the PgBackendStatus array */
+	pgstat_procstart();
 }
 
 /*
@@ -1774,6 +1777,8 @@ WalSndLoop(WalSndSendDataCallback send_data)
 
 		CHECK_FOR_INTERRUPTS();
 
+		pgstat_report_activity(STATE_RUNNING, NULL);
+
 		/* Process any requests or signals received recently */
 		if (got_SIGHUP)
 		{
@@ -1868,6 +1873,8 @@ WalSndLoop(WalSndSendDataCallback send_data)
 				wakeEvents |= WL_SOCKET_WRITEABLE;
 
 			/* Sleep until something happens or we time out */
+			pgstat_report_activity(STATE_IDLE, NULL);
+
 			WaitLatchOrSocket(MyLatch, wakeEvents,
 							  MyProcPort->sock, sleeptime,
 							  WAIT_EVENT_WAL_SENDER_MAIN);
-- 
1.8.3.1

From 1b96d656fae4c038e7fdac9a252b3b86bbea94ee Mon Sep 17 00:00:00 2001
From: Kuntal Ghosh <kuntal.ghosh@enterprisedb.com>
Date: Wed, 15 Feb 2017 17:18:32 +0530
Subject: [PATCH] Expose stats for autovacuum launcher and bgworker

---
 src/backend/postmaster/autovacuum.c        |  4 ++++
 src/backend/replication/logical/launcher.c |  4 ++++
 src/backend/utils/init/postinit.c          | 16 +++++++++++++++-
 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index 0c5ffa0..f6132bc 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -597,6 +597,8 @@ AutoVacLauncherMain(int argc, char *argv[])
 		 * Wait until naptime expires or we get some type of signal (all the
 		 * signal handlers will wake us by calling SetLatch).
 		 */
+		pgstat_report_activity(STATE_IDLE, NULL);
+
 		rc = WaitLatch(MyLatch,
 					   WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
 					   (nap.tv_sec * 1000L) + (nap.tv_usec / 1000L),
@@ -614,6 +616,8 @@ AutoVacLauncherMain(int argc, char *argv[])
 		if (rc & WL_POSTMASTER_DEATH)
 			proc_exit(1);
 
+		pgstat_report_activity(STATE_RUNNING, NULL);
+
 		/* the normal shutdown case */
 		if (got_SIGTERM)
 			break;
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 39530f96..2f927c8 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -590,6 +590,8 @@ ApplyLauncherMain(Datum main_arg)
 
 		now = GetCurrentTimestamp();
 
+		pgstat_report_activity(STATE_RUNNING, NULL);
+
 		/* Limit the start retry to once a wal_retrieve_retry_interval */
 		if (TimestampDifferenceExceeds(last_start_time, now,
 									   wal_retrieve_retry_interval))
@@ -647,6 +649,8 @@ ApplyLauncherMain(Datum main_arg)
 		}
 
 		/* Wait for more work. */
+		pgstat_report_activity(STATE_IDLE, NULL);
+
 		rc = WaitLatch(&MyProc->procLatch,
 					   WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
 					   wait_time,
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index f8c36c0..b831cf9 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -665,7 +665,14 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 
 	/* The autovacuum launcher is done here */
 	if (IsAutoVacuumLauncherProcess())
+	{
+		/*
+		 * Before returning, report autovacuum launcher process in the
+		 * PgBackendStatus array.
+		 */
+		pgstat_procstart();
 		return;
+	}
 
 	/*
 	 * Start a new transaction here before first access to db, and get a
@@ -808,7 +815,7 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 		/* initialize client encoding */
 		InitializeClientEncoding();
 
-		/* report this backend in the PgBackendStatus array */
+		/* report walsender process in the PgBackendStatus array */
 		pgstat_procstart();
 
 		/* close the transaction we started above */
@@ -875,6 +882,13 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 		 */
 		if (!bootstrap)
 			CommitTransactionCommand();
+
+		/*
+		 * Before returning, report the background worker process in the
+		 * PgBackendStatus array.
+		 */
+		if (!bootstrap)
+			pgstat_procstart();
 		return;
 	}
 
-- 
1.8.3.1

From a6bbbf6a3f3ff739f362f4b3722d060051f6591e Mon Sep 17 00:00:00 2001
From: Kuntal Ghosh <kuntal.ghosh@enterprisedb.com>
Date: Wed, 15 Feb 2017 17:41:08 +0530
Subject: [PATCH] Add proc_type column in pg_stat_get_activity

proc_type indicates the type of process in the stat table.
---
 src/backend/catalog/system_views.sql | 3 ++-
 src/backend/utils/adt/pgstatfuncs.c  | 5 ++++-
 src/include/catalog/pg_proc.h        | 2 +-
 src/test/regress/expected/rules.out  | 9 +++++----
 4 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 38be9cf..dfa6430 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -684,7 +684,8 @@ CREATE VIEW pg_stat_activity AS
             S.state,
             S.backend_xid,
             s.backend_xmin,
-            S.query
+            S.query,
+            S.proc_type
     FROM pg_stat_get_activity(NULL) AS S
         LEFT JOIN pg_database AS D ON (S.datid = D.oid)
         LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index e858e4d..cb2109a 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -539,7 +539,7 @@ pg_stat_get_progress_info(PG_FUNCTION_ARGS)
 Datum
 pg_stat_get_activity(PG_FUNCTION_ARGS)
 {
-#define PG_STAT_GET_ACTIVITY_COLS	23
+#define PG_STAT_GET_ACTIVITY_COLS	24
 	int			num_procs = pgstat_fetch_stat_numprocs();
 	int			curr_proc;
 	int			pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
@@ -819,6 +819,8 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 					nulls[14] = true;
 				}
 			}
+			/* Add process type */
+			values[23] = CStringGetTextDatum(pgstat_get_proctype_desc(procentry->st_procType));
 		}
 		else
 		{
@@ -834,6 +836,7 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			nulls[12] = true;
 			nulls[13] = true;
 			nulls[14] = true;
+			nulls[23] = true;
 		}
 
 		tuplestore_putvalues(tupstore, tupdesc, values, nulls);
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 41c12af..27aa552 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -2768,7 +2768,7 @@ DATA(insert OID = 3057 ( pg_stat_get_autoanalyze_count PGNSP PGUID 12 1 0 0 0 f
 DESCR("statistics: number of auto analyzes for a table");
 DATA(insert OID = 1936 (  pg_stat_get_backend_idset		PGNSP PGUID 12 1 100 0 0 f f f f t t s r 0 0 23 "" _null_ _null_ _null_ _null_ _null_ pg_stat_get_backend_idset _null_ _null_ _null_ ));
 DESCR("statistics: currently active backend IDs");
-DATA(insert OID = 2022 (  pg_stat_get_activity			PGNSP PGUID 12 1 100 0 0 f f f f f t s r 1 0 2249 "23" "{23,26,23,26,25,25,25,25,25,1184,1184,1184,1184,869,25,23,28,28,16,25,25,23,16,25}" "{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,ssl,sslversion,sslcipher,sslbits,sslcompression,sslclientdn}" _null_ _null_ pg_stat_get_activity _null_ _null_ _null_ ));
+DATA(insert OID = 2022 (  pg_stat_get_activity			PGNSP PGUID 12 1 100 0 0 f f f f f t s r 1 0 2249 "23" "{23,26,23,26,25,25,25,25,25,1184,1184,1184,1184,869,25,23,28,28,16,25,25,23,16,25,25}" "{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,ssl,sslversion,sslcipher,sslbits,sslcompression,sslclientdn,proc_type}" _null_ _null_ pg_stat_get_activity _null_ _null_ _null_ ));
 DESCR("statistics: information about currently active backends");
 DATA(insert OID = 3318 (  pg_stat_get_progress_info			  PGNSP PGUID 12 1 100 0 0 f f f f t t s r 1 0 2249 "25" "{25,23,26,26,20,20,20,20,20,20,20,20,20,20}" "{i,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{cmdtype,pid,datid,relid,param1,param2,param3,param4,param5,param6,param7,param8,param9,param10}" _null_ _null_ pg_stat_get_progress_info _null_ _null_ _null_ ));
 DESCR("statistics: information about progress of backends running maintenance command");
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index c661f1d..69d61c6 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1704,8 +1704,9 @@ pg_stat_activity| SELECT s.datid,
     s.state,
     s.backend_xid,
     s.backend_xmin,
-    s.query
-   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn)
+    s.query,
+    s.proc_type
+   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn, proc_type)
      LEFT JOIN pg_database d ON ((s.datid = d.oid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_all_indexes| SELECT c.oid AS relid,
@@ -1833,7 +1834,7 @@ pg_stat_replication| SELECT s.pid,
     w.replay_location,
     w.sync_priority,
     w.sync_state
-   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn)
+   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn, proc_type)
      JOIN pg_stat_get_wal_senders() w(pid, state, sent_location, write_location, flush_location, replay_location, sync_priority, sync_state) ON ((s.pid = w.pid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_ssl| SELECT s.pid,
@@ -1843,7 +1844,7 @@ pg_stat_ssl| SELECT s.pid,
     s.sslbits AS bits,
     s.sslcompression AS compression,
     s.sslclientdn AS clientdn
-   FROM pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn);
+   FROM pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn, proc_type);
 pg_stat_subscription| SELECT su.oid AS subid,
     su.subname,
     st.pid,
-- 
1.8.3.1

From 3e5cd604d729e5f8fb68cc7458fadcd3331f6e8c Mon Sep 17 00:00:00 2001
From: Kuntal Ghosh <kuntal.ghosh@enterprisedb.com>
Date: Wed, 15 Feb 2017 15:34:18 +0530
Subject: [PATCH] Infra to expose non-backend processes in pg_stat_get_activity

This patch implements the infrastructure required to expose
non-backend processes in pg_stat_activity. BackendStatusArray
is extended to store auxiliary processes as well. Backends use slots
indexed in the range from 1 to MaxBackends (inclusive), so we use
MaxBackends + AuxProcType + 1 as the index of the slot for an
auxiliary process.
---
 src/backend/postmaster/pgstat.c     | 302 ++++++++++++++++++++++++++++++------
 src/backend/storage/lmgr/proc.c     |  27 ++++
 src/backend/utils/adt/pgstatfuncs.c | 120 ++++++++------
 src/backend/utils/init/postinit.c   |   4 +-
 src/include/pgstat.h                |  35 ++++-
 src/include/storage/proc.h          |   1 +
 6 files changed, 391 insertions(+), 98 deletions(-)

diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 7cacb1e..a530c3b 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -50,6 +50,7 @@
 #include "postmaster/autovacuum.h"
 #include "postmaster/fork_process.h"
 #include "postmaster/postmaster.h"
+#include "replication/walsender.h"
 #include "storage/backendid.h"
 #include "storage/dsm.h"
 #include "storage/fd.h"
@@ -212,7 +213,17 @@ typedef struct TwoPhasePgStatRecord
  */
 static MemoryContext pgStatLocalContext = NULL;
 static HTAB *pgStatDBHash = NULL;
-static LocalPgBackendStatus *localBackendStatusTable = NULL;
+
+/* Status for backends and auxiliary processes */
+static LocalPgBackendStatus *localProcStatusTable = NULL;
+
+/* Total number of processes including backends and auxiliary */
+static int	localNumProcs = 0;
+
+/* Index to backends in localProcStatusTable */
+static int *localBackendStatusIndex = NULL;
+
+/* Total number of backend processes */
 static int	localNumBackends = 0;
 
 /*
@@ -2404,7 +2415,29 @@ pgstat_fetch_stat_beentry(int beid)
 	if (beid < 1 || beid > localNumBackends)
 		return NULL;
 
-	return &localBackendStatusTable[beid - 1].backendStatus;
+	return &localProcStatusTable[localBackendStatusIndex[beid - 1]].backendStatus;
+}
+
+
+/* ----------
+ * pgstat_fetch_stat_procentry() -
+ *
+ *	Support function for the SQL-callable pgstat* functions. Returns
+ *	our local copy of the current-activity entry for one process.
+ *
+ *	NB: caller is responsible for a check if the user is permitted to see
+ *	this info (especially the querystring).
+ * ----------
+ */
+PgBackendStatus *
+pgstat_fetch_stat_procentry(int procid)
+{
+	pgstat_read_current_status();
+
+	if (procid < 1 || procid > localNumProcs)
+		return NULL;
+
+	return &localProcStatusTable[procid - 1].backendStatus;
 }
 
 
@@ -2426,7 +2459,29 @@ pgstat_fetch_stat_local_beentry(int beid)
 	if (beid < 1 || beid > localNumBackends)
 		return NULL;
 
-	return &localBackendStatusTable[beid - 1];
+	return &localProcStatusTable[localBackendStatusIndex[beid - 1]];
+}
+
+
+/* ----------
+ * pgstat_fetch_stat_local_procentry() -
+ *
+ *	Like pgstat_fetch_stat_procentry() but with locally computed additions (like
+ *	xid and xmin values of the backend)
+ *
+ *	NB: caller is responsible for a check if the user is permitted to see
+ *	this info (especially the querystring).
+ * ----------
+ */
+LocalPgBackendStatus *
+pgstat_fetch_stat_local_procentry(int procid)
+{
+	pgstat_read_current_status();
+
+	if (procid < 1 || procid > localNumProcs)
+		return NULL;
+
+	return &localProcStatusTable[procid - 1];
 }
 
 
@@ -2445,6 +2500,22 @@ pgstat_fetch_stat_numbackends(void)
 	return localNumBackends;
 }
 
+
+/* ----------
+ * pgstat_fetch_stat_numprocs() -
+ *
+ *	Support function for the SQL-callable pgstat* functions. Returns
+ *	the maximum current process id.
+ * ----------
+ */
+int
+pgstat_fetch_stat_numprocs(void)
+{
+	pgstat_read_current_status();
+
+	return localNumProcs;
+}
+
 /*
  * ---------
  * pgstat_fetch_stat_archiver() -
@@ -2504,20 +2575,20 @@ BackendStatusShmemSize(void)
 	Size		size;
 
 	/* BackendStatusArray: */
-	size = mul_size(sizeof(PgBackendStatus), MaxBackends);
+	size = mul_size(sizeof(PgBackendStatus), NumProcStatSlots);
 	/* BackendAppnameBuffer: */
 	size = add_size(size,
-					mul_size(NAMEDATALEN, MaxBackends));
+					mul_size(NAMEDATALEN, NumProcStatSlots));
 	/* BackendClientHostnameBuffer: */
 	size = add_size(size,
-					mul_size(NAMEDATALEN, MaxBackends));
+					mul_size(NAMEDATALEN, NumProcStatSlots));
 	/* BackendActivityBuffer: */
 	size = add_size(size,
-					mul_size(pgstat_track_activity_query_size, MaxBackends));
+				mul_size(pgstat_track_activity_query_size, NumProcStatSlots));
 #ifdef USE_SSL
 	/* BackendSslStatusBuffer: */
 	size = add_size(size,
-					mul_size(sizeof(PgBackendSSLStatus), MaxBackends));
+					mul_size(sizeof(PgBackendSSLStatus), NumProcStatSlots));
 #endif
 	return size;
 }
@@ -2535,7 +2606,7 @@ CreateSharedBackendStatus(void)
 	char	   *buffer;
 
 	/* Create or attach to the shared array */
-	size = mul_size(sizeof(PgBackendStatus), MaxBackends);
+	size = mul_size(sizeof(PgBackendStatus), NumProcStatSlots);
 	BackendStatusArray = (PgBackendStatus *)
 		ShmemInitStruct("Backend Status Array", size, &found);
 
@@ -2558,7 +2629,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_appname pointers. */
 		buffer = BackendAppnameBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumProcStatSlots; i++)
 		{
 			BackendStatusArray[i].st_appname = buffer;
 			buffer += NAMEDATALEN;
@@ -2576,7 +2647,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_clienthostname pointers. */
 		buffer = BackendClientHostnameBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumProcStatSlots; i++)
 		{
 			BackendStatusArray[i].st_clienthostname = buffer;
 			buffer += NAMEDATALEN;
@@ -2585,7 +2656,7 @@ CreateSharedBackendStatus(void)
 
 	/* Create or attach to the shared activity buffer */
 	BackendActivityBufferSize = mul_size(pgstat_track_activity_query_size,
-										 MaxBackends);
+										 NumProcStatSlots);
 	BackendActivityBuffer = (char *)
 		ShmemInitStruct("Backend Activity Buffer",
 						BackendActivityBufferSize,
@@ -2597,7 +2668,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_activity pointers. */
 		buffer = BackendActivityBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumProcStatSlots; i++)
 		{
 			BackendStatusArray[i].st_activity = buffer;
 			buffer += pgstat_track_activity_query_size;
@@ -2606,7 +2677,7 @@ CreateSharedBackendStatus(void)
 
 #ifdef USE_SSL
 	/* Create or attach to the shared SSL status buffer */
-	size = mul_size(sizeof(PgBackendSSLStatus), MaxBackends);
+	size = mul_size(sizeof(PgBackendSSLStatus), NumProcStatSlots);
 	BackendSslStatusBuffer = (PgBackendSSLStatus *)
 		ShmemInitStruct("Backend SSL Status Buffer", size, &found);
 
@@ -2618,7 +2689,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_sslstatus pointers. */
 		ptr = BackendSslStatusBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumProcStatSlots; i++)
 		{
 			BackendStatusArray[i].st_sslstatus = ptr;
 			ptr++;
@@ -2632,7 +2703,8 @@ CreateSharedBackendStatus(void)
  * pgstat_initialize() -
  *
  *	Initialize pgstats state, and set up our on-proc-exit hook.
- *	Called from InitPostgres.  MyBackendId must be set,
+ *	Called from InitPostgres and AuxiliaryProcessMain. For auxiliary process,
+ *	MyBackendId is invalid. Otherwise, MyBackendId must be set,
  *	but we must not have started any transaction yet (since the
  *	exit hook must run after the last transaction exit).
  *	NOTE: MyDatabaseId isn't set yet; so the shutdown hook has to be careful.
@@ -2642,27 +2714,47 @@ void
 pgstat_initialize(void)
 {
 	/* Initialize MyBEEntry */
-	Assert(MyBackendId >= 1 && MyBackendId <= MaxBackends);
-	MyBEEntry = &BackendStatusArray[MyBackendId - 1];
+	if (MyBackendId != InvalidBackendId)
+	{
+		/* Just a backend process */
+		Assert(MyBackendId >= 1 && MyBackendId <= MaxBackends);
+		MyBEEntry = &BackendStatusArray[MyBackendId - 1];
+	}
+	else
+	{
+		/* Must be an auxiliary process */
+		Assert(MyAuxProcType != NotAnAuxProcess);
+
+		/*
+		 * Assign the MyBEEntry for an auxiliary process.  Since it doesn't
+		 * have a BackendId, the slot is statically allocated based on the
+		 * auxiliary process type (MyAuxProcType).  Backends use slots indexed
+		 * in the range from 1 to MaxBackends (inclusive), so we use
+		 * MaxBackends + AuxProcType + 1 as the index of the slot for an
+		 * auxiliary process.
+		 */
+		MyBEEntry = &BackendStatusArray[MaxBackends + MyAuxProcType];
+	}
 
 	/* Set up a process-exit hook to clean up */
 	on_shmem_exit(pgstat_beshutdown_hook, 0);
 }
 
 /* ----------
- * pgstat_bestart() -
+ * pgstat_procstart() -
  *
- *	Initialize this backend's entry in the PgBackendStatus array.
+ *	Initialize this process's entry in the PgBackendStatus array.
  *	Called from InitPostgres.
- *	MyDatabaseId, session userid, and application_name must be set
- *	(hence, this cannot be combined with pgstat_initialize).
+ *
+ *	For a backend process, MyDatabaseId, session userid,
+ *	and application_name must be set (hence, this cannot be combined
+ *	with pgstat_initialize).
  * ----------
  */
 void
-pgstat_bestart(void)
+pgstat_procstart(void)
 {
 	TimestampTz proc_start_timestamp;
-	Oid			userid;
 	SockAddr	clientaddr;
 	volatile PgBackendStatus *beentry;
 
@@ -2677,7 +2769,6 @@ pgstat_bestart(void)
 		proc_start_timestamp = MyProcPort->SessionStartTime;
 	else
 		proc_start_timestamp = GetCurrentTimestamp();
-	userid = GetSessionUserId();
 
 	/*
 	 * We may not have a MyProcPort (eg, if this is the autovacuum process).
@@ -2696,6 +2787,55 @@ pgstat_bestart(void)
 	 * cute.
 	 */
 	beentry = MyBEEntry;
+
+	if (MyBackendId != InvalidBackendId)
+	{
+		/* Must be a backend process */
+		if (IsAutoVacuumLauncherProcess())
+		{
+			/* Autovacuum Launcher */
+			beentry->st_procType = PROC_AUTOVAC_LAUNCHER;
+		}
+		else if (am_walsender)
+		{
+			/* Wal sender */
+			beentry->st_procType = PROC_WAL_SENDER;
+		}
+		else if (IsBackgroundWorker)
+		{
+			/* bgworker */
+			beentry->st_procType = PROC_BG_WORKER;
+		}
+		else
+		{
+			/* client-backend */
+			beentry->st_procType = PROC_BACKEND;
+		}
+	}
+	else
+	{
+		/* Must be an auxiliary process */
+		Assert(MyAuxProcType != NotAnAuxProcess);
+		switch (MyAuxProcType)
+		{
+			case BgWriterProcess:
+				beentry->st_procType = PROC_BG_WRITER;
+				break;
+			case CheckpointerProcess:
+				beentry->st_procType = PROC_CHECKPOINTER;
+				break;
+			case WalWriterProcess:
+				beentry->st_procType = PROC_WAL_WRITER;
+				break;
+			case WalReceiverProcess:
+				beentry->st_procType = PROC_WAL_RECEIVER;
+				break;
+			default:
+				elog(PANIC, "unrecognized process type: %d", (int) MyAuxProcType);
+				proc_exit(1);
+		}
+	}
+
 	do
 	{
 		pgstat_increment_changecount_before(beentry);
@@ -2707,8 +2847,15 @@ pgstat_bestart(void)
 	beentry->st_state_start_timestamp = 0;
 	beentry->st_xact_start_timestamp = 0;
 	beentry->st_databaseid = MyDatabaseId;
-	beentry->st_userid = userid;
+
+	/* We have userid for client-backends and wal-sender processes */
+	if (beentry->st_procType == PROC_BACKEND || beentry->st_procType == PROC_WAL_SENDER)
+		beentry->st_userid = GetSessionUserId();
+	else
+		beentry->st_userid = InvalidOid;
+
 	beentry->st_clientaddr = clientaddr;
+
 	if (MyProcPort && MyProcPort->remote_hostname)
 		strlcpy(beentry->st_clienthostname, MyProcPort->remote_hostname,
 				NAMEDATALEN);
@@ -3027,7 +3174,7 @@ pgstat_report_xact_timestamp(TimestampTz tstamp)
 static void
 pgstat_read_current_status(void)
 {
-	volatile PgBackendStatus *beentry;
+	volatile PgBackendStatus *procentry;
 	LocalPgBackendStatus *localtable;
 	LocalPgBackendStatus *localentry;
 	char	   *localappname,
@@ -3038,31 +3185,31 @@ pgstat_read_current_status(void)
 	int			i;
 
 	Assert(!pgStatRunningInCollector);
-	if (localBackendStatusTable)
+	if (localProcStatusTable && localBackendStatusIndex)
 		return;					/* already done */
 
 	pgstat_setup_memcxt();
 
 	localtable = (LocalPgBackendStatus *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   sizeof(LocalPgBackendStatus) * MaxBackends);
+						   sizeof(LocalPgBackendStatus) * NumProcStatSlots);
 	localappname = (char *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   NAMEDATALEN * MaxBackends);
+						   NAMEDATALEN * NumProcStatSlots);
 	localactivity = (char *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   pgstat_track_activity_query_size * MaxBackends);
+					   pgstat_track_activity_query_size * NumProcStatSlots);
 #ifdef USE_SSL
 	localsslstatus = (PgBackendSSLStatus *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   sizeof(PgBackendSSLStatus) * MaxBackends);
+						   sizeof(PgBackendSSLStatus) * NumProcStatSlots);
 #endif
 
-	localNumBackends = 0;
+	localNumProcs = 0;
 
-	beentry = BackendStatusArray;
+	procentry = BackendStatusArray;
 	localentry = localtable;
-	for (i = 1; i <= MaxBackends; i++)
+	for (i = 1; i <= NumProcStatSlots; i++)
 	{
 		/*
 		 * Follow the protocol of retrying if st_changecount changes while we
@@ -3076,32 +3223,32 @@ pgstat_read_current_status(void)
 			int			before_changecount;
 			int			after_changecount;
 
-			pgstat_save_changecount_before(beentry, before_changecount);
+			pgstat_save_changecount_before(procentry, before_changecount);
 
-			localentry->backendStatus.st_procpid = beentry->st_procpid;
+			localentry->backendStatus.st_procpid = procentry->st_procpid;
 			if (localentry->backendStatus.st_procpid > 0)
 			{
-				memcpy(&localentry->backendStatus, (char *) beentry, sizeof(PgBackendStatus));
+				memcpy(&localentry->backendStatus, (char *) procentry, sizeof(PgBackendStatus));
 
 				/*
 				 * strcpy is safe even if the string is modified concurrently,
 				 * because there's always a \0 at the end of the buffer.
 				 */
-				strcpy(localappname, (char *) beentry->st_appname);
+				strcpy(localappname, (char *) procentry->st_appname);
 				localentry->backendStatus.st_appname = localappname;
-				strcpy(localactivity, (char *) beentry->st_activity);
+				strcpy(localactivity, (char *) procentry->st_activity);
 				localentry->backendStatus.st_activity = localactivity;
-				localentry->backendStatus.st_ssl = beentry->st_ssl;
+				localentry->backendStatus.st_ssl = procentry->st_ssl;
 #ifdef USE_SSL
-				if (beentry->st_ssl)
+				if (procentry->st_ssl)
 				{
-					memcpy(localsslstatus, beentry->st_sslstatus, sizeof(PgBackendSSLStatus));
+					memcpy(localsslstatus, procentry->st_sslstatus, sizeof(PgBackendSSLStatus));
 					localentry->backendStatus.st_sslstatus = localsslstatus;
 				}
 #endif
 			}
 
-			pgstat_save_changecount_after(beentry, after_changecount);
+			pgstat_save_changecount_after(procentry, after_changecount);
 			if (before_changecount == after_changecount &&
 				(before_changecount & 1) == 0)
 				break;
@@ -3110,7 +3257,7 @@ pgstat_read_current_status(void)
 			CHECK_FOR_INTERRUPTS();
 		}
 
-		beentry++;
+		procentry++;
 		/* Only valid entries get included into the local array */
 		if (localentry->backendStatus.st_procpid > 0)
 		{
@@ -3124,12 +3271,35 @@ pgstat_read_current_status(void)
 #ifdef USE_SSL
 			localsslstatus++;
 #endif
-			localNumBackends++;
+			localNumProcs++;
 		}
 	}
 
 	/* Set the pointer only after completion of a valid table */
-	localBackendStatusTable = localtable;
+	localProcStatusTable = localtable;
+
+	/*
+	 * In localBackendStatusIndex, we store the backend indices from
+	 * localProcStatusTable. We need this information since there are
+	 * user-defined functions which expect ids of backends starting from 1 to
+	 * the number of active backends. Hence, we don't want to surprise the
+	 * end-user by including auxiliary processes in the result.
+	 *
+	 * See pg_stat_get_backend_idset for further info.
+	 */
+	localBackendStatusIndex = (int *)
+		MemoryContextAlloc(pgStatLocalContext,
+						   sizeof(int) * NumProcStatSlots);
+
+	localNumBackends = 0;
+	for (i = 0; i < localNumProcs; i++)
+	{
+		if (localProcStatusTable[i].backendStatus.st_procType == PROC_BACKEND)
+		{
+			localBackendStatusIndex[localNumBackends] = i;
+			localNumBackends++;
+		}
+	}
 }
 
 /* ----------
@@ -3590,7 +3760,41 @@ pgstat_get_crashed_backend_activity(int pid, char *buffer, int buflen)
 	return NULL;
 }
 
+const char *
+pgstat_get_proctype_desc(ProcType procType)
+{
+	const char *procDesc = "unknown process type";
+
+	switch (procType)
+	{
+		case PROC_BACKEND:
+			procDesc = "client backend";
+			break;
+		case PROC_AUTOVAC_LAUNCHER:
+			procDesc = "autovacuum launcher";
+			break;
+		case PROC_WAL_SENDER:
+			procDesc = "wal sender";
+			break;
+		case PROC_BG_WORKER:
+			procDesc = "bgworker";
+			break;
+		case PROC_BG_WRITER:
+			procDesc = "writer";
+			break;
+		case PROC_CHECKPOINTER:
+			procDesc = "checkpointer";
+			break;
+		case PROC_WAL_WRITER:
+			procDesc = "wal writer";
+			break;
+		case PROC_WAL_RECEIVER:
+			procDesc = "wal receiver";
+			break;
+	}
 
+	return procDesc;
+}
 /* ------------------------------------------------------------
  * Local support functions follow
  * ------------------------------------------------------------
@@ -5054,7 +5258,9 @@ pgstat_clear_snapshot(void)
 	/* Reset variables */
 	pgStatLocalContext = NULL;
 	pgStatDBHash = NULL;
-	localBackendStatusTable = NULL;
+	localProcStatusTable = NULL;
+	localNumProcs = 0;
+	localBackendStatusIndex = NULL;
 	localNumBackends = 0;
 }
 
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 8f467be..3e716b1 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -941,6 +941,33 @@ AuxiliaryProcKill(int code, Datum arg)
 	SpinLockRelease(ProcStructLock);
 }
 
+/*
+ * AuxiliaryPidGetProc -- get PGPROC for an auxiliary process
+ * given its PID
+ *
+ * Returns NULL if not found.
+ */
+PGPROC *
+AuxiliaryPidGetProc(int pid)
+{
+	PGPROC	   *result = NULL;
+	int			index;
+
+	if (pid == 0)				/* never match dummy PGPROCs */
+		return NULL;
+
+	for (index = 0; index < NUM_AUXILIARY_PROCS; index++)
+	{
+		PGPROC	   *proc = &AuxiliaryProcs[index];
+
+		if (proc->pid == pid)
+		{
+			result = proc;
+			break;
+		}
+	}
+	return result;
+}
 
 /*
  * ProcQueue package: routines for putting processes to sleep
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index a987d0d..8bb9b7e 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -20,6 +20,7 @@
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "pgstat.h"
+#include "postmaster/postmaster.h"
 #include "storage/proc.h"
 #include "storage/procarray.h"
 #include "utils/acl.h"
@@ -533,14 +534,14 @@ pg_stat_get_progress_info(PG_FUNCTION_ARGS)
 }
 
 /*
- * Returns activity of PG backends.
+ * Returns activity of PG processes.
  */
 Datum
 pg_stat_get_activity(PG_FUNCTION_ARGS)
 {
 #define PG_STAT_GET_ACTIVITY_COLS	23
-	int			num_backends = pgstat_fetch_stat_numbackends();
-	int			curr_backend;
+	int			num_procs = pgstat_fetch_stat_numprocs();
+	int			curr_proc;
 	int			pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
 	ReturnSetInfo *rsinfo = (ReturnSetInfo *) fcinfo->resultinfo;
 	TupleDesc	tupdesc;
@@ -574,13 +575,13 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 	MemoryContextSwitchTo(oldcontext);
 
 	/* 1-based index */
-	for (curr_backend = 1; curr_backend <= num_backends; curr_backend++)
+	for (curr_proc = 1; curr_proc <= num_procs; curr_proc++)
 	{
 		/* for each row */
 		Datum		values[PG_STAT_GET_ACTIVITY_COLS];
 		bool		nulls[PG_STAT_GET_ACTIVITY_COLS];
-		LocalPgBackendStatus *local_beentry;
-		PgBackendStatus *beentry;
+		LocalPgBackendStatus *local_procentry;
+		PgBackendStatus *procentry;
 		PGPROC	   *proc;
 		const char *wait_event_type;
 		const char *wait_event;
@@ -589,8 +590,8 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 		MemSet(nulls, 0, sizeof(nulls));
 
 		/* Get the next one in the list */
-		local_beentry = pgstat_fetch_stat_local_beentry(curr_backend);
-		if (!local_beentry)
+		local_procentry = pgstat_fetch_stat_local_procentry(curr_proc);
+		if (!local_procentry)
 		{
 			int			i;
 
@@ -608,39 +609,48 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			continue;
 		}
 
-		beentry = &local_beentry->backendStatus;
+		procentry = &local_procentry->backendStatus;
 
 		/* If looking for specific PID, ignore all the others */
-		if (pid != -1 && beentry->st_procpid != pid)
+		if (pid != -1 && procentry->st_procpid != pid)
 			continue;
 
 		/* Values available to all callers */
-		values[0] = ObjectIdGetDatum(beentry->st_databaseid);
-		values[1] = Int32GetDatum(beentry->st_procpid);
-		values[2] = ObjectIdGetDatum(beentry->st_userid);
-		if (beentry->st_appname)
-			values[3] = CStringGetTextDatum(beentry->st_appname);
+		if (procentry->st_databaseid != InvalidOid)
+			values[0] = ObjectIdGetDatum(procentry->st_databaseid);
+		else
+			nulls[0] = true;
+
+		values[1] = Int32GetDatum(procentry->st_procpid);
+
+		if (procentry->st_userid != InvalidOid)
+			values[2] = ObjectIdGetDatum(procentry->st_userid);
+		else
+			nulls[2] = true;
+
+		if (procentry->st_appname)
+			values[3] = CStringGetTextDatum(procentry->st_appname);
 		else
 			nulls[3] = true;
 
-		if (TransactionIdIsValid(local_beentry->backend_xid))
-			values[15] = TransactionIdGetDatum(local_beentry->backend_xid);
+		if (TransactionIdIsValid(local_procentry->backend_xid))
+			values[15] = TransactionIdGetDatum(local_procentry->backend_xid);
 		else
 			nulls[15] = true;
 
-		if (TransactionIdIsValid(local_beentry->backend_xmin))
-			values[16] = TransactionIdGetDatum(local_beentry->backend_xmin);
+		if (TransactionIdIsValid(local_procentry->backend_xmin))
+			values[16] = TransactionIdGetDatum(local_procentry->backend_xmin);
 		else
 			nulls[16] = true;
 
-		if (beentry->st_ssl)
+		if (procentry->st_ssl)
 		{
 			values[17] = BoolGetDatum(true);	/* ssl */
-			values[18] = CStringGetTextDatum(beentry->st_sslstatus->ssl_version);
-			values[19] = CStringGetTextDatum(beentry->st_sslstatus->ssl_cipher);
-			values[20] = Int32GetDatum(beentry->st_sslstatus->ssl_bits);
-			values[21] = BoolGetDatum(beentry->st_sslstatus->ssl_compression);
-			values[22] = CStringGetTextDatum(beentry->st_sslstatus->ssl_clientdn);
+			values[18] = CStringGetTextDatum(procentry->st_sslstatus->ssl_version);
+			values[19] = CStringGetTextDatum(procentry->st_sslstatus->ssl_cipher);
+			values[20] = Int32GetDatum(procentry->st_sslstatus->ssl_bits);
+			values[21] = BoolGetDatum(procentry->st_sslstatus->ssl_compression);
+			values[22] = CStringGetTextDatum(procentry->st_sslstatus->ssl_clientdn);
 		}
 		else
 		{
@@ -649,11 +659,11 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 		}
 
 		/* Values only available to role member */
-		if (has_privs_of_role(GetUserId(), beentry->st_userid))
+		if (has_privs_of_role(GetUserId(), procentry->st_userid))
 		{
 			SockAddr	zero_clientaddr;
 
-			switch (beentry->st_state)
+			switch (procentry->st_state)
 			{
 				case STATE_IDLE:
 					values[4] = CStringGetTextDatum("idle");
@@ -678,9 +688,9 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 					break;
 			}
 
-			values[5] = CStringGetTextDatum(beentry->st_activity);
+			values[5] = CStringGetTextDatum(procentry->st_activity);
 
-			proc = BackendPidGetProc(beentry->st_procpid);
+			proc = BackendPidGetProc(procentry->st_procpid);
 			if (proc != NULL)
 			{
 				uint32		raw_wait_event;
@@ -690,6 +700,22 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 				wait_event = pgstat_get_wait_event(raw_wait_event);
 
 			}
+			else if (procentry->st_procType != PROC_BACKEND)
+			{
+				uint32		raw_wait_event;
+
+				/*
+				 * For auxiliary process, retrieve proc info from
+				 * AuxiliaryProcs stored in shared-mem.
+				 */
+				proc = AuxiliaryPidGetProc(procentry->st_procpid);
+
+				/* Check whether this is indeed an auxiliary process */
+				Assert(proc != NULL);
+				raw_wait_event = UINT32_ACCESS_ONCE(proc->wait_event_info);
+				wait_event_type = pgstat_get_wait_event_type(raw_wait_event);
+				wait_event = pgstat_get_wait_event(raw_wait_event);
+			}
 			else
 			{
 				wait_event_type = NULL;
@@ -706,29 +732,29 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			else
 				nulls[7] = true;
 
-			if (beentry->st_xact_start_timestamp != 0)
-				values[8] = TimestampTzGetDatum(beentry->st_xact_start_timestamp);
+			if (procentry->st_xact_start_timestamp != 0)
+				values[8] = TimestampTzGetDatum(procentry->st_xact_start_timestamp);
 			else
 				nulls[8] = true;
 
-			if (beentry->st_activity_start_timestamp != 0)
-				values[9] = TimestampTzGetDatum(beentry->st_activity_start_timestamp);
+			if (procentry->st_activity_start_timestamp != 0)
+				values[9] = TimestampTzGetDatum(procentry->st_activity_start_timestamp);
 			else
 				nulls[9] = true;
 
-			if (beentry->st_proc_start_timestamp != 0)
-				values[10] = TimestampTzGetDatum(beentry->st_proc_start_timestamp);
+			if (procentry->st_proc_start_timestamp != 0)
+				values[10] = TimestampTzGetDatum(procentry->st_proc_start_timestamp);
 			else
 				nulls[10] = true;
 
-			if (beentry->st_state_start_timestamp != 0)
-				values[11] = TimestampTzGetDatum(beentry->st_state_start_timestamp);
+			if (procentry->st_state_start_timestamp != 0)
+				values[11] = TimestampTzGetDatum(procentry->st_state_start_timestamp);
 			else
 				nulls[11] = true;
 
 			/* A zeroed client addr means we don't know */
 			memset(&zero_clientaddr, 0, sizeof(zero_clientaddr));
-			if (memcmp(&(beentry->st_clientaddr), &zero_clientaddr,
+			if (memcmp(&(procentry->st_clientaddr), &zero_clientaddr,
 					   sizeof(zero_clientaddr)) == 0)
 			{
 				nulls[12] = true;
@@ -737,9 +763,9 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			}
 			else
 			{
-				if (beentry->st_clientaddr.addr.ss_family == AF_INET
+				if (procentry->st_clientaddr.addr.ss_family == AF_INET
 #ifdef HAVE_IPV6
-					|| beentry->st_clientaddr.addr.ss_family == AF_INET6
+					|| procentry->st_clientaddr.addr.ss_family == AF_INET6
 #endif
 					)
 				{
@@ -749,19 +775,19 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 
 					remote_host[0] = '\0';
 					remote_port[0] = '\0';
-					ret = pg_getnameinfo_all(&beentry->st_clientaddr.addr,
-											 beentry->st_clientaddr.salen,
+					ret = pg_getnameinfo_all(&procentry->st_clientaddr.addr,
+											 procentry->st_clientaddr.salen,
 											 remote_host, sizeof(remote_host),
 											 remote_port, sizeof(remote_port),
 											 NI_NUMERICHOST | NI_NUMERICSERV);
 					if (ret == 0)
 					{
-						clean_ipv6_addr(beentry->st_clientaddr.addr.ss_family, remote_host);
+						clean_ipv6_addr(procentry->st_clientaddr.addr.ss_family, remote_host);
 						values[12] = DirectFunctionCall1(inet_in,
 											   CStringGetDatum(remote_host));
-						if (beentry->st_clienthostname &&
-							beentry->st_clienthostname[0])
-							values[13] = CStringGetTextDatum(beentry->st_clienthostname);
+						if (procentry->st_clienthostname &&
+							procentry->st_clienthostname[0])
+							values[13] = CStringGetTextDatum(procentry->st_clienthostname);
 						else
 							nulls[13] = true;
 						values[14] = Int32GetDatum(atoi(remote_port));
@@ -773,7 +799,7 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 						nulls[14] = true;
 					}
 				}
-				else if (beentry->st_clientaddr.addr.ss_family == AF_UNIX)
+				else if (procentry->st_clientaddr.addr.ss_family == AF_UNIX)
 				{
 					/*
 					 * Unix sockets always reports NULL for host and -1 for
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index 9f938f2..f8c36c0 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -809,7 +809,7 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 		InitializeClientEncoding();
 
 		/* report this backend in the PgBackendStatus array */
-		pgstat_bestart();
+		pgstat_procstart();
 
 		/* close the transaction we started above */
 		CommitTransactionCommand();
@@ -1021,7 +1021,7 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 
 	/* report this backend in the PgBackendStatus array */
 	if (!bootstrap)
-		pgstat_bestart();
+		pgstat_procstart();
 
 	/* close the transaction we started above */
 	if (!bootstrap)
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 60c78d1..440e78d 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -41,6 +41,9 @@ typedef enum TrackFunctionsLevel
 	TRACK_FUNC_ALL
 }	TrackFunctionsLevel;
 
+/* Total number of PG processes */
+#define NumProcStatSlots	(MaxBackends + NUM_AUXPROCTYPES)
+
 /* ----------
  * The types of backend -> collector messages
  * ----------
@@ -696,6 +699,23 @@ typedef struct PgStat_GlobalStats
 
 
 /* ----------
+ * Process types
+ * ----------
+ */
+typedef enum ProcType
+{
+	PROC_BACKEND,
+	PROC_AUTOVAC_LAUNCHER,
+	PROC_WAL_SENDER,
+	PROC_BG_WORKER,
+	PROC_BG_WRITER,
+	PROC_CHECKPOINTER,
+	PROC_WAL_WRITER,
+	PROC_WAL_RECEIVER
+} ProcType;
+
+
+/* ----------
  * Backend states
  * ----------
  */
@@ -847,6 +867,12 @@ typedef struct PgBackendSSLStatus
  * showing its current activity.  (The structs are allocated according to
  * BackendId, but that is not critical.)  Note that the collector process
  * has no involvement in, or even access to, these structs.
+ *
+ * Each auxliliary process also maintains a PgBackendStatus struct in shared
+ * memory.
+ * XXX: PgBackendStatus should be renamed as PgProcStatus since it is used for
+ * backends as well as auxiliary process. But, to avoid massive code refactoring,
+ * we've kept it this way for now.
  * ----------
  */
 typedef struct PgBackendStatus
@@ -871,6 +897,9 @@ typedef struct PgBackendStatus
 	/* The entry is valid iff st_procpid > 0, unused if st_procpid == 0 */
 	int			st_procpid;
 
+	/* Type of process */
+	ProcType	st_procType;
+
 	/* Times when current backend, transaction, and activity started */
 	TimestampTz st_proc_start_timestamp;
 	TimestampTz st_xact_start_timestamp;
@@ -1058,7 +1087,7 @@ extern void pgstat_report_recovery_conflict(int reason);
 extern void pgstat_report_deadlock(void);
 
 extern void pgstat_initialize(void);
-extern void pgstat_bestart(void);
+extern void pgstat_procstart(void);
 
 extern void pgstat_report_activity(BackendState state, const char *cmd_str);
 extern void pgstat_report_tempfile(size_t filesize);
@@ -1069,6 +1098,7 @@ extern const char *pgstat_get_wait_event_type(uint32 wait_event_info);
 extern const char *pgstat_get_backend_current_activity(int pid, bool checkUser);
 extern const char *pgstat_get_crashed_backend_activity(int pid, char *buffer,
 									int buflen);
+extern const char *pgstat_get_proctype_desc(ProcType procType);
 
 extern void pgstat_progress_start_command(ProgressCommandType cmdtype,
 							  Oid relid);
@@ -1212,8 +1242,11 @@ extern PgStat_StatDBEntry *pgstat_fetch_stat_dbentry(Oid dbid);
 extern PgStat_StatTabEntry *pgstat_fetch_stat_tabentry(Oid relid);
 extern PgBackendStatus *pgstat_fetch_stat_beentry(int beid);
 extern LocalPgBackendStatus *pgstat_fetch_stat_local_beentry(int beid);
+extern PgBackendStatus *pgstat_fetch_stat_procentry(int procid);
+extern LocalPgBackendStatus *pgstat_fetch_stat_local_procentry(int procid);
 extern PgStat_StatFuncEntry *pgstat_fetch_stat_funcentry(Oid funcid);
 extern int	pgstat_fetch_stat_numbackends(void);
+extern int	pgstat_fetch_stat_numprocs(void);
 extern PgStat_ArchiverStats *pgstat_fetch_stat_archiver(void);
 extern PgStat_GlobalStats *pgstat_fetch_global(void);
 
diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h
index 5f38fa6..be3bd01 100644
--- a/src/include/storage/proc.h
+++ b/src/include/storage/proc.h
@@ -262,6 +262,7 @@ extern PGPROC *PreparedXactProcs;
  */
 #define NUM_AUXILIARY_PROCS		4
 
+extern PGPROC *AuxiliaryPidGetProc(int pid);
 
 /* configurable options */
 extern int	DeadlockTimeout;
-- 
1.8.3.1

From e1ee0a536b38540ff2251277b424590f5c392c9a Mon Sep 17 00:00:00 2001
From: Kuntal Ghosh <kuntal.ghosh@enterprisedb.com>
Date: Wed, 15 Feb 2017 16:26:20 +0530
Subject: [PATCH] Expose stats for auxiliary processes in pg_stat_get_activity

---
 src/backend/bootstrap/bootstrap.c     |  3 +++
 src/backend/postmaster/bgwriter.c     |  6 ++++++
 src/backend/postmaster/checkpointer.c |  7 +++++++
 src/backend/postmaster/pgstat.c       |  3 ++-
 src/backend/postmaster/walwriter.c    |  7 +++++++
 src/backend/replication/walreceiver.c | 14 ++++++++++++++
 src/backend/replication/walsender.c   |  7 +++++++
 7 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/src/backend/bootstrap/bootstrap.c b/src/backend/bootstrap/bootstrap.c
index 6511c60..f56e229 100644
--- a/src/backend/bootstrap/bootstrap.c
+++ b/src/backend/bootstrap/bootstrap.c
@@ -387,6 +387,9 @@ AuxiliaryProcessMain(int argc, char *argv[])
 		/* finish setting up bufmgr.c */
 		InitBufferPoolBackend();
 
+		/* Initialize stats collection */
+		pgstat_initialize();
+
 		/* register a before-shutdown callback for LWLock cleanup */
 		before_shmem_exit(ShutdownAuxiliaryProcess, 0);
 	}
diff --git a/src/backend/postmaster/bgwriter.c b/src/backend/postmaster/bgwriter.c
index dcb4cf2..1e8bbc3 100644
--- a/src/backend/postmaster/bgwriter.c
+++ b/src/backend/postmaster/bgwriter.c
@@ -248,6 +248,9 @@ BackgroundWriterMain(void)
 	 */
 	prev_hibernate = false;
 
+	/* report writer process in the PgBackendStatus array */
+	pgstat_procstart();
+
 	/*
 	 * Loop forever
 	 */
@@ -284,6 +287,7 @@ BackgroundWriterMain(void)
 		 * Send off activity statistics to the stats collector
 		 */
 		pgstat_send_bgwriter();
+		pgstat_report_activity(STATE_RUNNING, NULL);
 
 		if (FirstCallSinceLastCheckpoint())
 		{
@@ -345,6 +349,8 @@ BackgroundWriterMain(void)
 		 * down with latch events that are likely to happen frequently during
 		 * normal operation.
 		 */
+		pgstat_report_activity(STATE_IDLE, NULL);
+
 		rc = WaitLatch(MyLatch,
 					   WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
 					   BgWriterDelay /* ms */, WAIT_EVENT_BGWRITER_MAIN);
diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c
index fe9041f..62a3f7c 100644
--- a/src/backend/postmaster/checkpointer.c
+++ b/src/backend/postmaster/checkpointer.c
@@ -345,6 +345,9 @@ CheckpointerMain(void)
 	 */
 	ProcGlobal->checkpointerLatch = &MyProc->procLatch;
 
+	/* report checkpointer proc in the PgBackendStatus array */
+	pgstat_procstart();
+
 	/*
 	 * Loop forever
 	 */
@@ -365,6 +368,8 @@ CheckpointerMain(void)
 		 */
 		AbsorbFsyncRequests();
 
+		pgstat_report_activity(STATE_RUNNING, NULL);
+
 		if (got_SIGHUP)
 		{
 			got_SIGHUP = false;
@@ -556,6 +561,8 @@ CheckpointerMain(void)
 			cur_timeout = Min(cur_timeout, XLogArchiveTimeout - elapsed_secs);
 		}
 
+		pgstat_report_activity(STATE_IDLE, NULL);
+
 		rc = WaitLatch(MyLatch,
 					   WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
 					   cur_timeout * 1000L /* convert to ms */,
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index a530c3b..166c351 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -2744,7 +2744,8 @@ pgstat_initialize(void)
  * pgstat_procstart() -
  *
  *	Initialize this process's entry in the PgBackendStatus array.
- *	Called from InitPostgres.
+ *	Called from InitPostgres and other main entrypoints for
+ *	auxiliary processes.
  *
  *	For a backend process, MyDatabaseId, session userid,
  *	and application_name must be set (hence, this cannot be combined
diff --git a/src/backend/postmaster/walwriter.c b/src/backend/postmaster/walwriter.c
index a575d8f..dfb641b 100644
--- a/src/backend/postmaster/walwriter.c
+++ b/src/backend/postmaster/walwriter.c
@@ -231,6 +231,9 @@ WalWriterMain(void)
 	 */
 	ProcGlobal->walwriterLatch = &MyProc->procLatch;
 
+	/* report walwriter proc in the PgBackendStatus array */
+	pgstat_procstart();
+
 	/*
 	 * Loop forever
 	 */
@@ -257,6 +260,8 @@ WalWriterMain(void)
 		/* Clear any already-pending wakeups */
 		ResetLatch(MyLatch);
 
+		pgstat_report_activity(STATE_RUNNING, NULL);
+
 		/*
 		 * Process any requests or signals received recently.
 		 */
@@ -290,6 +295,8 @@ WalWriterMain(void)
 		else
 			cur_timeout = WalWriterDelay * HIBERNATE_FACTOR;
 
+		pgstat_report_activity(STATE_IDLE, NULL);
+
 		rc = WaitLatch(MyLatch,
 					   WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
 					   cur_timeout,
diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index 18d9d7e..9232790 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -316,6 +316,10 @@ WalReceiverMain(void)
 	SpinLockRelease(&walrcv->mutex);
 
 	first_stream = true;
+
+	/* report walreceiver proc in the PgBackendStatus array */
+	pgstat_procstart();
+
 	for (;;)
 	{
 		char	   *primary_sysid;
@@ -323,6 +327,8 @@ WalReceiverMain(void)
 		int			server_version;
 		WalRcvStreamOptions options;
 
+		pgstat_report_activity(STATE_RUNNING, NULL);
+
 		/*
 		 * Check that we're connected to a valid server using the
 		 * IDENTIFY_SYSTEM replication command.
@@ -423,6 +429,8 @@ WalReceiverMain(void)
 				/* Process any requests or signals received recently */
 				ProcessWalRcvInterrupts();
 
+				pgstat_report_activity(STATE_RUNNING, NULL);
+
 				if (got_SIGHUP)
 				{
 					got_SIGHUP = false;
@@ -491,6 +499,8 @@ WalReceiverMain(void)
 				 * could add and remove just the socket each time, potentially
 				 * avoiding some system calls.
 				 */
+				pgstat_report_activity(STATE_IDLE, NULL);
+
 				Assert(wait_fd != PGINVALID_SOCKET);
 				rc = WaitLatchOrSocket(walrcv->latch,
 								   WL_POSTMASTER_DEATH | WL_SOCKET_READABLE |
@@ -663,6 +673,8 @@ WalRcvWaitForStartPosition(XLogRecPtr *startpoint, TimeLineID *startpointTLI)
 	{
 		ResetLatch(walrcv->latch);
 
+		pgstat_report_activity(STATE_RUNNING, NULL);
+
 		/*
 		 * Emergency bailout if postmaster has died.  This is to avoid the
 		 * necessity for manual cleanup of all postmaster children.
@@ -696,6 +708,8 @@ WalRcvWaitForStartPosition(XLogRecPtr *startpoint, TimeLineID *startpointTLI)
 		}
 		SpinLockRelease(&walrcv->mutex);
 
+		pgstat_report_activity(STATE_IDLE, NULL);
+
 		WaitLatch(walrcv->latch, WL_LATCH_SET | WL_POSTMASTER_DEATH, 0,
 				  WAIT_EVENT_WAL_RECEIVER_WAIT_START);
 	}
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index dd3a936..8204e1c 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -244,6 +244,9 @@ InitWalSender(void)
 	 */
 	MarkPostmasterChildWalSender();
 	SendPostmasterSignal(PMSIGNAL_ADVANCE_STATE_MACHINE);
+
+	/* report walsender proc in the PgBackendStatus array */
+	pgstat_procstart();
 }
 
 /*
@@ -1778,6 +1781,8 @@ WalSndLoop(WalSndSendDataCallback send_data)
 
 		CHECK_FOR_INTERRUPTS();
 
+		pgstat_report_activity(STATE_RUNNING, NULL);
+
 		/* Process any requests or signals received recently */
 		if (got_SIGHUP)
 		{
@@ -1872,6 +1877,8 @@ WalSndLoop(WalSndSendDataCallback send_data)
 				wakeEvents |= WL_SOCKET_WRITEABLE;
 
 			/* Sleep until something happens or we time out */
+			pgstat_report_activity(STATE_IDLE, NULL);
+
 			WaitLatchOrSocket(MyLatch, wakeEvents,
 							  MyProcPort->sock, sleeptime,
 							  WAIT_EVENT_WAL_SENDER_MAIN);
-- 
1.8.3.1

From 1b96d656fae4c038e7fdac9a252b3b86bbea94ee Mon Sep 17 00:00:00 2001
From: Kuntal Ghosh <kuntal.ghosh@enterprisedb.com>
Date: Wed, 15 Feb 2017 17:18:32 +0530
Subject: [PATCH] Expose stats for autovacuum launcher and bgworker

---
 src/backend/postmaster/autovacuum.c        |  4 ++++
 src/backend/replication/logical/launcher.c |  4 ++++
 src/backend/utils/init/postinit.c          | 16 +++++++++++++++-
 3 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index 0c5ffa0..f6132bc 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -597,6 +597,8 @@ AutoVacLauncherMain(int argc, char *argv[])
 		 * Wait until naptime expires or we get some type of signal (all the
 		 * signal handlers will wake us by calling SetLatch).
 		 */
+		pgstat_report_activity(STATE_IDLE, NULL);
+
 		rc = WaitLatch(MyLatch,
 					   WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
 					   (nap.tv_sec * 1000L) + (nap.tv_usec / 1000L),
@@ -614,6 +616,8 @@ AutoVacLauncherMain(int argc, char *argv[])
 		if (rc & WL_POSTMASTER_DEATH)
 			proc_exit(1);
 
+		pgstat_report_activity(STATE_RUNNING, NULL);
+
 		/* the normal shutdown case */
 		if (got_SIGTERM)
 			break;
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 39530f96..2f927c8 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -590,6 +590,8 @@ ApplyLauncherMain(Datum main_arg)
 
 		now = GetCurrentTimestamp();
 
+		pgstat_report_activity(STATE_RUNNING, NULL);
+
 		/* Limit the start retry to once a wal_retrieve_retry_interval */
 		if (TimestampDifferenceExceeds(last_start_time, now,
 									   wal_retrieve_retry_interval))
@@ -647,6 +649,8 @@ ApplyLauncherMain(Datum main_arg)
 		}
 
 		/* Wait for more work. */
+		pgstat_report_activity(STATE_IDLE, NULL);
+
 		rc = WaitLatch(&MyProc->procLatch,
 					   WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,
 					   wait_time,
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index f8c36c0..b831cf9 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -665,7 +665,14 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 
 	/* The autovacuum launcher is done here */
 	if (IsAutoVacuumLauncherProcess())
+	{
+		/*
+		 * Before returning, report autovacuum launcher process in the
+		 * PgBackendStatus array.
+		 */
+		pgstat_procstart();
 		return;
+	}
 
 	/*
 	 * Start a new transaction here before first access to db, and get a
@@ -808,7 +815,7 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 		/* initialize client encoding */
 		InitializeClientEncoding();
 
-		/* report this backend in the PgBackendStatus array */
+		/* report walsender process in the PgBackendStatus array */
 		pgstat_procstart();
 
 		/* close the transaction we started above */
@@ -875,6 +882,13 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 		 */
 		if (!bootstrap)
 			CommitTransactionCommand();
+
+		/*
+		 * Before returning, report the background worker process in the
+		 * PgBackendStatus array.
+		 */
+		if (!bootstrap)
+			pgstat_procstart();
 		return;
 	}
 
-- 
1.8.3.1

From c751597a2fd168995fa2cb531f0bc2bf69b5f268 Mon Sep 17 00:00:00 2001
From: Kuntal Ghosh <kuntal.ghosh@enterprisedb.com>
Date: Wed, 15 Feb 2017 17:41:08 +0530
Subject: [PATCH] Add proc_type column in pg_stat_get_activity

proc_type indicates the type of process in the stat table.
---
 doc/src/sgml/monitoring.sgml         | 11 +++++++++--
 src/backend/catalog/system_views.sql |  3 ++-
 src/backend/utils/adt/pgstatfuncs.c  |  5 ++++-
 src/include/catalog/pg_proc.h        |  2 +-
 src/test/regress/expected/rules.out  |  9 +++++----
 5 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 4d03531..059bb1e 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -620,8 +620,7 @@ postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: ser
     <row>
      <entry><structfield>backend_start</></entry>
      <entry><type>timestamp with time zone</></entry>
-     <entry>Time when this process was started, i.e., when the
-      client connected to the server
+     <entry>Time when this process was started.
      </entry>
     </row>
     <row>
@@ -791,6 +790,14 @@ postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: ser
       <xref linkend="guc-track-activity-query-size">.
      </entry>
     </row>
+    <row>
+     <entry><structfield>proc_type</structfield></entry>
+     <entry><type>text</type></entry>
+     <entry>Type of the current server process. Possible types are:
+      autovacuum launcher, bgworker, checkpointer, client backend,
+      wal receiver, wal sender, wal writer and writer.
+     </entry>
+    </row>
    </tbody>
    </tgroup>
   </table>
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index ba980de..9108445 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -684,7 +684,8 @@ CREATE VIEW pg_stat_activity AS
             S.state,
             S.backend_xid,
             s.backend_xmin,
-            S.query
+            S.query,
+            S.proc_type
     FROM pg_stat_get_activity(NULL) AS S
         LEFT JOIN pg_database AS D ON (S.datid = D.oid)
         LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 8bb9b7e..e1099ab 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -539,7 +539,7 @@ pg_stat_get_progress_info(PG_FUNCTION_ARGS)
 Datum
 pg_stat_get_activity(PG_FUNCTION_ARGS)
 {
-#define PG_STAT_GET_ACTIVITY_COLS	23
+#define PG_STAT_GET_ACTIVITY_COLS	24
 	int			num_procs = pgstat_fetch_stat_numprocs();
 	int			curr_proc;
 	int			pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
@@ -819,6 +819,8 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 					nulls[14] = true;
 				}
 			}
+			/* Add process type */
+			values[23] = CStringGetTextDatum(pgstat_get_proctype_desc(procentry->st_procType));
 		}
 		else
 		{
@@ -834,6 +836,7 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			nulls[12] = true;
 			nulls[13] = true;
 			nulls[14] = true;
+			nulls[23] = true;
 		}
 
 		tuplestore_putvalues(tupstore, tupdesc, values, nulls);
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index ec4aedb..1c747fe 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -2768,7 +2768,7 @@ DATA(insert OID = 3057 ( pg_stat_get_autoanalyze_count PGNSP PGUID 12 1 0 0 0 f
 DESCR("statistics: number of auto analyzes for a table");
 DATA(insert OID = 1936 (  pg_stat_get_backend_idset		PGNSP PGUID 12 1 100 0 0 f f f f t t s r 0 0 23 "" _null_ _null_ _null_ _null_ _null_ pg_stat_get_backend_idset _null_ _null_ _null_ ));
 DESCR("statistics: currently active backend IDs");
-DATA(insert OID = 2022 (  pg_stat_get_activity			PGNSP PGUID 12 1 100 0 0 f f f f f t s r 1 0 2249 "23" "{23,26,23,26,25,25,25,25,25,1184,1184,1184,1184,869,25,23,28,28,16,25,25,23,16,25}" "{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,ssl,sslversion,sslcipher,sslbits,sslcompression,sslclientdn}" _null_ _null_ pg_stat_get_activity _null_ _null_ _null_ ));
+DATA(insert OID = 2022 (  pg_stat_get_activity			PGNSP PGUID 12 1 100 0 0 f f f f f t s r 1 0 2249 "23" "{23,26,23,26,25,25,25,25,25,1184,1184,1184,1184,869,25,23,28,28,16,25,25,23,16,25,25}" "{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,ssl,sslversion,sslcipher,sslbits,sslcompression,sslclientdn,proc_type}" _null_ _null_ pg_stat_get_activity _null_ _null_ _null_ ));
 DESCR("statistics: information about currently active backends");
 DATA(insert OID = 3318 (  pg_stat_get_progress_info			  PGNSP PGUID 12 1 100 0 0 f f f f t t s r 1 0 2249 "25" "{25,23,26,26,20,20,20,20,20,20,20,20,20,20}" "{i,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{cmdtype,pid,datid,relid,param1,param2,param3,param4,param5,param6,param7,param8,param9,param10}" _null_ _null_ pg_stat_get_progress_info _null_ _null_ _null_ ));
 DESCR("statistics: information about progress of backends running maintenance command");
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index c661f1d..69d61c6 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1704,8 +1704,9 @@ pg_stat_activity| SELECT s.datid,
     s.state,
     s.backend_xid,
     s.backend_xmin,
-    s.query
-   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn)
+    s.query,
+    s.proc_type
+   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn, proc_type)
      LEFT JOIN pg_database d ON ((s.datid = d.oid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_all_indexes| SELECT c.oid AS relid,
@@ -1833,7 +1834,7 @@ pg_stat_replication| SELECT s.pid,
     w.replay_location,
     w.sync_priority,
     w.sync_state
-   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn)
+   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn, proc_type)
      JOIN pg_stat_get_wal_senders() w(pid, state, sent_location, write_location, flush_location, replay_location, sync_priority, sync_state) ON ((s.pid = w.pid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_ssl| SELECT s.pid,
@@ -1843,7 +1844,7 @@ pg_stat_ssl| SELECT s.pid,
     s.sslbits AS bits,
     s.sslcompression AS compression,
     s.sslclientdn AS clientdn
-   FROM pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn);
+   FROM pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn, proc_type);
 pg_stat_subscription| SELECT su.oid AS subid,
     su.subname,
     st.pid,
-- 
1.8.3.1

From e06a4a0e415190971dcbb21ef107fab5944ca5e7 Mon Sep 17 00:00:00 2001
From: Kuntal Ghosh <kuntal.ghosh@enterprisedb.com>
Date: Wed, 15 Mar 2017 12:53:11 +0530
Subject: [PATCH 3/3] Add backend_type column in pg_stat_get_activity

backend_type indicates the type of process in the stat table.
---
 doc/src/sgml/monitoring.sgml         | 14 ++++++++++++--
 src/backend/catalog/system_views.sql |  3 ++-
 src/backend/utils/adt/pgstatfuncs.c  |  5 ++++-
 src/include/catalog/pg_proc.h        |  2 +-
 src/test/regress/expected/rules.out  |  9 +++++----
 5 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 9eaf43a..695928f 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -620,8 +620,7 @@ postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: ser
     <row>
      <entry><structfield>backend_start</></entry>
      <entry><type>timestamp with time zone</></entry>
-     <entry>Time when this process was started, i.e., when the
-      client connected to the server
+     <entry>Time when this process was started.
      </entry>
     </row>
     <row>
@@ -791,6 +790,17 @@ postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: ser
       <xref linkend="guc-track-activity-query-size">.
      </entry>
     </row>
+    <row>
+     <entry><structfield>backend_type</structfield></entry>
+     <entry><type>text</type></entry>
+     <entry>Type of current backend. Possible types are 
+      <literal>autovacuum launcher</>, <literal>autovacuum worker</>,
+      <literal>bgworker</>, <literal>background writer</>,
+      <literal>client backend</>, <literal>checkpointer</>,
+      <literal>startup</>, <literal>walreceiver</>,
+      <literal>walsender</> and <literal>walwriter</>.
+     </entry>
+    </row>
    </tbody>
    </tgroup>
   </table>
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 0bce209..67351f9 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -684,7 +684,8 @@ CREATE VIEW pg_stat_activity AS
             S.state,
             S.backend_xid,
             s.backend_xmin,
-            S.query
+            S.query,
+            S.backend_type
     FROM pg_stat_get_activity(NULL) AS S
         LEFT JOIN pg_database AS D ON (S.datid = D.oid)
         LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 96a1188..02a164b 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -539,7 +539,7 @@ pg_stat_get_progress_info(PG_FUNCTION_ARGS)
 Datum
 pg_stat_get_activity(PG_FUNCTION_ARGS)
 {
-#define PG_STAT_GET_ACTIVITY_COLS	23
+#define PG_STAT_GET_ACTIVITY_COLS	24
 	int			num_backends = pgstat_fetch_stat_numbackends();
 	int			curr_backend;
 	int			pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
@@ -819,6 +819,8 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 					nulls[14] = true;
 				}
 			}
+			/* Add process type */
+			values[23] = CStringGetTextDatum(pgstat_get_backend_desc(beentry->st_backendType));
 		}
 		else
 		{
@@ -834,6 +836,7 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			nulls[12] = true;
 			nulls[13] = true;
 			nulls[14] = true;
+			nulls[23] = true;
 		}
 
 		tuplestore_putvalues(tupstore, tupdesc, values, nulls);
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index ec4aedb..6d37484 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -2768,7 +2768,7 @@ DATA(insert OID = 3057 ( pg_stat_get_autoanalyze_count PGNSP PGUID 12 1 0 0 0 f
 DESCR("statistics: number of auto analyzes for a table");
 DATA(insert OID = 1936 (  pg_stat_get_backend_idset		PGNSP PGUID 12 1 100 0 0 f f f f t t s r 0 0 23 "" _null_ _null_ _null_ _null_ _null_ pg_stat_get_backend_idset _null_ _null_ _null_ ));
 DESCR("statistics: currently active backend IDs");
-DATA(insert OID = 2022 (  pg_stat_get_activity			PGNSP PGUID 12 1 100 0 0 f f f f f t s r 1 0 2249 "23" "{23,26,23,26,25,25,25,25,25,1184,1184,1184,1184,869,25,23,28,28,16,25,25,23,16,25}" "{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,ssl,sslversion,sslcipher,sslbits,sslcompression,sslclientdn}" _null_ _null_ pg_stat_get_activity _null_ _null_ _null_ ));
+DATA(insert OID = 2022 (  pg_stat_get_activity			PGNSP PGUID 12 1 100 0 0 f f f f f t s r 1 0 2249 "23" "{23,26,23,26,25,25,25,25,25,1184,1184,1184,1184,869,25,23,28,28,16,25,25,23,16,25,25}" "{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,ssl,sslversion,sslcipher,sslbits,sslcompression,sslclientdn,backend_type}" _null_ _null_ pg_stat_get_activity _null_ _null_ _null_ ));
 DESCR("statistics: information about currently active backends");
 DATA(insert OID = 3318 (  pg_stat_get_progress_info			  PGNSP PGUID 12 1 100 0 0 f f f f t t s r 1 0 2249 "25" "{25,23,26,26,20,20,20,20,20,20,20,20,20,20}" "{i,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{cmdtype,pid,datid,relid,param1,param2,param3,param4,param5,param6,param7,param8,param9,param10}" _null_ _null_ pg_stat_get_progress_info _null_ _null_ _null_ ));
 DESCR("statistics: information about progress of backends running maintenance command");
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index bd13ae6..a317bff 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1704,8 +1704,9 @@ pg_stat_activity| SELECT s.datid,
     s.state,
     s.backend_xid,
     s.backend_xmin,
-    s.query
-   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn)
+    s.query,
+    s.backend_type
+   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn, backend_type)
      LEFT JOIN pg_database d ON ((s.datid = d.oid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_all_indexes| SELECT c.oid AS relid,
@@ -1833,7 +1834,7 @@ pg_stat_replication| SELECT s.pid,
     w.replay_location,
     w.sync_priority,
     w.sync_state
-   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn)
+   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn, backend_type)
      JOIN pg_stat_get_wal_senders() w(pid, state, sent_location, write_location, flush_location, replay_location, sync_priority, sync_state) ON ((s.pid = w.pid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_ssl| SELECT s.pid,
@@ -1843,7 +1844,7 @@ pg_stat_ssl| SELECT s.pid,
     s.sslbits AS bits,
     s.sslcompression AS compression,
     s.sslclientdn AS clientdn
-   FROM pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn);
+   FROM pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn, backend_type);
 pg_stat_subscription| SELECT su.oid AS subid,
     su.subname,
     st.pid,
-- 
1.8.3.1

From 13b82c63aae4f0a0529abca65cd1f570ebcdfd12 Mon Sep 17 00:00:00 2001
From: Kuntal Ghosh <kuntal.ghosh@enterprisedb.com>
Date: Wed, 15 Mar 2017 12:27:00 +0530
Subject: [PATCH 2/3] Expose stats for all backends

All backends include auxiliary procs, autovacuum launcher and
bgworkers.
---
 src/backend/bootstrap/bootstrap.c     |  3 +++
 src/backend/postmaster/bgwriter.c     |  3 +++
 src/backend/postmaster/checkpointer.c |  3 +++
 src/backend/postmaster/pgstat.c       |  3 ++-
 src/backend/postmaster/startup.c      |  4 ++++
 src/backend/postmaster/walwriter.c    |  3 +++
 src/backend/replication/walreceiver.c |  4 ++++
 src/backend/replication/walsender.c   |  5 ++++-
 src/backend/utils/init/postinit.c     | 16 +++++++++++++++-
 9 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/src/backend/bootstrap/bootstrap.c b/src/backend/bootstrap/bootstrap.c
index 6511c60..f56e229 100644
--- a/src/backend/bootstrap/bootstrap.c
+++ b/src/backend/bootstrap/bootstrap.c
@@ -387,6 +387,9 @@ AuxiliaryProcessMain(int argc, char *argv[])
 		/* finish setting up bufmgr.c */
 		InitBufferPoolBackend();
 
+		/* Initialize stats collection */
+		pgstat_initialize();
+
 		/* register a before-shutdown callback for LWLock cleanup */
 		before_shmem_exit(ShutdownAuxiliaryProcess, 0);
 	}
diff --git a/src/backend/postmaster/bgwriter.c b/src/backend/postmaster/bgwriter.c
index dcb4cf2..6ba2e2e 100644
--- a/src/backend/postmaster/bgwriter.c
+++ b/src/backend/postmaster/bgwriter.c
@@ -248,6 +248,9 @@ BackgroundWriterMain(void)
 	 */
 	prev_hibernate = false;
 
+	/* report bgwriter process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/*
 	 * Loop forever
 	 */
diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c
index fe9041f..8eb0a2a 100644
--- a/src/backend/postmaster/checkpointer.c
+++ b/src/backend/postmaster/checkpointer.c
@@ -345,6 +345,9 @@ CheckpointerMain(void)
 	 */
 	ProcGlobal->checkpointerLatch = &MyProc->procLatch;
 
+	/* report checkpointer process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/*
 	 * Loop forever
 	 */
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 34cca73..215df08 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -2677,7 +2677,8 @@ pgstat_initialize(void)
  * pgstat_bestart() -
  *
  *	Initialize this backend's entry in the PgBackendStatus array.
- *	Called from InitPostgres.
+ *	Called from InitPostgres and other main entry points for
+ *	auxiliary processes.
  *
  *	Apart from auxiliary processes, MyDatabaseId, session userid,
  *	and application_name must be set for a backend (hence, this
diff --git a/src/backend/postmaster/startup.c b/src/backend/postmaster/startup.c
index b172b5e..56ff042 100644
--- a/src/backend/postmaster/startup.c
+++ b/src/backend/postmaster/startup.c
@@ -25,6 +25,7 @@
 #include "access/xlog.h"
 #include "libpq/pqsignal.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/startup.h"
 #include "storage/ipc.h"
 #include "storage/latch.h"
@@ -210,6 +211,9 @@ StartupProcessMain(void)
 	 */
 	PG_SETMASK(&UnBlockSig);
 
+	/* report startup process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/*
 	 * Do what we came for.
 	 */
diff --git a/src/backend/postmaster/walwriter.c b/src/backend/postmaster/walwriter.c
index a575d8f..9056652 100644
--- a/src/backend/postmaster/walwriter.c
+++ b/src/backend/postmaster/walwriter.c
@@ -231,6 +231,9 @@ WalWriterMain(void)
 	 */
 	ProcGlobal->walwriterLatch = &MyProc->procLatch;
 
+	/* report walwriter process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/*
 	 * Loop forever
 	 */
diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index 18d9d7e..3265d03 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -316,6 +316,10 @@ WalReceiverMain(void)
 	SpinLockRelease(&walrcv->mutex);
 
 	first_stream = true;
+
+	/* report walreceiver process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	for (;;)
 	{
 		char	   *primary_sysid;
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 127efec..9b80284 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -245,6 +245,9 @@ InitWalSender(void)
 	 */
 	MarkPostmasterChildWalSender();
 	SendPostmasterSignal(PMSIGNAL_ADVANCE_STATE_MACHINE);
+
+	/* report walsender process in the PgBackendStatus array */
+	pgstat_bestart();
 }
 
 /*
@@ -1806,7 +1809,7 @@ WalSndLoop(WalSndSendDataCallback send_data)
 	waiting_for_ping_response = false;
 
 	/* Report to pgstat that this process is a WAL sender */
-	pgstat_report_activity(STATE_RUNNING, "walsender");
+	pgstat_report_activity(STATE_RUNNING, NULL);
 
 	/*
 	 * Loop until we reach the end of this timeline or the client requests to
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index 9f938f2..6f88b0f 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -665,7 +665,14 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 
 	/* The autovacuum launcher is done here */
 	if (IsAutoVacuumLauncherProcess())
+	{
+		/*
+		 * Before returning, report autovacuum launcher process in the
+		 * PgBackendStatus array.
+		 */
+		pgstat_bestart();
 		return;
+	}
 
 	/*
 	 * Start a new transaction here before first access to db, and get a
@@ -808,7 +815,7 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 		/* initialize client encoding */
 		InitializeClientEncoding();
 
-		/* report this backend in the PgBackendStatus array */
+		/* report walsender process in the PgBackendStatus array */
 		pgstat_bestart();
 
 		/* close the transaction we started above */
@@ -875,6 +882,13 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 		 */
 		if (!bootstrap)
 			CommitTransactionCommand();
+
+		/*
+		 * Before returning, report the background worker process in the
+		 * PgBackendStatus array.
+		 */
+		if (!bootstrap)
+			pgstat_bestart();
 		return;
 	}
 
-- 
1.8.3.1

From 586019bd39fa5a0665b1e3bd76e1968e4228d626 Mon Sep 17 00:00:00 2001
From: Kuntal Ghosh <kuntal.ghosh@enterprisedb.com>
Date: Wed, 15 Mar 2017 11:32:49 +0530
Subject: [PATCH 1/3] Infra to expose all backend processes in
 pg_stat_get_activity

This patch implements the infrastructure required to expose
all backend processes including auxiliary procs in pg_stat_activity.
BackendStatusArray is extended to store auxiliary processes. Backends
use slots indexed in the range from 1 to MaxBackends (inclusive),
so we use MaxBackends + AuxBackendType + 1 as the index of the slot for an
auxiliary process.
---
 src/backend/postmaster/pgstat.c     | 176 +++++++++++++++++++++++++++++++-----
 src/backend/storage/lmgr/proc.c     |  27 ++++++
 src/backend/utils/adt/pgstatfuncs.c |  30 +++++-
 src/include/pgstat.h                |  30 +++++-
 src/include/storage/proc.h          |   1 +
 5 files changed, 236 insertions(+), 28 deletions(-)

diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 7cacb1e..34cca73 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -50,6 +50,7 @@
 #include "postmaster/autovacuum.h"
 #include "postmaster/fork_process.h"
 #include "postmaster/postmaster.h"
+#include "replication/walsender.h"
 #include "storage/backendid.h"
 #include "storage/dsm.h"
 #include "storage/fd.h"
@@ -212,7 +213,11 @@ typedef struct TwoPhasePgStatRecord
  */
 static MemoryContext pgStatLocalContext = NULL;
 static HTAB *pgStatDBHash = NULL;
+
+/* Status for backends including auxiliary */
 static LocalPgBackendStatus *localBackendStatusTable = NULL;
+
+/* Total number of backends including auxiliary */
 static int	localNumBackends = 0;
 
 /*
@@ -2504,20 +2509,20 @@ BackendStatusShmemSize(void)
 	Size		size;
 
 	/* BackendStatusArray: */
-	size = mul_size(sizeof(PgBackendStatus), MaxBackends);
+	size = mul_size(sizeof(PgBackendStatus), NumBackendStatSlots);
 	/* BackendAppnameBuffer: */
 	size = add_size(size,
-					mul_size(NAMEDATALEN, MaxBackends));
+					mul_size(NAMEDATALEN, NumBackendStatSlots));
 	/* BackendClientHostnameBuffer: */
 	size = add_size(size,
-					mul_size(NAMEDATALEN, MaxBackends));
+					mul_size(NAMEDATALEN, NumBackendStatSlots));
 	/* BackendActivityBuffer: */
 	size = add_size(size,
-					mul_size(pgstat_track_activity_query_size, MaxBackends));
+			mul_size(pgstat_track_activity_query_size, NumBackendStatSlots));
 #ifdef USE_SSL
 	/* BackendSslStatusBuffer: */
 	size = add_size(size,
-					mul_size(sizeof(PgBackendSSLStatus), MaxBackends));
+				  mul_size(sizeof(PgBackendSSLStatus), NumBackendStatSlots));
 #endif
 	return size;
 }
@@ -2535,7 +2540,7 @@ CreateSharedBackendStatus(void)
 	char	   *buffer;
 
 	/* Create or attach to the shared array */
-	size = mul_size(sizeof(PgBackendStatus), MaxBackends);
+	size = mul_size(sizeof(PgBackendStatus), NumBackendStatSlots);
 	BackendStatusArray = (PgBackendStatus *)
 		ShmemInitStruct("Backend Status Array", size, &found);
 
@@ -2558,7 +2563,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_appname pointers. */
 		buffer = BackendAppnameBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumBackendStatSlots; i++)
 		{
 			BackendStatusArray[i].st_appname = buffer;
 			buffer += NAMEDATALEN;
@@ -2576,7 +2581,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_clienthostname pointers. */
 		buffer = BackendClientHostnameBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumBackendStatSlots; i++)
 		{
 			BackendStatusArray[i].st_clienthostname = buffer;
 			buffer += NAMEDATALEN;
@@ -2585,7 +2590,7 @@ CreateSharedBackendStatus(void)
 
 	/* Create or attach to the shared activity buffer */
 	BackendActivityBufferSize = mul_size(pgstat_track_activity_query_size,
-										 MaxBackends);
+										 NumBackendStatSlots);
 	BackendActivityBuffer = (char *)
 		ShmemInitStruct("Backend Activity Buffer",
 						BackendActivityBufferSize,
@@ -2597,7 +2602,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_activity pointers. */
 		buffer = BackendActivityBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumBackendStatSlots; i++)
 		{
 			BackendStatusArray[i].st_activity = buffer;
 			buffer += pgstat_track_activity_query_size;
@@ -2606,7 +2611,7 @@ CreateSharedBackendStatus(void)
 
 #ifdef USE_SSL
 	/* Create or attach to the shared SSL status buffer */
-	size = mul_size(sizeof(PgBackendSSLStatus), MaxBackends);
+	size = mul_size(sizeof(PgBackendSSLStatus), NumBackendStatSlots);
 	BackendSslStatusBuffer = (PgBackendSSLStatus *)
 		ShmemInitStruct("Backend SSL Status Buffer", size, &found);
 
@@ -2618,7 +2623,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_sslstatus pointers. */
 		ptr = BackendSslStatusBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumBackendStatSlots; i++)
 		{
 			BackendStatusArray[i].st_sslstatus = ptr;
 			ptr++;
@@ -2632,7 +2637,8 @@ CreateSharedBackendStatus(void)
  * pgstat_initialize() -
  *
  *	Initialize pgstats state, and set up our on-proc-exit hook.
- *	Called from InitPostgres.  MyBackendId must be set,
+ *	Called from InitPostgres and AuxiliaryProcessMain. For auxiliary process,
+ *	MyBackendId is invalid. Otherwise, MyBackendId must be set,
  *	but we must not have started any transaction yet (since the
  *	exit hook must run after the last transaction exit).
  *	NOTE: MyDatabaseId isn't set yet; so the shutdown hook has to be careful.
@@ -2642,8 +2648,26 @@ void
 pgstat_initialize(void)
 {
 	/* Initialize MyBEEntry */
-	Assert(MyBackendId >= 1 && MyBackendId <= MaxBackends);
-	MyBEEntry = &BackendStatusArray[MyBackendId - 1];
+	if (MyBackendId != InvalidBackendId)
+	{
+		Assert(MyBackendId >= 1 && MyBackendId <= MaxBackends);
+		MyBEEntry = &BackendStatusArray[MyBackendId - 1];
+	}
+	else
+	{
+		/* Must be an auxiliary process */
+		Assert(MyAuxProcType != NotAnAuxProcess);
+
+		/*
+		 * Assign the MyBEEntry for an auxiliary process.  Since it doesn't
+		 * have a BackendId, the slot is statically allocated based on the
+		 * auxiliary process type (MyAuxProcType).  Backends use slots indexed
+		 * in the range from 1 to MaxBackends (inclusive), so we use
+		 * MaxBackends + AuxBackendType + 1 as the index of the slot for an
+		 * auxiliary process.
+		 */
+		MyBEEntry = &BackendStatusArray[MaxBackends + MyAuxProcType];
+	}
 
 	/* Set up a process-exit hook to clean up */
 	on_shmem_exit(pgstat_beshutdown_hook, 0);
@@ -2654,15 +2678,16 @@ pgstat_initialize(void)
  *
  *	Initialize this backend's entry in the PgBackendStatus array.
  *	Called from InitPostgres.
- *	MyDatabaseId, session userid, and application_name must be set
- *	(hence, this cannot be combined with pgstat_initialize).
+ *
+ *	Apart from auxiliary processes, MyDatabaseId, session userid,
+ *	and application_name must be set for a backend (hence, this
+ *	cannot be combined with pgstat_initialize).
  * ----------
  */
 void
 pgstat_bestart(void)
 {
 	TimestampTz proc_start_timestamp;
-	Oid			userid;
 	SockAddr	clientaddr;
 	volatile PgBackendStatus *beentry;
 
@@ -2677,7 +2702,6 @@ pgstat_bestart(void)
 		proc_start_timestamp = MyProcPort->SessionStartTime;
 	else
 		proc_start_timestamp = GetCurrentTimestamp();
-	userid = GetSessionUserId();
 
 	/*
 	 * We may not have a MyProcPort (eg, if this is the autovacuum process).
@@ -2696,6 +2720,62 @@ pgstat_bestart(void)
 	 * cute.
 	 */
 	beentry = MyBEEntry;
+
+	if (MyBackendId != InvalidBackendId)
+	{
+		if (IsAutoVacuumLauncherProcess())
+		{
+			/* Autovacuum Launcher */
+			beentry->st_backendType = B_AUTOVAC_LAUNCHER;
+		}
+		else if (IsAutoVacuumWorkerProcess())
+		{
+			/* Autovacuum Worker */
+			beentry->st_backendType = B_AUTOVAC_WORKER;
+		}
+		else if (am_walsender)
+		{
+			/* Wal sender */
+			beentry->st_backendType = B_WAL_SENDER;
+		}
+		else if (IsBackgroundWorker)
+		{
+			/* bgworker */
+			beentry->st_backendType = B_BG_WORKER;
+		}
+		else
+		{
+			/* client-backend */
+			beentry->st_backendType = B_BACKEND;
+		}
+	}
+	else
+	{
+		/* Must be an auxiliary process */
+		Assert(MyAuxProcType != NotAnAuxProcess);
+		switch (MyAuxProcType)
+		{
+			case StartupProcess:
+				beentry->st_backendType = B_STARTUP;
+				break;
+			case BgWriterProcess:
+				beentry->st_backendType = B_BG_WRITER;
+				break;
+			case CheckpointerProcess:
+				beentry->st_backendType = B_CHECKPOINTER;
+				break;
+			case WalWriterProcess:
+				beentry->st_backendType = B_WAL_WRITER;
+				break;
+			case WalReceiverProcess:
+				beentry->st_backendType = B_WAL_RECEIVER;
+				break;
+			default:
+				elog(PANIC, "unrecognized process type: %d", (int) MyAuxProcType);
+				proc_exit(1);
+		}
+	}
+
 	do
 	{
 		pgstat_increment_changecount_before(beentry);
@@ -2707,7 +2787,13 @@ pgstat_bestart(void)
 	beentry->st_state_start_timestamp = 0;
 	beentry->st_xact_start_timestamp = 0;
 	beentry->st_databaseid = MyDatabaseId;
-	beentry->st_userid = userid;
+
+	/* We have userid for client-backends and wal-sender processes */
+	if (beentry->st_backendType == B_BACKEND || beentry->st_backendType == B_WAL_SENDER)
+		beentry->st_userid = GetSessionUserId();
+	else
+		beentry->st_userid = InvalidOid;
+
 	beentry->st_clientaddr = clientaddr;
 	if (MyProcPort && MyProcPort->remote_hostname)
 		strlcpy(beentry->st_clienthostname, MyProcPort->remote_hostname,
@@ -3045,24 +3131,24 @@ pgstat_read_current_status(void)
 
 	localtable = (LocalPgBackendStatus *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   sizeof(LocalPgBackendStatus) * MaxBackends);
+						 sizeof(LocalPgBackendStatus) * NumBackendStatSlots);
 	localappname = (char *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   NAMEDATALEN * MaxBackends);
+						   NAMEDATALEN * NumBackendStatSlots);
 	localactivity = (char *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   pgstat_track_activity_query_size * MaxBackends);
+					 pgstat_track_activity_query_size * NumBackendStatSlots);
 #ifdef USE_SSL
 	localsslstatus = (PgBackendSSLStatus *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   sizeof(PgBackendSSLStatus) * MaxBackends);
+						   sizeof(PgBackendSSLStatus) * NumBackendStatSlots);
 #endif
 
 	localNumBackends = 0;
 
 	beentry = BackendStatusArray;
 	localentry = localtable;
-	for (i = 1; i <= MaxBackends; i++)
+	for (i = 1; i <= NumBackendStatSlots; i++)
 	{
 		/*
 		 * Follow the protocol of retrying if st_changecount changes while we
@@ -3590,7 +3676,47 @@ pgstat_get_crashed_backend_activity(int pid, char *buffer, int buflen)
 	return NULL;
 }
 
+const char *
+pgstat_get_backend_desc(BackendType backendType)
+{
+	const char *backendDesc = "unknown process type";
+
+	switch (backendType)
+	{
+		case B_AUTOVAC_LAUNCHER:
+			backendDesc = "autovacuum launcher";
+			break;
+		case B_AUTOVAC_WORKER:
+			backendDesc = "autovacuum worker";
+			break;
+		case B_BACKEND:
+			backendDesc = "client backend";
+			break;
+		case B_BG_WORKER:
+			backendDesc = "bgworker";
+			break;
+		case B_BG_WRITER:
+			backendDesc = "background writer";
+			break;
+		case B_CHECKPOINTER:
+			backendDesc = "checkpointer";
+			break;
+		case B_STARTUP:
+			backendDesc = "startup";
+			break;
+		case B_WAL_RECEIVER:
+			backendDesc = "walreceiver";
+			break;
+		case B_WAL_SENDER:
+			backendDesc = "walsender";
+			break;
+		case B_WAL_WRITER:
+			backendDesc = "walwriter";
+			break;
+	}
 
+	return backendDesc;
+}
 /* ------------------------------------------------------------
  * Local support functions follow
  * ------------------------------------------------------------
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 8f467be..3e716b1 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -941,6 +941,33 @@ AuxiliaryProcKill(int code, Datum arg)
 	SpinLockRelease(ProcStructLock);
 }
 
+/*
+ * AuxiliaryPidGetProc -- get PGPROC for an auxiliary process
+ * given its PID
+ *
+ * Returns NULL if not found.
+ */
+PGPROC *
+AuxiliaryPidGetProc(int pid)
+{
+	PGPROC	   *result = NULL;
+	int			index;
+
+	if (pid == 0)				/* never match dummy PGPROCs */
+		return NULL;
+
+	for (index = 0; index < NUM_AUXILIARY_PROCS; index++)
+	{
+		PGPROC	   *proc = &AuxiliaryProcs[index];
+
+		if (proc->pid == pid)
+		{
+			result = proc;
+			break;
+		}
+	}
+	return result;
+}
 
 /*
  * ProcQueue package: routines for putting processes to sleep
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index a987d0d..96a1188 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -20,6 +20,7 @@
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "pgstat.h"
+#include "postmaster/postmaster.h"
 #include "storage/proc.h"
 #include "storage/procarray.h"
 #include "utils/acl.h"
@@ -615,9 +616,18 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			continue;
 
 		/* Values available to all callers */
-		values[0] = ObjectIdGetDatum(beentry->st_databaseid);
+		if (beentry->st_databaseid != InvalidOid)
+			values[0] = ObjectIdGetDatum(beentry->st_databaseid);
+		else
+			nulls[0] = true;
+
 		values[1] = Int32GetDatum(beentry->st_procpid);
-		values[2] = ObjectIdGetDatum(beentry->st_userid);
+
+		if (beentry->st_userid != InvalidOid)
+			values[2] = ObjectIdGetDatum(beentry->st_userid);
+		else
+			nulls[2] = true;
+
 		if (beentry->st_appname)
 			values[3] = CStringGetTextDatum(beentry->st_appname);
 		else
@@ -690,6 +700,22 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 				wait_event = pgstat_get_wait_event(raw_wait_event);
 
 			}
+			else if (beentry->st_backendType != B_BACKEND)
+			{
+				uint32		raw_wait_event;
+
+				/*
+				 * For an auxiliary process, retrieve process info from
+				 * AuxiliaryProcs stored in shared-memory.
+				 */
+				proc = AuxiliaryPidGetProc(beentry->st_procpid);
+
+				/* Check whether this is indeed an auxiliary process */
+				Assert(proc != NULL);
+				raw_wait_event = UINT32_ACCESS_ONCE(proc->wait_event_info);
+				wait_event_type = pgstat_get_wait_event_type(raw_wait_event);
+				wait_event = pgstat_get_wait_event(raw_wait_event);
+			}
 			else
 			{
 				wait_event_type = NULL;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 60c78d1..a1a0193 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -41,6 +41,9 @@ typedef enum TrackFunctionsLevel
 	TRACK_FUNC_ALL
 }	TrackFunctionsLevel;
 
+/* Total number of backends including auxiliary */
+#define NumBackendStatSlots (MaxBackends + NUM_AUXPROCTYPES)
+
 /* ----------
  * The types of backend -> collector messages
  * ----------
@@ -696,6 +699,25 @@ typedef struct PgStat_GlobalStats
 
 
 /* ----------
+ * Backend types
+ * ----------
+ */
+typedef enum BackendType
+{
+	B_AUTOVAC_LAUNCHER,
+	B_AUTOVAC_WORKER,
+	B_BACKEND,
+	B_BG_WORKER,
+	B_BG_WRITER,
+	B_CHECKPOINTER,
+	B_STARTUP,
+	B_WAL_RECEIVER,
+	B_WAL_SENDER,
+	B_WAL_WRITER
+} BackendType;
+
+
+/* ----------
  * Backend states
  * ----------
  */
@@ -847,7 +869,9 @@ typedef struct PgBackendSSLStatus
  * showing its current activity.  (The structs are allocated according to
  * BackendId, but that is not critical.)  Note that the collector process
  * has no involvement in, or even access to, these structs.
- * ----------
+ *
+ * Each auxiliary process also maintains a PgBackendStatus struct in shared
+ * memory.
  */
 typedef struct PgBackendStatus
 {
@@ -871,6 +895,9 @@ typedef struct PgBackendStatus
 	/* The entry is valid iff st_procpid > 0, unused if st_procpid == 0 */
 	int			st_procpid;
 
+	/* Type of backends */
+	BackendType st_backendType;
+
 	/* Times when current backend, transaction, and activity started */
 	TimestampTz st_proc_start_timestamp;
 	TimestampTz st_xact_start_timestamp;
@@ -1069,6 +1096,7 @@ extern const char *pgstat_get_wait_event_type(uint32 wait_event_info);
 extern const char *pgstat_get_backend_current_activity(int pid, bool checkUser);
 extern const char *pgstat_get_crashed_backend_activity(int pid, char *buffer,
 									int buflen);
+extern const char *pgstat_get_backend_desc(BackendType backendType);
 
 extern void pgstat_progress_start_command(ProgressCommandType cmdtype,
 							  Oid relid);
diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h
index 5f38fa6..be3bd01 100644
--- a/src/include/storage/proc.h
+++ b/src/include/storage/proc.h
@@ -262,6 +262,7 @@ extern PGPROC *PreparedXactProcs;
  */
 #define NUM_AUXILIARY_PROCS		4
 
+extern PGPROC *AuxiliaryPidGetProc(int pid);
 
 /* configurable options */
 extern int	DeadlockTimeout;
-- 
1.8.3.1

From 99c0aca7e7cdc683c05a3dd831d12a82e4f7db34 Mon Sep 17 00:00:00 2001
From: Kuntal Ghosh <kuntal.ghosh@enterprisedb.com>
Date: Wed, 15 Mar 2017 11:32:49 +0530
Subject: [PATCH 1/3] Infra to expose all backend processes in
 pg_stat_get_activity

This patch implements the infrastructure required to expose
all backend processes including auxiliary procs in pg_stat_activity.
BackendStatusArray is extended to store auxiliary processes. Backends
use slots indexed in the range from 1 to MaxBackends (inclusive),
so we use MaxBackends + AuxBackendType + 1 as the index of the slot for an
auxiliary process.
---
 src/backend/postmaster/pgstat.c     | 190 +++++++++++++++++++++++++++++++-----
 src/backend/storage/lmgr/proc.c     |  27 +++++
 src/backend/utils/adt/pgstatfuncs.c |  30 +++++-
 src/include/pgstat.h                |  26 +++++
 src/include/storage/proc.h          |   1 +
 5 files changed, 247 insertions(+), 27 deletions(-)

diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 7cacb1e..5b7804a 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -50,6 +50,7 @@
 #include "postmaster/autovacuum.h"
 #include "postmaster/fork_process.h"
 #include "postmaster/postmaster.h"
+#include "replication/walsender.h"
 #include "storage/backendid.h"
 #include "storage/dsm.h"
 #include "storage/fd.h"
@@ -103,6 +104,18 @@
 
 
 /* ----------
+ * Total number of backends including auxiliary
+ *
+ * We reserve a slot for each possible BackendId, plus one for each
+ * possible auxiliary process type.  (This scheme assumes there is not
+ * more than one of any auxiliary process type at a time.) MaxBackends
+ * includes autovacuum workers and background workers as well.
+ * ----------
+ */
+#define NumBackendStatSlots (MaxBackends + NUM_AUXPROCTYPES)
+
+
+/* ----------
  * GUC parameters
  * ----------
  */
@@ -212,7 +225,11 @@ typedef struct TwoPhasePgStatRecord
  */
 static MemoryContext pgStatLocalContext = NULL;
 static HTAB *pgStatDBHash = NULL;
+
+/* Status for backends including auxiliary */
 static LocalPgBackendStatus *localBackendStatusTable = NULL;
+
+/* Total number of backends including auxiliary */
 static int	localNumBackends = 0;
 
 /*
@@ -2504,20 +2521,20 @@ BackendStatusShmemSize(void)
 	Size		size;
 
 	/* BackendStatusArray: */
-	size = mul_size(sizeof(PgBackendStatus), MaxBackends);
+	size = mul_size(sizeof(PgBackendStatus), NumBackendStatSlots);
 	/* BackendAppnameBuffer: */
 	size = add_size(size,
-					mul_size(NAMEDATALEN, MaxBackends));
+					mul_size(NAMEDATALEN, NumBackendStatSlots));
 	/* BackendClientHostnameBuffer: */
 	size = add_size(size,
-					mul_size(NAMEDATALEN, MaxBackends));
+					mul_size(NAMEDATALEN, NumBackendStatSlots));
 	/* BackendActivityBuffer: */
 	size = add_size(size,
-					mul_size(pgstat_track_activity_query_size, MaxBackends));
+			mul_size(pgstat_track_activity_query_size, NumBackendStatSlots));
 #ifdef USE_SSL
 	/* BackendSslStatusBuffer: */
 	size = add_size(size,
-					mul_size(sizeof(PgBackendSSLStatus), MaxBackends));
+				  mul_size(sizeof(PgBackendSSLStatus), NumBackendStatSlots));
 #endif
 	return size;
 }
@@ -2535,7 +2552,7 @@ CreateSharedBackendStatus(void)
 	char	   *buffer;
 
 	/* Create or attach to the shared array */
-	size = mul_size(sizeof(PgBackendStatus), MaxBackends);
+	size = mul_size(sizeof(PgBackendStatus), NumBackendStatSlots);
 	BackendStatusArray = (PgBackendStatus *)
 		ShmemInitStruct("Backend Status Array", size, &found);
 
@@ -2558,7 +2575,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_appname pointers. */
 		buffer = BackendAppnameBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumBackendStatSlots; i++)
 		{
 			BackendStatusArray[i].st_appname = buffer;
 			buffer += NAMEDATALEN;
@@ -2576,7 +2593,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_clienthostname pointers. */
 		buffer = BackendClientHostnameBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumBackendStatSlots; i++)
 		{
 			BackendStatusArray[i].st_clienthostname = buffer;
 			buffer += NAMEDATALEN;
@@ -2585,7 +2602,7 @@ CreateSharedBackendStatus(void)
 
 	/* Create or attach to the shared activity buffer */
 	BackendActivityBufferSize = mul_size(pgstat_track_activity_query_size,
-										 MaxBackends);
+										 NumBackendStatSlots);
 	BackendActivityBuffer = (char *)
 		ShmemInitStruct("Backend Activity Buffer",
 						BackendActivityBufferSize,
@@ -2597,7 +2614,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_activity pointers. */
 		buffer = BackendActivityBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumBackendStatSlots; i++)
 		{
 			BackendStatusArray[i].st_activity = buffer;
 			buffer += pgstat_track_activity_query_size;
@@ -2606,7 +2623,7 @@ CreateSharedBackendStatus(void)
 
 #ifdef USE_SSL
 	/* Create or attach to the shared SSL status buffer */
-	size = mul_size(sizeof(PgBackendSSLStatus), MaxBackends);
+	size = mul_size(sizeof(PgBackendSSLStatus), NumBackendStatSlots);
 	BackendSslStatusBuffer = (PgBackendSSLStatus *)
 		ShmemInitStruct("Backend SSL Status Buffer", size, &found);
 
@@ -2618,7 +2635,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_sslstatus pointers. */
 		ptr = BackendSslStatusBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumBackendStatSlots; i++)
 		{
 			BackendStatusArray[i].st_sslstatus = ptr;
 			ptr++;
@@ -2632,7 +2649,8 @@ CreateSharedBackendStatus(void)
  * pgstat_initialize() -
  *
  *	Initialize pgstats state, and set up our on-proc-exit hook.
- *	Called from InitPostgres.  MyBackendId must be set,
+ *	Called from InitPostgres and AuxiliaryProcessMain. For auxiliary process,
+ *	MyBackendId is invalid. Otherwise, MyBackendId must be set,
  *	but we must not have started any transaction yet (since the
  *	exit hook must run after the last transaction exit).
  *	NOTE: MyDatabaseId isn't set yet; so the shutdown hook has to be careful.
@@ -2642,8 +2660,26 @@ void
 pgstat_initialize(void)
 {
 	/* Initialize MyBEEntry */
-	Assert(MyBackendId >= 1 && MyBackendId <= MaxBackends);
-	MyBEEntry = &BackendStatusArray[MyBackendId - 1];
+	if (MyBackendId != InvalidBackendId)
+	{
+		Assert(MyBackendId >= 1 && MyBackendId <= MaxBackends);
+		MyBEEntry = &BackendStatusArray[MyBackendId - 1];
+	}
+	else
+	{
+		/* Must be an auxiliary process */
+		Assert(MyAuxProcType != NotAnAuxProcess);
+
+		/*
+		 * Assign the MyBEEntry for an auxiliary process.  Since it doesn't
+		 * have a BackendId, the slot is statically allocated based on the
+		 * auxiliary process type (MyAuxProcType).  Backends use slots indexed
+		 * in the range from 1 to MaxBackends (inclusive), so we use
+		 * MaxBackends + AuxBackendType + 1 as the index of the slot for an
+		 * auxiliary process.
+		 */
+		MyBEEntry = &BackendStatusArray[MaxBackends + MyAuxProcType];
+	}
 
 	/* Set up a process-exit hook to clean up */
 	on_shmem_exit(pgstat_beshutdown_hook, 0);
@@ -2654,15 +2690,16 @@ pgstat_initialize(void)
  *
  *	Initialize this backend's entry in the PgBackendStatus array.
  *	Called from InitPostgres.
- *	MyDatabaseId, session userid, and application_name must be set
- *	(hence, this cannot be combined with pgstat_initialize).
+ *
+ *	Apart from auxiliary processes, MyDatabaseId, session userid,
+ *	and application_name must be set for a backend (hence, this
+ *	cannot be combined with pgstat_initialize).
  * ----------
  */
 void
 pgstat_bestart(void)
 {
 	TimestampTz proc_start_timestamp;
-	Oid			userid;
 	SockAddr	clientaddr;
 	volatile PgBackendStatus *beentry;
 
@@ -2677,7 +2714,6 @@ pgstat_bestart(void)
 		proc_start_timestamp = MyProcPort->SessionStartTime;
 	else
 		proc_start_timestamp = GetCurrentTimestamp();
-	userid = GetSessionUserId();
 
 	/*
 	 * We may not have a MyProcPort (eg, if this is the autovacuum process).
@@ -2696,6 +2732,62 @@ pgstat_bestart(void)
 	 * cute.
 	 */
 	beentry = MyBEEntry;
+
+	if (MyBackendId != InvalidBackendId)
+	{
+		if (IsAutoVacuumLauncherProcess())
+		{
+			/* Autovacuum Launcher */
+			beentry->st_backendType = B_AUTOVAC_LAUNCHER;
+		}
+		else if (IsAutoVacuumWorkerProcess())
+		{
+			/* Autovacuum Worker */
+			beentry->st_backendType = B_AUTOVAC_WORKER;
+		}
+		else if (am_walsender)
+		{
+			/* Wal sender */
+			beentry->st_backendType = B_WAL_SENDER;
+		}
+		else if (IsBackgroundWorker)
+		{
+			/* bgworker */
+			beentry->st_backendType = B_BG_WORKER;
+		}
+		else
+		{
+			/* client-backend */
+			beentry->st_backendType = B_BACKEND;
+		}
+	}
+	else
+	{
+		/* Must be an auxiliary process */
+		Assert(MyAuxProcType != NotAnAuxProcess);
+		switch (MyAuxProcType)
+		{
+			case StartupProcess:
+				beentry->st_backendType = B_STARTUP;
+				break;
+			case BgWriterProcess:
+				beentry->st_backendType = B_BG_WRITER;
+				break;
+			case CheckpointerProcess:
+				beentry->st_backendType = B_CHECKPOINTER;
+				break;
+			case WalWriterProcess:
+				beentry->st_backendType = B_WAL_WRITER;
+				break;
+			case WalReceiverProcess:
+				beentry->st_backendType = B_WAL_RECEIVER;
+				break;
+			default:
+				elog(PANIC, "unrecognized process type: %d", (int) MyAuxProcType);
+				proc_exit(1);
+		}
+	}
+
 	do
 	{
 		pgstat_increment_changecount_before(beentry);
@@ -2707,7 +2799,15 @@ pgstat_bestart(void)
 	beentry->st_state_start_timestamp = 0;
 	beentry->st_xact_start_timestamp = 0;
 	beentry->st_databaseid = MyDatabaseId;
-	beentry->st_userid = userid;
+
+	/* We have userid for client-backends, wal-sender and bgworker processes */
+	if (beentry->st_backendType == B_BACKEND
+			|| beentry->st_backendType == B_WAL_SENDER
+			|| beentry->st_backendType == B_BG_WORKER)
+		beentry->st_userid = GetSessionUserId();
+	else
+		beentry->st_userid = InvalidOid;
+
 	beentry->st_clientaddr = clientaddr;
 	if (MyProcPort && MyProcPort->remote_hostname)
 		strlcpy(beentry->st_clienthostname, MyProcPort->remote_hostname,
@@ -3045,24 +3145,24 @@ pgstat_read_current_status(void)
 
 	localtable = (LocalPgBackendStatus *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   sizeof(LocalPgBackendStatus) * MaxBackends);
+						 sizeof(LocalPgBackendStatus) * NumBackendStatSlots);
 	localappname = (char *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   NAMEDATALEN * MaxBackends);
+						   NAMEDATALEN * NumBackendStatSlots);
 	localactivity = (char *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   pgstat_track_activity_query_size * MaxBackends);
+					 pgstat_track_activity_query_size * NumBackendStatSlots);
 #ifdef USE_SSL
 	localsslstatus = (PgBackendSSLStatus *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   sizeof(PgBackendSSLStatus) * MaxBackends);
+						   sizeof(PgBackendSSLStatus) * NumBackendStatSlots);
 #endif
 
 	localNumBackends = 0;
 
 	beentry = BackendStatusArray;
 	localentry = localtable;
-	for (i = 1; i <= MaxBackends; i++)
+	for (i = 1; i <= NumBackendStatSlots; i++)
 	{
 		/*
 		 * Follow the protocol of retrying if st_changecount changes while we
@@ -3590,7 +3690,47 @@ pgstat_get_crashed_backend_activity(int pid, char *buffer, int buflen)
 	return NULL;
 }
 
+const char *
+pgstat_get_backend_desc(BackendType backendType)
+{
+	const char *backendDesc = "unknown process type";
 
+	switch (backendType)
+	{
+		case B_AUTOVAC_LAUNCHER:
+			backendDesc = "autovacuum launcher";
+			break;
+		case B_AUTOVAC_WORKER:
+			backendDesc = "autovacuum worker";
+			break;
+		case B_BACKEND:
+			backendDesc = "client backend";
+			break;
+		case B_BG_WORKER:
+			backendDesc = "background worker";
+			break;
+		case B_BG_WRITER:
+			backendDesc = "background writer";
+			break;
+		case B_CHECKPOINTER:
+			backendDesc = "checkpointer";
+			break;
+		case B_STARTUP:
+			backendDesc = "startup";
+			break;
+		case B_WAL_RECEIVER:
+			backendDesc = "walreceiver";
+			break;
+		case B_WAL_SENDER:
+			backendDesc = "walsender";
+			break;
+		case B_WAL_WRITER:
+			backendDesc = "walwriter";
+			break;
+	}
+
+	return backendDesc;
+}
 /* ------------------------------------------------------------
  * Local support functions follow
  * ------------------------------------------------------------
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 8f467be..3e716b1 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -941,6 +941,33 @@ AuxiliaryProcKill(int code, Datum arg)
 	SpinLockRelease(ProcStructLock);
 }
 
+/*
+ * AuxiliaryPidGetProc -- get PGPROC for an auxiliary process
+ * given its PID
+ *
+ * Returns NULL if not found.
+ */
+PGPROC *
+AuxiliaryPidGetProc(int pid)
+{
+	PGPROC	   *result = NULL;
+	int			index;
+
+	if (pid == 0)				/* never match dummy PGPROCs */
+		return NULL;
+
+	for (index = 0; index < NUM_AUXILIARY_PROCS; index++)
+	{
+		PGPROC	   *proc = &AuxiliaryProcs[index];
+
+		if (proc->pid == pid)
+		{
+			result = proc;
+			break;
+		}
+	}
+	return result;
+}
 
 /*
  * ProcQueue package: routines for putting processes to sleep
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index a987d0d..96a1188 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -20,6 +20,7 @@
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "pgstat.h"
+#include "postmaster/postmaster.h"
 #include "storage/proc.h"
 #include "storage/procarray.h"
 #include "utils/acl.h"
@@ -615,9 +616,18 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			continue;
 
 		/* Values available to all callers */
-		values[0] = ObjectIdGetDatum(beentry->st_databaseid);
+		if (beentry->st_databaseid != InvalidOid)
+			values[0] = ObjectIdGetDatum(beentry->st_databaseid);
+		else
+			nulls[0] = true;
+
 		values[1] = Int32GetDatum(beentry->st_procpid);
-		values[2] = ObjectIdGetDatum(beentry->st_userid);
+
+		if (beentry->st_userid != InvalidOid)
+			values[2] = ObjectIdGetDatum(beentry->st_userid);
+		else
+			nulls[2] = true;
+
 		if (beentry->st_appname)
 			values[3] = CStringGetTextDatum(beentry->st_appname);
 		else
@@ -690,6 +700,22 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 				wait_event = pgstat_get_wait_event(raw_wait_event);
 
 			}
+			else if (beentry->st_backendType != B_BACKEND)
+			{
+				uint32		raw_wait_event;
+
+				/*
+				 * For an auxiliary process, retrieve process info from
+				 * AuxiliaryProcs stored in shared-memory.
+				 */
+				proc = AuxiliaryPidGetProc(beentry->st_procpid);
+
+				/* Check whether this is indeed an auxiliary process */
+				Assert(proc != NULL);
+				raw_wait_event = UINT32_ACCESS_ONCE(proc->wait_event_info);
+				wait_event_type = pgstat_get_wait_event_type(raw_wait_event);
+				wait_event = pgstat_get_wait_event(raw_wait_event);
+			}
 			else
 			{
 				wait_event_type = NULL;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 60c78d1..217df45 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -696,6 +696,25 @@ typedef struct PgStat_GlobalStats
 
 
 /* ----------
+ * Backend types
+ * ----------
+ */
+typedef enum BackendType
+{
+	B_AUTOVAC_LAUNCHER,
+	B_AUTOVAC_WORKER,
+	B_BACKEND,
+	B_BG_WORKER,
+	B_BG_WRITER,
+	B_CHECKPOINTER,
+	B_STARTUP,
+	B_WAL_RECEIVER,
+	B_WAL_SENDER,
+	B_WAL_WRITER
+} BackendType;
+
+
+/* ----------
  * Backend states
  * ----------
  */
@@ -847,6 +866,9 @@ typedef struct PgBackendSSLStatus
  * showing its current activity.  (The structs are allocated according to
  * BackendId, but that is not critical.)  Note that the collector process
  * has no involvement in, or even access to, these structs.
+ *
+ * Each auxiliary process also maintains a PgBackendStatus struct in shared
+ * memory.
  * ----------
  */
 typedef struct PgBackendStatus
@@ -871,6 +893,9 @@ typedef struct PgBackendStatus
 	/* The entry is valid iff st_procpid > 0, unused if st_procpid == 0 */
 	int			st_procpid;
 
+	/* Type of backends */
+	BackendType st_backendType;
+
 	/* Times when current backend, transaction, and activity started */
 	TimestampTz st_proc_start_timestamp;
 	TimestampTz st_xact_start_timestamp;
@@ -1069,6 +1094,7 @@ extern const char *pgstat_get_wait_event_type(uint32 wait_event_info);
 extern const char *pgstat_get_backend_current_activity(int pid, bool checkUser);
 extern const char *pgstat_get_crashed_backend_activity(int pid, char *buffer,
 									int buflen);
+extern const char *pgstat_get_backend_desc(BackendType backendType);
 
 extern void pgstat_progress_start_command(ProgressCommandType cmdtype,
 							  Oid relid);
diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h
index 5f38fa6..be3bd01 100644
--- a/src/include/storage/proc.h
+++ b/src/include/storage/proc.h
@@ -262,6 +262,7 @@ extern PGPROC *PreparedXactProcs;
  */
 #define NUM_AUXILIARY_PROCS		4
 
+extern PGPROC *AuxiliaryPidGetProc(int pid);
 
 /* configurable options */
 extern int	DeadlockTimeout;
-- 
1.8.3.1

From 191f6daebabcccb50a363801cb93edae71c12504 Mon Sep 17 00:00:00 2001
From: Kuntal Ghosh <kuntal.ghosh@enterprisedb.com>
Date: Wed, 15 Mar 2017 12:27:00 +0530
Subject: [PATCH 2/3] Expose stats for all backends

All backends include auxiliary procs, autovacuum launcher and
bgworkers.
---
 src/backend/bootstrap/bootstrap.c     | 3 +++
 src/backend/postmaster/autovacuum.c   | 3 +++
 src/backend/postmaster/bgwriter.c     | 3 +++
 src/backend/postmaster/checkpointer.c | 3 +++
 src/backend/postmaster/pgstat.c       | 1 -
 src/backend/postmaster/postmaster.c   | 6 ++++++
 src/backend/postmaster/startup.c      | 4 ++++
 src/backend/postmaster/walwriter.c    | 3 +++
 src/backend/replication/walreceiver.c | 4 ++++
 src/backend/replication/walsender.c   | 5 ++++-
 src/backend/utils/init/postinit.c     | 5 ++++-
 11 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/src/backend/bootstrap/bootstrap.c b/src/backend/bootstrap/bootstrap.c
index 6511c60..f56e229 100644
--- a/src/backend/bootstrap/bootstrap.c
+++ b/src/backend/bootstrap/bootstrap.c
@@ -387,6 +387,9 @@ AuxiliaryProcessMain(int argc, char *argv[])
 		/* finish setting up bufmgr.c */
 		InitBufferPoolBackend();
 
+		/* Initialize stats collection */
+		pgstat_initialize();
+
 		/* register a before-shutdown callback for LWLock cleanup */
 		before_shmem_exit(ShutdownAuxiliaryProcess, 0);
 	}
diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index fa8de13..550a731 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -453,6 +453,9 @@ AutoVacLauncherMain(int argc, char *argv[])
 
 	InitPostgres(NULL, InvalidOid, NULL, InvalidOid, NULL);
 
+	/* report autovacuum launcher process in the  PgBackendStatus array */
+	pgstat_bestart();
+
 	SetProcessingMode(NormalProcessing);
 
 	/*
diff --git a/src/backend/postmaster/bgwriter.c b/src/backend/postmaster/bgwriter.c
index dcb4cf2..6ba2e2e 100644
--- a/src/backend/postmaster/bgwriter.c
+++ b/src/backend/postmaster/bgwriter.c
@@ -248,6 +248,9 @@ BackgroundWriterMain(void)
 	 */
 	prev_hibernate = false;
 
+	/* report bgwriter process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/*
 	 * Loop forever
 	 */
diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c
index fe9041f..8eb0a2a 100644
--- a/src/backend/postmaster/checkpointer.c
+++ b/src/backend/postmaster/checkpointer.c
@@ -345,6 +345,9 @@ CheckpointerMain(void)
 	 */
 	ProcGlobal->checkpointerLatch = &MyProc->procLatch;
 
+	/* report checkpointer process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/*
 	 * Loop forever
 	 */
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 5b7804a..1b01b53 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -2689,7 +2689,6 @@ pgstat_initialize(void)
  * pgstat_bestart() -
  *
  *	Initialize this backend's entry in the PgBackendStatus array.
- *	Called from InitPostgres.
  *
  *	Apart from auxiliary processes, MyDatabaseId, session userid,
  *	and application_name must be set for a backend (hence, this
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 6831342..7d78bff 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -5461,6 +5461,9 @@ BackgroundWorkerInitializeConnection(char *dbname, char *username)
 
 	InitPostgres(dbname, InvalidOid, username, InvalidOid, NULL);
 
+	/* report the background worker process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/* it had better not gotten out of "init" mode yet */
 	if (!IsInitProcessingMode())
 		ereport(ERROR,
@@ -5484,6 +5487,9 @@ BackgroundWorkerInitializeConnectionByOid(Oid dboid, Oid useroid)
 
 	InitPostgres(NULL, dboid, NULL, useroid, NULL);
 
+	/* report the background worker process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/* it had better not gotten out of "init" mode yet */
 	if (!IsInitProcessingMode())
 		ereport(ERROR,
diff --git a/src/backend/postmaster/startup.c b/src/backend/postmaster/startup.c
index b172b5e..56ff042 100644
--- a/src/backend/postmaster/startup.c
+++ b/src/backend/postmaster/startup.c
@@ -25,6 +25,7 @@
 #include "access/xlog.h"
 #include "libpq/pqsignal.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/startup.h"
 #include "storage/ipc.h"
 #include "storage/latch.h"
@@ -210,6 +211,9 @@ StartupProcessMain(void)
 	 */
 	PG_SETMASK(&UnBlockSig);
 
+	/* report startup process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/*
 	 * Do what we came for.
 	 */
diff --git a/src/backend/postmaster/walwriter.c b/src/backend/postmaster/walwriter.c
index a575d8f..9056652 100644
--- a/src/backend/postmaster/walwriter.c
+++ b/src/backend/postmaster/walwriter.c
@@ -231,6 +231,9 @@ WalWriterMain(void)
 	 */
 	ProcGlobal->walwriterLatch = &MyProc->procLatch;
 
+	/* report walwriter process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/*
 	 * Loop forever
 	 */
diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index 18d9d7e..3265d03 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -316,6 +316,10 @@ WalReceiverMain(void)
 	SpinLockRelease(&walrcv->mutex);
 
 	first_stream = true;
+
+	/* report walreceiver process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	for (;;)
 	{
 		char	   *primary_sysid;
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 127efec..9b80284 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -245,6 +245,9 @@ InitWalSender(void)
 	 */
 	MarkPostmasterChildWalSender();
 	SendPostmasterSignal(PMSIGNAL_ADVANCE_STATE_MACHINE);
+
+	/* report walsender process in the PgBackendStatus array */
+	pgstat_bestart();
 }
 
 /*
@@ -1806,7 +1809,7 @@ WalSndLoop(WalSndSendDataCallback send_data)
 	waiting_for_ping_response = false;
 
 	/* Report to pgstat that this process is a WAL sender */
-	pgstat_report_activity(STATE_RUNNING, "walsender");
+	pgstat_report_activity(STATE_RUNNING, NULL);
 
 	/*
 	 * Loop until we reach the end of this timeline or the client requests to
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index 9f938f2..cbe9b49 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -665,7 +665,9 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 
 	/* The autovacuum launcher is done here */
 	if (IsAutoVacuumLauncherProcess())
+	{
 		return;
+	}
 
 	/*
 	 * Start a new transaction here before first access to db, and get a
@@ -808,7 +810,7 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 		/* initialize client encoding */
 		InitializeClientEncoding();
 
-		/* report this backend in the PgBackendStatus array */
+		/* report walsender process in the PgBackendStatus array */
 		pgstat_bestart();
 
 		/* close the transaction we started above */
@@ -875,6 +877,7 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 		 */
 		if (!bootstrap)
 			CommitTransactionCommand();
+
 		return;
 	}
 
-- 
1.8.3.1

From 19c3a51356ccf01cc6f1e396518af360e104b648 Mon Sep 17 00:00:00 2001
From: Kuntal Ghosh <kuntal.ghosh@enterprisedb.com>
Date: Wed, 15 Mar 2017 12:53:11 +0530
Subject: [PATCH 3/3] Add backend_type column in pg_stat_get_activity

backend_type indicates the type of process in the stat table.
---
 doc/src/sgml/monitoring.sgml         | 14 ++++++++++++--
 src/backend/catalog/system_views.sql |  3 ++-
 src/backend/utils/adt/pgstatfuncs.c  |  4 +++-
 src/include/catalog/pg_proc.h        |  2 +-
 src/test/regress/expected/rules.out  |  9 +++++----
 5 files changed, 23 insertions(+), 9 deletions(-)

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index 9eaf43a..320cec3 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -620,8 +620,7 @@ postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: ser
     <row>
      <entry><structfield>backend_start</></entry>
      <entry><type>timestamp with time zone</></entry>
-     <entry>Time when this process was started, i.e., when the
-      client connected to the server
+     <entry>Time when this process was started.
      </entry>
     </row>
     <row>
@@ -791,6 +790,17 @@ postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: ser
       <xref linkend="guc-track-activity-query-size">.
      </entry>
     </row>
+    <row>
+     <entry><structfield>backend_type</structfield></entry>
+     <entry><type>text</type></entry>
+     <entry>Type of current backend. Possible types are 
+      <literal>autovacuum launcher</>, <literal>autovacuum worker</>,
+      <literal>background worker</>, <literal>background writer</>,
+      <literal>client backend</>, <literal>checkpointer</>,
+      <literal>startup</>, <literal>walreceiver</>,
+      <literal>walsender</> and <literal>walwriter</>.
+     </entry>
+    </row>
    </tbody>
    </tgroup>
   </table>
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index b6552da..bdbb5b8 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -684,7 +684,8 @@ CREATE VIEW pg_stat_activity AS
             S.state,
             S.backend_xid,
             s.backend_xmin,
-            S.query
+            S.query,
+            S.backend_type
     FROM pg_stat_get_activity(NULL) AS S
         LEFT JOIN pg_database AS D ON (S.datid = D.oid)
         LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 96a1188..eafb0bf 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -539,7 +539,7 @@ pg_stat_get_progress_info(PG_FUNCTION_ARGS)
 Datum
 pg_stat_get_activity(PG_FUNCTION_ARGS)
 {
-#define PG_STAT_GET_ACTIVITY_COLS	23
+#define PG_STAT_GET_ACTIVITY_COLS	24
 	int			num_backends = pgstat_fetch_stat_numbackends();
 	int			curr_backend;
 	int			pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
@@ -835,6 +835,8 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			nulls[13] = true;
 			nulls[14] = true;
 		}
+		/* Add backend type */
+		values[23] = CStringGetTextDatum(pgstat_get_backend_desc(beentry->st_backendType));
 
 		tuplestore_putvalues(tupstore, tupdesc, values, nulls);
 
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 836d6ff..8494648 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -2797,7 +2797,7 @@ DATA(insert OID = 3057 ( pg_stat_get_autoanalyze_count PGNSP PGUID 12 1 0 0 0 f
 DESCR("statistics: number of auto analyzes for a table");
 DATA(insert OID = 1936 (  pg_stat_get_backend_idset		PGNSP PGUID 12 1 100 0 0 f f f f t t s r 0 0 23 "" _null_ _null_ _null_ _null_ _null_ pg_stat_get_backend_idset _null_ _null_ _null_ ));
 DESCR("statistics: currently active backend IDs");
-DATA(insert OID = 2022 (  pg_stat_get_activity			PGNSP PGUID 12 1 100 0 0 f f f f f t s r 1 0 2249 "23" "{23,26,23,26,25,25,25,25,25,1184,1184,1184,1184,869,25,23,28,28,16,25,25,23,16,25}" "{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,ssl,sslversion,sslcipher,sslbits,sslcompression,sslclientdn}" _null_ _null_ pg_stat_get_activity _null_ _null_ _null_ ));
+DATA(insert OID = 2022 (  pg_stat_get_activity			PGNSP PGUID 12 1 100 0 0 f f f f f t s r 1 0 2249 "23" "{23,26,23,26,25,25,25,25,25,1184,1184,1184,1184,869,25,23,28,28,16,25,25,23,16,25,25}" "{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,ssl,sslversion,sslcipher,sslbits,sslcompression,sslclientdn,backend_type}" _null_ _null_ pg_stat_get_activity _null_ _null_ _null_ ));
 DESCR("statistics: information about currently active backends");
 DATA(insert OID = 3318 (  pg_stat_get_progress_info			  PGNSP PGUID 12 1 100 0 0 f f f f t t s r 1 0 2249 "25" "{25,23,26,26,20,20,20,20,20,20,20,20,20,20}" "{i,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{cmdtype,pid,datid,relid,param1,param2,param3,param4,param5,param6,param7,param8,param9,param10}" _null_ _null_ pg_stat_get_progress_info _null_ _null_ _null_ ));
 DESCR("statistics: information about progress of backends running maintenance command");
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index bd13ae6..a317bff 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1704,8 +1704,9 @@ pg_stat_activity| SELECT s.datid,
     s.state,
     s.backend_xid,
     s.backend_xmin,
-    s.query
-   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn)
+    s.query,
+    s.backend_type
+   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn, backend_type)
      LEFT JOIN pg_database d ON ((s.datid = d.oid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_all_indexes| SELECT c.oid AS relid,
@@ -1833,7 +1834,7 @@ pg_stat_replication| SELECT s.pid,
     w.replay_location,
     w.sync_priority,
     w.sync_state
-   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn)
+   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn, backend_type)
      JOIN pg_stat_get_wal_senders() w(pid, state, sent_location, write_location, flush_location, replay_location, sync_priority, sync_state) ON ((s.pid = w.pid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_ssl| SELECT s.pid,
@@ -1843,7 +1844,7 @@ pg_stat_ssl| SELECT s.pid,
     s.sslbits AS bits,
     s.sslcompression AS compression,
     s.sslclientdn AS clientdn
-   FROM pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn);
+   FROM pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn, backend_type);
 pg_stat_subscription| SELECT su.oid AS subid,
     su.subname,
     st.pid,
-- 
1.8.3.1

From 9b83396077a4b5847621cd572f626507accf77e6 Mon Sep 17 00:00:00 2001
From: Kuntal Ghosh <kuntal.ghosh@enterprisedb.com>
Date: Wed, 15 Mar 2017 11:32:49 +0530
Subject: [PATCH 1/3] Infra to expose all backend processes in
 pg_stat_get_activity

This patch implements the infrastructure required to expose
all backend processes including auxiliary procs in pg_stat_activity.
BackendStatusArray is extended to store auxiliary processes. Backends
use slots indexed in the range from 1 to MaxBackends (inclusive),
so we use MaxBackends + AuxBackendType + 1 as the index of the slot for an
auxiliary process.
---
 src/backend/postmaster/pgstat.c     | 193 +++++++++++++++++++++++++++++++-----
 src/backend/storage/lmgr/proc.c     |  27 +++++
 src/backend/utils/adt/pgstatfuncs.c |  30 +++++-
 src/include/pgstat.h                |  26 +++++
 src/include/storage/proc.h          |   1 +
 5 files changed, 250 insertions(+), 27 deletions(-)

diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 3a50488..a2b9bbf 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -50,6 +50,7 @@
 #include "postmaster/autovacuum.h"
 #include "postmaster/fork_process.h"
 #include "postmaster/postmaster.h"
+#include "replication/walsender.h"
 #include "storage/backendid.h"
 #include "storage/dsm.h"
 #include "storage/fd.h"
@@ -103,6 +104,18 @@
 
 
 /* ----------
+ * Total number of backends including auxiliary
+ *
+ * We reserve a slot for each possible BackendId, plus one for each
+ * possible auxiliary process type.  (This scheme assumes there is not
+ * more than one of any auxiliary process type at a time.) MaxBackends
+ * includes autovacuum workers and background workers as well.
+ * ----------
+ */
+#define NumBackendStatSlots (MaxBackends + NUM_AUXPROCTYPES)
+
+
+/* ----------
  * GUC parameters
  * ----------
  */
@@ -212,7 +225,11 @@ typedef struct TwoPhasePgStatRecord
  */
 static MemoryContext pgStatLocalContext = NULL;
 static HTAB *pgStatDBHash = NULL;
+
+/* Status for backends including auxiliary */
 static LocalPgBackendStatus *localBackendStatusTable = NULL;
+
+/* Total number of backends including auxiliary */
 static int	localNumBackends = 0;
 
 /*
@@ -2505,20 +2522,20 @@ BackendStatusShmemSize(void)
 	Size		size;
 
 	/* BackendStatusArray: */
-	size = mul_size(sizeof(PgBackendStatus), MaxBackends);
+	size = mul_size(sizeof(PgBackendStatus), NumBackendStatSlots);
 	/* BackendAppnameBuffer: */
 	size = add_size(size,
-					mul_size(NAMEDATALEN, MaxBackends));
+					mul_size(NAMEDATALEN, NumBackendStatSlots));
 	/* BackendClientHostnameBuffer: */
 	size = add_size(size,
-					mul_size(NAMEDATALEN, MaxBackends));
+					mul_size(NAMEDATALEN, NumBackendStatSlots));
 	/* BackendActivityBuffer: */
 	size = add_size(size,
-					mul_size(pgstat_track_activity_query_size, MaxBackends));
+			mul_size(pgstat_track_activity_query_size, NumBackendStatSlots));
 #ifdef USE_SSL
 	/* BackendSslStatusBuffer: */
 	size = add_size(size,
-					mul_size(sizeof(PgBackendSSLStatus), MaxBackends));
+				  mul_size(sizeof(PgBackendSSLStatus), NumBackendStatSlots));
 #endif
 	return size;
 }
@@ -2536,7 +2553,7 @@ CreateSharedBackendStatus(void)
 	char	   *buffer;
 
 	/* Create or attach to the shared array */
-	size = mul_size(sizeof(PgBackendStatus), MaxBackends);
+	size = mul_size(sizeof(PgBackendStatus), NumBackendStatSlots);
 	BackendStatusArray = (PgBackendStatus *)
 		ShmemInitStruct("Backend Status Array", size, &found);
 
@@ -2559,7 +2576,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_appname pointers. */
 		buffer = BackendAppnameBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumBackendStatSlots; i++)
 		{
 			BackendStatusArray[i].st_appname = buffer;
 			buffer += NAMEDATALEN;
@@ -2577,7 +2594,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_clienthostname pointers. */
 		buffer = BackendClientHostnameBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumBackendStatSlots; i++)
 		{
 			BackendStatusArray[i].st_clienthostname = buffer;
 			buffer += NAMEDATALEN;
@@ -2586,7 +2603,7 @@ CreateSharedBackendStatus(void)
 
 	/* Create or attach to the shared activity buffer */
 	BackendActivityBufferSize = mul_size(pgstat_track_activity_query_size,
-										 MaxBackends);
+										 NumBackendStatSlots);
 	BackendActivityBuffer = (char *)
 		ShmemInitStruct("Backend Activity Buffer",
 						BackendActivityBufferSize,
@@ -2598,7 +2615,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_activity pointers. */
 		buffer = BackendActivityBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumBackendStatSlots; i++)
 		{
 			BackendStatusArray[i].st_activity = buffer;
 			buffer += pgstat_track_activity_query_size;
@@ -2607,7 +2624,7 @@ CreateSharedBackendStatus(void)
 
 #ifdef USE_SSL
 	/* Create or attach to the shared SSL status buffer */
-	size = mul_size(sizeof(PgBackendSSLStatus), MaxBackends);
+	size = mul_size(sizeof(PgBackendSSLStatus), NumBackendStatSlots);
 	BackendSslStatusBuffer = (PgBackendSSLStatus *)
 		ShmemInitStruct("Backend SSL Status Buffer", size, &found);
 
@@ -2619,7 +2636,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_sslstatus pointers. */
 		ptr = BackendSslStatusBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumBackendStatSlots; i++)
 		{
 			BackendStatusArray[i].st_sslstatus = ptr;
 			ptr++;
@@ -2633,7 +2650,8 @@ CreateSharedBackendStatus(void)
  * pgstat_initialize() -
  *
  *	Initialize pgstats state, and set up our on-proc-exit hook.
- *	Called from InitPostgres.  MyBackendId must be set,
+ *	Called from InitPostgres and AuxiliaryProcessMain. For auxiliary process,
+ *	MyBackendId is invalid. Otherwise, MyBackendId must be set,
  *	but we must not have started any transaction yet (since the
  *	exit hook must run after the last transaction exit).
  *	NOTE: MyDatabaseId isn't set yet; so the shutdown hook has to be careful.
@@ -2643,8 +2661,26 @@ void
 pgstat_initialize(void)
 {
 	/* Initialize MyBEEntry */
-	Assert(MyBackendId >= 1 && MyBackendId <= MaxBackends);
-	MyBEEntry = &BackendStatusArray[MyBackendId - 1];
+	if (MyBackendId != InvalidBackendId)
+	{
+		Assert(MyBackendId >= 1 && MyBackendId <= MaxBackends);
+		MyBEEntry = &BackendStatusArray[MyBackendId - 1];
+	}
+	else
+	{
+		/* Must be an auxiliary process */
+		Assert(MyAuxProcType != NotAnAuxProcess);
+
+		/*
+		 * Assign the MyBEEntry for an auxiliary process.  Since it doesn't
+		 * have a BackendId, the slot is statically allocated based on the
+		 * auxiliary process type (MyAuxProcType).  Backends use slots indexed
+		 * in the range from 1 to MaxBackends (inclusive), so we use
+		 * MaxBackends + AuxBackendType + 1 as the index of the slot for an
+		 * auxiliary process.
+		 */
+		MyBEEntry = &BackendStatusArray[MaxBackends + MyAuxProcType];
+	}
 
 	/* Set up a process-exit hook to clean up */
 	on_shmem_exit(pgstat_beshutdown_hook, 0);
@@ -2655,15 +2691,16 @@ pgstat_initialize(void)
  *
  *	Initialize this backend's entry in the PgBackendStatus array.
  *	Called from InitPostgres.
- *	MyDatabaseId, session userid, and application_name must be set
- *	(hence, this cannot be combined with pgstat_initialize).
+ *
+ *	Apart from auxiliary processes, MyBackendId, MyDatabaseId,
+ *	session userid, and application_name must be set for a
+ *	backend (hence, this cannot be combined with pgstat_initialize).
  * ----------
  */
 void
 pgstat_bestart(void)
 {
 	TimestampTz proc_start_timestamp;
-	Oid			userid;
 	SockAddr	clientaddr;
 	volatile PgBackendStatus *beentry;
 
@@ -2678,7 +2715,6 @@ pgstat_bestart(void)
 		proc_start_timestamp = MyProcPort->SessionStartTime;
 	else
 		proc_start_timestamp = GetCurrentTimestamp();
-	userid = GetSessionUserId();
 
 	/*
 	 * We may not have a MyProcPort (eg, if this is the autovacuum process).
@@ -2697,6 +2733,65 @@ pgstat_bestart(void)
 	 * cute.
 	 */
 	beentry = MyBEEntry;
+
+	/* pgstats state must be initialized from pgstat_initialize() */
+	Assert(beentry != NULL);
+
+	if (MyBackendId != InvalidBackendId)
+	{
+		if (IsAutoVacuumLauncherProcess())
+		{
+			/* Autovacuum Launcher */
+			beentry->st_backendType = B_AUTOVAC_LAUNCHER;
+		}
+		else if (IsAutoVacuumWorkerProcess())
+		{
+			/* Autovacuum Worker */
+			beentry->st_backendType = B_AUTOVAC_WORKER;
+		}
+		else if (am_walsender)
+		{
+			/* Wal sender */
+			beentry->st_backendType = B_WAL_SENDER;
+		}
+		else if (IsBackgroundWorker)
+		{
+			/* bgworker */
+			beentry->st_backendType = B_BG_WORKER;
+		}
+		else
+		{
+			/* client-backend */
+			beentry->st_backendType = B_BACKEND;
+		}
+	}
+	else
+	{
+		/* Must be an auxiliary process */
+		Assert(MyAuxProcType != NotAnAuxProcess);
+		switch (MyAuxProcType)
+		{
+			case StartupProcess:
+				beentry->st_backendType = B_STARTUP;
+				break;
+			case BgWriterProcess:
+				beentry->st_backendType = B_BG_WRITER;
+				break;
+			case CheckpointerProcess:
+				beentry->st_backendType = B_CHECKPOINTER;
+				break;
+			case WalWriterProcess:
+				beentry->st_backendType = B_WAL_WRITER;
+				break;
+			case WalReceiverProcess:
+				beentry->st_backendType = B_WAL_RECEIVER;
+				break;
+			default:
+				elog(PANIC, "unrecognized process type: %d", (int) MyAuxProcType);
+				proc_exit(1);
+		}
+	}
+
 	do
 	{
 		pgstat_increment_changecount_before(beentry);
@@ -2708,7 +2803,15 @@ pgstat_bestart(void)
 	beentry->st_state_start_timestamp = 0;
 	beentry->st_xact_start_timestamp = 0;
 	beentry->st_databaseid = MyDatabaseId;
-	beentry->st_userid = userid;
+
+	/* We have userid for client-backends, wal-sender and bgworker processes */
+	if (beentry->st_backendType == B_BACKEND
+			|| beentry->st_backendType == B_WAL_SENDER
+			|| beentry->st_backendType == B_BG_WORKER)
+		beentry->st_userid = GetSessionUserId();
+	else
+		beentry->st_userid = InvalidOid;
+
 	beentry->st_clientaddr = clientaddr;
 	if (MyProcPort && MyProcPort->remote_hostname)
 		strlcpy(beentry->st_clienthostname, MyProcPort->remote_hostname,
@@ -3046,24 +3149,24 @@ pgstat_read_current_status(void)
 
 	localtable = (LocalPgBackendStatus *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   sizeof(LocalPgBackendStatus) * MaxBackends);
+						 sizeof(LocalPgBackendStatus) * NumBackendStatSlots);
 	localappname = (char *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   NAMEDATALEN * MaxBackends);
+						   NAMEDATALEN * NumBackendStatSlots);
 	localactivity = (char *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   pgstat_track_activity_query_size * MaxBackends);
+					 pgstat_track_activity_query_size * NumBackendStatSlots);
 #ifdef USE_SSL
 	localsslstatus = (PgBackendSSLStatus *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   sizeof(PgBackendSSLStatus) * MaxBackends);
+						   sizeof(PgBackendSSLStatus) * NumBackendStatSlots);
 #endif
 
 	localNumBackends = 0;
 
 	beentry = BackendStatusArray;
 	localentry = localtable;
-	for (i = 1; i <= MaxBackends; i++)
+	for (i = 1; i <= NumBackendStatSlots; i++)
 	{
 		/*
 		 * Follow the protocol of retrying if st_changecount changes while we
@@ -3823,7 +3926,47 @@ pgstat_get_crashed_backend_activity(int pid, char *buffer, int buflen)
 	return NULL;
 }
 
+const char *
+pgstat_get_backend_desc(BackendType backendType)
+{
+	const char *backendDesc = "unknown process type";
+
+	switch (backendType)
+	{
+		case B_AUTOVAC_LAUNCHER:
+			backendDesc = "autovacuum launcher";
+			break;
+		case B_AUTOVAC_WORKER:
+			backendDesc = "autovacuum worker";
+			break;
+		case B_BACKEND:
+			backendDesc = "client backend";
+			break;
+		case B_BG_WORKER:
+			backendDesc = "background worker";
+			break;
+		case B_BG_WRITER:
+			backendDesc = "background writer";
+			break;
+		case B_CHECKPOINTER:
+			backendDesc = "checkpointer";
+			break;
+		case B_STARTUP:
+			backendDesc = "startup";
+			break;
+		case B_WAL_RECEIVER:
+			backendDesc = "walreceiver";
+			break;
+		case B_WAL_SENDER:
+			backendDesc = "walsender";
+			break;
+		case B_WAL_WRITER:
+			backendDesc = "walwriter";
+			break;
+	}
 
+	return backendDesc;
+}
 /* ------------------------------------------------------------
  * Local support functions follow
  * ------------------------------------------------------------
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 8f467be..3e716b1 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -941,6 +941,33 @@ AuxiliaryProcKill(int code, Datum arg)
 	SpinLockRelease(ProcStructLock);
 }
 
+/*
+ * AuxiliaryPidGetProc -- get PGPROC for an auxiliary process
+ * given its PID
+ *
+ * Returns NULL if not found.
+ */
+PGPROC *
+AuxiliaryPidGetProc(int pid)
+{
+	PGPROC	   *result = NULL;
+	int			index;
+
+	if (pid == 0)				/* never match dummy PGPROCs */
+		return NULL;
+
+	for (index = 0; index < NUM_AUXILIARY_PROCS; index++)
+	{
+		PGPROC	   *proc = &AuxiliaryProcs[index];
+
+		if (proc->pid == pid)
+		{
+			result = proc;
+			break;
+		}
+	}
+	return result;
+}
 
 /*
  * ProcQueue package: routines for putting processes to sleep
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index a987d0d..96a1188 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -20,6 +20,7 @@
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "pgstat.h"
+#include "postmaster/postmaster.h"
 #include "storage/proc.h"
 #include "storage/procarray.h"
 #include "utils/acl.h"
@@ -615,9 +616,18 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			continue;
 
 		/* Values available to all callers */
-		values[0] = ObjectIdGetDatum(beentry->st_databaseid);
+		if (beentry->st_databaseid != InvalidOid)
+			values[0] = ObjectIdGetDatum(beentry->st_databaseid);
+		else
+			nulls[0] = true;
+
 		values[1] = Int32GetDatum(beentry->st_procpid);
-		values[2] = ObjectIdGetDatum(beentry->st_userid);
+
+		if (beentry->st_userid != InvalidOid)
+			values[2] = ObjectIdGetDatum(beentry->st_userid);
+		else
+			nulls[2] = true;
+
 		if (beentry->st_appname)
 			values[3] = CStringGetTextDatum(beentry->st_appname);
 		else
@@ -690,6 +700,22 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 				wait_event = pgstat_get_wait_event(raw_wait_event);
 
 			}
+			else if (beentry->st_backendType != B_BACKEND)
+			{
+				uint32		raw_wait_event;
+
+				/*
+				 * For an auxiliary process, retrieve process info from
+				 * AuxiliaryProcs stored in shared-memory.
+				 */
+				proc = AuxiliaryPidGetProc(beentry->st_procpid);
+
+				/* Check whether this is indeed an auxiliary process */
+				Assert(proc != NULL);
+				raw_wait_event = UINT32_ACCESS_ONCE(proc->wait_event_info);
+				wait_event_type = pgstat_get_wait_event_type(raw_wait_event);
+				wait_event = pgstat_get_wait_event(raw_wait_event);
+			}
 			else
 			{
 				wait_event_type = NULL;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index f2daf32..14562d5 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -696,6 +696,25 @@ typedef struct PgStat_GlobalStats
 
 
 /* ----------
+ * Backend types
+ * ----------
+ */
+typedef enum BackendType
+{
+	B_AUTOVAC_LAUNCHER,
+	B_AUTOVAC_WORKER,
+	B_BACKEND,
+	B_BG_WORKER,
+	B_BG_WRITER,
+	B_CHECKPOINTER,
+	B_STARTUP,
+	B_WAL_RECEIVER,
+	B_WAL_SENDER,
+	B_WAL_WRITER
+} BackendType;
+
+
+/* ----------
  * Backend states
  * ----------
  */
@@ -925,6 +944,9 @@ typedef struct PgBackendSSLStatus
  * showing its current activity.  (The structs are allocated according to
  * BackendId, but that is not critical.)  Note that the collector process
  * has no involvement in, or even access to, these structs.
+ *
+ * Each auxiliary process also maintains a PgBackendStatus struct in shared
+ * memory.
  * ----------
  */
 typedef struct PgBackendStatus
@@ -949,6 +971,9 @@ typedef struct PgBackendStatus
 	/* The entry is valid iff st_procpid > 0, unused if st_procpid == 0 */
 	int			st_procpid;
 
+	/* Type of backends */
+	BackendType st_backendType;
+
 	/* Times when current backend, transaction, and activity started */
 	TimestampTz st_proc_start_timestamp;
 	TimestampTz st_xact_start_timestamp;
@@ -1147,6 +1172,7 @@ extern const char *pgstat_get_wait_event_type(uint32 wait_event_info);
 extern const char *pgstat_get_backend_current_activity(int pid, bool checkUser);
 extern const char *pgstat_get_crashed_backend_activity(int pid, char *buffer,
 									int buflen);
+extern const char *pgstat_get_backend_desc(BackendType backendType);
 
 extern void pgstat_progress_start_command(ProgressCommandType cmdtype,
 							  Oid relid);
diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h
index 5f38fa6..be3bd01 100644
--- a/src/include/storage/proc.h
+++ b/src/include/storage/proc.h
@@ -262,6 +262,7 @@ extern PGPROC *PreparedXactProcs;
  */
 #define NUM_AUXILIARY_PROCS		4
 
+extern PGPROC *AuxiliaryPidGetProc(int pid);
 
 /* configurable options */
 extern int	DeadlockTimeout;
-- 
1.8.3.1

From d9328739f9fab8ca4d9919085af45f711bfce90a Mon Sep 17 00:00:00 2001
From: Kuntal Ghosh <kuntal.ghosh@enterprisedb.com>
Date: Tue, 21 Mar 2017 18:18:22 +0530
Subject: [PATCH 2/3] Expose stats for all backends

All backends include auxiliary procs, autovacuum launcher and
bgworkers having valid BackendIds.
---
 src/backend/access/transam/parallel.c      | 3 +++
 src/backend/bootstrap/bootstrap.c          | 3 +++
 src/backend/postmaster/autovacuum.c        | 3 +++
 src/backend/postmaster/bgwriter.c          | 3 +++
 src/backend/postmaster/checkpointer.c      | 3 +++
 src/backend/postmaster/pgstat.c            | 1 -
 src/backend/postmaster/startup.c           | 4 ++++
 src/backend/postmaster/walwriter.c         | 3 +++
 src/backend/replication/logical/launcher.c | 3 +++
 src/backend/replication/logical/worker.c   | 3 +++
 src/backend/replication/walreceiver.c      | 4 ++++
 src/backend/replication/walsender.c        | 5 ++++-
 src/backend/utils/init/postinit.c          | 3 ++-
 src/test/modules/worker_spi/worker_spi.c   | 3 +++
 14 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/src/backend/access/transam/parallel.c b/src/backend/access/transam/parallel.c
index 3e0ee87..ed2ac47 100644
--- a/src/backend/access/transam/parallel.c
+++ b/src/backend/access/transam/parallel.c
@@ -1044,6 +1044,9 @@ ParallelWorkerMain(Datum main_arg)
 	BackgroundWorkerInitializeConnectionByOid(fps->database_id,
 											  fps->authenticated_user_id);
 
+	/* report the parallel worker process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/*
 	 * Set the client encoding to the database encoding, since that is what
 	 * the leader will expect.
diff --git a/src/backend/bootstrap/bootstrap.c b/src/backend/bootstrap/bootstrap.c
index 6511c60..f56e229 100644
--- a/src/backend/bootstrap/bootstrap.c
+++ b/src/backend/bootstrap/bootstrap.c
@@ -387,6 +387,9 @@ AuxiliaryProcessMain(int argc, char *argv[])
 		/* finish setting up bufmgr.c */
 		InitBufferPoolBackend();
 
+		/* Initialize stats collection */
+		pgstat_initialize();
+
 		/* register a before-shutdown callback for LWLock cleanup */
 		before_shmem_exit(ShutdownAuxiliaryProcess, 0);
 	}
diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index 33ca749..0dd8ccc 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -453,6 +453,9 @@ AutoVacLauncherMain(int argc, char *argv[])
 
 	InitPostgres(NULL, InvalidOid, NULL, InvalidOid, NULL);
 
+	/* report autovacuum launcher process in the  PgBackendStatus array */
+	pgstat_bestart();
+
 	SetProcessingMode(NormalProcessing);
 
 	/*
diff --git a/src/backend/postmaster/bgwriter.c b/src/backend/postmaster/bgwriter.c
index dcb4cf2..6ba2e2e 100644
--- a/src/backend/postmaster/bgwriter.c
+++ b/src/backend/postmaster/bgwriter.c
@@ -248,6 +248,9 @@ BackgroundWriterMain(void)
 	 */
 	prev_hibernate = false;
 
+	/* report bgwriter process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/*
 	 * Loop forever
 	 */
diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c
index fe9041f..8eb0a2a 100644
--- a/src/backend/postmaster/checkpointer.c
+++ b/src/backend/postmaster/checkpointer.c
@@ -345,6 +345,9 @@ CheckpointerMain(void)
 	 */
 	ProcGlobal->checkpointerLatch = &MyProc->procLatch;
 
+	/* report checkpointer process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/*
 	 * Loop forever
 	 */
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index a2b9bbf..ff565a3 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -2690,7 +2690,6 @@ pgstat_initialize(void)
  * pgstat_bestart() -
  *
  *	Initialize this backend's entry in the PgBackendStatus array.
- *	Called from InitPostgres.
  *
  *	Apart from auxiliary processes, MyBackendId, MyDatabaseId,
  *	session userid, and application_name must be set for a
diff --git a/src/backend/postmaster/startup.c b/src/backend/postmaster/startup.c
index b172b5e..56ff042 100644
--- a/src/backend/postmaster/startup.c
+++ b/src/backend/postmaster/startup.c
@@ -25,6 +25,7 @@
 #include "access/xlog.h"
 #include "libpq/pqsignal.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/startup.h"
 #include "storage/ipc.h"
 #include "storage/latch.h"
@@ -210,6 +211,9 @@ StartupProcessMain(void)
 	 */
 	PG_SETMASK(&UnBlockSig);
 
+	/* report startup process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/*
 	 * Do what we came for.
 	 */
diff --git a/src/backend/postmaster/walwriter.c b/src/backend/postmaster/walwriter.c
index a575d8f..9056652 100644
--- a/src/backend/postmaster/walwriter.c
+++ b/src/backend/postmaster/walwriter.c
@@ -231,6 +231,9 @@ WalWriterMain(void)
 	 */
 	ProcGlobal->walwriterLatch = &MyProc->procLatch;
 
+	/* report walwriter process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/*
 	 * Loop forever
 	 */
diff --git a/src/backend/replication/logical/launcher.c b/src/backend/replication/logical/launcher.c
index 20b4362..221adb0 100644
--- a/src/backend/replication/logical/launcher.c
+++ b/src/backend/replication/logical/launcher.c
@@ -571,6 +571,9 @@ ApplyLauncherMain(Datum main_arg)
 	 */
 	BackgroundWorkerInitializeConnection(NULL, NULL);
 
+	/* report the apply launcher process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/* Enter main loop */
 	while (!got_SIGTERM)
 	{
diff --git a/src/backend/replication/logical/worker.c b/src/backend/replication/logical/worker.c
index c3e54af..db09540 100644
--- a/src/backend/replication/logical/worker.c
+++ b/src/backend/replication/logical/worker.c
@@ -1376,6 +1376,9 @@ ApplyWorkerMain(Datum main_arg)
 	BackgroundWorkerInitializeConnectionByOid(MyLogicalRepWorker->dbid,
 											  MyLogicalRepWorker->userid);
 
+	/* report the apply worker process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/* Load the subscription into persistent memory context. */
 	CreateCacheMemoryContext();
 	ApplyCacheContext = AllocSetContextCreate(CacheMemoryContext,
diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index 18d9d7e..3265d03 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -316,6 +316,10 @@ WalReceiverMain(void)
 	SpinLockRelease(&walrcv->mutex);
 
 	first_stream = true;
+
+	/* report walreceiver process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	for (;;)
 	{
 		char	   *primary_sysid;
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 0f6b828..de1edc6 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -245,6 +245,9 @@ InitWalSender(void)
 	 */
 	MarkPostmasterChildWalSender();
 	SendPostmasterSignal(PMSIGNAL_ADVANCE_STATE_MACHINE);
+
+	/* report walsender process in the PgBackendStatus array */
+	pgstat_bestart();
 }
 
 /*
@@ -1808,7 +1811,7 @@ WalSndLoop(WalSndSendDataCallback send_data)
 	waiting_for_ping_response = false;
 
 	/* Report to pgstat that this process is a WAL sender */
-	pgstat_report_activity(STATE_RUNNING, "walsender");
+	pgstat_report_activity(STATE_RUNNING, NULL);
 
 	/*
 	 * Loop until we reach the end of this timeline or the client requests to
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index 9f938f2..cc4a639 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -808,7 +808,7 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 		/* initialize client encoding */
 		InitializeClientEncoding();
 
-		/* report this backend in the PgBackendStatus array */
+		/* report walsender process in the PgBackendStatus array */
 		pgstat_bestart();
 
 		/* close the transaction we started above */
@@ -875,6 +875,7 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 		 */
 		if (!bootstrap)
 			CommitTransactionCommand();
+
 		return;
 	}
 
diff --git a/src/test/modules/worker_spi/worker_spi.c b/src/test/modules/worker_spi/worker_spi.c
index 72ab846..bea6aa63 100644
--- a/src/test/modules/worker_spi/worker_spi.c
+++ b/src/test/modules/worker_spi/worker_spi.c
@@ -181,6 +181,9 @@ worker_spi_main(Datum main_arg)
 	/* Connect to our database */
 	BackgroundWorkerInitializeConnection("postgres", NULL);
 
+	/* report the worker spi process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	elog(LOG, "%s initialized with %s.%s",
 		 MyBgworkerEntry->bgw_name, table->schema, table->name);
 	initialize_worker_spi(table);
-- 
1.8.3.1

From c59011315e90b8558ca80e835068e9c5f8cc1ac2 Mon Sep 17 00:00:00 2001
From: Kuntal Ghosh <kuntal.ghosh@enterprisedb.com>
Date: Wed, 15 Mar 2017 12:53:11 +0530
Subject: [PATCH 3/3] Add backend_type column in pg_stat_get_activity

backend_type indicates the type of process in the stat table.
---
 doc/src/sgml/monitoring.sgml         | 14 ++++++++++++--
 src/backend/catalog/system_views.sql |  3 ++-
 src/backend/utils/adt/pgstatfuncs.c  |  5 ++++-
 src/include/catalog/pg_proc.h        |  2 +-
 src/test/regress/expected/rules.out  |  9 +++++----
 5 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index dcb2d33..f77c5a7 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -620,8 +620,7 @@ postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: ser
     <row>
      <entry><structfield>backend_start</></entry>
      <entry><type>timestamp with time zone</></entry>
-     <entry>Time when this process was started, i.e., when the
-      client connected to the server
+     <entry>Time when this process was started.
      </entry>
     </row>
     <row>
@@ -797,6 +796,17 @@ postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: ser
       <xref linkend="guc-track-activity-query-size">.
      </entry>
     </row>
+    <row>
+     <entry><structfield>backend_type</structfield></entry>
+     <entry><type>text</type></entry>
+     <entry>Type of current backend. Possible types are 
+      <literal>autovacuum launcher</>, <literal>autovacuum worker</>,
+      <literal>background worker</>, <literal>background writer</>,
+      <literal>client backend</>, <literal>checkpointer</>,
+      <literal>startup</>, <literal>walreceiver</>,
+      <literal>walsender</> and <literal>walwriter</>.
+     </entry>
+    </row>
    </tbody>
    </tgroup>
   </table>
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index b6552da..bdbb5b8 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -684,7 +684,8 @@ CREATE VIEW pg_stat_activity AS
             S.state,
             S.backend_xid,
             s.backend_xmin,
-            S.query
+            S.query,
+            S.backend_type
     FROM pg_stat_get_activity(NULL) AS S
         LEFT JOIN pg_database AS D ON (S.datid = D.oid)
         LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 96a1188..0085335 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -539,7 +539,7 @@ pg_stat_get_progress_info(PG_FUNCTION_ARGS)
 Datum
 pg_stat_get_activity(PG_FUNCTION_ARGS)
 {
-#define PG_STAT_GET_ACTIVITY_COLS	23
+#define PG_STAT_GET_ACTIVITY_COLS	24
 	int			num_backends = pgstat_fetch_stat_numbackends();
 	int			curr_backend;
 	int			pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
@@ -819,6 +819,8 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 					nulls[14] = true;
 				}
 			}
+			/* Add backend type */
+			values[23] = CStringGetTextDatum(pgstat_get_backend_desc(beentry->st_backendType));
 		}
 		else
 		{
@@ -834,6 +836,7 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			nulls[12] = true;
 			nulls[13] = true;
 			nulls[14] = true;
+			nulls[23] = true;
 		}
 
 		tuplestore_putvalues(tupstore, tupdesc, values, nulls);
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 836d6ff..8494648 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -2797,7 +2797,7 @@ DATA(insert OID = 3057 ( pg_stat_get_autoanalyze_count PGNSP PGUID 12 1 0 0 0 f
 DESCR("statistics: number of auto analyzes for a table");
 DATA(insert OID = 1936 (  pg_stat_get_backend_idset		PGNSP PGUID 12 1 100 0 0 f f f f t t s r 0 0 23 "" _null_ _null_ _null_ _null_ _null_ pg_stat_get_backend_idset _null_ _null_ _null_ ));
 DESCR("statistics: currently active backend IDs");
-DATA(insert OID = 2022 (  pg_stat_get_activity			PGNSP PGUID 12 1 100 0 0 f f f f f t s r 1 0 2249 "23" "{23,26,23,26,25,25,25,25,25,1184,1184,1184,1184,869,25,23,28,28,16,25,25,23,16,25}" "{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,ssl,sslversion,sslcipher,sslbits,sslcompression,sslclientdn}" _null_ _null_ pg_stat_get_activity _null_ _null_ _null_ ));
+DATA(insert OID = 2022 (  pg_stat_get_activity			PGNSP PGUID 12 1 100 0 0 f f f f f t s r 1 0 2249 "23" "{23,26,23,26,25,25,25,25,25,1184,1184,1184,1184,869,25,23,28,28,16,25,25,23,16,25,25}" "{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,ssl,sslversion,sslcipher,sslbits,sslcompression,sslclientdn,backend_type}" _null_ _null_ pg_stat_get_activity _null_ _null_ _null_ ));
 DESCR("statistics: information about currently active backends");
 DATA(insert OID = 3318 (  pg_stat_get_progress_info			  PGNSP PGUID 12 1 100 0 0 f f f f t t s r 1 0 2249 "25" "{25,23,26,26,20,20,20,20,20,20,20,20,20,20}" "{i,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{cmdtype,pid,datid,relid,param1,param2,param3,param4,param5,param6,param7,param8,param9,param10}" _null_ _null_ pg_stat_get_progress_info _null_ _null_ _null_ ));
 DESCR("statistics: information about progress of backends running maintenance command");
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index bd13ae6..a317bff 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1704,8 +1704,9 @@ pg_stat_activity| SELECT s.datid,
     s.state,
     s.backend_xid,
     s.backend_xmin,
-    s.query
-   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn)
+    s.query,
+    s.backend_type
+   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn, backend_type)
      LEFT JOIN pg_database d ON ((s.datid = d.oid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_all_indexes| SELECT c.oid AS relid,
@@ -1833,7 +1834,7 @@ pg_stat_replication| SELECT s.pid,
     w.replay_location,
     w.sync_priority,
     w.sync_state
-   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn)
+   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn, backend_type)
      JOIN pg_stat_get_wal_senders() w(pid, state, sent_location, write_location, flush_location, replay_location, sync_priority, sync_state) ON ((s.pid = w.pid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_ssl| SELECT s.pid,
@@ -1843,7 +1844,7 @@ pg_stat_ssl| SELECT s.pid,
     s.sslbits AS bits,
     s.sslcompression AS compression,
     s.sslclientdn AS clientdn
-   FROM pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn);
+   FROM pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn, backend_type);
 pg_stat_subscription| SELECT su.oid AS subid,
     su.subname,
     st.pid,
-- 
1.8.3.1

From 207cd2047902e6d82d02de081347b52b711dc58a Mon Sep 17 00:00:00 2001
From: Kuntal Ghosh <kuntal.ghosh@enterprisedb.com>
Date: Wed, 15 Mar 2017 11:32:49 +0530
Subject: [PATCH 1/3] Infra to expose all backend processes in
 pg_stat_get_activity

This patch implements the infrastructure required to expose
all backend processes including auxiliary procs in pg_stat_activity.
BackendStatusArray is extended to store auxiliary processes. Backends
use slots indexed in the range from 1 to MaxBackends (inclusive),
so we use MaxBackends + AuxBackendType + 1 as the index of the slot for an
auxiliary process.
---
 src/backend/postmaster/pgstat.c     | 193 +++++++++++++++++++++++++++++++-----
 src/backend/storage/lmgr/proc.c     |  27 +++++
 src/backend/utils/adt/pgstatfuncs.c |  30 +++++-
 src/include/pgstat.h                |  26 +++++
 src/include/storage/proc.h          |   1 +
 5 files changed, 250 insertions(+), 27 deletions(-)

diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index 3a50488..a2b9bbf 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -50,6 +50,7 @@
 #include "postmaster/autovacuum.h"
 #include "postmaster/fork_process.h"
 #include "postmaster/postmaster.h"
+#include "replication/walsender.h"
 #include "storage/backendid.h"
 #include "storage/dsm.h"
 #include "storage/fd.h"
@@ -103,6 +104,18 @@
 
 
 /* ----------
+ * Total number of backends including auxiliary
+ *
+ * We reserve a slot for each possible BackendId, plus one for each
+ * possible auxiliary process type.  (This scheme assumes there is not
+ * more than one of any auxiliary process type at a time.) MaxBackends
+ * includes autovacuum workers and background workers as well.
+ * ----------
+ */
+#define NumBackendStatSlots (MaxBackends + NUM_AUXPROCTYPES)
+
+
+/* ----------
  * GUC parameters
  * ----------
  */
@@ -212,7 +225,11 @@ typedef struct TwoPhasePgStatRecord
  */
 static MemoryContext pgStatLocalContext = NULL;
 static HTAB *pgStatDBHash = NULL;
+
+/* Status for backends including auxiliary */
 static LocalPgBackendStatus *localBackendStatusTable = NULL;
+
+/* Total number of backends including auxiliary */
 static int	localNumBackends = 0;
 
 /*
@@ -2505,20 +2522,20 @@ BackendStatusShmemSize(void)
 	Size		size;
 
 	/* BackendStatusArray: */
-	size = mul_size(sizeof(PgBackendStatus), MaxBackends);
+	size = mul_size(sizeof(PgBackendStatus), NumBackendStatSlots);
 	/* BackendAppnameBuffer: */
 	size = add_size(size,
-					mul_size(NAMEDATALEN, MaxBackends));
+					mul_size(NAMEDATALEN, NumBackendStatSlots));
 	/* BackendClientHostnameBuffer: */
 	size = add_size(size,
-					mul_size(NAMEDATALEN, MaxBackends));
+					mul_size(NAMEDATALEN, NumBackendStatSlots));
 	/* BackendActivityBuffer: */
 	size = add_size(size,
-					mul_size(pgstat_track_activity_query_size, MaxBackends));
+			mul_size(pgstat_track_activity_query_size, NumBackendStatSlots));
 #ifdef USE_SSL
 	/* BackendSslStatusBuffer: */
 	size = add_size(size,
-					mul_size(sizeof(PgBackendSSLStatus), MaxBackends));
+				  mul_size(sizeof(PgBackendSSLStatus), NumBackendStatSlots));
 #endif
 	return size;
 }
@@ -2536,7 +2553,7 @@ CreateSharedBackendStatus(void)
 	char	   *buffer;
 
 	/* Create or attach to the shared array */
-	size = mul_size(sizeof(PgBackendStatus), MaxBackends);
+	size = mul_size(sizeof(PgBackendStatus), NumBackendStatSlots);
 	BackendStatusArray = (PgBackendStatus *)
 		ShmemInitStruct("Backend Status Array", size, &found);
 
@@ -2559,7 +2576,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_appname pointers. */
 		buffer = BackendAppnameBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumBackendStatSlots; i++)
 		{
 			BackendStatusArray[i].st_appname = buffer;
 			buffer += NAMEDATALEN;
@@ -2577,7 +2594,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_clienthostname pointers. */
 		buffer = BackendClientHostnameBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumBackendStatSlots; i++)
 		{
 			BackendStatusArray[i].st_clienthostname = buffer;
 			buffer += NAMEDATALEN;
@@ -2586,7 +2603,7 @@ CreateSharedBackendStatus(void)
 
 	/* Create or attach to the shared activity buffer */
 	BackendActivityBufferSize = mul_size(pgstat_track_activity_query_size,
-										 MaxBackends);
+										 NumBackendStatSlots);
 	BackendActivityBuffer = (char *)
 		ShmemInitStruct("Backend Activity Buffer",
 						BackendActivityBufferSize,
@@ -2598,7 +2615,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_activity pointers. */
 		buffer = BackendActivityBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumBackendStatSlots; i++)
 		{
 			BackendStatusArray[i].st_activity = buffer;
 			buffer += pgstat_track_activity_query_size;
@@ -2607,7 +2624,7 @@ CreateSharedBackendStatus(void)
 
 #ifdef USE_SSL
 	/* Create or attach to the shared SSL status buffer */
-	size = mul_size(sizeof(PgBackendSSLStatus), MaxBackends);
+	size = mul_size(sizeof(PgBackendSSLStatus), NumBackendStatSlots);
 	BackendSslStatusBuffer = (PgBackendSSLStatus *)
 		ShmemInitStruct("Backend SSL Status Buffer", size, &found);
 
@@ -2619,7 +2636,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_sslstatus pointers. */
 		ptr = BackendSslStatusBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumBackendStatSlots; i++)
 		{
 			BackendStatusArray[i].st_sslstatus = ptr;
 			ptr++;
@@ -2633,7 +2650,8 @@ CreateSharedBackendStatus(void)
  * pgstat_initialize() -
  *
  *	Initialize pgstats state, and set up our on-proc-exit hook.
- *	Called from InitPostgres.  MyBackendId must be set,
+ *	Called from InitPostgres and AuxiliaryProcessMain. For auxiliary process,
+ *	MyBackendId is invalid. Otherwise, MyBackendId must be set,
  *	but we must not have started any transaction yet (since the
  *	exit hook must run after the last transaction exit).
  *	NOTE: MyDatabaseId isn't set yet; so the shutdown hook has to be careful.
@@ -2643,8 +2661,26 @@ void
 pgstat_initialize(void)
 {
 	/* Initialize MyBEEntry */
-	Assert(MyBackendId >= 1 && MyBackendId <= MaxBackends);
-	MyBEEntry = &BackendStatusArray[MyBackendId - 1];
+	if (MyBackendId != InvalidBackendId)
+	{
+		Assert(MyBackendId >= 1 && MyBackendId <= MaxBackends);
+		MyBEEntry = &BackendStatusArray[MyBackendId - 1];
+	}
+	else
+	{
+		/* Must be an auxiliary process */
+		Assert(MyAuxProcType != NotAnAuxProcess);
+
+		/*
+		 * Assign the MyBEEntry for an auxiliary process.  Since it doesn't
+		 * have a BackendId, the slot is statically allocated based on the
+		 * auxiliary process type (MyAuxProcType).  Backends use slots indexed
+		 * in the range from 1 to MaxBackends (inclusive), so we use
+		 * MaxBackends + AuxBackendType + 1 as the index of the slot for an
+		 * auxiliary process.
+		 */
+		MyBEEntry = &BackendStatusArray[MaxBackends + MyAuxProcType];
+	}
 
 	/* Set up a process-exit hook to clean up */
 	on_shmem_exit(pgstat_beshutdown_hook, 0);
@@ -2655,15 +2691,16 @@ pgstat_initialize(void)
  *
  *	Initialize this backend's entry in the PgBackendStatus array.
  *	Called from InitPostgres.
- *	MyDatabaseId, session userid, and application_name must be set
- *	(hence, this cannot be combined with pgstat_initialize).
+ *
+ *	Apart from auxiliary processes, MyBackendId, MyDatabaseId,
+ *	session userid, and application_name must be set for a
+ *	backend (hence, this cannot be combined with pgstat_initialize).
  * ----------
  */
 void
 pgstat_bestart(void)
 {
 	TimestampTz proc_start_timestamp;
-	Oid			userid;
 	SockAddr	clientaddr;
 	volatile PgBackendStatus *beentry;
 
@@ -2678,7 +2715,6 @@ pgstat_bestart(void)
 		proc_start_timestamp = MyProcPort->SessionStartTime;
 	else
 		proc_start_timestamp = GetCurrentTimestamp();
-	userid = GetSessionUserId();
 
 	/*
 	 * We may not have a MyProcPort (eg, if this is the autovacuum process).
@@ -2697,6 +2733,65 @@ pgstat_bestart(void)
 	 * cute.
 	 */
 	beentry = MyBEEntry;
+
+	/* pgstats state must be initialized from pgstat_initialize() */
+	Assert(beentry != NULL);
+
+	if (MyBackendId != InvalidBackendId)
+	{
+		if (IsAutoVacuumLauncherProcess())
+		{
+			/* Autovacuum Launcher */
+			beentry->st_backendType = B_AUTOVAC_LAUNCHER;
+		}
+		else if (IsAutoVacuumWorkerProcess())
+		{
+			/* Autovacuum Worker */
+			beentry->st_backendType = B_AUTOVAC_WORKER;
+		}
+		else if (am_walsender)
+		{
+			/* Wal sender */
+			beentry->st_backendType = B_WAL_SENDER;
+		}
+		else if (IsBackgroundWorker)
+		{
+			/* bgworker */
+			beentry->st_backendType = B_BG_WORKER;
+		}
+		else
+		{
+			/* client-backend */
+			beentry->st_backendType = B_BACKEND;
+		}
+	}
+	else
+	{
+		/* Must be an auxiliary process */
+		Assert(MyAuxProcType != NotAnAuxProcess);
+		switch (MyAuxProcType)
+		{
+			case StartupProcess:
+				beentry->st_backendType = B_STARTUP;
+				break;
+			case BgWriterProcess:
+				beentry->st_backendType = B_BG_WRITER;
+				break;
+			case CheckpointerProcess:
+				beentry->st_backendType = B_CHECKPOINTER;
+				break;
+			case WalWriterProcess:
+				beentry->st_backendType = B_WAL_WRITER;
+				break;
+			case WalReceiverProcess:
+				beentry->st_backendType = B_WAL_RECEIVER;
+				break;
+			default:
+				elog(PANIC, "unrecognized process type: %d", (int) MyAuxProcType);
+				proc_exit(1);
+		}
+	}
+
 	do
 	{
 		pgstat_increment_changecount_before(beentry);
@@ -2708,7 +2803,15 @@ pgstat_bestart(void)
 	beentry->st_state_start_timestamp = 0;
 	beentry->st_xact_start_timestamp = 0;
 	beentry->st_databaseid = MyDatabaseId;
-	beentry->st_userid = userid;
+
+	/* We have userid for client-backends, wal-sender and bgworker processes */
+	if (beentry->st_backendType == B_BACKEND
+			|| beentry->st_backendType == B_WAL_SENDER
+			|| beentry->st_backendType == B_BG_WORKER)
+		beentry->st_userid = GetSessionUserId();
+	else
+		beentry->st_userid = InvalidOid;
+
 	beentry->st_clientaddr = clientaddr;
 	if (MyProcPort && MyProcPort->remote_hostname)
 		strlcpy(beentry->st_clienthostname, MyProcPort->remote_hostname,
@@ -3046,24 +3149,24 @@ pgstat_read_current_status(void)
 
 	localtable = (LocalPgBackendStatus *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   sizeof(LocalPgBackendStatus) * MaxBackends);
+						 sizeof(LocalPgBackendStatus) * NumBackendStatSlots);
 	localappname = (char *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   NAMEDATALEN * MaxBackends);
+						   NAMEDATALEN * NumBackendStatSlots);
 	localactivity = (char *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   pgstat_track_activity_query_size * MaxBackends);
+					 pgstat_track_activity_query_size * NumBackendStatSlots);
 #ifdef USE_SSL
 	localsslstatus = (PgBackendSSLStatus *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   sizeof(PgBackendSSLStatus) * MaxBackends);
+						   sizeof(PgBackendSSLStatus) * NumBackendStatSlots);
 #endif
 
 	localNumBackends = 0;
 
 	beentry = BackendStatusArray;
 	localentry = localtable;
-	for (i = 1; i <= MaxBackends; i++)
+	for (i = 1; i <= NumBackendStatSlots; i++)
 	{
 		/*
 		 * Follow the protocol of retrying if st_changecount changes while we
@@ -3823,7 +3926,47 @@ pgstat_get_crashed_backend_activity(int pid, char *buffer, int buflen)
 	return NULL;
 }
 
+const char *
+pgstat_get_backend_desc(BackendType backendType)
+{
+	const char *backendDesc = "unknown process type";
+
+	switch (backendType)
+	{
+		case B_AUTOVAC_LAUNCHER:
+			backendDesc = "autovacuum launcher";
+			break;
+		case B_AUTOVAC_WORKER:
+			backendDesc = "autovacuum worker";
+			break;
+		case B_BACKEND:
+			backendDesc = "client backend";
+			break;
+		case B_BG_WORKER:
+			backendDesc = "background worker";
+			break;
+		case B_BG_WRITER:
+			backendDesc = "background writer";
+			break;
+		case B_CHECKPOINTER:
+			backendDesc = "checkpointer";
+			break;
+		case B_STARTUP:
+			backendDesc = "startup";
+			break;
+		case B_WAL_RECEIVER:
+			backendDesc = "walreceiver";
+			break;
+		case B_WAL_SENDER:
+			backendDesc = "walsender";
+			break;
+		case B_WAL_WRITER:
+			backendDesc = "walwriter";
+			break;
+	}
 
+	return backendDesc;
+}
 /* ------------------------------------------------------------
  * Local support functions follow
  * ------------------------------------------------------------
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 8f467be..3e716b1 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -941,6 +941,33 @@ AuxiliaryProcKill(int code, Datum arg)
 	SpinLockRelease(ProcStructLock);
 }
 
+/*
+ * AuxiliaryPidGetProc -- get PGPROC for an auxiliary process
+ * given its PID
+ *
+ * Returns NULL if not found.
+ */
+PGPROC *
+AuxiliaryPidGetProc(int pid)
+{
+	PGPROC	   *result = NULL;
+	int			index;
+
+	if (pid == 0)				/* never match dummy PGPROCs */
+		return NULL;
+
+	for (index = 0; index < NUM_AUXILIARY_PROCS; index++)
+	{
+		PGPROC	   *proc = &AuxiliaryProcs[index];
+
+		if (proc->pid == pid)
+		{
+			result = proc;
+			break;
+		}
+	}
+	return result;
+}
 
 /*
  * ProcQueue package: routines for putting processes to sleep
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index a987d0d..96a1188 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -20,6 +20,7 @@
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "pgstat.h"
+#include "postmaster/postmaster.h"
 #include "storage/proc.h"
 #include "storage/procarray.h"
 #include "utils/acl.h"
@@ -615,9 +616,18 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			continue;
 
 		/* Values available to all callers */
-		values[0] = ObjectIdGetDatum(beentry->st_databaseid);
+		if (beentry->st_databaseid != InvalidOid)
+			values[0] = ObjectIdGetDatum(beentry->st_databaseid);
+		else
+			nulls[0] = true;
+
 		values[1] = Int32GetDatum(beentry->st_procpid);
-		values[2] = ObjectIdGetDatum(beentry->st_userid);
+
+		if (beentry->st_userid != InvalidOid)
+			values[2] = ObjectIdGetDatum(beentry->st_userid);
+		else
+			nulls[2] = true;
+
 		if (beentry->st_appname)
 			values[3] = CStringGetTextDatum(beentry->st_appname);
 		else
@@ -690,6 +700,22 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 				wait_event = pgstat_get_wait_event(raw_wait_event);
 
 			}
+			else if (beentry->st_backendType != B_BACKEND)
+			{
+				uint32		raw_wait_event;
+
+				/*
+				 * For an auxiliary process, retrieve process info from
+				 * AuxiliaryProcs stored in shared-memory.
+				 */
+				proc = AuxiliaryPidGetProc(beentry->st_procpid);
+
+				/* Check whether this is indeed an auxiliary process */
+				Assert(proc != NULL);
+				raw_wait_event = UINT32_ACCESS_ONCE(proc->wait_event_info);
+				wait_event_type = pgstat_get_wait_event_type(raw_wait_event);
+				wait_event = pgstat_get_wait_event(raw_wait_event);
+			}
 			else
 			{
 				wait_event_type = NULL;
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index f2daf32..14562d5 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -696,6 +696,25 @@ typedef struct PgStat_GlobalStats
 
 
 /* ----------
+ * Backend types
+ * ----------
+ */
+typedef enum BackendType
+{
+	B_AUTOVAC_LAUNCHER,
+	B_AUTOVAC_WORKER,
+	B_BACKEND,
+	B_BG_WORKER,
+	B_BG_WRITER,
+	B_CHECKPOINTER,
+	B_STARTUP,
+	B_WAL_RECEIVER,
+	B_WAL_SENDER,
+	B_WAL_WRITER
+} BackendType;
+
+
+/* ----------
  * Backend states
  * ----------
  */
@@ -925,6 +944,9 @@ typedef struct PgBackendSSLStatus
  * showing its current activity.  (The structs are allocated according to
  * BackendId, but that is not critical.)  Note that the collector process
  * has no involvement in, or even access to, these structs.
+ *
+ * Each auxiliary process also maintains a PgBackendStatus struct in shared
+ * memory.
  * ----------
  */
 typedef struct PgBackendStatus
@@ -949,6 +971,9 @@ typedef struct PgBackendStatus
 	/* The entry is valid iff st_procpid > 0, unused if st_procpid == 0 */
 	int			st_procpid;
 
+	/* Type of backends */
+	BackendType st_backendType;
+
 	/* Times when current backend, transaction, and activity started */
 	TimestampTz st_proc_start_timestamp;
 	TimestampTz st_xact_start_timestamp;
@@ -1147,6 +1172,7 @@ extern const char *pgstat_get_wait_event_type(uint32 wait_event_info);
 extern const char *pgstat_get_backend_current_activity(int pid, bool checkUser);
 extern const char *pgstat_get_crashed_backend_activity(int pid, char *buffer,
 									int buflen);
+extern const char *pgstat_get_backend_desc(BackendType backendType);
 
 extern void pgstat_progress_start_command(ProgressCommandType cmdtype,
 							  Oid relid);
diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h
index 945dd1d..7ad3094 100644
--- a/src/include/storage/proc.h
+++ b/src/include/storage/proc.h
@@ -267,6 +267,7 @@ extern PGPROC *PreparedXactProcs;
  */
 #define NUM_AUXILIARY_PROCS		4
 
+extern PGPROC *AuxiliaryPidGetProc(int pid);
 
 /* configurable options */
 extern int	DeadlockTimeout;
-- 
1.8.3.1

From aacedd4fca9dc52367a250c67459605849c7291e Mon Sep 17 00:00:00 2001
From: Kuntal Ghosh <kuntal.ghosh@enterprisedb.com>
Date: Thu, 23 Mar 2017 16:39:05 +0530
Subject: [PATCH 2/3] Expose stats for all backends

All backends include auxiliary procs, autovacuum launcher and
bgworkers having valid BackendIds.
---
 src/backend/bootstrap/bootstrap.c     | 3 +++
 src/backend/postmaster/autovacuum.c   | 3 +++
 src/backend/postmaster/bgwriter.c     | 3 +++
 src/backend/postmaster/checkpointer.c | 3 +++
 src/backend/postmaster/pgstat.c       | 1 -
 src/backend/postmaster/postmaster.c   | 6 ++++++
 src/backend/postmaster/startup.c      | 4 ++++
 src/backend/postmaster/walwriter.c    | 3 +++
 src/backend/replication/walreceiver.c | 4 ++++
 src/backend/replication/walsender.c   | 5 ++++-
 src/backend/utils/init/postinit.c     | 3 ---
 11 files changed, 33 insertions(+), 5 deletions(-)

diff --git a/src/backend/bootstrap/bootstrap.c b/src/backend/bootstrap/bootstrap.c
index 6511c60..f56e229 100644
--- a/src/backend/bootstrap/bootstrap.c
+++ b/src/backend/bootstrap/bootstrap.c
@@ -387,6 +387,9 @@ AuxiliaryProcessMain(int argc, char *argv[])
 		/* finish setting up bufmgr.c */
 		InitBufferPoolBackend();
 
+		/* Initialize stats collection */
+		pgstat_initialize();
+
 		/* register a before-shutdown callback for LWLock cleanup */
 		before_shmem_exit(ShutdownAuxiliaryProcess, 0);
 	}
diff --git a/src/backend/postmaster/autovacuum.c b/src/backend/postmaster/autovacuum.c
index 33ca749..0dd8ccc 100644
--- a/src/backend/postmaster/autovacuum.c
+++ b/src/backend/postmaster/autovacuum.c
@@ -453,6 +453,9 @@ AutoVacLauncherMain(int argc, char *argv[])
 
 	InitPostgres(NULL, InvalidOid, NULL, InvalidOid, NULL);
 
+	/* report autovacuum launcher process in the  PgBackendStatus array */
+	pgstat_bestart();
+
 	SetProcessingMode(NormalProcessing);
 
 	/*
diff --git a/src/backend/postmaster/bgwriter.c b/src/backend/postmaster/bgwriter.c
index dcb4cf2..6ba2e2e 100644
--- a/src/backend/postmaster/bgwriter.c
+++ b/src/backend/postmaster/bgwriter.c
@@ -248,6 +248,9 @@ BackgroundWriterMain(void)
 	 */
 	prev_hibernate = false;
 
+	/* report bgwriter process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/*
 	 * Loop forever
 	 */
diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c
index fe9041f..8eb0a2a 100644
--- a/src/backend/postmaster/checkpointer.c
+++ b/src/backend/postmaster/checkpointer.c
@@ -345,6 +345,9 @@ CheckpointerMain(void)
 	 */
 	ProcGlobal->checkpointerLatch = &MyProc->procLatch;
 
+	/* report checkpointer process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/*
 	 * Loop forever
 	 */
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index a2b9bbf..ff565a3 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -2690,7 +2690,6 @@ pgstat_initialize(void)
  * pgstat_bestart() -
  *
  *	Initialize this backend's entry in the PgBackendStatus array.
- *	Called from InitPostgres.
  *
  *	Apart from auxiliary processes, MyBackendId, MyDatabaseId,
  *	session userid, and application_name must be set for a
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 6831342..4f62b99 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -5461,6 +5461,9 @@ BackgroundWorkerInitializeConnection(char *dbname, char *username)
 
 	InitPostgres(dbname, InvalidOid, username, InvalidOid, NULL);
 
+	/* report the parallel worker process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/* it had better not gotten out of "init" mode yet */
 	if (!IsInitProcessingMode())
 		ereport(ERROR,
@@ -5484,6 +5487,9 @@ BackgroundWorkerInitializeConnectionByOid(Oid dboid, Oid useroid)
 
 	InitPostgres(NULL, dboid, NULL, useroid, NULL);
 
+	/* report the parallel worker process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/* it had better not gotten out of "init" mode yet */
 	if (!IsInitProcessingMode())
 		ereport(ERROR,
diff --git a/src/backend/postmaster/startup.c b/src/backend/postmaster/startup.c
index b172b5e..56ff042 100644
--- a/src/backend/postmaster/startup.c
+++ b/src/backend/postmaster/startup.c
@@ -25,6 +25,7 @@
 #include "access/xlog.h"
 #include "libpq/pqsignal.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/startup.h"
 #include "storage/ipc.h"
 #include "storage/latch.h"
@@ -210,6 +211,9 @@ StartupProcessMain(void)
 	 */
 	PG_SETMASK(&UnBlockSig);
 
+	/* report startup process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/*
 	 * Do what we came for.
 	 */
diff --git a/src/backend/postmaster/walwriter.c b/src/backend/postmaster/walwriter.c
index a575d8f..9056652 100644
--- a/src/backend/postmaster/walwriter.c
+++ b/src/backend/postmaster/walwriter.c
@@ -231,6 +231,9 @@ WalWriterMain(void)
 	 */
 	ProcGlobal->walwriterLatch = &MyProc->procLatch;
 
+	/* report walwriter process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	/*
 	 * Loop forever
 	 */
diff --git a/src/backend/replication/walreceiver.c b/src/backend/replication/walreceiver.c
index 31c567b..cdd35e2 100644
--- a/src/backend/replication/walreceiver.c
+++ b/src/backend/replication/walreceiver.c
@@ -316,6 +316,10 @@ WalReceiverMain(void)
 	SpinLockRelease(&walrcv->mutex);
 
 	first_stream = true;
+
+	/* report walreceiver process in the PgBackendStatus array */
+	pgstat_bestart();
+
 	for (;;)
 	{
 		char	   *primary_sysid;
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index 7561770..f79d4a5 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -246,6 +246,9 @@ InitWalSender(void)
 	 */
 	MarkPostmasterChildWalSender();
 	SendPostmasterSignal(PMSIGNAL_ADVANCE_STATE_MACHINE);
+
+	/* report walsender process in the PgBackendStatus array */
+	pgstat_bestart();
 }
 
 /*
@@ -1811,7 +1814,7 @@ WalSndLoop(WalSndSendDataCallback send_data)
 	waiting_for_ping_response = false;
 
 	/* Report to pgstat that this process is a WAL sender */
-	pgstat_report_activity(STATE_RUNNING, "walsender");
+	pgstat_report_activity(STATE_RUNNING, NULL);
 
 	/*
 	 * Loop until we reach the end of this timeline or the client requests to
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index 9f938f2..2470f24 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -808,9 +808,6 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 		/* initialize client encoding */
 		InitializeClientEncoding();
 
-		/* report this backend in the PgBackendStatus array */
-		pgstat_bestart();
-
 		/* close the transaction we started above */
 		CommitTransactionCommand();
 
-- 
1.8.3.1

From 29cc1ce9eee41840cc4f3023f9ae3a6812ed614d Mon Sep 17 00:00:00 2001
From: Kuntal Ghosh <kuntal.ghosh@enterprisedb.com>
Date: Wed, 15 Mar 2017 12:53:11 +0530
Subject: [PATCH 3/3] Add backend_type column in pg_stat_get_activity

backend_type indicates the type of process in the stat table.
---
 doc/src/sgml/monitoring.sgml         | 14 ++++++++++++--
 src/backend/catalog/system_views.sql |  3 ++-
 src/backend/utils/adt/pgstatfuncs.c  |  5 ++++-
 src/include/catalog/pg_proc.h        |  2 +-
 src/test/regress/expected/rules.out  |  9 +++++----
 5 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index dcb2d33..f77c5a7 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -620,8 +620,7 @@ postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: ser
     <row>
      <entry><structfield>backend_start</></entry>
      <entry><type>timestamp with time zone</></entry>
-     <entry>Time when this process was started, i.e., when the
-      client connected to the server
+     <entry>Time when this process was started.
      </entry>
     </row>
     <row>
@@ -797,6 +796,17 @@ postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: ser
       <xref linkend="guc-track-activity-query-size">.
      </entry>
     </row>
+    <row>
+     <entry><structfield>backend_type</structfield></entry>
+     <entry><type>text</type></entry>
+     <entry>Type of current backend. Possible types are 
+      <literal>autovacuum launcher</>, <literal>autovacuum worker</>,
+      <literal>background worker</>, <literal>background writer</>,
+      <literal>client backend</>, <literal>checkpointer</>,
+      <literal>startup</>, <literal>walreceiver</>,
+      <literal>walsender</> and <literal>walwriter</>.
+     </entry>
+    </row>
    </tbody>
    </tgroup>
   </table>
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index c2b0bed..c0974db 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -684,7 +684,8 @@ CREATE VIEW pg_stat_activity AS
             S.state,
             S.backend_xid,
             s.backend_xmin,
-            S.query
+            S.query,
+            S.backend_type
     FROM pg_stat_get_activity(NULL) AS S
         LEFT JOIN pg_database AS D ON (S.datid = D.oid)
         LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index 96a1188..0085335 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -539,7 +539,7 @@ pg_stat_get_progress_info(PG_FUNCTION_ARGS)
 Datum
 pg_stat_get_activity(PG_FUNCTION_ARGS)
 {
-#define PG_STAT_GET_ACTIVITY_COLS	23
+#define PG_STAT_GET_ACTIVITY_COLS	24
 	int			num_backends = pgstat_fetch_stat_numbackends();
 	int			curr_backend;
 	int			pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
@@ -819,6 +819,8 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 					nulls[14] = true;
 				}
 			}
+			/* Add backend type */
+			values[23] = CStringGetTextDatum(pgstat_get_backend_desc(beentry->st_backendType));
 		}
 		else
 		{
@@ -834,6 +836,7 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			nulls[12] = true;
 			nulls[13] = true;
 			nulls[14] = true;
+			nulls[23] = true;
 		}
 
 		tuplestore_putvalues(tupstore, tupdesc, values, nulls);
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 2263565..5dcc93d 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -2797,7 +2797,7 @@ DATA(insert OID = 3057 ( pg_stat_get_autoanalyze_count PGNSP PGUID 12 1 0 0 0 f
 DESCR("statistics: number of auto analyzes for a table");
 DATA(insert OID = 1936 (  pg_stat_get_backend_idset		PGNSP PGUID 12 1 100 0 0 f f f f t t s r 0 0 23 "" _null_ _null_ _null_ _null_ _null_ pg_stat_get_backend_idset _null_ _null_ _null_ ));
 DESCR("statistics: currently active backend IDs");
-DATA(insert OID = 2022 (  pg_stat_get_activity			PGNSP PGUID 12 1 100 0 0 f f f f f t s r 1 0 2249 "23" "{23,26,23,26,25,25,25,25,25,1184,1184,1184,1184,869,25,23,28,28,16,25,25,23,16,25}" "{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,ssl,sslversion,sslcipher,sslbits,sslcompression,sslclientdn}" _null_ _null_ pg_stat_get_activity _null_ _null_ _null_ ));
+DATA(insert OID = 2022 (  pg_stat_get_activity			PGNSP PGUID 12 1 100 0 0 f f f f f t s r 1 0 2249 "23" "{23,26,23,26,25,25,25,25,25,1184,1184,1184,1184,869,25,23,28,28,16,25,25,23,16,25,25}" "{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,ssl,sslversion,sslcipher,sslbits,sslcompression,sslclientdn,backend_type}" _null_ _null_ pg_stat_get_activity _null_ _null_ _null_ ));
 DESCR("statistics: information about currently active backends");
 DATA(insert OID = 3318 (  pg_stat_get_progress_info			  PGNSP PGUID 12 1 100 0 0 f f f f t t s r 1 0 2249 "25" "{25,23,26,26,20,20,20,20,20,20,20,20,20,20}" "{i,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{cmdtype,pid,datid,relid,param1,param2,param3,param4,param5,param6,param7,param8,param9,param10}" _null_ _null_ pg_stat_get_progress_info _null_ _null_ _null_ ));
 DESCR("statistics: information about progress of backends running maintenance command");
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index bd13ae6..a317bff 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1704,8 +1704,9 @@ pg_stat_activity| SELECT s.datid,
     s.state,
     s.backend_xid,
     s.backend_xmin,
-    s.query
-   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn)
+    s.query,
+    s.backend_type
+   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn, backend_type)
      LEFT JOIN pg_database d ON ((s.datid = d.oid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_all_indexes| SELECT c.oid AS relid,
@@ -1833,7 +1834,7 @@ pg_stat_replication| SELECT s.pid,
     w.replay_location,
     w.sync_priority,
     w.sync_state
-   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn)
+   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn, backend_type)
      JOIN pg_stat_get_wal_senders() w(pid, state, sent_location, write_location, flush_location, replay_location, sync_priority, sync_state) ON ((s.pid = w.pid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_ssl| SELECT s.pid,
@@ -1843,7 +1844,7 @@ pg_stat_ssl| SELECT s.pid,
     s.sslbits AS bits,
     s.sslcompression AS compression,
     s.sslclientdn AS clientdn
-   FROM pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn);
+   FROM pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn, backend_type);
 pg_stat_subscription| SELECT su.oid AS subid,
     su.subname,
     st.pid,
-- 
1.8.3.1

diff --git a/doc/src/sgml/monitoring.sgml b/doc/src/sgml/monitoring.sgml
index e930731..9856968 100644
--- a/doc/src/sgml/monitoring.sgml
+++ b/doc/src/sgml/monitoring.sgml
@@ -620,8 +620,8 @@ postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: ser
     <row>
      <entry><structfield>backend_start</></entry>
      <entry><type>timestamp with time zone</></entry>
-     <entry>Time when this process was started, i.e., when the
-      client connected to the server
+     <entry>Time when this process was started.  For client backends,
+      this is the time the client connected to the server.
      </entry>
     </row>
     <row>
@@ -797,6 +797,17 @@ postgres   27093  0.0  0.0  30096  2752 ?        Ss   11:34   0:00 postgres: ser
       <xref linkend="guc-track-activity-query-size">.
      </entry>
     </row>
+    <row>
+     <entry><structfield>backend_type</structfield></entry>
+     <entry><type>text</type></entry>
+     <entry>Type of current backend. Possible types are 
+      <literal>autovacuum launcher</>, <literal>autovacuum worker</>,
+      <literal>background worker</>, <literal>background writer</>,
+      <literal>client backend</>, <literal>checkpointer</>,
+      <literal>startup</>, <literal>walreceiver</>,
+      <literal>walsender</> and <literal>walwriter</>.
+     </entry>
+    </row>
    </tbody>
    </tgroup>
   </table>
diff --git a/src/backend/bootstrap/bootstrap.c b/src/backend/bootstrap/bootstrap.c
index 6511c60..6b5feaf 100644
--- a/src/backend/bootstrap/bootstrap.c
+++ b/src/backend/bootstrap/bootstrap.c
@@ -387,6 +387,10 @@ AuxiliaryProcessMain(int argc, char *argv[])
 		/* finish setting up bufmgr.c */
 		InitBufferPoolBackend();
 
+		/* Initialize backend status information */
+		pgstat_initialize();
+		pgstat_bestart();
+
 		/* register a before-shutdown callback for LWLock cleanup */
 		before_shmem_exit(ShutdownAuxiliaryProcess, 0);
 	}
diff --git a/src/backend/catalog/system_views.sql b/src/backend/catalog/system_views.sql
index 80d1429..bab76df 100644
--- a/src/backend/catalog/system_views.sql
+++ b/src/backend/catalog/system_views.sql
@@ -684,7 +684,8 @@ CREATE VIEW pg_stat_activity AS
             S.state,
             S.backend_xid,
             s.backend_xmin,
-            S.query
+            S.query,
+            S.backend_type
     FROM pg_stat_get_activity(NULL) AS S
         LEFT JOIN pg_database AS D ON (S.datid = D.oid)
         LEFT JOIN pg_authid AS U ON (S.usesysid = U.oid);
diff --git a/src/backend/postmaster/pgstat.c b/src/backend/postmaster/pgstat.c
index b704788..869afd4 100644
--- a/src/backend/postmaster/pgstat.c
+++ b/src/backend/postmaster/pgstat.c
@@ -50,6 +50,7 @@
 #include "postmaster/autovacuum.h"
 #include "postmaster/fork_process.h"
 #include "postmaster/postmaster.h"
+#include "replication/walsender.h"
 #include "storage/backendid.h"
 #include "storage/dsm.h"
 #include "storage/fd.h"
@@ -103,6 +104,18 @@
 
 
 /* ----------
+ * Total number of backends including auxiliary
+ *
+ * We reserve a slot for each possible BackendId, plus one for each
+ * possible auxiliary process type.  (This scheme assumes there is not
+ * more than one of any auxiliary process type at a time.) MaxBackends
+ * includes autovacuum workers and background workers as well.
+ * ----------
+ */
+#define NumBackendStatSlots (MaxBackends + NUM_AUXPROCTYPES)
+
+
+/* ----------
  * GUC parameters
  * ----------
  */
@@ -212,7 +225,11 @@ typedef struct TwoPhasePgStatRecord
  */
 static MemoryContext pgStatLocalContext = NULL;
 static HTAB *pgStatDBHash = NULL;
+
+/* Status for backends including auxiliary */
 static LocalPgBackendStatus *localBackendStatusTable = NULL;
+
+/* Total number of backends including auxiliary */
 static int	localNumBackends = 0;
 
 /*
@@ -2505,20 +2522,20 @@ BackendStatusShmemSize(void)
 	Size		size;
 
 	/* BackendStatusArray: */
-	size = mul_size(sizeof(PgBackendStatus), MaxBackends);
+	size = mul_size(sizeof(PgBackendStatus), NumBackendStatSlots);
 	/* BackendAppnameBuffer: */
 	size = add_size(size,
-					mul_size(NAMEDATALEN, MaxBackends));
+					mul_size(NAMEDATALEN, NumBackendStatSlots));
 	/* BackendClientHostnameBuffer: */
 	size = add_size(size,
-					mul_size(NAMEDATALEN, MaxBackends));
+					mul_size(NAMEDATALEN, NumBackendStatSlots));
 	/* BackendActivityBuffer: */
 	size = add_size(size,
-					mul_size(pgstat_track_activity_query_size, MaxBackends));
+			mul_size(pgstat_track_activity_query_size, NumBackendStatSlots));
 #ifdef USE_SSL
 	/* BackendSslStatusBuffer: */
 	size = add_size(size,
-					mul_size(sizeof(PgBackendSSLStatus), MaxBackends));
+				  mul_size(sizeof(PgBackendSSLStatus), NumBackendStatSlots));
 #endif
 	return size;
 }
@@ -2536,7 +2553,7 @@ CreateSharedBackendStatus(void)
 	char	   *buffer;
 
 	/* Create or attach to the shared array */
-	size = mul_size(sizeof(PgBackendStatus), MaxBackends);
+	size = mul_size(sizeof(PgBackendStatus), NumBackendStatSlots);
 	BackendStatusArray = (PgBackendStatus *)
 		ShmemInitStruct("Backend Status Array", size, &found);
 
@@ -2559,7 +2576,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_appname pointers. */
 		buffer = BackendAppnameBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumBackendStatSlots; i++)
 		{
 			BackendStatusArray[i].st_appname = buffer;
 			buffer += NAMEDATALEN;
@@ -2577,7 +2594,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_clienthostname pointers. */
 		buffer = BackendClientHostnameBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumBackendStatSlots; i++)
 		{
 			BackendStatusArray[i].st_clienthostname = buffer;
 			buffer += NAMEDATALEN;
@@ -2586,7 +2603,7 @@ CreateSharedBackendStatus(void)
 
 	/* Create or attach to the shared activity buffer */
 	BackendActivityBufferSize = mul_size(pgstat_track_activity_query_size,
-										 MaxBackends);
+										 NumBackendStatSlots);
 	BackendActivityBuffer = (char *)
 		ShmemInitStruct("Backend Activity Buffer",
 						BackendActivityBufferSize,
@@ -2598,7 +2615,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_activity pointers. */
 		buffer = BackendActivityBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumBackendStatSlots; i++)
 		{
 			BackendStatusArray[i].st_activity = buffer;
 			buffer += pgstat_track_activity_query_size;
@@ -2607,7 +2624,7 @@ CreateSharedBackendStatus(void)
 
 #ifdef USE_SSL
 	/* Create or attach to the shared SSL status buffer */
-	size = mul_size(sizeof(PgBackendSSLStatus), MaxBackends);
+	size = mul_size(sizeof(PgBackendSSLStatus), NumBackendStatSlots);
 	BackendSslStatusBuffer = (PgBackendSSLStatus *)
 		ShmemInitStruct("Backend SSL Status Buffer", size, &found);
 
@@ -2619,7 +2636,7 @@ CreateSharedBackendStatus(void)
 
 		/* Initialize st_sslstatus pointers. */
 		ptr = BackendSslStatusBuffer;
-		for (i = 0; i < MaxBackends; i++)
+		for (i = 0; i < NumBackendStatSlots; i++)
 		{
 			BackendStatusArray[i].st_sslstatus = ptr;
 			ptr++;
@@ -2633,7 +2650,8 @@ CreateSharedBackendStatus(void)
  * pgstat_initialize() -
  *
  *	Initialize pgstats state, and set up our on-proc-exit hook.
- *	Called from InitPostgres.  MyBackendId must be set,
+ *	Called from InitPostgres and AuxiliaryProcessMain. For auxiliary process,
+ *	MyBackendId is invalid. Otherwise, MyBackendId must be set,
  *	but we must not have started any transaction yet (since the
  *	exit hook must run after the last transaction exit).
  *	NOTE: MyDatabaseId isn't set yet; so the shutdown hook has to be careful.
@@ -2643,8 +2661,26 @@ void
 pgstat_initialize(void)
 {
 	/* Initialize MyBEEntry */
-	Assert(MyBackendId >= 1 && MyBackendId <= MaxBackends);
-	MyBEEntry = &BackendStatusArray[MyBackendId - 1];
+	if (MyBackendId != InvalidBackendId)
+	{
+		Assert(MyBackendId >= 1 && MyBackendId <= MaxBackends);
+		MyBEEntry = &BackendStatusArray[MyBackendId - 1];
+	}
+	else
+	{
+		/* Must be an auxiliary process */
+		Assert(MyAuxProcType != NotAnAuxProcess);
+
+		/*
+		 * Assign the MyBEEntry for an auxiliary process.  Since it doesn't
+		 * have a BackendId, the slot is statically allocated based on the
+		 * auxiliary process type (MyAuxProcType).  Backends use slots indexed
+		 * in the range from 1 to MaxBackends (inclusive), so we use
+		 * MaxBackends + AuxBackendType + 1 as the index of the slot for an
+		 * auxiliary process.
+		 */
+		MyBEEntry = &BackendStatusArray[MaxBackends + MyAuxProcType];
+	}
 
 	/* Set up a process-exit hook to clean up */
 	on_shmem_exit(pgstat_beshutdown_hook, 0);
@@ -2655,15 +2691,16 @@ pgstat_initialize(void)
  *
  *	Initialize this backend's entry in the PgBackendStatus array.
  *	Called from InitPostgres.
- *	MyDatabaseId, session userid, and application_name must be set
- *	(hence, this cannot be combined with pgstat_initialize).
+ *
+ *	Apart from auxiliary processes, MyBackendId, MyDatabaseId,
+ *	session userid, and application_name must be set for a
+ *	backend (hence, this cannot be combined with pgstat_initialize).
  * ----------
  */
 void
 pgstat_bestart(void)
 {
 	TimestampTz proc_start_timestamp;
-	Oid			userid;
 	SockAddr	clientaddr;
 	volatile PgBackendStatus *beentry;
 
@@ -2678,7 +2715,6 @@ pgstat_bestart(void)
 		proc_start_timestamp = MyProcPort->SessionStartTime;
 	else
 		proc_start_timestamp = GetCurrentTimestamp();
-	userid = GetSessionUserId();
 
 	/*
 	 * We may not have a MyProcPort (eg, if this is the autovacuum process).
@@ -2697,6 +2733,66 @@ pgstat_bestart(void)
 	 * cute.
 	 */
 	beentry = MyBEEntry;
+
+	/* pgstats state must be initialized from pgstat_initialize() */
+	Assert(beentry != NULL);
+
+	if (MyBackendId != InvalidBackendId)
+	{
+		if (IsAutoVacuumLauncherProcess())
+		{
+			/* Autovacuum Launcher */
+			beentry->st_backendType = B_AUTOVAC_LAUNCHER;
+		}
+		else if (IsAutoVacuumWorkerProcess())
+		{
+			/* Autovacuum Worker */
+			beentry->st_backendType = B_AUTOVAC_WORKER;
+		}
+		else if (am_walsender)
+		{
+			/* Wal sender */
+			beentry->st_backendType = B_WAL_SENDER;
+		}
+		else if (IsBackgroundWorker)
+		{
+			/* bgworker */
+			beentry->st_backendType = B_BG_WORKER;
+		}
+		else
+		{
+			/* client-backend */
+			beentry->st_backendType = B_BACKEND;
+		}
+	}
+	else
+	{
+		/* Must be an auxiliary process */
+		Assert(MyAuxProcType != NotAnAuxProcess);
+		switch (MyAuxProcType)
+		{
+			case StartupProcess:
+				beentry->st_backendType = B_STARTUP;
+				break;
+			case BgWriterProcess:
+				beentry->st_backendType = B_BG_WRITER;
+				break;
+			case CheckpointerProcess:
+				beentry->st_backendType = B_CHECKPOINTER;
+				break;
+			case WalWriterProcess:
+				beentry->st_backendType = B_WAL_WRITER;
+				break;
+			case WalReceiverProcess:
+				beentry->st_backendType = B_WAL_RECEIVER;
+				break;
+			default:
+				elog(FATAL, "unrecognized process type: %d",
+					(int) MyAuxProcType);
+				proc_exit(1);
+		}
+	}
+
 	do
 	{
 		pgstat_increment_changecount_before(beentry);
@@ -2708,7 +2804,15 @@ pgstat_bestart(void)
 	beentry->st_state_start_timestamp = 0;
 	beentry->st_xact_start_timestamp = 0;
 	beentry->st_databaseid = MyDatabaseId;
-	beentry->st_userid = userid;
+
+	/* We have userid for client-backends, wal-sender and bgworker processes */
+	if (beentry->st_backendType == B_BACKEND
+			|| beentry->st_backendType == B_WAL_SENDER
+			|| beentry->st_backendType == B_BG_WORKER)
+		beentry->st_userid = GetSessionUserId();
+	else
+		beentry->st_userid = InvalidOid;
+
 	beentry->st_clientaddr = clientaddr;
 	if (MyProcPort && MyProcPort->remote_hostname)
 		strlcpy(beentry->st_clienthostname, MyProcPort->remote_hostname,
@@ -3046,24 +3150,24 @@ pgstat_read_current_status(void)
 
 	localtable = (LocalPgBackendStatus *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   sizeof(LocalPgBackendStatus) * MaxBackends);
+						 sizeof(LocalPgBackendStatus) * NumBackendStatSlots);
 	localappname = (char *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   NAMEDATALEN * MaxBackends);
+						   NAMEDATALEN * NumBackendStatSlots);
 	localactivity = (char *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   pgstat_track_activity_query_size * MaxBackends);
+					 pgstat_track_activity_query_size * NumBackendStatSlots);
 #ifdef USE_SSL
 	localsslstatus = (PgBackendSSLStatus *)
 		MemoryContextAlloc(pgStatLocalContext,
-						   sizeof(PgBackendSSLStatus) * MaxBackends);
+						   sizeof(PgBackendSSLStatus) * NumBackendStatSlots);
 #endif
 
 	localNumBackends = 0;
 
 	beentry = BackendStatusArray;
 	localentry = localtable;
-	for (i = 1; i <= MaxBackends; i++)
+	for (i = 1; i <= NumBackendStatSlots; i++)
 	{
 		/*
 		 * Follow the protocol of retrying if st_changecount changes while we
@@ -3829,7 +3933,47 @@ pgstat_get_crashed_backend_activity(int pid, char *buffer, int buflen)
 	return NULL;
 }
 
+const char *
+pgstat_get_backend_desc(BackendType backendType)
+{
+	const char *backendDesc = "unknown process type";
+
+	switch (backendType)
+	{
+		case B_AUTOVAC_LAUNCHER:
+			backendDesc = "autovacuum launcher";
+			break;
+		case B_AUTOVAC_WORKER:
+			backendDesc = "autovacuum worker";
+			break;
+		case B_BACKEND:
+			backendDesc = "client backend";
+			break;
+		case B_BG_WORKER:
+			backendDesc = "background worker";
+			break;
+		case B_BG_WRITER:
+			backendDesc = "background writer";
+			break;
+		case B_CHECKPOINTER:
+			backendDesc = "checkpointer";
+			break;
+		case B_STARTUP:
+			backendDesc = "startup";
+			break;
+		case B_WAL_RECEIVER:
+			backendDesc = "walreceiver";
+			break;
+		case B_WAL_SENDER:
+			backendDesc = "walsender";
+			break;
+		case B_WAL_WRITER:
+			backendDesc = "walwriter";
+			break;
+	}
 
+	return backendDesc;
+}
 /* ------------------------------------------------------------
  * Local support functions follow
  * ------------------------------------------------------------
diff --git a/src/backend/postmaster/startup.c b/src/backend/postmaster/startup.c
index b172b5e..b623252 100644
--- a/src/backend/postmaster/startup.c
+++ b/src/backend/postmaster/startup.c
@@ -25,6 +25,7 @@
 #include "access/xlog.h"
 #include "libpq/pqsignal.h"
 #include "miscadmin.h"
+#include "pgstat.h"
 #include "postmaster/startup.h"
 #include "storage/ipc.h"
 #include "storage/latch.h"
diff --git a/src/backend/replication/walsender.c b/src/backend/replication/walsender.c
index a29d0e7..e9fef1a 100644
--- a/src/backend/replication/walsender.c
+++ b/src/backend/replication/walsender.c
@@ -1961,8 +1961,8 @@ WalSndLoop(WalSndSendDataCallback send_data)
 	last_reply_timestamp = GetCurrentTimestamp();
 	waiting_for_ping_response = false;
 
-	/* Report to pgstat that this process is a WAL sender */
-	pgstat_report_activity(STATE_RUNNING, "walsender");
+	/* Report to pgstat that this process is running */
+	pgstat_report_activity(STATE_RUNNING, NULL);
 
 	/*
 	 * Loop until we reach the end of this timeline or the client requests to
diff --git a/src/backend/storage/lmgr/proc.c b/src/backend/storage/lmgr/proc.c
index 8f467be..3e716b1 100644
--- a/src/backend/storage/lmgr/proc.c
+++ b/src/backend/storage/lmgr/proc.c
@@ -941,6 +941,33 @@ AuxiliaryProcKill(int code, Datum arg)
 	SpinLockRelease(ProcStructLock);
 }
 
+/*
+ * AuxiliaryPidGetProc -- get PGPROC for an auxiliary process
+ * given its PID
+ *
+ * Returns NULL if not found.
+ */
+PGPROC *
+AuxiliaryPidGetProc(int pid)
+{
+	PGPROC	   *result = NULL;
+	int			index;
+
+	if (pid == 0)				/* never match dummy PGPROCs */
+		return NULL;
+
+	for (index = 0; index < NUM_AUXILIARY_PROCS; index++)
+	{
+		PGPROC	   *proc = &AuxiliaryProcs[index];
+
+		if (proc->pid == pid)
+		{
+			result = proc;
+			break;
+		}
+	}
+	return result;
+}
 
 /*
  * ProcQueue package: routines for putting processes to sleep
diff --git a/src/backend/utils/adt/pgstatfuncs.c b/src/backend/utils/adt/pgstatfuncs.c
index a987d0d..dd2b924 100644
--- a/src/backend/utils/adt/pgstatfuncs.c
+++ b/src/backend/utils/adt/pgstatfuncs.c
@@ -20,6 +20,7 @@
 #include "funcapi.h"
 #include "miscadmin.h"
 #include "pgstat.h"
+#include "postmaster/postmaster.h"
 #include "storage/proc.h"
 #include "storage/procarray.h"
 #include "utils/acl.h"
@@ -538,7 +539,7 @@ pg_stat_get_progress_info(PG_FUNCTION_ARGS)
 Datum
 pg_stat_get_activity(PG_FUNCTION_ARGS)
 {
-#define PG_STAT_GET_ACTIVITY_COLS	23
+#define PG_STAT_GET_ACTIVITY_COLS	24
 	int			num_backends = pgstat_fetch_stat_numbackends();
 	int			curr_backend;
 	int			pid = PG_ARGISNULL(0) ? -1 : PG_GETARG_INT32(0);
@@ -582,8 +583,8 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 		LocalPgBackendStatus *local_beentry;
 		PgBackendStatus *beentry;
 		PGPROC	   *proc;
-		const char *wait_event_type;
-		const char *wait_event;
+		const char *wait_event_type = NULL;
+		const char *wait_event = NULL;
 
 		MemSet(values, 0, sizeof(values));
 		MemSet(nulls, 0, sizeof(nulls));
@@ -615,9 +616,18 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			continue;
 
 		/* Values available to all callers */
-		values[0] = ObjectIdGetDatum(beentry->st_databaseid);
+		if (beentry->st_databaseid != InvalidOid)
+			values[0] = ObjectIdGetDatum(beentry->st_databaseid);
+		else
+			nulls[0] = true;
+
 		values[1] = Int32GetDatum(beentry->st_procpid);
-		values[2] = ObjectIdGetDatum(beentry->st_userid);
+
+		if (beentry->st_userid != InvalidOid)
+			values[2] = ObjectIdGetDatum(beentry->st_userid);
+		else
+			nulls[2] = true;
+
 		if (beentry->st_appname)
 			values[3] = CStringGetTextDatum(beentry->st_appname);
 		else
@@ -635,17 +645,17 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 
 		if (beentry->st_ssl)
 		{
-			values[17] = BoolGetDatum(true);	/* ssl */
-			values[18] = CStringGetTextDatum(beentry->st_sslstatus->ssl_version);
-			values[19] = CStringGetTextDatum(beentry->st_sslstatus->ssl_cipher);
-			values[20] = Int32GetDatum(beentry->st_sslstatus->ssl_bits);
-			values[21] = BoolGetDatum(beentry->st_sslstatus->ssl_compression);
-			values[22] = CStringGetTextDatum(beentry->st_sslstatus->ssl_clientdn);
+			values[18] = BoolGetDatum(true);	/* ssl */
+			values[19] = CStringGetTextDatum(beentry->st_sslstatus->ssl_version);
+			values[20] = CStringGetTextDatum(beentry->st_sslstatus->ssl_cipher);
+			values[21] = Int32GetDatum(beentry->st_sslstatus->ssl_bits);
+			values[22] = BoolGetDatum(beentry->st_sslstatus->ssl_compression);
+			values[23] = CStringGetTextDatum(beentry->st_sslstatus->ssl_clientdn);
 		}
 		else
 		{
-			values[17] = BoolGetDatum(false);	/* ssl */
-			nulls[18] = nulls[19] = nulls[20] = nulls[21] = nulls[22] = true;
+			values[18] = BoolGetDatum(false);	/* ssl */
+			nulls[19] = nulls[20] = nulls[21] = nulls[22] = nulls[23] = true;
 		}
 
 		/* Values only available to role member */
@@ -690,10 +700,24 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 				wait_event = pgstat_get_wait_event(raw_wait_event);
 
 			}
-			else
+			else if (beentry->st_backendType != B_BACKEND)
 			{
-				wait_event_type = NULL;
-				wait_event = NULL;
+				/*
+				 * For an auxiliary process, retrieve process info from
+				 * AuxiliaryProcs stored in shared-memory.
+				 */
+				proc = AuxiliaryPidGetProc(beentry->st_procpid);
+
+				if (proc != NULL)
+				{
+					uint32		raw_wait_event;
+
+					raw_wait_event =
+						UINT32_ACCESS_ONCE(proc->wait_event_info);
+					wait_event_type =
+						pgstat_get_wait_event_type(raw_wait_event);
+					wait_event = pgstat_get_wait_event(raw_wait_event);
+				}
 			}
 
 			if (wait_event_type)
@@ -793,6 +817,9 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 					nulls[14] = true;
 				}
 			}
+			/* Add backend type */
+			values[17] =
+				CStringGetTextDatum(pgstat_get_backend_desc(beentry->st_backendType));
 		}
 		else
 		{
@@ -808,6 +835,7 @@ pg_stat_get_activity(PG_FUNCTION_ARGS)
 			nulls[12] = true;
 			nulls[13] = true;
 			nulls[14] = true;
+			nulls[17] = true;
 		}
 
 		tuplestore_putvalues(tupstore, tupdesc, values, nulls);
diff --git a/src/backend/utils/init/postinit.c b/src/backend/utils/init/postinit.c
index 9f938f2..b8b4a06 100644
--- a/src/backend/utils/init/postinit.c
+++ b/src/backend/utils/init/postinit.c
@@ -665,7 +665,12 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 
 	/* The autovacuum launcher is done here */
 	if (IsAutoVacuumLauncherProcess())
+	{
+		/* report this backend in the PgBackendStatus array */
+		pgstat_bestart();
+
 		return;
+	}
 
 	/*
 	 * Start a new transaction here before first access to db, and get a
@@ -874,7 +879,10 @@ InitPostgres(const char *in_dbname, Oid dboid, const char *username,
 		 * transaction we started before returning.
 		 */
 		if (!bootstrap)
+		{
+			pgstat_bestart();
 			CommitTransactionCommand();
+		}
 		return;
 	}
 
diff --git a/src/include/catalog/pg_proc.h b/src/include/catalog/pg_proc.h
index 0d18ab8..41f7fae 100644
--- a/src/include/catalog/pg_proc.h
+++ b/src/include/catalog/pg_proc.h
@@ -2800,7 +2800,7 @@ DATA(insert OID = 3057 ( pg_stat_get_autoanalyze_count PGNSP PGUID 12 1 0 0 0 f
 DESCR("statistics: number of auto analyzes for a table");
 DATA(insert OID = 1936 (  pg_stat_get_backend_idset		PGNSP PGUID 12 1 100 0 0 f f f f t t s r 0 0 23 "" _null_ _null_ _null_ _null_ _null_ pg_stat_get_backend_idset _null_ _null_ _null_ ));
 DESCR("statistics: currently active backend IDs");
-DATA(insert OID = 2022 (  pg_stat_get_activity			PGNSP PGUID 12 1 100 0 0 f f f f f t s r 1 0 2249 "23" "{23,26,23,26,25,25,25,25,25,1184,1184,1184,1184,869,25,23,28,28,16,25,25,23,16,25}" "{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,ssl,sslversion,sslcipher,sslbits,sslcompression,sslclientdn}" _null_ _null_ pg_stat_get_activity _null_ _null_ _null_ ));
+DATA(insert OID = 2022 (  pg_stat_get_activity			PGNSP PGUID 12 1 100 0 0 f f f f f t s r 1 0 2249 "23" "{23,26,23,26,25,25,25,25,25,1184,1184,1184,1184,869,25,23,28,28,25,16,25,25,23,16,25}" "{i,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{pid,datid,pid,usesysid,application_name,state,query,wait_event_type,wait_event,xact_start,query_start,backend_start,state_change,client_addr,client_hostname,client_port,backend_xid,backend_xmin,backend_type,ssl,sslversion,sslcipher,sslbits,sslcompression,sslclientdn}" _null_ _null_ pg_stat_get_activity _null_ _null_ _null_ ));
 DESCR("statistics: information about currently active backends");
 DATA(insert OID = 3318 (  pg_stat_get_progress_info			  PGNSP PGUID 12 1 100 0 0 f f f f t t s r 1 0 2249 "25" "{25,23,26,26,20,20,20,20,20,20,20,20,20,20}" "{i,o,o,o,o,o,o,o,o,o,o,o,o,o}" "{cmdtype,pid,datid,relid,param1,param2,param3,param4,param5,param6,param7,param8,param9,param10}" _null_ _null_ pg_stat_get_progress_info _null_ _null_ _null_ ));
 DESCR("statistics: information about progress of backends running maintenance command");
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index 2015625..e29397f 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -696,6 +696,25 @@ typedef struct PgStat_GlobalStats
 
 
 /* ----------
+ * Backend types
+ * ----------
+ */
+typedef enum BackendType
+{
+	B_AUTOVAC_LAUNCHER,
+	B_AUTOVAC_WORKER,
+	B_BACKEND,
+	B_BG_WORKER,
+	B_BG_WRITER,
+	B_CHECKPOINTER,
+	B_STARTUP,
+	B_WAL_RECEIVER,
+	B_WAL_SENDER,
+	B_WAL_WRITER
+} BackendType;
+
+
+/* ----------
  * Backend states
  * ----------
  */
@@ -927,6 +946,9 @@ typedef struct PgBackendSSLStatus
  * showing its current activity.  (The structs are allocated according to
  * BackendId, but that is not critical.)  Note that the collector process
  * has no involvement in, or even access to, these structs.
+ *
+ * Each auxiliary process also maintains a PgBackendStatus struct in shared
+ * memory.
  * ----------
  */
 typedef struct PgBackendStatus
@@ -951,6 +973,9 @@ typedef struct PgBackendStatus
 	/* The entry is valid iff st_procpid > 0, unused if st_procpid == 0 */
 	int			st_procpid;
 
+	/* Type of backends */
+	BackendType st_backendType;
+
 	/* Times when current backend, transaction, and activity started */
 	TimestampTz st_proc_start_timestamp;
 	TimestampTz st_xact_start_timestamp;
@@ -1149,6 +1174,7 @@ extern const char *pgstat_get_wait_event_type(uint32 wait_event_info);
 extern const char *pgstat_get_backend_current_activity(int pid, bool checkUser);
 extern const char *pgstat_get_crashed_backend_activity(int pid, char *buffer,
 									int buflen);
+extern const char *pgstat_get_backend_desc(BackendType backendType);
 
 extern void pgstat_progress_start_command(ProgressCommandType cmdtype,
 							  Oid relid);
diff --git a/src/include/storage/proc.h b/src/include/storage/proc.h
index 945dd1d..e4de3ca 100644
--- a/src/include/storage/proc.h
+++ b/src/include/storage/proc.h
@@ -267,7 +267,6 @@ extern PGPROC *PreparedXactProcs;
  */
 #define NUM_AUXILIARY_PROCS		4
 
-
 /* configurable options */
 extern int	DeadlockTimeout;
 extern int	StatementTimeout;
@@ -304,6 +303,8 @@ extern void LockErrorCleanup(void);
 extern void ProcWaitForSignal(uint32 wait_event_info);
 extern void ProcSendSignal(int pid);
 
+extern PGPROC *AuxiliaryPidGetProc(int pid);
+
 extern void BecomeLockGroupLeader(void);
 extern bool BecomeLockGroupMember(PGPROC *leader, int pid);
 
diff --git a/src/test/regress/expected/rules.out b/src/test/regress/expected/rules.out
index c4c8450..771694e 100644
--- a/src/test/regress/expected/rules.out
+++ b/src/test/regress/expected/rules.out
@@ -1704,8 +1704,9 @@ pg_stat_activity| SELECT s.datid,
     s.state,
     s.backend_xid,
     s.backend_xmin,
-    s.query
-   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn)
+    s.query,
+    s.backend_type
+   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, backend_type, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn)
      LEFT JOIN pg_database d ON ((s.datid = d.oid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_all_indexes| SELECT c.oid AS relid,
@@ -1836,7 +1837,7 @@ pg_stat_replication| SELECT s.pid,
     w.replay_lag,
     w.sync_priority,
     w.sync_state
-   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn)
+   FROM ((pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, backend_type, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn)
      JOIN pg_stat_get_wal_senders() w(pid, state, sent_location, write_location, flush_location, replay_location, write_lag, flush_lag, replay_lag, sync_priority, sync_state) ON ((s.pid = w.pid)))
      LEFT JOIN pg_authid u ON ((s.usesysid = u.oid)));
 pg_stat_ssl| SELECT s.pid,
@@ -1846,7 +1847,7 @@ pg_stat_ssl| SELECT s.pid,
     s.sslbits AS bits,
     s.sslcompression AS compression,
     s.sslclientdn AS clientdn
-   FROM pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn);
+   FROM pg_stat_get_activity(NULL::integer) s(datid, pid, usesysid, application_name, state, query, wait_event_type, wait_event, xact_start, query_start, backend_start, state_change, client_addr, client_hostname, client_port, backend_xid, backend_xmin, backend_type, ssl, sslversion, sslcipher, sslbits, sslcompression, sslclientdn);
 pg_stat_subscription| SELECT su.oid AS subid,
     su.subname,
     st.pid,