Rename min_recovery_apply_delay to recovery_min_apply_delay.

Per discussion, this seems like a more consistent choice of name.

Fabrízio de Royes Mello, after a suggestion by Peter Eisentraut;
some additional documentation wordsmithing by me

doc/src/sgml/recovery-config.sgml

@@ -403,15 +403,15 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"'  # Windows
         </listitem>
        </varlistentry>
 
-     <varlistentry id="min-recovery-apply-delay" xreflabel="min_recovery_apply_delay">
-      <term><varname>min_recovery_apply_delay</varname> (<type>integer</type>)
+     <varlistentry id="recovery-min-apply-delay" xreflabel="recovery_min_apply_delay">
+      <term><varname>recovery_min_apply_delay</varname> (<type>integer</type>)
       <indexterm>
-        <primary><varname>min_recovery_apply_delay</> recovery parameter</primary>
+        <primary><varname>recovery_min_apply_delay</> recovery parameter</primary>
       </indexterm>
       </term>
       <listitem>
        <para>
-        By default, a standby server keeps restoring WAL records from the
+        By default, a standby server restores WAL records from the
         primary as soon as possible. It may be useful to have a time-delayed
         copy of the data, offering various options to correct data loss errors.
         This parameter allows you to delay recovery by a fixed period of time,
@@ -428,15 +428,15 @@ restore_command = 'copy "C:\\server\\archivedir\\%f" "%p"'  # Windows
         in transfer because of networks or cascading replication configurations
         may reduce the actual wait time significantly. If the system
         clocks on master and standby are not synchronised, this may lead to
-        recovery applying records earlier than expected but is not a major issue
-        because the useful settings of the parameter are much larger than
-        typical time deviation between the servers. Be careful to allow for
+        recovery applying records earlier than expected; but that is not a
+        major issue because useful settings of the parameter are much larger
+        than typical time deviations between servers. Be careful to allow for
         different timezone settings on master and standby.
        </para>
        <para>
         The delay occurs only on WAL records for COMMIT and Restore Points.
         Other records may be replayed earlier than the specified delay, which
-        is not an issue for MVCC though may potentially increase the number
+        is not an issue for MVCC though it may potentially increase the number
         of recovery conflicts generated.
        </para>
        <para>

doc/src/sgml/release-9.4.sgml

@@ -775,10 +775,10 @@
 
       <listitem>
        <para>
-        Allow <link
+        Add <link
         linkend="recovery-config"><filename>recovery.conf</></link>
         parameter <link
-        linkend="min-recovery-apply-delay"><varname>min_recovery_apply_delay</></link>
+        linkend="recovery-min-apply-delay"><varname>recovery_min_apply_delay</></link>
         to force delayed replication (Robert Haas, Fabr&iacute;zio de
         Royes Mello, Simon Riggs)
        </para>

src/backend/access/transam/recovery.conf.sample

@@ -129,20 +129,20 @@
 #
 # By default, a standby server keeps restoring XLOG records from the
 # primary indefinitely. If you want to stop the standby mode, finish recovery
-# and open the system in read/write mode, specify path to a trigger file.
+# and open the system in read/write mode, specify a path to a trigger file.
 # The server will poll the trigger file path periodically and start as a
 # primary server when it's found.
 #
 #trigger_file = ''
 #
-# By default, a standby server keeps restoring XLOG records from the
-# primary as soon as possible. If you want to explicitly delay the replay of
-# committed transactions from the master, specify a recovery apply delay.
-# For example, if you set this parameter to 5min, the standby will replay
-# each transaction commit only when the system time on the standby is at
-# least five minutes past the commit time reported by the master.
+# By default, a standby server restores XLOG records from the primary as
+# soon as possible. If you want to explicitly delay the replay of committed
+# transactions from the master, specify a minimum apply delay. For example,
+# if you set this parameter to 5min, the standby will replay each transaction
+# commit only when the system time on the standby is at least five minutes
+# past the commit time reported by the master.
 #
-#min_recovery_apply_delay = 0
+#recovery_min_apply_delay = 0
 #
 #---------------------------------------------------------------------------
 # HOT STANDBY PARAMETERS

src/backend/access/transam/xlog.c

@@ -223,7 +223,7 @@ static bool recoveryPauseAtTarget = true;
 static TransactionId recoveryTargetXid;
 static TimestampTz recoveryTargetTime;
 static char *recoveryTargetName;
-static int	min_recovery_apply_delay = 0;
+static int	recovery_min_apply_delay = 0;
 static TimestampTz recoveryDelayUntilTime;
 
 /* options taken from recovery.conf for XLOG streaming */
@@ -5236,18 +5236,19 @@ readRecoveryCommandFile(void)
 					(errmsg_internal("trigger_file = '%s'",
 									 TriggerFile)));
 		}
-		else if (strcmp(item->name, "min_recovery_apply_delay") == 0)
+		else if (strcmp(item->name, "recovery_min_apply_delay") == 0)
 		{
 			const char *hintmsg;
 
-			if (!parse_int(item->value, &min_recovery_apply_delay, GUC_UNIT_MS,
+			if (!parse_int(item->value, &recovery_min_apply_delay, GUC_UNIT_MS,
 						   &hintmsg))
 				ereport(ERROR,
 						(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-						 errmsg("parameter \"%s\" requires a temporal value", "min_recovery_apply_delay"),
+						 errmsg("parameter \"%s\" requires a temporal value",
+								"recovery_min_apply_delay"),
 						 hintmsg ? errhint("%s", _(hintmsg)) : 0));
 			ereport(DEBUG2,
-					(errmsg("min_recovery_apply_delay = '%s'", item->value)));
+					(errmsg("recovery_min_apply_delay = '%s'", item->value)));
 		}
 		else
 			ereport(FATAL,
@@ -5669,7 +5670,7 @@ SetRecoveryPause(bool recoveryPause)
 }
 
 /*
- * When min_recovery_apply_delay is set, we wait long enough to make sure
+ * When recovery_min_apply_delay is set, we wait long enough to make sure
  * certain record types are applied at least that interval behind the master.
  *
  * Returns true if we waited.
@@ -5690,7 +5691,7 @@ recoveryApplyDelay(XLogRecord *record)
 	int			microsecs;
 
 	/* nothing to do if no delay configured */
-	if (min_recovery_apply_delay == 0)
+	if (recovery_min_apply_delay == 0)
 		return false;
 
 	/*
@@ -5711,7 +5712,7 @@ recoveryApplyDelay(XLogRecord *record)
 		return false;
 
 	recoveryDelayUntilTime =
-		TimestampTzPlusMilliseconds(xtime, min_recovery_apply_delay);
+		TimestampTzPlusMilliseconds(xtime, recovery_min_apply_delay);
 
 	/*
 	 * Exit without arming the latch if it's already past time to apply this