Revert 0f5ca02f

0f5ca02f introduces 3 new keywords.  It appears to be too much for relatively
small feature.  Given now we past feature freeze, it's already late for
discussion of the new syntax.  So, revert.

Discussion: https://postgr.es/m/28209.1586294824%40sss.pgh.pa.us

doc/src/sgml/ref/begin.sgml

@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-BEGIN [ WORK | TRANSACTION ] [ <replaceable class="parameter">transaction_mode</replaceable> [, ...] ] [ WAIT FOR LSN <replaceable class="parameter">lsn_value</replaceable> [TIMEOUT <replaceable class="parameter">number_of_milliseconds</replaceable> ] ]
+BEGIN [ WORK | TRANSACTION ] [ <replaceable class="parameter">transaction_mode</replaceable> [, ...] ]
 
 <phrase>where <replaceable class="parameter">transaction_mode</replaceable> is one of:</phrase>
 
@@ -63,17 +63,6 @@ BEGIN [ WORK | TRANSACTION ] [ <replaceable class="parameter">transaction_mode</
    <xref linkend="sql-set-transaction"/>
    was executed.
   </para>
-
-  <para>
-   The <literal>WAIT FOR</literal> clause allows to wait for the target log
-   sequence number (<acronym>LSN</acronym>) to be replayed on standby before
-   starting the transaction in <productname>PostgreSQL</productname> databases
-   with master-standby asynchronous replication. Wait time can be limited by
-   specifying a timeout, which is measured in milliseconds and must be a positive
-   integer. If <acronym>LSN</acronym> was not reached before timeout, transaction
-   doesn't begin. Waiting can be interrupted by cancelling
-   <literal>BEGIN</literal> command.
-  </para>
  </refsect1>
 
  <refsect1>
@@ -157,10 +146,6 @@ BEGIN;
    different purpose in embedded SQL. You are advised to be careful
    about the transaction semantics when porting database applications.
   </para>
-
-  <para>
-   There is no <literal>WAIT FOR</literal> clause in the SQL standard.
-  </para>
  </refsect1>
 
  <refsect1>

doc/src/sgml/ref/start_transaction.sgml

@@ -21,7 +21,7 @@ PostgreSQL documentation
 
  <refsynopsisdiv>
 <synopsis>
-START TRANSACTION [ <replaceable class="parameter">transaction_mode</replaceable> [, ...] ] [ WAIT FOR LSN <replaceable class="parameter">lsn_value</replaceable> [TIMEOUT <replaceable class="parameter">number_of_milliseconds</replaceable> ] ]
+START TRANSACTION [ <replaceable class="parameter">transaction_mode</replaceable> [, ...] ]
 
 <phrase>where <replaceable class="parameter">transaction_mode</replaceable> is one of:</phrase>
 
@@ -40,17 +40,6 @@ START TRANSACTION [ <replaceable class="parameter">transaction_mode</replaceable
    characteristics, as if <xref linkend="sql-set-transaction"/> was executed. This is the same
    as the <xref linkend="sql-begin"/> command.
   </para>
-
-  <para>
-   The <literal>WAIT FOR</literal> clause allows to wait for the target log
-   sequence number (<acronym>LSN</acronym>) to be replayed on standby before
-   starting the transaction in <productname>PostgreSQL</productname> databases
-   with master-standby asynchronous replication. Wait time can be limited by
-   specifying a timeout, which is measured in milliseconds and must be a positive
-   integer. If <acronym>LSN</acronym> was not reached before timeout, transaction
-   doesn't begin. Waiting can be interrupted by cancelling
-   <literal>START TRANSACTION</literal> command.
-  </para>
  </refsect1>
 
  <refsect1>
@@ -89,10 +78,6 @@ START TRANSACTION [ <replaceable class="parameter">transaction_mode</replaceable
    omitted.
   </para>
 
-  <para>
-   There is no <literal>WAIT FOR</literal> clause in the SQL standard.
-  </para>
-
   <para>
    See also the compatibility section of <xref linkend="sql-set-transaction"/>.
   </para>

src/backend/access/transam/xlog.c

@@ -42,7 +42,6 @@
 #include "catalog/pg_database.h"
 #include "commands/progress.h"
 #include "commands/tablespace.h"
-#include "commands/wait.h"
 #include "common/controldata_utils.h"
 #include "executor/instrument.h"
 #include "miscadmin.h"
@@ -7157,7 +7156,6 @@ StartupXLOG(void)
 			do
 			{
 				bool		switchedTLI = false;
-				XLogRecPtr	minWaitedLSN;
 
 #ifdef WAL_DEBUG
 				if (XLOG_DEBUG ||
@@ -7361,17 +7359,6 @@ StartupXLOG(void)
 					break;
 				}
 
-				/*
-				 * If we replayed an LSN that someone was waiting for, set
-				 * latches in shared memory array to notify the waiter.
-				 */
-				minWaitedLSN = WaitLSNGetMin();
-				if (!XLogRecPtrIsInvalid(minWaitedLSN) &&
-					minWaitedLSN <= XLogCtl->lastReplayedEndRecPtr)
-				{
-					WaitLSNSetLatch(XLogCtl->lastReplayedEndRecPtr);
-				}
-
 				/* Else, try to fetch the next WAL record */
 				record = ReadRecord(xlogreader, LOG, false);
 			} while (record != NULL);

src/backend/commands/Makefile

@@ -57,7 +57,6 @@ OBJS = \
 	user.o \
 	vacuum.o \
 	variable.o \
-	view.o \
-	wait.o
+	view.o
 
 include $(top_srcdir)/src/backend/common.mk

src/backend/commands/wait.c

-/*-------------------------------------------------------------------------
- *
- * wait.c
- *	  Implements WAIT FOR clause for BEGIN and START TRANSACTION commands.
- *	  This clause allows waiting for given LSN to be replayed on standby.
- *
- * Copyright (c) 2020, PostgreSQL Global Development Group
- *
- * IDENTIFICATION
- *	  src/backend/commands/wait.c
- *
- *-------------------------------------------------------------------------
- */
-#include "postgres.h"
-
-#include <math.h>
-
-#include "access/xlog.h"
-#include "access/xlogdefs.h"
-#include "commands/wait.h"
-#include "funcapi.h"
-#include "miscadmin.h"
-#include "pgstat.h"
-#include "storage/backendid.h"
-#include "storage/pmsignal.h"
-#include "storage/proc.h"
-#include "storage/shmem.h"
-#include "storage/sinvaladt.h"
-#include "storage/spin.h"
-#include "utils/builtins.h"
-#include "utils/pg_lsn.h"
-#include "utils/timestamp.h"
-
-/*
- * Shared memory structure representing information about LSNs, which backends
- * are waiting for replay.
- */
-typedef struct
-{
-	slock_t		mutex;			/* mutex protecting the fields below */
-	int			max_backend_id; /* max backend_id present in lsns[] */
-	pg_atomic_uint64 min_lsn;	/* minimal waited LSN */
-	/* per-backend array of waited LSNs */
-	XLogRecPtr	lsns[FLEXIBLE_ARRAY_MEMBER];
-}			WaitLSNState;
-
-static WaitLSNState * state;
-
-/*
- * Add the wait event of the current backend to shared memory array
- */
-static void
-WaitLSNAdd(XLogRecPtr lsn_to_wait)
-{
-	SpinLockAcquire(&state->mutex);
-	if (state->max_backend_id < MyBackendId)
-		state->max_backend_id = MyBackendId;
-
-	state->lsns[MyBackendId] = lsn_to_wait;
-
-	if (lsn_to_wait < state->min_lsn.value)
-		state->min_lsn.value = lsn_to_wait;
-	SpinLockRelease(&state->mutex);
-}
-
-/*
- * Delete wait event of the current backend from the shared memory array.
- */
-void
-WaitLSNDelete(void)
-{
-	int			i;
-	XLogRecPtr	deleted_lsn;
-
-	SpinLockAcquire(&state->mutex);
-
-	deleted_lsn = state->lsns[MyBackendId];
-	state->lsns[MyBackendId] = InvalidXLogRecPtr;
-
-	/* If we are deleting the minimal LSN, then choose the next min_lsn */
-	if (!XLogRecPtrIsInvalid(deleted_lsn) &&
-		deleted_lsn == state->min_lsn.value)
-	{
-		state->min_lsn.value = InvalidXLogRecPtr;
-		for (i = 2; i <= state->max_backend_id; i++)
-		{
-			if (!XLogRecPtrIsInvalid(state->lsns[i]) &&
-				(state->lsns[i] < state->min_lsn.value ||
-				 XLogRecPtrIsInvalid(state->min_lsn.value)))
-			{
-				state->min_lsn.value = state->lsns[i];
-			}
-		}
-	}
-
-	/* If deleting from the end of the array, shorten the array's used part */
-	if (state->max_backend_id == MyBackendId)
-	{
-		for (i = (MyBackendId); i >= 2; i--)
-			if (!XLogRecPtrIsInvalid(state->lsns[i]))
-			{
-				state->max_backend_id = i;
-				break;
-			}
-	}
-
-	SpinLockRelease(&state->mutex);
-}
-
-/*
- * Report amount of shared memory space needed for WaitLSNState
- */
-Size
-WaitLSNShmemSize(void)
-{
-	Size		size;
-
-	size = offsetof(WaitLSNState, lsns);
-	size = add_size(size, mul_size(MaxBackends + 1, sizeof(XLogRecPtr)));
-	return size;
-}
-
-/*
- * Initialize an shared memory structure for waiting for LSN
- */
-void
-WaitLSNShmemInit(void)
-{
-	bool		found;
-	uint32		i;
-
-	state = (WaitLSNState *) ShmemInitStruct("pg_wait_lsn",
-											 WaitLSNShmemSize(),
-											 &found);
-	if (!found)
-	{
-		SpinLockInit(&state->mutex);
-
-		for (i = 0; i < (MaxBackends + 1); i++)
-			state->lsns[i] = InvalidXLogRecPtr;
-
-		state->max_backend_id = 0;
-		pg_atomic_init_u64(&state->min_lsn, InvalidXLogRecPtr);
-	}
-}
-
-/*
- * Set latches in shared memory to signal that new LSN has been replayed
- */
-void
-WaitLSNSetLatch(XLogRecPtr cur_lsn)
-{
-	uint32		i;
-	int			max_backend_id;
-	PGPROC	   *backend;
-
-	SpinLockAcquire(&state->mutex);
-	max_backend_id = state->max_backend_id;
-
-	for (i = 2; i <= max_backend_id; i++)
-	{
-		backend = BackendIdGetProc(i);
-
-		if (backend && state->lsns[i] != 0 &&
-			state->lsns[i] <= cur_lsn)
-		{
-			SetLatch(&backend->procLatch);
-		}
-	}
-	SpinLockRelease(&state->mutex);
-}
-
-/*
- * Get minimal LSN that some backend is waiting for
- */
-XLogRecPtr
-WaitLSNGetMin(void)
-{
-	return state->min_lsn.value;
-}
-
-/*
- * On WAIT use a latch to wait till LSN is replayed, postmaster dies or timeout
- * happens. Timeout is specified in milliseconds.  Returns true if LSN was
- * reached and false otherwise.
- */
-bool
-WaitLSNUtility(XLogRecPtr target_lsn, const int timeout_ms)
-{
-	XLogRecPtr	cur_lsn;
-	int			latch_events;
-	float8		endtime;
-	bool		res = false;
-	bool		wait_forever = (timeout_ms <= 0);
-
-	endtime = GetNowFloat() + timeout_ms / 1000.0;
-
-	latch_events = WL_LATCH_SET | WL_TIMEOUT | WL_EXIT_ON_PM_DEATH;
-
-	/* Check if we already reached the needed LSN */
-	cur_lsn = GetXLogReplayRecPtr(NULL);
-	if (cur_lsn >= target_lsn)
-		return true;
-
-	WaitLSNAdd(target_lsn);
-	ResetLatch(MyLatch);
-
-	/* Recheck if LSN was reached while WaitLSNAdd() and ResetLatch() */
-	cur_lsn = GetXLogReplayRecPtr(NULL);
-	if (cur_lsn >= target_lsn)
-		return true;
-
-	for (;;)
-	{
-		int			rc;
-		float8		time_left = 0;
-		long		time_left_ms = 0;
-
-		time_left = endtime - GetNowFloat();
-
-		/* Use 1 second as the default timeout to check for interrupts */
-		if (wait_forever || time_left < 0 || time_left > 1.0)
-			time_left_ms = 1000;
-		else
-			time_left_ms = (long) ceil(time_left * 1000.0);
-
-		/* If interrupt, LockErrorCleanup() will do WaitLSNDelete() for us */
-		CHECK_FOR_INTERRUPTS();
-
-		/* If postmaster dies, finish immediately */
-		if (!PostmasterIsAlive())
-			break;
-
-		rc = WaitLatch(MyLatch, latch_events, time_left_ms,
-					   WAIT_EVENT_CLIENT_READ);
-
-		ResetLatch(MyLatch);
-
-		if (rc & WL_LATCH_SET)
-			cur_lsn = GetXLogReplayRecPtr(NULL);
-
-		if (rc & WL_TIMEOUT)
-		{
-			time_left = endtime - GetNowFloat();
-			/* If the time specified by user has passed, stop waiting */
-			if (!wait_forever && time_left <= 0.0)
-				break;
-			cur_lsn = GetXLogReplayRecPtr(NULL);
-		}
-
-		/* If LSN has been replayed */
-		if (target_lsn <= cur_lsn)
-			break;
-	}
-
-	WaitLSNDelete();
-
-	if (cur_lsn < target_lsn)
-		ereport(WARNING,
-				(errcode(ERRCODE_IN_FAILED_SQL_TRANSACTION),
-				 errmsg("didn't start transaction because LSN was not reached"),
-				 errhint("Try to increase wait timeout.")));
-	else
-		res = true;
-
-	return res;
-}
-
-/*
- * Implementation of WAIT FOR clause for BEGIN and START TRANSACTION commands
- */
-int
-WaitLSNMain(WaitClause *stmt, DestReceiver *dest)
-{
-	TupleDesc	tupdesc;
-	TupOutputState *tstate;
-	XLogRecPtr	target_lsn;
-	bool		res = false;
-
-	target_lsn = DatumGetLSN(DirectFunctionCall1(pg_lsn_in,
-												 CStringGetDatum(stmt->lsn)));
-	res = WaitLSNUtility(target_lsn, stmt->timeout);
-
-	/* Need a tuple descriptor representing a single TEXT column */
-	tupdesc = CreateTemplateTupleDesc(1);
-	TupleDescInitEntry(tupdesc, (AttrNumber) 1, "LSN reached", TEXTOID, -1, 0);
-
-	/* Prepare for projection of tuples */
-	tstate = begin_tup_output_tupdesc(dest, tupdesc, &TTSOpsMinimalTuple);
-
-	/* Send the result */
-	do_text_output_oneline(tstate, res ? "t" : "f");
-	end_tup_output(tstate);
-	return res;
-}

src/backend/nodes/copyfuncs.c

@@ -3748,22 +3748,10 @@ _copyTransactionStmt(const TransactionStmt *from)
 	COPY_STRING_FIELD(savepoint_name);
 	COPY_STRING_FIELD(gid);
 	COPY_SCALAR_FIELD(chain);
-	COPY_NODE_FIELD(wait);
 
 	return newnode;
 }
 
-static WaitClause *
-_copyWaitClause(const WaitClause *from)
-{
-	WaitClause *newnode = makeNode(WaitClause);
-
-	COPY_STRING_FIELD(lsn);
-	COPY_SCALAR_FIELD(timeout);
-
-	return newnode;
-};
-
 static CompositeTypeStmt *
 _copyCompositeTypeStmt(const CompositeTypeStmt *from)
 {
@@ -5351,9 +5339,6 @@ copyObjectImpl(const void *from)
 		case T_TransactionStmt:
 			retval = _copyTransactionStmt(from);
 			break;
-		case T_WaitClause:
-			retval = _copyWaitClause(from);
-			break;
 		case T_CompositeTypeStmt:
 			retval = _copyCompositeTypeStmt(from);
 			break;

src/backend/nodes/equalfuncs.c

@@ -1541,16 +1541,6 @@ _equalTransactionStmt(const TransactionStmt *a, const TransactionStmt *b)
 	COMPARE_STRING_FIELD(savepoint_name);
 	COMPARE_STRING_FIELD(gid);
 	COMPARE_SCALAR_FIELD(chain);
-	COMPARE_NODE_FIELD(wait);
-
-	return true;
-}
-
-static bool
-_equalWaitClause(const WaitClause *a, const WaitClause *b)
-{
-	COMPARE_STRING_FIELD(lsn);
-	COMPARE_SCALAR_FIELD(timeout);
 
 	return true;
 }
@@ -3401,9 +3391,6 @@ equal(const void *a, const void *b)
 		case T_TransactionStmt:
 			retval = _equalTransactionStmt(a, b);
 			break;
-		case T_WaitClause:
-			retval = _equalWaitClause(a, b);
-			break;
 		case T_CompositeTypeStmt:
 			retval = _equalCompositeTypeStmt(a, b);
 			break;

src/backend/nodes/outfuncs.c

@@ -2786,28 +2786,6 @@ _outDefElem(StringInfo str, const DefElem *node)
 	WRITE_LOCATION_FIELD(location);
 }
 
-static void
-_outTransactionStmt(StringInfo str, const TransactionStmt *node)
-{
-	WRITE_NODE_TYPE("TRANSACTIONSTMT");
-
-	WRITE_STRING_FIELD(savepoint_name);
-	WRITE_STRING_FIELD(gid);
-	WRITE_NODE_FIELD(options);
-	WRITE_BOOL_FIELD(chain);
-	WRITE_ENUM_FIELD(kind, TransactionStmtKind);
-	WRITE_NODE_FIELD(wait);
-}
-
-static void
-_outWaitClause(StringInfo str, const WaitClause *node)
-{
-	WRITE_NODE_TYPE("WAITCLAUSE");
-
-	WRITE_STRING_FIELD(lsn);
-	WRITE_UINT_FIELD(timeout);
-}
-
 static void
 _outTableLikeClause(StringInfo str, const TableLikeClause *node)
 {
@@ -4358,12 +4336,6 @@ outNode(StringInfo str, const void *obj)
 			case T_PartitionRangeDatum:
 				_outPartitionRangeDatum(str, obj);
 				break;
-			case T_TransactionStmt:
-				_outTransactionStmt(str, obj);
-				break;
-			case T_WaitClause:
-				_outWaitClause(str, obj);
-				break;
 
 			default:
 

src/backend/parser/gram.y

@@ -601,8 +601,6 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 %type <partboundspec> PartitionBoundSpec
 %type <list>		hash_partbound
 %type <defelt>		hash_partbound_elem
-%type <ival>		wait_time
-%type <node>		wait_for
 
 /*
  * Non-keyword token types.  These are hard-wired into the "flex" lexer.
@@ -672,7 +670,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 
 	LABEL LANGUAGE LARGE_P LAST_P LATERAL_P
 	LEADING LEAKPROOF LEAST LEFT LEVEL LIKE LIMIT LISTEN LOAD LOCAL
-	LOCALTIME LOCALTIMESTAMP LOCATION LOCK_P LOCKED LOGGED LSN
+	LOCALTIME LOCALTIMESTAMP LOCATION LOCK_P LOCKED LOGGED
 
 	MAPPING MATCH MATERIALIZED MAXVALUE METHOD MINUTE_P MINVALUE MODE MONTH_P MOVE
 
@@ -703,7 +701,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	SUBSCRIPTION SUBSTRING SUPPORT SYMMETRIC SYSID SYSTEM_P
 
 	TABLE TABLES TABLESAMPLE TABLESPACE TEMP TEMPLATE TEMPORARY TEXT_P THEN
-	TIES TIME TIMEOUT TIMESTAMP TO TRAILING TRANSACTION TRANSFORM
+	TIES TIME TIMESTAMP TO TRAILING TRANSACTION TRANSFORM
 	TREAT TRIGGER TRIM TRUE_P
 	TRUNCATE TRUSTED TYPE_P TYPES_P
 
@@ -713,8 +711,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	VACUUM VALID VALIDATE VALIDATOR VALUE_P VALUES VARCHAR VARIADIC VARYING
 	VERBOSE VERSION_P VIEW VIEWS VOLATILE
 
-	WAIT WHEN WHERE WHITESPACE_P WINDOW
-	WITH WITHIN WITHOUT WORK WRAPPER WRITE
+	WHEN WHERE WHITESPACE_P WINDOW WITH WITHIN WITHOUT WORK WRAPPER WRITE
 
 	XML_P XMLATTRIBUTES XMLCONCAT XMLELEMENT XMLEXISTS XMLFOREST XMLNAMESPACES
 	XMLPARSE XMLPI XMLROOT XMLSERIALIZE XMLTABLE
@@ -9958,20 +9955,18 @@ TransactionStmt:
 					n->chain = $3;
 					$$ = (Node *)n;
 				}
-			| BEGIN_P opt_transaction transaction_mode_list_or_empty wait_for
+			| BEGIN_P opt_transaction transaction_mode_list_or_empty
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->kind = TRANS_STMT_BEGIN;
 					n->options = $3;
-					n->wait = $4;
 					$$ = (Node *)n;
 				}
-			| START TRANSACTION transaction_mode_list_or_empty wait_for
+			| START TRANSACTION transaction_mode_list_or_empty
 				{
 					TransactionStmt *n = makeNode(TransactionStmt);
 					n->kind = TRANS_STMT_START;
 					n->options = $3;
-					n->wait = $4;
 					$$ = (Node *)n;
 				}
 			| COMMIT opt_transaction opt_transaction_chain
@@ -14245,25 +14240,6 @@ xml_passing_mech:
 			| BY VALUE_P
 		;
 
-/*
- * WAIT FOR clause of BEGIN and START TRANSACTION statements
- */
-wait_for:
-			WAIT FOR LSN Sconst wait_time
-				{
-					WaitClause *n = makeNode(WaitClause);
-					n->lsn = $4;
-					n->timeout = $5;
-					$$ = (Node *)n;
-				}
-			| /* EMPTY */		{ $$ = NULL; }
-		;
-
-wait_time:
-			TIMEOUT Iconst		{ $$ = $2; }
-			| /* EMPTY */		{ $$ = 0; }
-		;
-
 
 /*
  * Aggregate decoration clauses
@@ -15415,7 +15391,6 @@ unreserved_keyword:
 			| LOCK_P
 			| LOCKED
 			| LOGGED
-			| LSN
 			| MAPPING
 			| MATCH
 			| MATERIALIZED
@@ -15543,7 +15518,6 @@ unreserved_keyword:
 			| TEMPORARY
 			| TEXT_P
 			| TIES
-			| TIMEOUT
 			| TRANSACTION
 			| TRANSFORM
 			| TRIGGER
@@ -15570,7 +15544,6 @@ unreserved_keyword:
 			| VIEW
 			| VIEWS
 			| VOLATILE
-			| WAIT
 			| WHITESPACE_P
 			| WITHIN
 			| WITHOUT

src/backend/storage/ipc/ipci.c

@@ -22,7 +22,6 @@
 #include "access/subtrans.h"
 #include "access/twophase.h"
 #include "commands/async.h"
-#include "commands/wait.h"
 #include "miscadmin.h"
 #include "pgstat.h"
 #include "postmaster/autovacuum.h"
@@ -148,7 +147,6 @@ CreateSharedMemoryAndSemaphores(void)
 		size = add_size(size, BTreeShmemSize());
 		size = add_size(size, SyncScanShmemSize());
 		size = add_size(size, AsyncShmemSize());
-		size = add_size(size, WaitLSNShmemSize());
 #ifdef EXEC_BACKEND
 		size = add_size(size, ShmemBackendArraySize());
 #endif
@@ -266,11 +264,6 @@ CreateSharedMemoryAndSemaphores(void)
 	SyncScanShmemInit();
 	AsyncShmemInit();
 
-	/*
-	 * Init array of Latches in shared memory for WAIT
-	 */
-	WaitLSNShmemInit();
-
 #ifdef EXEC_BACKEND
 
 	/*

src/backend/storage/lmgr/proc.c

@@ -38,7 +38,6 @@
 #include "access/transam.h"
 #include "access/twophase.h"
 #include "access/xact.h"
-#include "commands/wait.h"
 #include "miscadmin.h"
 #include "pgstat.h"
 #include "postmaster/autovacuum.h"
@@ -718,9 +717,6 @@ LockErrorCleanup(void)
 
 	AbortStrongLockAcquire();
 
-	/* If BEGIN WAIT FOR LSN was interrupted, then stop waiting for that LSN */
-	WaitLSNDelete();
-
 	/* Nothing to do if we weren't waiting for a lock */
 	if (lockAwaited == NULL)
 	{

src/backend/tcop/utility.c

@@ -57,7 +57,6 @@
 #include "commands/user.h"
 #include "commands/vacuum.h"
 #include "commands/view.h"
-#include "commands/wait.h"
 #include "miscadmin.h"
 #include "parser/parse_utilcmd.h"
 #include "postmaster/bgwriter.h"
@@ -592,18 +591,6 @@ standard_ProcessUtility(PlannedStmt *pstmt,
 					case TRANS_STMT_START:
 						{
 							ListCell   *lc;
-							WaitClause *waitstmt = (WaitClause *) stmt->wait;
-
-							/* WAIT FOR cannot be used on master */
-							if (stmt->wait && !RecoveryInProgress())
-								ereport(ERROR,
-										(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
-										 errmsg("WAIT FOR can only be "
-												"used on standby")));
-
-							/* If needed to WAIT FOR something but failed */
-							if (stmt->wait && WaitLSNMain(waitstmt, dest) == 0)
-								break;
 
 							BeginTransactionBlock();
 							foreach(lc, stmt->options)

src/backend/utils/adt/misc.c

@@ -372,6 +372,8 @@ pg_sleep(PG_FUNCTION_ARGS)
 	 * less than the specified time when WaitLatch is terminated early by a
 	 * non-query-canceling signal such as SIGHUP.
 	 */
+#define GetNowFloat()	((float8) GetCurrentTimestamp() / 1000000.0)
+
 	endtime = GetNowFloat() + secs;
 
 	for (;;)

src/include/commands/wait.h

-/*-------------------------------------------------------------------------
- *
- * wait.h
- *	  prototypes for commands/wait.c
- *
- * Copyright (c) 2020, PostgreSQL Global Development Group
- *
- * src/include/commands/wait.h
- *
- *-------------------------------------------------------------------------
- */
-#ifndef WAIT_H
-#define WAIT_H
-
-#include "tcop/dest.h"
-#include "nodes/parsenodes.h"
-
-extern bool WaitLSNUtility(XLogRecPtr lsn, const int timeout_ms);
-extern Size WaitLSNShmemSize(void);
-extern void WaitLSNShmemInit(void);
-extern void WaitLSNSetLatch(XLogRecPtr cur_lsn);
-extern XLogRecPtr WaitLSNGetMin(void);
-extern int	WaitLSNMain(WaitClause *stmt, DestReceiver *dest);
-extern void WaitLSNDelete(void);
-
-#endif							/* WAIT_H */

src/include/nodes/nodes.h

@@ -492,7 +492,6 @@ typedef enum NodeTag
 	T_StartReplicationCmd,
 	T_TimeLineHistoryCmd,
 	T_SQLCmd,
-	T_WaitClause,
 
 	/*
 	 * TAGS FOR RANDOM OTHER STUFF

src/include/nodes/parsenodes.h

@@ -1431,17 +1431,6 @@ typedef struct OnConflictClause
 	int			location;		/* token location, or -1 if unknown */
 } OnConflictClause;
 
-/*
- * WaitClause -
- *		representation of WAIT FOR clause for BEGIN and START TRANSACTION.
- */
-typedef struct WaitClause
-{
-	NodeTag		type;
-	char	   *lsn;			/* LSN to wait for */
-	int			timeout;		/* Number of milliseconds to limit wait time */
-} WaitClause;
-
 /*
  * CommonTableExpr -
  *	   representation of WITH list element
@@ -3071,7 +3060,6 @@ typedef struct TransactionStmt
 	char	   *savepoint_name; /* for savepoint commands */
 	char	   *gid;			/* for two-phase-commit related commands */
 	bool		chain;			/* AND CHAIN option */
-	Node	   *wait;			/* WAIT FOR clause */
 } TransactionStmt;
 
 /* ----------------------

src/include/parser/kwlist.h

@@ -243,7 +243,6 @@ PG_KEYWORD("location", LOCATION, UNRESERVED_KEYWORD)
 PG_KEYWORD("lock", LOCK_P, UNRESERVED_KEYWORD)
 PG_KEYWORD("locked", LOCKED, UNRESERVED_KEYWORD)
 PG_KEYWORD("logged", LOGGED, UNRESERVED_KEYWORD)
-PG_KEYWORD("lsn", LSN, UNRESERVED_KEYWORD)
 PG_KEYWORD("mapping", MAPPING, UNRESERVED_KEYWORD)
 PG_KEYWORD("match", MATCH, UNRESERVED_KEYWORD)
 PG_KEYWORD("materialized", MATERIALIZED, UNRESERVED_KEYWORD)
@@ -411,7 +410,6 @@ PG_KEYWORD("text", TEXT_P, UNRESERVED_KEYWORD)
 PG_KEYWORD("then", THEN, RESERVED_KEYWORD)
 PG_KEYWORD("ties", TIES, UNRESERVED_KEYWORD)
 PG_KEYWORD("time", TIME, COL_NAME_KEYWORD)
-PG_KEYWORD("timeout", TIMEOUT, UNRESERVED_KEYWORD)
 PG_KEYWORD("timestamp", TIMESTAMP, COL_NAME_KEYWORD)
 PG_KEYWORD("to", TO, RESERVED_KEYWORD)
 PG_KEYWORD("trailing", TRAILING, RESERVED_KEYWORD)
@@ -452,7 +450,6 @@ PG_KEYWORD("version", VERSION_P, UNRESERVED_KEYWORD)
 PG_KEYWORD("view", VIEW, UNRESERVED_KEYWORD)
 PG_KEYWORD("views", VIEWS, UNRESERVED_KEYWORD)
 PG_KEYWORD("volatile", VOLATILE, UNRESERVED_KEYWORD)
-PG_KEYWORD("wait", WAIT, UNRESERVED_KEYWORD)
 PG_KEYWORD("when", WHEN, RESERVED_KEYWORD)
 PG_KEYWORD("where", WHERE, RESERVED_KEYWORD)
 PG_KEYWORD("whitespace", WHITESPACE_P, UNRESERVED_KEYWORD)

src/include/utils/timestamp.h

@@ -109,6 +109,4 @@ extern int	date2isoyearday(int year, int mon, int mday);
 
 extern bool TimestampTimestampTzRequiresRewrite(void);
 
-#define GetNowFloat() ((float8) GetCurrentTimestamp() / 1000000.0)
-
 #endif							/* TIMESTAMP_H */

src/test/recovery/t/020_begin_wait.pl

-# Checks for BEGIN WAIT FOR LSN
-use strict;
-use warnings;
-
-use PostgresNode;
-use TestLib;
-use Test::More tests => 8;
-
-# Initialize master node
-my $node_master = get_new_node('master');
-$node_master->init(allows_streaming => 1);
-$node_master->start;
-
-# And some content and take a backup
-$node_master->safe_psql('postgres',
-	"CREATE TABLE wait_test AS SELECT generate_series(1,10) AS a");
-my $backup_name = 'my_backup';
-$node_master->backup($backup_name);
-
-# Using the backup, create a streaming standby with a 1 second delay
-my $node_standby = get_new_node('standby');
-my $delay        = 1;
-$node_standby->init_from_backup($node_master, $backup_name,
-	has_streaming => 1);
-$node_standby->append_conf('postgresql.conf', qq[
-	recovery_min_apply_delay = '${delay}s'
-]);
-$node_standby->start;
-
-
-# Check that timeouts make us wait for the specified time (1s here)
-my $current_time = $node_standby->safe_psql('postgres', "SELECT now()");
-my $two_seconds = 2000; # in milliseconds
-my $start_time = time();
-$node_standby->safe_psql('postgres',
-	"BEGIN WAIT FOR LSN '0/FFFFFFFF' TIMEOUT $two_seconds");
-my $time_waited = (time() - $start_time) * 1000; # convert to milliseconds
-ok($time_waited >= $two_seconds, "WAIT FOR TIMEOUT waits for enough time");
-
-
-# Check that timeouts let us stop waiting right away, before reaching target LSN
-$node_master->safe_psql('postgres',
-	"INSERT INTO wait_test VALUES (generate_series(11, 20))");
-my $lsn1 = $node_master->safe_psql('postgres', "SELECT pg_current_wal_lsn()");
-my ($ret, $out, $err) = $node_standby->psql('postgres',
-	"BEGIN WAIT FOR LSN '$lsn1' TIMEOUT 1");
-
-ok($ret == 0, "zero return value when failed to WAIT FOR LSN on standby");
-ok($err =~ /WARNING:  didn't start transaction because LSN was not reached/,
-	"correct error message when failed to WAIT FOR LSN on standby");
-ok($out eq "f", "if given too little wait time, WAIT doesn't reach target LSN");
-
-
-# Check that WAIT FOR works fine and reaches target LSN if given no timeout
-
-# Add data on master, memorize master's last LSN
-$node_master->safe_psql('postgres',
-	"INSERT INTO wait_test VALUES (generate_series(21, 30))");
-my $lsn2 = $node_master->safe_psql('postgres', "SELECT pg_current_wal_lsn()");
-
-# Wait for it to appear on replica, memorize replica's last LSN
-$node_standby->safe_psql('postgres',
-	"BEGIN WAIT FOR LSN '$lsn2'");
-my $reached_lsn = $node_standby->safe_psql('postgres',
-	"SELECT pg_last_wal_replay_lsn()");
-
-# Make sure that master's and replica's LSNs are the same after WAIT
-my $compare_lsns = $node_standby->safe_psql('postgres',
-	"SELECT pg_lsn_cmp('$reached_lsn'::pg_lsn, '$lsn2'::pg_lsn)");
-ok($compare_lsns eq 0,
-	"standby reached the same LSN as master before starting transaction");
-
-
-# Make sure that it's not allowed to use WAIT FOR on master
-($ret, $out, $err) = $node_master->psql('postgres',
-	"BEGIN WAIT FOR LSN '0/FFFFFFFF'");
-
-ok($ret != 0, "non-zero return value when trying to WAIT FOR LSN on master");
-ok($err =~ /ERROR:  WAIT FOR can only be used on standby/,
-	"correct error message when trying to WAIT FOR LSN on master");
-ok($out eq '', "empty output when trying to WAIT FOR LSN on master");
-
-
-$node_standby->stop;
-$node_master->stop;

src/tools/pgindent/typedefs.list

@@ -2621,7 +2621,6 @@ WSABUF
 WSADATA
 WSANETWORKEVENTS
 WSAPROTOCOL_INFO
-WaitClause
 WaitEvent
 WaitEventActivity
 WaitEventClient
@@ -2629,7 +2628,6 @@ WaitEventIO
 WaitEventIPC
 WaitEventSet
 WaitEventTimeout
-WaitLSNState
 WaitPMResult
 WalCloseMethod
 WalLevel