Rename CHECKPOINT_IMMEDIATE to CHECKPOINT_FAST.

The new name more accurately reflects the effects of this flag on a
requested checkpoint.  Checkpoint-related log messages (i.e., those
controlled by the log_checkpoints configuration parameter) will now
say "fast" instead of "immediate", too.  Likewise, references to
"immediate" checkpoints in the documentation have been updated to
say "fast".  This is preparatory work for a follow-up commit that
will add a MODE option to the CHECKPOINT command.

Author: Christoph Berg <myon@debian.org>
Discussion: https://postgr.es/m/aDnaKTEf-0dLiEfz%40msg.df7cb.de

doc/src/sgml/backup.sgml

@@ -991,7 +991,7 @@ SELECT pg_backup_start(label => 'label', fast => false);
      usually preferable as it minimizes the impact on the running system.  If you
      want to start the backup as soon as possible, pass <literal>true</literal> as
      the second parameter to <function>pg_backup_start</function> and it will
-     request an immediate checkpoint, which will finish as fast as possible using
+     request a fast checkpoint, which will finish as fast as possible using
      as much I/O as possible.
     </para>
 

doc/src/sgml/func.sgml

@@ -28973,7 +28973,7 @@ LOG:  Grand total: 1651920 bytes in 201 blocks; 622360 free (88 chunks); 1029560
         will be stored.)
         If the optional second parameter is given as <literal>true</literal>,
         it specifies executing <function>pg_backup_start</function> as quickly
-        as possible.  This forces an immediate checkpoint which will cause a
+        as possible.  This forces a fast checkpoint which will cause a
         spike in I/O operations, slowing any concurrently executing queries.
        </para>
        <para>

doc/src/sgml/ref/checkpoint.sgml

@@ -37,7 +37,7 @@ CHECKPOINT
   </para>
 
   <para>
-   The <command>CHECKPOINT</command> command forces an immediate
+   The <command>CHECKPOINT</command> command forces a fast
    checkpoint when the command is issued, without waiting for a
    regular checkpoint scheduled by the system (controlled by the settings in
    <xref linkend="runtime-config-wal-checkpoints"/>).

doc/src/sgml/ref/pg_basebackup.sgml

@@ -500,8 +500,9 @@ PostgreSQL documentation
       <term><option>--checkpoint={fast|spread}</option></term>
       <listitem>
        <para>
-        Sets checkpoint mode to fast (immediate) or spread (the default)
+        Sets checkpoint mode to fast or spread
         (see <xref linkend="backup-lowlevel-base-backup"/>).
+        The default is spread.
        </para>
       </listitem>
      </varlistentry>

src/backend/access/transam/xlog.c

@@ -6486,7 +6486,7 @@ PerformRecoveryXLogAction(void)
 	else
 	{
 		RequestCheckpoint(CHECKPOINT_END_OF_RECOVERY |
-						  CHECKPOINT_IMMEDIATE |
+						  CHECKPOINT_FAST |
 						  CHECKPOINT_WAIT);
 	}
 
@@ -6795,7 +6795,7 @@ ShutdownXLOG(int code, Datum arg)
 	WalSndWaitStopping();
 
 	if (RecoveryInProgress())
-		CreateRestartPoint(CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_IMMEDIATE);
+		CreateRestartPoint(CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_FAST);
 	else
 	{
 		/*
@@ -6807,7 +6807,7 @@ ShutdownXLOG(int code, Datum arg)
 		if (XLogArchivingActive())
 			RequestXLogSwitch(false);
 
-		CreateCheckPoint(CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_IMMEDIATE);
+		CreateCheckPoint(CHECKPOINT_IS_SHUTDOWN | CHECKPOINT_FAST);
 	}
 }
 
@@ -6823,7 +6823,7 @@ LogCheckpointStart(int flags, bool restartpoint)
 				(errmsg("restartpoint starting:%s%s%s%s%s%s%s%s",
 						(flags & CHECKPOINT_IS_SHUTDOWN) ? " shutdown" : "",
 						(flags & CHECKPOINT_END_OF_RECOVERY) ? " end-of-recovery" : "",
-						(flags & CHECKPOINT_IMMEDIATE) ? " immediate" : "",
+						(flags & CHECKPOINT_FAST) ? " fast" : "",
 						(flags & CHECKPOINT_FORCE) ? " force" : "",
 						(flags & CHECKPOINT_WAIT) ? " wait" : "",
 						(flags & CHECKPOINT_CAUSE_XLOG) ? " wal" : "",
@@ -6835,7 +6835,7 @@ LogCheckpointStart(int flags, bool restartpoint)
 				(errmsg("checkpoint starting:%s%s%s%s%s%s%s%s",
 						(flags & CHECKPOINT_IS_SHUTDOWN) ? " shutdown" : "",
 						(flags & CHECKPOINT_END_OF_RECOVERY) ? " end-of-recovery" : "",
-						(flags & CHECKPOINT_IMMEDIATE) ? " immediate" : "",
+						(flags & CHECKPOINT_FAST) ? " fast" : "",
 						(flags & CHECKPOINT_FORCE) ? " force" : "",
 						(flags & CHECKPOINT_WAIT) ? " wait" : "",
 						(flags & CHECKPOINT_CAUSE_XLOG) ? " wal" : "",
@@ -7023,8 +7023,8 @@ update_checkpoint_display(int flags, bool restartpoint, bool reset)
  * flags is a bitwise OR of the following:
  *	CHECKPOINT_IS_SHUTDOWN: checkpoint is for database shutdown.
  *	CHECKPOINT_END_OF_RECOVERY: checkpoint is for end of WAL recovery.
- *	CHECKPOINT_IMMEDIATE: finish the checkpoint ASAP,
+ *	CHECKPOINT_FAST: finish the checkpoint ASAP, ignoring
- *		ignoring checkpoint_completion_target parameter.
+ *		checkpoint_completion_target parameter.
  *	CHECKPOINT_FORCE: force a checkpoint even if no XLOG activity has occurred
  *		since the last one (implied by CHECKPOINT_IS_SHUTDOWN or
  *		CHECKPOINT_END_OF_RECOVERY).
@@ -8929,9 +8929,8 @@ issue_xlog_fsync(int fd, XLogSegNo segno, TimeLineID tli)
  * backup state and tablespace map.
  *
  * Input parameters are "state" (the backup state), "fast" (if true, we do
- * the checkpoint in immediate mode to make it faster), and "tablespaces"
+ * the checkpoint in fast mode), and "tablespaces" (if non-NULL, indicates a
- * (if non-NULL, indicates a list of tablespaceinfo structs describing the
+ * list of tablespaceinfo structs describing the cluster's tablespaces.).
- * cluster's tablespaces.).
  *
  * The tablespace map contents are appended to passed-in parameter
  * tablespace_map and the caller is responsible for including it in the backup
@@ -9059,11 +9058,11 @@ do_pg_backup_start(const char *backupidstr, bool fast, List **tablespaces,
 			 * during recovery means that checkpointer is running, we can use
 			 * RequestCheckpoint() to establish a restartpoint.
 			 *
-			 * We use CHECKPOINT_IMMEDIATE only if requested by user (via
+			 * We use CHECKPOINT_FAST only if requested by user (via passing
-			 * passing fast = true).  Otherwise this can take awhile.
+			 * fast = true).  Otherwise this can take awhile.
 			 */
 			RequestCheckpoint(CHECKPOINT_FORCE | CHECKPOINT_WAIT |
-							  (fast ? CHECKPOINT_IMMEDIATE : 0));
+							  (fast ? CHECKPOINT_FAST : 0));
 
 			/*
 			 * Now we need to fetch the checkpoint record location, and also

src/backend/commands/dbcommands.c

@@ -570,7 +570,7 @@ CreateDatabaseUsingFileCopy(Oid src_dboid, Oid dst_dboid, Oid src_tsid,
 	 * any CREATE DATABASE commands.
 	 */
 	if (!IsBinaryUpgrade)
-		RequestCheckpoint(CHECKPOINT_IMMEDIATE | CHECKPOINT_FORCE |
+		RequestCheckpoint(CHECKPOINT_FAST | CHECKPOINT_FORCE |
 						  CHECKPOINT_WAIT | CHECKPOINT_FLUSH_UNLOGGED);
 
 	/*
@@ -673,7 +673,7 @@ CreateDatabaseUsingFileCopy(Oid src_dboid, Oid dst_dboid, Oid src_tsid,
 	 * strategy that avoids these problems.
 	 */
 	if (!IsBinaryUpgrade)
-		RequestCheckpoint(CHECKPOINT_IMMEDIATE | CHECKPOINT_FORCE |
+		RequestCheckpoint(CHECKPOINT_FAST | CHECKPOINT_FORCE |
 						  CHECKPOINT_WAIT);
 }
 
@@ -1870,7 +1870,7 @@ dropdb(const char *dbname, bool missing_ok, bool force)
 	 * Force a checkpoint to make sure the checkpointer has received the
 	 * message sent by ForgetDatabaseSyncRequests.
 	 */
-	RequestCheckpoint(CHECKPOINT_IMMEDIATE | CHECKPOINT_FORCE | CHECKPOINT_WAIT);
+	RequestCheckpoint(CHECKPOINT_FAST | CHECKPOINT_FORCE | CHECKPOINT_WAIT);
 
 	/* Close all smgr fds in all backends. */
 	WaitForProcSignalBarrier(EmitProcSignalBarrier(PROCSIGNAL_BARRIER_SMGRRELEASE));
@@ -2120,7 +2120,7 @@ movedb(const char *dbname, const char *tblspcname)
 	 * On Windows, this also ensures that background procs don't hold any open
 	 * files, which would cause rmdir() to fail.
 	 */
-	RequestCheckpoint(CHECKPOINT_IMMEDIATE | CHECKPOINT_FORCE | CHECKPOINT_WAIT
+	RequestCheckpoint(CHECKPOINT_FAST | CHECKPOINT_FORCE | CHECKPOINT_WAIT
 					  | CHECKPOINT_FLUSH_UNLOGGED);
 
 	/* Close all smgr fds in all backends. */
@@ -2252,7 +2252,7 @@ movedb(const char *dbname, const char *tblspcname)
 		 * any unlogged operations done in the new DB tablespace before the
 		 * next checkpoint.
 		 */
-		RequestCheckpoint(CHECKPOINT_IMMEDIATE | CHECKPOINT_FORCE | CHECKPOINT_WAIT);
+		RequestCheckpoint(CHECKPOINT_FAST | CHECKPOINT_FORCE | CHECKPOINT_WAIT);
 
 		/*
 		 * Force synchronous commit, thus minimizing the window between

src/backend/commands/tablespace.c

@@ -500,7 +500,7 @@ DropTableSpace(DropTableSpaceStmt *stmt)
 		 * mustn't delete.  So instead, we force a checkpoint which will clean
 		 * out any lingering files, and try again.
 		 */
-		RequestCheckpoint(CHECKPOINT_IMMEDIATE | CHECKPOINT_FORCE | CHECKPOINT_WAIT);
+		RequestCheckpoint(CHECKPOINT_FAST | CHECKPOINT_FORCE | CHECKPOINT_WAIT);
 
 		/*
 		 * On Windows, an unlinked file persists in the directory listing

src/backend/postmaster/checkpointer.c

@@ -161,7 +161,7 @@ static pg_time_t last_xlog_switch_time;
 static void ProcessCheckpointerInterrupts(void);
 static void CheckArchiveTimeout(void);
 static bool IsCheckpointOnSchedule(double progress);
-static bool ImmediateCheckpointRequested(void);
+static bool FastCheckpointRequested(void);
 static bool CompactCheckpointerRequestQueue(void);
 static void UpdateSharedMemoryConfig(void);
 
@@ -734,12 +734,12 @@ CheckArchiveTimeout(void)
 }
 
 /*
- * Returns true if an immediate checkpoint request is pending.  (Note that
+ * Returns true if a fast checkpoint request is pending.  (Note that this does
- * this does not check the *current* checkpoint's IMMEDIATE flag, but whether
+ * not check the *current* checkpoint's FAST flag, but whether there is one
- * there is one pending behind it.)
+ * pending behind it.)
  */
 static bool
-ImmediateCheckpointRequested(void)
+FastCheckpointRequested(void)
 {
 	volatile CheckpointerShmemStruct *cps = CheckpointerShmem;
 
@@ -747,7 +747,7 @@ ImmediateCheckpointRequested(void)
 	 * We don't need to acquire the ckpt_lck in this case because we're only
 	 * looking at a single flag bit.
 	 */
-	if (cps->ckpt_flags & CHECKPOINT_IMMEDIATE)
+	if (cps->ckpt_flags & CHECKPOINT_FAST)
 		return true;
 	return false;
 }
@@ -760,7 +760,7 @@ ImmediateCheckpointRequested(void)
  * checkpoint_completion_target.
  *
  * The checkpoint request flags should be passed in; currently the only one
- * examined is CHECKPOINT_IMMEDIATE, which disables delays between writes.
+ * examined is CHECKPOINT_FAST, which disables delays between writes.
  *
  * 'progress' is an estimate of how much of the work has been done, as a
  * fraction between 0.0 meaning none, and 1.0 meaning all done.
@@ -778,10 +778,10 @@ CheckpointWriteDelay(int flags, double progress)
 	 * Perform the usual duties and take a nap, unless we're behind schedule,
 	 * in which case we just try to catch up as quickly as possible.
 	 */
-	if (!(flags & CHECKPOINT_IMMEDIATE) &&
+	if (!(flags & CHECKPOINT_FAST) &&
 		!ShutdownXLOGPending &&
 		!ShutdownRequestPending &&
-		!ImmediateCheckpointRequested() &&
+		!FastCheckpointRequested() &&
 		IsCheckpointOnSchedule(progress))
 	{
 		if (ConfigReloadPending)
@@ -983,11 +983,11 @@ CheckpointerShmemInit(void)
  * flags is a bitwise OR of the following:
  *	CHECKPOINT_IS_SHUTDOWN: checkpoint is for database shutdown.
  *	CHECKPOINT_END_OF_RECOVERY: checkpoint is for end of WAL recovery.
- *	CHECKPOINT_IMMEDIATE: finish the checkpoint ASAP,
+ *	CHECKPOINT_FAST: finish the checkpoint ASAP,
  *		ignoring checkpoint_completion_target parameter.
  *	CHECKPOINT_FORCE: force a checkpoint even if no XLOG activity has occurred
  *		since the last one (implied by CHECKPOINT_IS_SHUTDOWN or
- *		CHECKPOINT_END_OF_RECOVERY).
+ *		CHECKPOINT_END_OF_RECOVERY, and the CHECKPOINT command).
  *	CHECKPOINT_WAIT: wait for completion before returning (otherwise,
  *		just signal checkpointer to do it, and return).
  *	CHECKPOINT_CAUSE_XLOG: checkpoint is requested due to xlog filling.
@@ -1009,7 +1009,7 @@ RequestCheckpoint(int flags)
 		 * There's no point in doing slow checkpoints in a standalone backend,
 		 * because there's no other backends the checkpoint could disrupt.
 		 */
-		CreateCheckPoint(flags | CHECKPOINT_IMMEDIATE);
+		CreateCheckPoint(flags | CHECKPOINT_FAST);
 
 		/* Free all smgr objects, as CheckpointerMain() normally would. */
 		smgrdestroyall();

src/backend/storage/buffer/bufmgr.c

@@ -3339,8 +3339,8 @@ UnpinBufferNoOwner(BufferDesc *buf)
  * BufferSync -- Write out all dirty buffers in the pool.
  *
  * This is called at checkpoint time to write out all dirty shared buffers.
- * The checkpoint request flags should be passed in.  If CHECKPOINT_IMMEDIATE
+ * The checkpoint request flags should be passed in.  If CHECKPOINT_FAST is
- * is set, we disable delays between writes; if CHECKPOINT_IS_SHUTDOWN,
+ * set, we disable delays between writes; if CHECKPOINT_IS_SHUTDOWN,
  * CHECKPOINT_END_OF_RECOVERY or CHECKPOINT_FLUSH_UNLOGGED is set, we write
  * even unlogged buffers, which are otherwise skipped.  The remaining flags
  * currently have no effect here.

src/backend/tcop/utility.c

@@ -952,7 +952,7 @@ standard_ProcessUtility(PlannedStmt *pstmt,
 						 errdetail("Only roles with privileges of the \"%s\" role may execute this command.",
 								   "pg_checkpoint")));
 
-			RequestCheckpoint(CHECKPOINT_IMMEDIATE | CHECKPOINT_WAIT |
+			RequestCheckpoint(CHECKPOINT_FAST | CHECKPOINT_WAIT |
 							  (RecoveryInProgress() ? 0 : CHECKPOINT_FORCE));
 			break;
 

src/include/access/xlog.h

@@ -139,7 +139,7 @@ extern PGDLLIMPORT bool XLOG_DEBUG;
 #define CHECKPOINT_IS_SHUTDOWN	0x0001	/* Checkpoint is for shutdown */
 #define CHECKPOINT_END_OF_RECOVERY	0x0002	/* Like shutdown checkpoint, but
 											 * issued at end of WAL recovery */
-#define CHECKPOINT_IMMEDIATE	0x0004	/* Do it without delays */
+#define CHECKPOINT_FAST			0x0004	/* Do it without delays */
 #define CHECKPOINT_FORCE		0x0008	/* Force even if no activity */
 #define CHECKPOINT_FLUSH_UNLOGGED	0x0010	/* Flush unlogged tables */
 /* These are important to RequestCheckpoint */

src/test/recovery/t/041_checkpoint_at_promote.pl

@@ -91,7 +91,7 @@ $node_standby->wait_for_event('checkpointer', 'create-restart-point');
 # Check the logs that the restart point has started on standby.  This is
 # optional, but let's be sure.
 ok( $node_standby->log_contains(
-		"restartpoint starting: immediate wait", $logstart),
+		"restartpoint starting: fast wait", $logstart),
 	"restartpoint has started");
 
 # Trigger promotion during the restart point.