Revert 0f5ca02

0f5ca02 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

Author: akorotkov

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