Using base backup exclusion filters to reduce data transferred with pg_rewind

From 6698d430ffb6bd2e33aba0b21dc2a9358cf6328c Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Mon, 5 Feb 2018 13:03:38 +0900
Subject: [PATCH 1/5] Refactor path definitions into a single header file,
 pg_paths.h

The definition of all internal paths of PostgreSQL are spread across the
code base, making tracing of those definitions difficult to begin with,
and resulting in a lot of code paths to be hardcoded.  While this has no
real practical consequences in practice, this makes the creation of
lists manipulating those paths less maintainable as as things stand the
already-hardcoded paths need to be copied around more.  In order to
improve things for the long-term, move all those definitions into a
single header file.

This commit does a first step by switching basebackup.c and initdb.c to
use them.  An upcoming commit will make all the definitions across the
code base use this new header more consistently.
---
 src/backend/postmaster/postmaster.c  |   1 +
 src/backend/postmaster/syslogger.c   |   1 +
 src/backend/replication/basebackup.c |  16 ++--
 src/backend/storage/ipc/dsm.c        |   1 +
 src/backend/storage/ipc/dsm_impl.c   |   1 +
 src/backend/storage/lmgr/predicate.c |   3 +-
 src/backend/utils/adt/misc.c         |   1 +
 src/bin/initdb/initdb.c              |  45 ++++++------
 src/include/access/xlog_internal.h   |   7 +-
 src/include/pg_paths.h               | 137 +++++++++++++++++++++++++++++++++++
 src/include/pgstat.h                 |   3 -
 src/include/postmaster/syslogger.h   |   7 --
 src/include/storage/dsm_impl.h       |   9 ---
 src/include/utils/guc.h              |   7 --
 14 files changed, 176 insertions(+), 63 deletions(-)
 create mode 100644 src/include/pg_paths.h

diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index f3ddf828bb..66d80914a0 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -105,6 +105,7 @@
 #include "libpq/pqsignal.h"
 #include "miscadmin.h"
 #include "pg_getopt.h"
+#include "pg_paths.h"
 #include "pgstat.h"
 #include "port/pg_bswap.h"
 #include "postmaster/autovacuum.h"
diff --git a/src/backend/postmaster/syslogger.c b/src/backend/postmaster/syslogger.c
index f70eea37df..c8770f6c61 100644
--- a/src/backend/postmaster/syslogger.c
+++ b/src/backend/postmaster/syslogger.c
@@ -35,6 +35,7 @@
 #include "libpq/pqsignal.h"
 #include "miscadmin.h"
 #include "nodes/pg_list.h"
+#include "pg_paths.h"
 #include "pgstat.h"
 #include "pgtime.h"
 #include "postmaster/fork_process.h"
diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c
index dd7ad64862..63ab81f837 100644
--- a/src/backend/replication/basebackup.c
+++ b/src/backend/replication/basebackup.c
@@ -117,25 +117,25 @@ static const char *excludeDirContents[] =
 	 * even if the intention is to restore to another master. See backup.sgml
 	 * for a more detailed description.
 	 */
-	"pg_replslot",
+	PG_REPLSLOT_DIR,
 
 	/* Contents removed on startup, see dsm_cleanup_for_mmap(). */
 	PG_DYNSHMEM_DIR,
 
 	/* Contents removed on startup, see AsyncShmemInit(). */
-	"pg_notify",
+	PG_NOTIFY_DIR,
 
 	/*
 	 * Old contents are loaded for possible debugging but are not required for
 	 * normal operation, see OldSerXidInit().
 	 */
-	"pg_serial",
+	PG_SERIAL_DIR,
 
 	/* Contents removed on startup, see DeleteAllExportedSnapshotFiles(). */
-	"pg_snapshots",
+	PG_SNAPSHOTS_DIR,
 
 	/* Contents zeroed on startup, see StartupSUBTRANS(). */
-	"pg_subtrans",
+	PG_SUBTRANS_DIR,
 
 	/* end of list */
 	NULL
@@ -147,7 +147,7 @@ static const char *excludeDirContents[] =
 static const char *excludeFiles[] =
 {
 	/* Skip auto conf temporary file. */
-	PG_AUTOCONF_FILENAME ".tmp",
+	PG_AUTOCONF_FILENAME_TMP,
 
 	/* Skip current log file temporary file */
 	LOG_METAINFO_DATAFILE_TMP,
@@ -164,8 +164,8 @@ static const char *excludeFiles[] =
 	BACKUP_LABEL_FILE,
 	TABLESPACE_MAP,
 
-	"postmaster.pid",
-	"postmaster.opts",
+	POSTMASTER_PID_FILE,
+	POSTMASTER_OPTS_FILE,
 
 	/* end of list */
 	NULL
diff --git a/src/backend/storage/ipc/dsm.c b/src/backend/storage/ipc/dsm.c
index f1f75b73f5..a0d69aa0d8 100644
--- a/src/backend/storage/ipc/dsm.c
+++ b/src/backend/storage/ipc/dsm.c
@@ -35,6 +35,7 @@
 
 #include "lib/ilist.h"
 #include "miscadmin.h"
+#include "pg_paths.h"
 #include "storage/dsm.h"
 #include "storage/ipc.h"
 #include "storage/lwlock.h"
diff --git a/src/backend/storage/ipc/dsm_impl.c b/src/backend/storage/ipc/dsm_impl.c
index 67e76b98fe..a2bb1e2288 100644
--- a/src/backend/storage/ipc/dsm_impl.c
+++ b/src/backend/storage/ipc/dsm_impl.c
@@ -62,6 +62,7 @@
 #endif
 #include "pgstat.h"
 
+#include "pg_paths.h"
 #include "portability/mem.h"
 #include "storage/dsm_impl.h"
 #include "storage/fd.h"
diff --git a/src/backend/storage/lmgr/predicate.c b/src/backend/storage/lmgr/predicate.c
index d1ff2b1edc..731ed66251 100644
--- a/src/backend/storage/lmgr/predicate.c
+++ b/src/backend/storage/lmgr/predicate.c
@@ -194,6 +194,7 @@
 #include "access/xact.h"
 #include "access/xlog.h"
 #include "miscadmin.h"
+#include "pg_paths.h"
 #include "pgstat.h"
 #include "storage/bufmgr.h"
 #include "storage/predicate.h"
@@ -806,7 +807,7 @@ OldSerXidInit(void)
 	 */
 	OldSerXidSlruCtl->PagePrecedes = OldSerXidPagePrecedesLogically;
 	SimpleLruInit(OldSerXidSlruCtl, "oldserxid",
-				  NUM_OLDSERXID_BUFFERS, 0, OldSerXidLock, "pg_serial",
+				  NUM_OLDSERXID_BUFFERS, 0, OldSerXidLock, PG_SERIAL_DIR,
 				  LWTRANCHE_OLDSERXID_BUFFERS);
 	/* Override default assumption that writes should be fsync'd */
 	OldSerXidSlruCtl->do_fsync = false;
diff --git a/src/backend/utils/adt/misc.c b/src/backend/utils/adt/misc.c
index 2e1e020c4b..9f98c03173 100644
--- a/src/backend/utils/adt/misc.c
+++ b/src/backend/utils/adt/misc.c
@@ -30,6 +30,7 @@
 #include "common/keywords.h"
 #include "funcapi.h"
 #include "miscadmin.h"
+#include "pg_paths.h"
 #include "pgstat.h"
 #include "parser/scansup.h"
 #include "postmaster/syslogger.h"
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index 2efd3b75b1..528fdf7f57 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -72,6 +72,7 @@
 #include "getopt_long.h"
 #include "mb/pg_wchar.h"
 #include "miscadmin.h"
+#include "pg_paths.h"
 
 
 /* Ideally this would be in a .h file, but it hardly seems worth the trouble */
@@ -199,28 +200,28 @@ static const char *boot_options = "-F";
 static const char *backend_options = "--single -F -O -j -c search_path=pg_catalog -c exit_on_error=true";
 
 static const char *const subdirs[] = {
-	"global",
-	"pg_wal/archive_status",
-	"pg_commit_ts",
-	"pg_dynshmem",
-	"pg_notify",
-	"pg_serial",
-	"pg_snapshots",
-	"pg_subtrans",
-	"pg_twophase",
-	"pg_multixact",
-	"pg_multixact/members",
-	"pg_multixact/offsets",
-	"base",
-	"base/1",
-	"pg_replslot",
-	"pg_tblspc",
-	"pg_stat",
-	"pg_stat_tmp",
-	"pg_xact",
-	"pg_logical",
-	"pg_logical/snapshots",
-	"pg_logical/mappings"
+	PG_GLOBAL_DIR,
+	XLOG_ARCHIVE_STATUS_DIR,
+	PG_COMMIT_TS_DIR,
+	PG_DYNSHMEM_DIR,
+	PG_NOTIFY_DIR,
+	PG_SERIAL_DIR,
+	PG_SNAPSHOTS_DIR,
+	PG_SUBTRANS_DIR,
+	PG_TWOPHASE_DIR,
+	PG_MULTIXACT_DIR,
+	PG_MULTIXACT_MEMBERS_DIR,
+	PG_MULTIXACT_OFFSETS_DIR,
+	PG_BASE_DIR,
+	PG_BASE_DIR "/1",
+	PG_REPLSLOT_DIR,
+	PG_TABLESPACE_DIR,
+	PG_STAT_DIR,
+	PG_STAT_TMP_DIR,
+	PG_XACT_DIR,
+	PG_LOGICAL_DIR,
+	PG_LOGICAL_SNAPSHOTS_DIR,
+	PG_LOGICAL_MAPPINGS_DIR
 };
 
 
diff --git a/src/include/access/xlog_internal.h b/src/include/access/xlog_internal.h
index a5c074642f..4ab8be61b5 100644
--- a/src/include/access/xlog_internal.h
+++ b/src/include/access/xlog_internal.h
@@ -23,6 +23,7 @@
 #include "access/xlogreader.h"
 #include "datatype/timestamp.h"
 #include "lib/stringinfo.h"
+#include "pg_paths.h"
 #include "pgtime.h"
 #include "storage/block.h"
 #include "storage/relfilenode.h"
@@ -137,12 +138,6 @@ typedef XLogLongPageHeaderData *XLogLongPageHeader;
 #define XRecOffIsValid(xlrp) \
 		((xlrp) % XLOG_BLCKSZ >= SizeOfXLogShortPHD)
 
-/*
- * The XLog directory and control file (relative to $PGDATA)
- */
-#define XLOGDIR				"pg_wal"
-#define XLOG_CONTROL_FILE	"global/pg_control"
-
 /*
  * These macros encapsulate knowledge about the exact layout of XLog file
  * names, timeline history file names, and archive-status file names.
diff --git a/src/include/pg_paths.h b/src/include/pg_paths.h
new file mode 100644
index 0000000000..a4746e75e4
--- /dev/null
+++ b/src/include/pg_paths.h
@@ -0,0 +1,137 @@
+/* ----------
+ *  pg_paths.h
+ *
+ *  Definitions for paths internal to PostgreSQL instances.  This can
+ *	be used by both frontend and backend.
+ *
+ *  Copyright (c) 2018, PostgreSQL Global Development Group
+ *
+ *  src/include/pg_paths.h
+ * ----------
+ */
+
+#ifndef PG_PATHS_H
+#define PG_PATHS_H
+
+/*
+ * Name of files saving meta-data information about the log
+ * files currently in use by the syslogger
+ */
+#define LOG_METAINFO_DATAFILE			"current_logfiles"
+#define LOG_METAINFO_DATAFILE_TMP		LOG_METAINFO_DATAFILE ".tmp"
+
+/*
+ * A file recording the command-line options the server was
+ * last started with.
+ */
+#define POSTMASTER_OPTS_FILE			"postmaster.opts"
+
+/*
+ * Lock file recording data about the current postmaster process, like
+ * its PID.
+ */
+#define POSTMASTER_PID_FILE				"postmaster.pid"
+
+/*
+ * Automatic configuration file name for ALTER SYSTEM.
+ * This file will be used to store values of configuration parameters
+ * set by ALTER SYSTEM command.
+ */
+#define PG_AUTOCONF_FILENAME			"postgresql.auto.conf"
+#define PG_AUTOCONF_FILENAME_TMP		PG_AUTOCONF_FILENAME ".tmp"
+
+/*
+ * Directory containing transaction commit timestamp data.
+ */
+#define PG_COMMIT_TS_DIR	"pg_commit_ts"
+
+/*
+ * Directory for on-disk state of dynamic shared memory segments.
+ *
+ * This is used by all implementations for crash recovery and by the mmap
+ * implementation for storage.
+ */
+#define PG_DYNSHMEM_DIR					"pg_dynshmem"
+#define PG_DYNSHMEM_MMAP_FILE_PREFIX	"mmap."
+
+/*
+ * Directory containing cluster-wide tables.
+ */
+#define PG_GLOBAL_DIR		"global"
+
+/*
+ * Directory containing per-database subdirectories
+ */
+#define PG_BASE_DIR			"base"
+
+/*
+ * WAL directory, archive status directory and control file.
+ */
+#define XLOGDIR					"pg_wal"
+#define XLOG_ARCHIVE_STATUS_DIR	XLOGDIR "/archive_status"
+#define XLOG_CONTROL_FILE		PG_GLOBAL_DIR "/pg_control"
+
+/*
+ * Directory containing status data for logical decoding.
+ */
+#define PG_LOGICAL_DIR				"pg_logical"
+#define PG_LOGICAL_MAPPINGS_DIR		PG_LOGICAL_DIR "/mappings"
+#define PG_LOGICAL_SNAPSHOTS_DIR	PG_LOGICAL_DIR "/snapshots"
+
+/*
+ * Directories containing multitransaction status data (used for shared
+ * row locks).
+ */
+#define PG_MULTIXACT_DIR			"pg_multixact"
+#define PG_MULTIXACT_MEMBERS_DIR    PG_MULTIXACT_DIR "/members"
+#define PG_MULTIXACT_OFFSETS_DIR    PG_MULTIXACT_DIR "/offsets"
+
+/*
+ * Directory containing LISTEN/NOTIFY status data.
+ */
+#define PG_NOTIFY_DIR		"pg_notify"
+
+/*
+ * Directory containing replication slot data.
+ */
+#define PG_REPLSLOT_DIR		"pg_replslot"
+
+/*
+ * Default directories to store permanent and temporary statistics
+ * data in.  Used by the statistics collector.
+ */
+#define PG_STAT_DIR			"pg_stat"
+#define PG_STAT_TMP_DIR		"pg_stat_tmp"
+
+/*
+ * Directory containing information about committed serializable
+ * transactions.
+ */
+#define PG_SERIAL_DIR		"pg_serial"
+
+/*
+ * Directory containing exported snapshots dara.
+ */
+#define PG_SNAPSHOTS_DIR	"pg_snapshots"
+
+/*
+ * Directory containing subtransaction status data.
+ */
+#define PG_SUBTRANS_DIR		"pg_subtrans"
+
+/*
+ * Directory containing symbolic links to tablespaces.
+ */
+#define PG_TABLESPACE_DIR	"pg_tblspc"
+
+/*
+ * Directory containing state files for prepared transactions.
+ */
+#define PG_TWOPHASE_DIR		"pg_twophase"
+
+/*
+ * Directory containing transaction commit status data.
+ */
+#define PG_XACT_DIR			"pg_xact"
+
+#endif							/* PG_PATHS_H */
diff --git a/src/include/pgstat.h b/src/include/pgstat.h
index be2f59239b..7ae4b9097e 100644
--- a/src/include/pgstat.h
+++ b/src/include/pgstat.h
@@ -30,9 +30,6 @@
 #define PGSTAT_STAT_PERMANENT_FILENAME		"pg_stat/global.stat"
 #define PGSTAT_STAT_PERMANENT_TMPFILE		"pg_stat/global.tmp"
 
-/* Default directory to store temporary statistics data in */
-#define PG_STAT_TMP_DIR		"pg_stat_tmp"
-
 /* Values for track_functions GUC variable --- order is significant! */
 typedef enum TrackFunctionsLevel
 {
diff --git a/src/include/postmaster/syslogger.h b/src/include/postmaster/syslogger.h
index b35fadc1bd..00cc7a3023 100644
--- a/src/include/postmaster/syslogger.h
+++ b/src/include/postmaster/syslogger.h
@@ -87,11 +87,4 @@ extern void write_syslogger_file(const char *buffer, int count, int dest);
 extern void SysLoggerMain(int argc, char *argv[]) pg_attribute_noreturn();
 #endif
 
-/*
- * Name of files saving meta-data information about the log
- * files currently in use by the syslogger
- */
-#define LOG_METAINFO_DATAFILE  "current_logfiles"
-#define LOG_METAINFO_DATAFILE_TMP  LOG_METAINFO_DATAFILE ".tmp"
-
 #endif							/* _SYSLOGGER_H */
diff --git a/src/include/storage/dsm_impl.h b/src/include/storage/dsm_impl.h
index 0e5730f7c5..f13b46b6c3 100644
--- a/src/include/storage/dsm_impl.h
+++ b/src/include/storage/dsm_impl.h
@@ -42,15 +42,6 @@
 /* GUC. */
 extern int	dynamic_shared_memory_type;
 
-/*
- * Directory for on-disk state.
- *
- * This is used by all implementations for crash recovery and by the mmap
- * implementation for storage.
- */
-#define PG_DYNSHMEM_DIR					"pg_dynshmem"
-#define PG_DYNSHMEM_MMAP_FILE_PREFIX	"mmap."
-
 /* A "name" for a dynamic shared memory segment. */
 typedef uint32 dsm_handle;
 
diff --git a/src/include/utils/guc.h b/src/include/utils/guc.h
index 77daa5a539..8bb5ba9198 100644
--- a/src/include/utils/guc.h
+++ b/src/include/utils/guc.h
@@ -26,13 +26,6 @@
 #define MAX_KILOBYTES	(INT_MAX / 1024)
 #endif
 
-/*
- * Automatic configuration file name for ALTER SYSTEM.
- * This file will be used to store values of configuration parameters
- * set by ALTER SYSTEM command.
- */
-#define PG_AUTOCONF_FILENAME		"postgresql.auto.conf"
-
 /*
  * Certain options can only be set at certain times. The rules are
  * like this:
-- 
2.16.1

commit 6ce93994d1d70d80431115473933fd70ea882a5c
Author: Anastasia <a.lubennikova@postgrespro.ru>
Date:   Tue Mar 13 12:20:54 2018 +0300

Subject: [PATCH 2/5] Replace all system paths hardcoded with data from
 pg_paths.h

This unifies the interface where system paths are defined and located,
making it easier to use such paths in frontend tools which aim at
manipulating them or a list of them.

An upcoming patch will externalize the list of paths used by base
backups for the exclude lists, which will then be used by pg_rewind to
do the same.

diff --git a/contrib/pg_stat_statements/pg_stat_statements.c b/contrib/pg_stat_statements/pg_stat_statements.c
index 9286734..e251a3e 100644
--- a/contrib/pg_stat_statements/pg_stat_statements.c
+++ b/contrib/pg_stat_statements/pg_stat_statements.c
@@ -71,6 +71,7 @@
 #include "parser/parsetree.h"
 #include "parser/scanner.h"
 #include "parser/scansup.h"
+#include "pg_paths.h"
 #include "pgstat.h"
 #include "storage/fd.h"
 #include "storage/ipc.h"
diff --git a/src/backend/access/heap/rewriteheap.c b/src/backend/access/heap/rewriteheap.c
index 7d466c2..dd3657f 100644
--- a/src/backend/access/heap/rewriteheap.c
+++ b/src/backend/access/heap/rewriteheap.c
@@ -119,6 +119,7 @@
 
 #include "lib/ilist.h"
 
+#include "pg_paths.h"
 #include "pgstat.h"
 
 #include "replication/logical.h"
@@ -1005,7 +1006,7 @@ logical_rewrite_log_mapping(RewriteState state, TransactionId xid,
 			dboid = MyDatabaseId;
 
 		snprintf(path, MAXPGPATH,
-				 "pg_logical/mappings/" LOGICAL_REWRITE_FORMAT,
+				 PG_LOGICAL_MAPPINGS_DIR "/" LOGICAL_REWRITE_FORMAT,
 				 dboid, relid,
 				 (uint32) (state->rs_begin_lsn >> 32),
 				 (uint32) state->rs_begin_lsn,
@@ -1128,7 +1129,7 @@ heap_xlog_logical_rewrite(XLogReaderState *r)
 	xlrec = (xl_heap_rewrite_mapping *) XLogRecGetData(r);
 
 	snprintf(path, MAXPGPATH,
-			 "pg_logical/mappings/" LOGICAL_REWRITE_FORMAT,
+			 PG_LOGICAL_MAPPINGS_DIR "/" LOGICAL_REWRITE_FORMAT,
 			 xlrec->mapped_db, xlrec->mapped_rel,
 			 (uint32) (xlrec->start_lsn >> 32),
 			 (uint32) xlrec->start_lsn,
@@ -1219,8 +1220,8 @@ CheckPointLogicalRewriteHeap(void)
 	if (cutoff != InvalidXLogRecPtr && redo < cutoff)
 		cutoff = redo;
 
-	mappings_dir = AllocateDir("pg_logical/mappings");
-	while ((mapping_de = ReadDir(mappings_dir, "pg_logical/mappings")) != NULL)
+	mappings_dir = AllocateDir(PG_LOGICAL_MAPPINGS_DIR);
+	while ((mapping_de = ReadDir(mappings_dir, PG_LOGICAL_MAPPINGS_DIR)) != NULL)
 	{
 		struct stat statbuf;
 		Oid			dboid;
@@ -1235,7 +1236,8 @@ CheckPointLogicalRewriteHeap(void)
 			strcmp(mapping_de->d_name, "..") == 0)
 			continue;
 
-		snprintf(path, sizeof(path), "pg_logical/mappings/%s", mapping_de->d_name);
+		snprintf(path, sizeof(path), "%s/%s", PG_LOGICAL_MAPPINGS_DIR,
+				 mapping_de->d_name);
 		if (lstat(path, &statbuf) == 0 && !S_ISREG(statbuf.st_mode))
 			continue;
 
diff --git a/src/backend/access/transam/clog.c b/src/backend/access/transam/clog.c
index 8b7ff5b..bf4db22 100644
--- a/src/backend/access/transam/clog.c
+++ b/src/backend/access/transam/clog.c
@@ -40,6 +40,7 @@
 #include "access/xlogutils.h"
 #include "miscadmin.h"
 #include "pgstat.h"
+#include "pg_paths.h"
 #include "pg_trace.h"
 #include "storage/proc.h"
 
@@ -699,7 +700,7 @@ CLOGShmemInit(void)
 {
 	ClogCtl->PagePrecedes = CLOGPagePrecedes;
 	SimpleLruInit(ClogCtl, "clog", CLOGShmemBuffers(), CLOG_LSNS_PER_PAGE,
-				  CLogControlLock, "pg_xact", LWTRANCHE_CLOG_BUFFERS);
+				  CLogControlLock, PG_XACT_DIR, LWTRANCHE_CLOG_BUFFERS);
 }
 
 /*
@@ -830,7 +831,7 @@ ShutdownCLOG(void)
 	 * fsync pg_xact to ensure that any files flushed previously are durably
 	 * on disk.
 	 */
-	fsync_fname("pg_xact", true);
+	fsync_fname(PG_XACT_DIR, true);
 
 	TRACE_POSTGRESQL_CLOG_CHECKPOINT_DONE(false);
 }
@@ -849,7 +850,7 @@ CheckPointCLOG(void)
 	 * fsync pg_xact to ensure that any files flushed previously are durably
 	 * on disk.
 	 */
-	fsync_fname("pg_xact", true);
+	fsync_fname(PG_XACT_DIR, true);
 
 	TRACE_POSTGRESQL_CLOG_CHECKPOINT_DONE(true);
 }
diff --git a/src/backend/access/transam/commit_ts.c b/src/backend/access/transam/commit_ts.c
index 04a15e4..5d0e4d0 100644
--- a/src/backend/access/transam/commit_ts.c
+++ b/src/backend/access/transam/commit_ts.c
@@ -31,6 +31,7 @@
 #include "catalog/pg_type.h"
 #include "funcapi.h"
 #include "miscadmin.h"
+#include "pg_paths.h"
 #include "pg_trace.h"
 #include "storage/shmem.h"
 #include "utils/builtins.h"
@@ -493,7 +494,7 @@ CommitTsShmemInit(void)
 
 	CommitTsCtl->PagePrecedes = CommitTsPagePrecedes;
 	SimpleLruInit(CommitTsCtl, "commit_timestamp", CommitTsShmemBuffers(), 0,
-				  CommitTsControlLock, "pg_commit_ts",
+				  CommitTsControlLock, PG_COMMIT_TS_DIR,
 				  LWTRANCHE_COMMITTS_BUFFERS);
 
 	commitTsShared = ShmemInitStruct("CommitTs shared",
@@ -751,7 +752,7 @@ ShutdownCommitTs(void)
 	 * fsync pg_commit_ts to ensure that any files flushed previously are
 	 * durably on disk.
 	 */
-	fsync_fname("pg_commit_ts", true);
+	fsync_fname(PG_COMMIT_TS_DIR, true);
 }
 
 /*
@@ -767,7 +768,7 @@ CheckPointCommitTs(void)
 	 * fsync pg_commit_ts to ensure that any files flushed previously are
 	 * durably on disk.
 	 */
-	fsync_fname("pg_commit_ts", true);
+	fsync_fname(PG_COMMIT_TS_DIR, true);
 }
 
 /*
diff --git a/src/backend/access/transam/multixact.c b/src/backend/access/transam/multixact.c
index 6d6f2e3..a158b49 100644
--- a/src/backend/access/transam/multixact.c
+++ b/src/backend/access/transam/multixact.c
@@ -81,6 +81,7 @@
 #include "funcapi.h"
 #include "lib/ilist.h"
 #include "miscadmin.h"
+#include "pg_paths.h"
 #include "pg_trace.h"
 #include "postmaster/autovacuum.h"
 #include "storage/lmgr.h"
@@ -1828,11 +1829,11 @@ MultiXactShmemInit(void)
 
 	SimpleLruInit(MultiXactOffsetCtl,
 				  "multixact_offset", NUM_MXACTOFFSET_BUFFERS, 0,
-				  MultiXactOffsetControlLock, "pg_multixact/offsets",
+				  MultiXactOffsetControlLock, PG_MULTIXACT_OFFSETS_DIR,
 				  LWTRANCHE_MXACTOFFSET_BUFFERS);
 	SimpleLruInit(MultiXactMemberCtl,
 				  "multixact_member", NUM_MXACTMEMBER_BUFFERS, 0,
-				  MultiXactMemberControlLock, "pg_multixact/members",
+				  MultiXactMemberControlLock, PG_MULTIXACT_MEMBERS_DIR,
 				  LWTRANCHE_MXACTMEMBER_BUFFERS);
 
 	/* Initialize our shared state struct */
diff --git a/src/backend/access/transam/subtrans.c b/src/backend/access/transam/subtrans.c
index 4faa21f..977d052 100644
--- a/src/backend/access/transam/subtrans.c
+++ b/src/backend/access/transam/subtrans.c
@@ -31,6 +31,7 @@
 #include "access/slru.h"
 #include "access/subtrans.h"
 #include "access/transam.h"
+#include "pg_paths.h"
 #include "pg_trace.h"
 #include "utils/snapmgr.h"
 
@@ -192,7 +193,7 @@ SUBTRANSShmemInit(void)
 {
 	SubTransCtl->PagePrecedes = SubTransPagePrecedes;
 	SimpleLruInit(SubTransCtl, "subtrans", NUM_SUBTRANS_BUFFERS, 0,
-				  SubtransControlLock, "pg_subtrans",
+				  SubtransControlLock, PG_SUBTRANS_DIR,
 				  LWTRANCHE_SUBTRANS_BUFFERS);
 	/* Override default assumption that writes should be fsync'd */
 	SubTransCtl->do_fsync = false;
diff --git a/src/backend/access/transam/twophase.c b/src/backend/access/transam/twophase.c
index c479c48..89e8164 100644
--- a/src/backend/access/transam/twophase.c
+++ b/src/backend/access/transam/twophase.c
@@ -91,6 +91,7 @@
 #include "catalog/storage.h"
 #include "funcapi.h"
 #include "miscadmin.h"
+#include "pg_paths.h"
 #include "pg_trace.h"
 #include "pgstat.h"
 #include "replication/origin.h"
@@ -108,11 +109,6 @@
 #include "utils/timestamp.h"
 
 
-/*
- * Directory where Two-phase commit files reside within PGDATA
- */
-#define TWOPHASE_DIR "pg_twophase"
-
 /* GUC variable, can't be changed after startup */
 int			max_prepared_xacts = 0;
 
@@ -877,7 +873,7 @@ TwoPhaseGetDummyProc(TransactionId xid)
 /************************************************************************/
 
 #define TwoPhaseFilePath(path, xid) \
-	snprintf(path, MAXPGPATH, TWOPHASE_DIR "/%08X", xid)
+	snprintf(path, MAXPGPATH, PG_TWOPHASE_DIR "/%08X", xid)
 
 /*
  * 2PC state file format:
@@ -1707,7 +1703,7 @@ CheckPointTwoPhase(XLogRecPtr redo_horizon)
 	 * removals need to be made persistent as well as any files newly created
 	 * previously since the last checkpoint.
 	 */
-	fsync_fname(TWOPHASE_DIR, true);
+	fsync_fname(PG_TWOPHASE_DIR, true);
 
 	TRACE_POSTGRESQL_TWOPHASE_CHECKPOINT_DONE();
 
@@ -1736,8 +1732,8 @@ restoreTwoPhaseData(void)
 	struct dirent *clde;
 
 	LWLockAcquire(TwoPhaseStateLock, LW_EXCLUSIVE);
-	cldir = AllocateDir(TWOPHASE_DIR);
-	while ((clde = ReadDir(cldir, TWOPHASE_DIR)) != NULL)
+	cldir = AllocateDir(PG_TWOPHASE_DIR);
+	while ((clde = ReadDir(cldir, PG_TWOPHASE_DIR)) != NULL)
 	{
 		if (strlen(clde->d_name) == 8 &&
 			strspn(clde->d_name, "0123456789ABCDEF") == 8)
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 47a6c4d..0598212 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6481,7 +6481,7 @@ StartupXLOG(void)
 				tablespaceinfo *ti = lfirst(lc);
 				char	   *linkloc;
 
-				linkloc = psprintf("pg_tblspc/%s", ti->oid);
+				linkloc = psprintf(PG_TABLESPACE_DIR "/%s", ti->oid);
 
 				/*
 				 * Remove the existing symlink if any and Create the symlink
@@ -10426,8 +10426,8 @@ do_pg_start_backup(const char *backupidstr, bool fast, TimeLineID *starttli_p,
 		datadirpathlen = strlen(DataDir);
 
 		/* Collect information about all tablespaces */
-		tblspcdir = AllocateDir("pg_tblspc");
-		while ((de = ReadDir(tblspcdir, "pg_tblspc")) != NULL)
+		tblspcdir = AllocateDir(PG_TABLESPACE_DIR);
+		while ((de = ReadDir(tblspcdir, PG_TABLESPACE_DIR)) != NULL)
 		{
 			char		fullpath[MAXPGPATH + 10];
 			char		linkpath[MAXPGPATH];
@@ -10440,7 +10440,8 @@ do_pg_start_backup(const char *backupidstr, bool fast, TimeLineID *starttli_p,
 			if (strcmp(de->d_name, ".") == 0 || strcmp(de->d_name, "..") == 0)
 				continue;
 
-			snprintf(fullpath, sizeof(fullpath), "pg_tblspc/%s", de->d_name);
+			snprintf(fullpath, sizeof(fullpath), PG_TABLESPACE_DIR "/%s",
+					 de->d_name);
 
 #if defined(HAVE_READLINK) || defined(WIN32)
 			rllen = readlink(fullpath, linkpath, sizeof(linkpath));
diff --git a/src/backend/commands/async.c b/src/backend/commands/async.c
index ee7c6d4..52bbb28 100644
--- a/src/backend/commands/async.c
+++ b/src/backend/commands/async.c
@@ -127,6 +127,7 @@
 #include "libpq/libpq.h"
 #include "libpq/pqformat.h"
 #include "miscadmin.h"
+#include "pg_paths.h"
 #include "storage/ipc.h"
 #include "storage/lmgr.h"
 #include "storage/proc.h"
@@ -480,7 +481,7 @@ AsyncShmemInit(void)
 	 */
 	AsyncCtl->PagePrecedes = asyncQueuePagePrecedes;
 	SimpleLruInit(AsyncCtl, "async", NUM_ASYNC_BUFFERS, 0,
-				  AsyncCtlLock, "pg_notify", LWTRANCHE_ASYNC_BUFFERS);
+				  AsyncCtlLock, PG_NOTIFY_DIR, LWTRANCHE_ASYNC_BUFFERS);
 	/* Override default assumption that writes should be fsync'd */
 	AsyncCtl->do_fsync = false;
 
diff --git a/src/backend/commands/tablespace.c b/src/backend/commands/tablespace.c
index 5c450ca..2894a62 100644
--- a/src/backend/commands/tablespace.c
+++ b/src/backend/commands/tablespace.c
@@ -69,6 +69,7 @@
 #include "commands/tablecmds.h"
 #include "commands/tablespace.h"
 #include "miscadmin.h"
+#include "pg_paths.h"
 #include "postmaster/bgwriter.h"
 #include "storage/fd.h"
 #include "storage/lmgr.h"
@@ -566,7 +567,7 @@ create_tablespace_directories(const char *location, const Oid tablespaceoid)
 	char	   *location_with_version_dir;
 	struct stat st;
 
-	linkloc = psprintf("pg_tblspc/%u", tablespaceoid);
+	linkloc = psprintf(PG_TABLESPACE_DIR "/%u", tablespaceoid);
 	location_with_version_dir = psprintf("%s/%s", location,
 										 TABLESPACE_VERSION_DIRECTORY);
 
@@ -667,7 +668,7 @@ destroy_tablespace_directories(Oid tablespaceoid, bool redo)
 	char	   *subfile;
 	struct stat st;
 
-	linkloc_with_version_dir = psprintf("pg_tblspc/%u/%s", tablespaceoid,
+	linkloc_with_version_dir = psprintf(PG_TABLESPACE_DIR "/%u/%s", tablespaceoid,
 										TABLESPACE_VERSION_DIRECTORY);
 
 	/*
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c
index 2093d87..e2d9d82 100644
--- a/src/backend/postmaster/postmaster.c
+++ b/src/backend/postmaster/postmaster.c
@@ -1546,7 +1546,7 @@ checkDataDir(void)
 	/* Look for PG_VERSION before looking for pg_control */
 	ValidatePgVersion(DataDir);
 
-	snprintf(path, sizeof(path), "%s/global/pg_control", DataDir);
+	snprintf(path, sizeof(path), "%s/%s", DataDir, XLOG_CONTROL_FILE);
 
 	fp = AllocateFile(path, PG_BINARY_R);
 	if (fp == NULL)
@@ -5538,11 +5538,9 @@ CreateOptsFile(int argc, char *argv[], char *fullprogname)
 	FILE	   *fp;
 	int			i;
 
-#define OPTS_FILE	"postmaster.opts"
-
-	if ((fp = fopen(OPTS_FILE, "w")) == NULL)
+	if ((fp = fopen(POSTMASTER_OPTS_FILE, "w")) == NULL)
 	{
-		elog(LOG, "could not create file \"%s\": %m", OPTS_FILE);
+		elog(LOG, "could not create file \"%s\": %m", POSTMASTER_OPTS_FILE);
 		return false;
 	}
 
@@ -5553,7 +5551,7 @@ CreateOptsFile(int argc, char *argv[], char *fullprogname)
 
 	if (fclose(fp))
 	{
-		elog(LOG, "could not write file \"%s\": %m", OPTS_FILE);
+		elog(LOG, "could not write file \"%s\": %m", POSTMASTER_OPTS_FILE);
 		return false;
 	}
 
diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c
index a23c999..a395175 100644
--- a/src/backend/replication/basebackup.c
+++ b/src/backend/replication/basebackup.c
@@ -366,8 +366,8 @@ perform_base_backup(basebackup_options *opt)
 		XLByteToPrevSeg(endptr, endsegno, wal_segment_size);
 		XLogFileName(lastoff, ThisTimeLineID, endsegno, wal_segment_size);
 
-		dir = AllocateDir("pg_wal");
-		while ((de = ReadDir(dir, "pg_wal")) != NULL)
+		dir = AllocateDir(XLOGDIR);
+		while ((de = ReadDir(dir, XLOGDIR)) != NULL)
 		{
 			/* Does it look like a WAL segment, and is it in the range? */
 			if (IsXLogFileName(de->d_name) &&
@@ -1010,7 +1010,7 @@ sendDir(const char *path, int basepathlen, bool sizeonly, List *tablespaces,
 		snprintf(pathbuf, sizeof(pathbuf), "%s/%s", path, de->d_name);
 
 		/* Skip pg_control here to back up it last */
-		if (strcmp(pathbuf, "./global/pg_control") == 0)
+		if (strcmp(pathbuf, "./" XLOG_CONTROL_FILE) == 0)
 			continue;
 
 		if (lstat(pathbuf, &statbuf) != 0)
@@ -1057,7 +1057,7 @@ sendDir(const char *path, int basepathlen, bool sizeonly, List *tablespaces,
 		 * WAL archive anyway. But include it as an empty directory anyway, so
 		 * we get permissions right.
 		 */
-		if (strcmp(pathbuf, "./pg_wal") == 0)
+		if (strcmp(pathbuf, "./" XLOGDIR) == 0)
 		{
 			/* If pg_wal is a symlink, write it as a directory anyway */
 			size += _tarWriteDir(pathbuf, basepathlen, &statbuf, sizeonly);
@@ -1066,14 +1066,14 @@ sendDir(const char *path, int basepathlen, bool sizeonly, List *tablespaces,
 			 * Also send archive_status directory (by hackishly reusing
 			 * statbuf from above ...).
 			 */
-			size += _tarWriteHeader("./pg_wal/archive_status", NULL, &statbuf,
+			size += _tarWriteHeader("./" XLOG_ARCHIVE_STATUS_DIR, NULL, &statbuf,
 									sizeonly);
 
 			continue;			/* don't recurse into pg_wal */
 		}
 
 		/* Allow symbolic links in pg_tblspc only */
-		if (strcmp(path, "./pg_tblspc") == 0 &&
+		if (strcmp(path, "./" PG_TABLESPACE_DIR) == 0 &&
 #ifndef WIN32
 			S_ISLNK(statbuf.st_mode)
 #else
@@ -1150,7 +1150,7 @@ sendDir(const char *path, int basepathlen, bool sizeonly, List *tablespaces,
 			/*
 			 * skip sending directories inside pg_tblspc, if not required.
 			 */
-			if (strcmp(pathbuf, "./pg_tblspc") == 0 && !sendtblspclinks)
+			if (strcmp(pathbuf, "./" PG_TABLESPACE_DIR) == 0 && !sendtblspclinks)
 				skip_this_dir = true;
 
 			if (!skip_this_dir)
diff --git a/src/backend/replication/logical/origin.c b/src/backend/replication/logical/origin.c
index 963878a..e2a2a3b 100644
--- a/src/backend/replication/logical/origin.c
+++ b/src/backend/replication/logical/origin.c
@@ -83,6 +83,7 @@
 
 #include "replication/origin.h"
 #include "replication/logical.h"
+#include "pg_paths.h"
 #include "pgstat.h"
 #include "storage/fd.h"
 #include "storage/ipc.h"
@@ -544,8 +545,8 @@ ReplicationOriginShmemInit(void)
 void
 CheckPointReplicationOrigin(void)
 {
-	const char *tmppath = "pg_logical/replorigin_checkpoint.tmp";
-	const char *path = "pg_logical/replorigin_checkpoint";
+	const char *tmppath = PG_LOGICAL_DIR "/replorigin_checkpoint.tmp";
+	const char *path = PG_LOGICAL_DIR "/replorigin_checkpoint";
 	int			tmpfd;
 	int			i;
 	uint32		magic = REPLICATION_STATE_MAGIC;
@@ -657,7 +658,7 @@ CheckPointReplicationOrigin(void)
 void
 StartupReplicationOrigin(void)
 {
-	const char *path = "pg_logical/replorigin_checkpoint";
+	const char *path = PG_LOGICAL_DIR "/replorigin_checkpoint";
 	int			fd;
 	int			readBytes;
 	uint32		magic = REPLICATION_STATE_MAGIC;
diff --git a/src/backend/replication/logical/reorderbuffer.c b/src/backend/replication/logical/reorderbuffer.c
index 7612cf5..8713a44 100644
--- a/src/backend/replication/logical/reorderbuffer.c
+++ b/src/backend/replication/logical/reorderbuffer.c
@@ -2581,7 +2581,7 @@ ReorderBufferCleanupSerializedTXNs(const char *slotname)
 	struct stat statbuf;
 	char		path[MAXPGPATH * 2 + 12];
 
-	sprintf(path, "pg_replslot/%s", slotname);
+	sprintf(path, "%s/%s", PG_REPLSLOT_DIR, slotname);
 
 	/* we're only handling directories here, skip if it's not ours */
 	if (lstat(path, &statbuf) == 0 && !S_ISDIR(statbuf.st_mode))
@@ -2594,14 +2594,14 @@ ReorderBufferCleanupSerializedTXNs(const char *slotname)
 		if (strncmp(spill_de->d_name, "xid", 3) == 0)
 		{
 			snprintf(path, sizeof(path),
-					 "pg_replslot/%s/%s", slotname,
+					 "%s/%s/%s",PG_REPLSLOT_DIR, slotname,
 					 spill_de->d_name);
 
 			if (unlink(path) != 0)
 				ereport(ERROR,
 						(errcode_for_file_access(),
-						 errmsg("could not remove file \"%s\" during removal of pg_replslot/%s/*.xid: %m",
-								path, slotname)));
+						 errmsg("could not remove file \"%s\" during removal of %s/%s/*.xid: %m",
+								PG_REPLSLOT_DIR, path, slotname)));
 		}
 	}
 	FreeDir(spill_dir);
@@ -2620,8 +2620,8 @@ ReorderBufferSerializedPath(char *path, ReplicationSlot *slot, TransactionId xid
 
 	XLogSegNoOffsetToRecPtr(segno, 0, recptr, wal_segment_size);
 
-	snprintf(path, MAXPGPATH, "pg_replslot/%s/xid-%u-lsn-%X-%X.snap",
-			NameStr(MyReplicationSlot->data.name),
+	snprintf(path, MAXPGPATH, "%s/%s/xid-%u-lsn-%X-%X.snap",
+			PG_REPLSLOT_DIR, NameStr(MyReplicationSlot->data.name),
 			xid,
 			(uint32) (recptr >> 32), (uint32) recptr);
 }
@@ -2636,8 +2636,8 @@ StartupReorderBuffer(void)
 	DIR		   *logical_dir;
 	struct dirent *logical_de;
 
-	logical_dir = AllocateDir("pg_replslot");
-	while ((logical_de = ReadDir(logical_dir, "pg_replslot")) != NULL)
+	logical_dir = AllocateDir(PG_REPLSLOT_DIR);
+	while ((logical_de = ReadDir(logical_dir, PG_REPLSLOT_DIR)) != NULL)
 	{
 		if (strcmp(logical_de->d_name, ".") == 0 ||
 			strcmp(logical_de->d_name, "..") == 0)
@@ -3034,7 +3034,7 @@ ApplyLogicalMappingFile(HTAB *tuplecid_data, Oid relid, const char *fname)
 	int			readBytes;
 	LogicalRewriteMappingData map;
 
-	sprintf(path, "pg_logical/mappings/%s", fname);
+	sprintf(path, "%s/%s", PG_LOGICAL_MAPPINGS_DIR, fname);
 	fd = OpenTransientFile(path, O_RDONLY | PG_BINARY);
 	if (fd < 0)
 		ereport(ERROR,
@@ -3157,8 +3157,8 @@ UpdateLogicalMappings(HTAB *tuplecid_data, Oid relid, Snapshot snapshot)
 	size_t		off;
 	Oid			dboid = IsSharedRelation(relid) ? InvalidOid : MyDatabaseId;
 
-	mapping_dir = AllocateDir("pg_logical/mappings");
-	while ((mapping_de = ReadDir(mapping_dir, "pg_logical/mappings")) != NULL)
+	mapping_dir = AllocateDir(PG_LOGICAL_MAPPINGS_DIR);
+	while ((mapping_de = ReadDir(mapping_dir, PG_LOGICAL_MAPPINGS_DIR)) != NULL)
 	{
 		Oid			f_dboid;
 		Oid			f_relid;
diff --git a/src/backend/replication/logical/snapbuild.c b/src/backend/replication/logical/snapbuild.c
index 4123cde..bc91330 100644
--- a/src/backend/replication/logical/snapbuild.c
+++ b/src/backend/replication/logical/snapbuild.c
@@ -126,6 +126,7 @@
 #include "access/transam.h"
 #include "access/xact.h"
 
+#include "pg_paths.h"
 #include "pgstat.h"
 
 #include "replication/logical.h"
@@ -1503,7 +1504,8 @@ SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn)
 	 * unless the user used pg_resetwal or similar. If a user did so, there's
 	 * no hope continuing to decode anyway.
 	 */
-	sprintf(path, "pg_logical/snapshots/%X-%X.snap",
+	sprintf(path, "%s/%X-%X.snap",
+			PG_LOGICAL_SNAPSHOTS_DIR,
 			(uint32) (lsn >> 32), (uint32) lsn);
 
 	/*
@@ -1529,7 +1531,7 @@ SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn)
 		 * be safely on disk.
 		 */
 		fsync_fname(path, false);
-		fsync_fname("pg_logical/snapshots", true);
+		fsync_fname(PG_LOGICAL_SNAPSHOTS_DIR, true);
 
 		builder->last_serialized_snapshot = lsn;
 		goto out;
@@ -1545,7 +1547,8 @@ SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn)
 	elog(DEBUG1, "serializing snapshot to %s", path);
 
 	/* to make sure only we will write to this tempfile, include pid */
-	sprintf(tmppath, "pg_logical/snapshots/%X-%X.snap.%u.tmp",
+	sprintf(tmppath, "%s/%X-%X.snap.%u.tmp",
+			PG_LOGICAL_SNAPSHOTS_DIR,
 			(uint32) (lsn >> 32), (uint32) lsn, MyProcPid);
 
 	/*
@@ -1631,7 +1634,7 @@ SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn)
 	pgstat_report_wait_end();
 	CloseTransientFile(fd);
 
-	fsync_fname("pg_logical/snapshots", true);
+	fsync_fname(PG_LOGICAL_SNAPSHOTS_DIR, true);
 
 	/*
 	 * We may overwrite the work from some other backend, but that's ok, our
@@ -1647,7 +1650,7 @@ SnapBuildSerialize(SnapBuild *builder, XLogRecPtr lsn)
 
 	/* make sure we persist */
 	fsync_fname(path, false);
-	fsync_fname("pg_logical/snapshots", true);
+	fsync_fname(PG_LOGICAL_SNAPSHOTS_DIR, true);
 
 	/*
 	 * Now there's no way we can loose the dumped state anymore, remember this
@@ -1678,7 +1681,8 @@ SnapBuildRestore(SnapBuild *builder, XLogRecPtr lsn)
 	if (builder->state == SNAPBUILD_CONSISTENT)
 		return false;
 
-	sprintf(path, "pg_logical/snapshots/%X-%X.snap",
+	sprintf(path, "%s/%X-%X.snap",
+			PG_LOGICAL_SNAPSHOTS_DIR,
 			(uint32) (lsn >> 32), (uint32) lsn);
 
 	fd = OpenTransientFile(path, O_RDONLY | PG_BINARY);
@@ -1699,7 +1703,7 @@ SnapBuildRestore(SnapBuild *builder, XLogRecPtr lsn)
 	 * ----
 	 */
 	fsync_fname(path, false);
-	fsync_fname("pg_logical/snapshots", true);
+	fsync_fname(PG_LOGICAL_SNAPSHOTS_DIR, true);
 
 
 	/* read statically sized portion of snapshot */
@@ -1880,8 +1884,8 @@ CheckPointSnapBuild(void)
 	if (redo < cutoff)
 		cutoff = redo;
 
-	snap_dir = AllocateDir("pg_logical/snapshots");
-	while ((snap_de = ReadDir(snap_dir, "pg_logical/snapshots")) != NULL)
+	snap_dir = AllocateDir(PG_LOGICAL_SNAPSHOTS_DIR);
+	while ((snap_de = ReadDir(snap_dir, PG_LOGICAL_SNAPSHOTS_DIR)) != NULL)
 	{
 		uint32		hi;
 		uint32		lo;
@@ -1892,7 +1896,8 @@ CheckPointSnapBuild(void)
 			strcmp(snap_de->d_name, "..") == 0)
 			continue;
 
-		snprintf(path, sizeof(path), "pg_logical/snapshots/%s", snap_de->d_name);
+		snprintf(path, sizeof(path), "%s/%s", PG_LOGICAL_SNAPSHOTS_DIR,
+				 snap_de->d_name);
 
 		if (lstat(path, &statbuf) == 0 && !S_ISREG(statbuf.st_mode))
 		{
diff --git a/src/backend/replication/slot.c b/src/backend/replication/slot.c
index fc9ef22..c64641a 100644
--- a/src/backend/replication/slot.c
+++ b/src/backend/replication/slot.c
@@ -549,8 +549,8 @@ ReplicationSlotDropPtr(ReplicationSlot *slot)
 	LWLockAcquire(ReplicationSlotAllocationLock, LW_EXCLUSIVE);
 
 	/* Generate pathnames. */
-	sprintf(path, "pg_replslot/%s", NameStr(slot->data.name));
-	sprintf(tmppath, "pg_replslot/%s.tmp", NameStr(slot->data.name));
+	sprintf(path, "%s/%s", PG_REPLSLOT_DIR, NameStr(slot->data.name));
+	sprintf(tmppath, "%s/%s.tmp", PG_REPLSLOT_DIR, NameStr(slot->data.name));
 
 	/*
 	 * Rename the slot directory on disk, so that we'll no longer recognize
@@ -571,7 +571,7 @@ ReplicationSlotDropPtr(ReplicationSlot *slot)
 		 */
 		START_CRIT_SECTION();
 		fsync_fname(tmppath, true);
-		fsync_fname("pg_replslot", true);
+		fsync_fname(PG_REPLSLOT_DIR, true);
 		END_CRIT_SECTION();
 	}
 	else
@@ -641,7 +641,8 @@ ReplicationSlotSave(void)
 
 	Assert(MyReplicationSlot != NULL);
 
-	sprintf(path, "pg_replslot/%s", NameStr(MyReplicationSlot->data.name));
+	sprintf(path, "%s/%s", PG_REPLSLOT_DIR,
+			NameStr(MyReplicationSlot->data.name));
 	SaveSlotToPath(MyReplicationSlot, path, ERROR);
 }
 
@@ -1076,7 +1077,7 @@ CheckPointReplicationSlots(void)
 			continue;
 
 		/* save the slot to disk, locking is handled in SaveSlotToPath() */
-		sprintf(path, "pg_replslot/%s", NameStr(s->data.name));
+		sprintf(path, "%s/%s", PG_REPLSLOT_DIR, NameStr(s->data.name));
 		SaveSlotToPath(s, path, LOG);
 	}
 	LWLockRelease(ReplicationSlotAllocationLock);
@@ -1095,8 +1096,8 @@ StartupReplicationSlots(void)
 	elog(DEBUG1, "starting up replication slots");
 
 	/* restore all slots by iterating over all on-disk entries */
-	replication_dir = AllocateDir("pg_replslot");
-	while ((replication_de = ReadDir(replication_dir, "pg_replslot")) != NULL)
+	replication_dir = AllocateDir(PG_REPLSLOT_DIR);
+	while ((replication_de = ReadDir(replication_dir, PG_REPLSLOT_DIR)) != NULL)
 	{
 		struct stat statbuf;
 		char		path[MAXPGPATH + 12];
@@ -1105,7 +1106,8 @@ StartupReplicationSlots(void)
 			strcmp(replication_de->d_name, "..") == 0)
 			continue;
 
-		snprintf(path, sizeof(path), "pg_replslot/%s", replication_de->d_name);
+		snprintf(path, sizeof(path), "%s/%s", PG_REPLSLOT_DIR,
+				 replication_de->d_name);
 
 		/* we're only creating directories here, skip if it's not our's */
 		if (lstat(path, &statbuf) == 0 && !S_ISDIR(statbuf.st_mode))
@@ -1121,7 +1123,7 @@ StartupReplicationSlots(void)
 						 errmsg("could not remove directory \"%s\"", path)));
 				continue;
 			}
-			fsync_fname("pg_replslot", true);
+			fsync_fname(PG_REPLSLOT_DIR, true);
 			continue;
 		}
 
@@ -1159,8 +1161,8 @@ CreateSlotOnDisk(ReplicationSlot *slot)
 	 * takes out the lock, if we'd take the lock here, we'd deadlock.
 	 */
 
-	sprintf(path, "pg_replslot/%s", NameStr(slot->data.name));
-	sprintf(tmppath, "pg_replslot/%s.tmp", NameStr(slot->data.name));
+	sprintf(path, "%s/%s", PG_REPLSLOT_DIR, NameStr(slot->data.name));
+	sprintf(tmppath, "%s/%s.tmp", PG_REPLSLOT_DIR, NameStr(slot->data.name));
 
 	/*
 	 * It's just barely possible that some previous effort to create or drop a
@@ -1198,7 +1200,7 @@ CreateSlotOnDisk(ReplicationSlot *slot)
 	START_CRIT_SECTION();
 
 	fsync_fname(path, true);
-	fsync_fname("pg_replslot", true);
+	fsync_fname(PG_REPLSLOT_DIR, true);
 
 	END_CRIT_SECTION();
 }
@@ -1309,7 +1311,7 @@ SaveSlotToPath(ReplicationSlot *slot, const char *dir, int elevel)
 
 	fsync_fname(path, false);
 	fsync_fname(dir, true);
-	fsync_fname("pg_replslot", true);
+	fsync_fname(PG_REPLSLOT_DIR, true);
 
 	END_CRIT_SECTION();
 
@@ -1342,13 +1344,13 @@ RestoreSlotFromDisk(const char *name)
 	/* no need to lock here, no concurrent access allowed yet */
 
 	/* delete temp file if it exists */
-	sprintf(path, "pg_replslot/%s/state.tmp", name);
+	sprintf(path, "%s/%s/state.tmp", PG_REPLSLOT_DIR, name);
 	if (unlink(path) < 0 && errno != ENOENT)
 		ereport(PANIC,
 				(errcode_for_file_access(),
 				 errmsg("could not remove file \"%s\": %m", path)));
 
-	sprintf(path, "pg_replslot/%s/state", name);
+	sprintf(path, "%s/%s/state", PG_REPLSLOT_DIR, name);
 
 	elog(DEBUG1, "restoring replication slot from \"%s\"", path);
 
@@ -1459,7 +1461,7 @@ RestoreSlotFromDisk(const char *name)
 	 */
 	if (cp.slotdata.persistency != RS_PERSISTENT)
 	{
-		sprintf(path, "pg_replslot/%s", name);
+		sprintf(path, "%s/%s", PG_REPLSLOT_DIR, name);
 
 		if (!rmtree(path, true))
 		{
@@ -1467,7 +1469,7 @@ RestoreSlotFromDisk(const char *name)
 					(errcode_for_file_access(),
 					 errmsg("could not remove directory \"%s\"", path)));
 		}
-		fsync_fname("pg_replslot", true);
+		fsync_fname(PG_REPLSLOT_DIR, true);
 		return;
 	}
 
diff --git a/src/backend/storage/file/fd.c b/src/backend/storage/file/fd.c
index 2a18e94..45888e9 100644
--- a/src/backend/storage/file/fd.c
+++ b/src/backend/storage/file/fd.c
@@ -84,6 +84,7 @@
 #include "access/xlog.h"
 #include "catalog/catalog.h"
 #include "catalog/pg_tablespace.h"
+#include "pg_paths.h"
 #include "pgstat.h"
 #include "portability/mem.h"
 #include "storage/fd.h"
@@ -1560,11 +1561,12 @@ TempTablespacePath(char *path, Oid tablespace)
 	if (tablespace == InvalidOid ||
 		tablespace == DEFAULTTABLESPACE_OID ||
 		tablespace == GLOBALTABLESPACE_OID)
-		snprintf(path, MAXPGPATH, "base/%s", PG_TEMP_FILES_DIR);
+		snprintf(path, MAXPGPATH, "%s/%s",
+				 PG_BASE_DIR, PG_TEMP_FILES_DIR);
 	else
 	{
 		/* All other tablespaces are accessed via symlinks */
-		snprintf(path, MAXPGPATH, "pg_tblspc/%u/%s/%s",
+		snprintf(path, MAXPGPATH, PG_TABLESPACE_DIR "/%u/%s/%s",
 				 tablespace, TABLESPACE_VERSION_DIRECTORY,
 				 PG_TEMP_FILES_DIR);
 	}
@@ -3020,26 +3022,27 @@ RemovePgTempFiles(void)
 	/*
 	 * First process temp files in pg_default ($PGDATA/base)
 	 */
-	snprintf(temp_path, sizeof(temp_path), "base/%s", PG_TEMP_FILES_DIR);
+	snprintf(temp_path, sizeof(temp_path), "%s/%s",
+			 PG_BASE_DIR, PG_TEMP_FILES_DIR);
 	RemovePgTempFilesInDir(temp_path, true, false);
-	RemovePgTempRelationFiles("base");
+	RemovePgTempRelationFiles(PG_BASE_DIR);
 
 	/*
 	 * Cycle through temp directories for all non-default tablespaces.
 	 */
-	spc_dir = AllocateDir("pg_tblspc");
+	spc_dir = AllocateDir(PG_TABLESPACE_DIR);
 
-	while ((spc_de = ReadDirExtended(spc_dir, "pg_tblspc", LOG)) != NULL)
+	while ((spc_de = ReadDirExtended(spc_dir, PG_TABLESPACE_DIR, LOG)) != NULL)
 	{
 		if (strcmp(spc_de->d_name, ".") == 0 ||
 			strcmp(spc_de->d_name, "..") == 0)
 			continue;
 
-		snprintf(temp_path, sizeof(temp_path), "pg_tblspc/%s/%s/%s",
+		snprintf(temp_path, sizeof(temp_path), PG_TABLESPACE_DIR "/%s/%s/%s",
 				 spc_de->d_name, TABLESPACE_VERSION_DIRECTORY, PG_TEMP_FILES_DIR);
 		RemovePgTempFilesInDir(temp_path, true, false);
 
-		snprintf(temp_path, sizeof(temp_path), "pg_tblspc/%s/%s",
+		snprintf(temp_path, sizeof(temp_path), PG_TABLESPACE_DIR "/%s/%s",
 				 spc_de->d_name, TABLESPACE_VERSION_DIRECTORY);
 		RemovePgTempRelationFiles(temp_path);
 	}
@@ -3278,16 +3281,16 @@ SyncDataDirectory(void)
 	{
 		struct stat st;
 
-		if (lstat("pg_wal", &st) < 0)
+		if (lstat(XLOGDIR, &st) < 0)
 			ereport(LOG,
 					(errcode_for_file_access(),
 					 errmsg("could not stat file \"%s\": %m",
-							"pg_wal")));
+							XLOGDIR)));
 		else if (S_ISLNK(st.st_mode))
 			xlog_is_symlink = true;
 	}
 #else
-	if (pgwin32_is_junction("pg_wal"))
+	if (pgwin32_is_junction(XLOGDIR))
 		xlog_is_symlink = true;
 #endif
 
@@ -3299,8 +3302,8 @@ SyncDataDirectory(void)
 #ifdef PG_FLUSH_DATA_WORKS
 	walkdir(".", pre_sync_fname, false, DEBUG1);
 	if (xlog_is_symlink)
-		walkdir("pg_wal", pre_sync_fname, false, DEBUG1);
-	walkdir("pg_tblspc", pre_sync_fname, true, DEBUG1);
+		walkdir(XLOGDIR, pre_sync_fname, false, DEBUG1);
+	walkdir(PG_TABLESPACE_DIR, pre_sync_fname, true, DEBUG1);
 #endif
 
 	/*
@@ -3314,8 +3317,8 @@ SyncDataDirectory(void)
 	 */
 	walkdir(".", datadir_fsync_fname, false, LOG);
 	if (xlog_is_symlink)
-		walkdir("pg_wal", datadir_fsync_fname, false, LOG);
-	walkdir("pg_tblspc", datadir_fsync_fname, true, LOG);
+		walkdir(XLOGDIR, datadir_fsync_fname, false, LOG);
+	walkdir(PG_TABLESPACE_DIR, datadir_fsync_fname, true, LOG);
 }
 
 /*
diff --git a/src/backend/storage/file/reinit.c b/src/backend/storage/file/reinit.c
index 92363ae..69e9c7b 100644
--- a/src/backend/storage/file/reinit.c
+++ b/src/backend/storage/file/reinit.c
@@ -18,6 +18,7 @@
 
 #include "catalog/catalog.h"
 #include "common/relpath.h"
+#include "pg_paths.h"
 #include "storage/copydir.h"
 #include "storage/fd.h"
 #include "storage/reinit.h"
@@ -71,20 +72,20 @@ ResetUnloggedRelations(int op)
 	/*
 	 * First process unlogged files in pg_default ($PGDATA/base)
 	 */
-	ResetUnloggedRelationsInTablespaceDir("base", op);
+	ResetUnloggedRelationsInTablespaceDir(PG_BASE_DIR, op);
 
 	/*
 	 * Cycle through directories for all non-default tablespaces.
 	 */
-	spc_dir = AllocateDir("pg_tblspc");
+	spc_dir = AllocateDir(PG_TABLESPACE_DIR);
 
-	while ((spc_de = ReadDir(spc_dir, "pg_tblspc")) != NULL)
+	while ((spc_de = ReadDir(spc_dir, PG_TABLESPACE_DIR)) != NULL)
 	{
 		if (strcmp(spc_de->d_name, ".") == 0 ||
 			strcmp(spc_de->d_name, "..") == 0)
 			continue;
 
-		snprintf(temp_path, sizeof(temp_path), "pg_tblspc/%s/%s",
+		snprintf(temp_path, sizeof(temp_path), PG_TABLESPACE_DIR "/%s/%s",
 				 spc_de->d_name, TABLESPACE_VERSION_DIRECTORY);
 		ResetUnloggedRelationsInTablespaceDir(temp_path, op);
 	}
diff --git a/src/backend/utils/adt/dbsize.c b/src/backend/utils/adt/dbsize.c
index 834a104..ee3cece 100644
--- a/src/backend/utils/adt/dbsize.c
+++ b/src/backend/utils/adt/dbsize.c
@@ -22,6 +22,7 @@
 #include "commands/dbcommands.h"
 #include "commands/tablespace.h"
 #include "miscadmin.h"
+#include "pg_paths.h"
 #include "storage/fd.h"
 #include "utils/acl.h"
 #include "utils/builtins.h"
@@ -104,11 +105,11 @@ calculate_database_size(Oid dbOid)
 	/* Shared storage in pg_global is not counted */
 
 	/* Include pg_default storage */
-	snprintf(pathname, sizeof(pathname), "base/%u", dbOid);
+	snprintf(pathname, sizeof(pathname), PG_BASE_DIR "/%u", dbOid);
 	totalsize = db_dir_size(pathname);
 
 	/* Scan the non-default tablespaces */
-	snprintf(dirpath, MAXPGPATH, "pg_tblspc");
+	snprintf(dirpath, MAXPGPATH, PG_TABLESPACE_DIR);
 	dirdesc = AllocateDir(dirpath);
 
 	while ((direntry = ReadDir(dirdesc, dirpath)) != NULL)
@@ -119,7 +120,7 @@ calculate_database_size(Oid dbOid)
 			strcmp(direntry->d_name, "..") == 0)
 			continue;
 
-		snprintf(pathname, sizeof(pathname), "pg_tblspc/%s/%s/%u",
+		snprintf(pathname, sizeof(pathname), PG_TABLESPACE_DIR "/%s/%s/%u",
 				 direntry->d_name, TABLESPACE_VERSION_DIRECTORY, dbOid);
 		totalsize += db_dir_size(pathname);
 	}
@@ -188,11 +189,11 @@ calculate_tablespace_size(Oid tblspcOid)
 	}
 
 	if (tblspcOid == DEFAULTTABLESPACE_OID)
-		snprintf(tblspcPath, MAXPGPATH, "base");
+		snprintf(tblspcPath, MAXPGPATH, PG_BASE_DIR);
 	else if (tblspcOid == GLOBALTABLESPACE_OID)
-		snprintf(tblspcPath, MAXPGPATH, "global");
+		snprintf(tblspcPath, MAXPGPATH, PG_GLOBAL_DIR);
 	else
-		snprintf(tblspcPath, MAXPGPATH, "pg_tblspc/%u/%s", tblspcOid,
+		snprintf(tblspcPath, MAXPGPATH, PG_TABLESPACE_DIR "/%u/%s", tblspcOid,
 				 TABLESPACE_VERSION_DIRECTORY);
 
 	dirdesc = AllocateDir(tblspcPath);
diff --git a/src/backend/utils/adt/misc.c b/src/backend/utils/adt/misc.c
index 9f98c03..41a2407 100644
--- a/src/backend/utils/adt/misc.c
+++ b/src/backend/utils/adt/misc.c
@@ -396,9 +396,9 @@ pg_tablespace_databases(PG_FUNCTION_ARGS)
 		else
 		{
 			if (tablespaceOid == DEFAULTTABLESPACE_OID)
-				fctx->location = psprintf("base");
+				fctx->location = psprintf(PG_BASE_DIR);
 			else
-				fctx->location = psprintf("pg_tblspc/%u/%s", tablespaceOid,
+				fctx->location = psprintf(PG_TABLESPACE_DIR "/%u/%s", tablespaceOid,
 										  TABLESPACE_VERSION_DIRECTORY);
 
 			fctx->dirdesc = AllocateDir(fctx->location);
@@ -484,7 +484,8 @@ pg_tablespace_location(PG_FUNCTION_ARGS)
 	 * Find the location of the tablespace by reading the symbolic link that
 	 * is in pg_tblspc/<oid>.
 	 */
-	snprintf(sourcepath, sizeof(sourcepath), "pg_tblspc/%u", tablespaceOid);
+	snprintf(sourcepath, sizeof(sourcepath), PG_TABLESPACE_DIR "/%u",
+			 tablespaceOid);
 
 	rllen = readlink(sourcepath, targetpath, sizeof(targetpath));
 	if (rllen < 0)
diff --git a/src/backend/utils/cache/relcache.c b/src/backend/utils/cache/relcache.c
index 6ab4db2..f3d932f 100644
--- a/src/backend/utils/cache/relcache.c
+++ b/src/backend/utils/cache/relcache.c
@@ -71,6 +71,7 @@
 #include "optimizer/clauses.h"
 #include "optimizer/prep.h"
 #include "optimizer/var.h"
+#include "pg_paths.h"
 #include "rewrite/rewriteDefine.h"
 #include "rewrite/rowsecurity.h"
 #include "storage/lmgr.h"
@@ -5352,7 +5353,8 @@ load_relcache_init_file(bool shared)
 	int			i;
 
 	if (shared)
-		snprintf(initfilename, sizeof(initfilename), "global/%s",
+		snprintf(initfilename, sizeof(initfilename), "%s/%s",
+				 PG_GLOBAL_DIR,
 				 RELCACHE_INIT_FILENAME);
 	else
 		snprintf(initfilename, sizeof(initfilename), "%s/%s",
@@ -5751,9 +5753,11 @@ write_relcache_init_file(bool shared)
 	 */
 	if (shared)
 	{
-		snprintf(tempfilename, sizeof(tempfilename), "global/%s.%d",
+		snprintf(tempfilename, sizeof(tempfilename), "%s/%s.%d",
+				 PG_GLOBAL_DIR,
 				 RELCACHE_INIT_FILENAME, MyProcPid);
-		snprintf(finalfilename, sizeof(finalfilename), "global/%s",
+		snprintf(finalfilename, sizeof(finalfilename), "%s/%s",
+				 PG_GLOBAL_DIR,
 				 RELCACHE_INIT_FILENAME);
 	}
 	else
@@ -6074,7 +6078,6 @@ RelationCacheInitFilePostInvalidate(void)
 void
 RelationCacheInitFileRemove(void)
 {
-	const char *tblspcdir = "pg_tblspc";
 	DIR		   *dir;
 	struct dirent *de;
 	char		path[MAXPGPATH + 10 + sizeof(TABLESPACE_VERSION_DIRECTORY)];
@@ -6083,23 +6086,25 @@ RelationCacheInitFileRemove(void)
 	 * We zap the shared cache file too.  In theory it can't get out of sync
 	 * enough to be a problem, but in data-corruption cases, who knows ...
 	 */
-	snprintf(path, sizeof(path), "global/%s",
+	snprintf(path, sizeof(path), "%s/%s",
+			 PG_GLOBAL_DIR,
 			 RELCACHE_INIT_FILENAME);
 	unlink_initfile(path);
 
 	/* Scan everything in the default tablespace */
-	RelationCacheInitFileRemoveInDir("base");
+	RelationCacheInitFileRemoveInDir(PG_BASE_DIR);
 
 	/* Scan the tablespace link directory to find non-default tablespaces */
-	dir = AllocateDir(tblspcdir);
+	dir = AllocateDir(PG_TABLESPACE_DIR);
 
-	while ((de = ReadDirExtended(dir, tblspcdir, LOG)) != NULL)
+	while ((de = ReadDirExtended(dir, PG_TABLESPACE_DIR, LOG)) != NULL)
 	{
 		if (strspn(de->d_name, "0123456789") == strlen(de->d_name))
 		{
 			/* Scan the tablespace dir for per-database dirs */
 			snprintf(path, sizeof(path), "%s/%s/%s",
-					 tblspcdir, de->d_name, TABLESPACE_VERSION_DIRECTORY);
+					 PG_TABLESPACE_DIR, de->d_name,
+					 TABLESPACE_VERSION_DIRECTORY);
 			RelationCacheInitFileRemoveInDir(path);
 		}
 	}
diff --git a/src/backend/utils/cache/relmapper.c b/src/backend/utils/cache/relmapper.c
index 99d095f..479082f 100644
--- a/src/backend/utils/cache/relmapper.c
+++ b/src/backend/utils/cache/relmapper.c
@@ -50,6 +50,7 @@
 #include "catalog/pg_tablespace.h"
 #include "catalog/storage.h"
 #include "miscadmin.h"
+#include "pg_paths.h"
 #include "pgstat.h"
 #include "storage/fd.h"
 #include "storage/lwlock.h"
@@ -632,7 +633,8 @@ load_relmap_file(bool shared)
 
 	if (shared)
 	{
-		snprintf(mapfilename, sizeof(mapfilename), "global/%s",
+		snprintf(mapfilename, sizeof(mapfilename), "%s/%s",
+				 PG_GLOBAL_DIR,
 				 RELMAPPER_FILENAME);
 		map = &shared_map;
 	}
@@ -733,7 +735,8 @@ write_relmap_file(bool shared, RelMapFile *newmap,
 	 */
 	if (shared)
 	{
-		snprintf(mapfilename, sizeof(mapfilename), "global/%s",
+		snprintf(mapfilename, sizeof(mapfilename), "%s/%s",
+				 PG_GLOBAL_DIR,
 				 RELMAPPER_FILENAME);
 		realmap = &shared_map;
 	}
diff --git a/src/backend/utils/init/miscinit.c b/src/backend/utils/init/miscinit.c
index 87ed7d3..4d1dd06 100644
--- a/src/backend/utils/init/miscinit.c
+++ b/src/backend/utils/init/miscinit.c
@@ -35,6 +35,7 @@
 #include "libpq/libpq.h"
 #include "mb/pg_wchar.h"
 #include "miscadmin.h"
+#include "pg_paths.h"
 #include "pgstat.h"
 #include "postmaster/autovacuum.h"
 #include "postmaster/postmaster.h"
@@ -52,7 +53,7 @@
 #include "utils/varlena.h"
 
 
-#define DIRECTORY_LOCK_FILE		"postmaster.pid"
+#define DIRECTORY_LOCK_FILE		POSTMASTER_PID_FILE
 
 ProcessingMode Mode = InitProcessing;
 
diff --git a/src/backend/utils/time/snapmgr.c b/src/backend/utils/time/snapmgr.c
index e58c69d..6c3571f 100644
--- a/src/backend/utils/time/snapmgr.c
+++ b/src/backend/utils/time/snapmgr.c
@@ -54,6 +54,7 @@
 #include "catalog/catalog.h"
 #include "lib/pairingheap.h"
 #include "miscadmin.h"
+#include "pg_paths.h"
 #include "storage/predicate.h"
 #include "storage/proc.h"
 #include "storage/procarray.h"
@@ -209,9 +210,6 @@ bool		FirstSnapshotSet = false;
  */
 static Snapshot FirstXactSnapshot = NULL;
 
-/* Define pathname of exported-snapshot files */
-#define SNAPSHOT_EXPORT_DIR "pg_snapshots"
-
 /* Structure holding info about exported snapshot. */
 typedef struct ExportedSnapshot
 {
@@ -1210,7 +1208,7 @@ ExportSnapshot(Snapshot snapshot)
 	 * Generate file path for the snapshot.  We start numbering of snapshots
 	 * inside the transaction from 1.
 	 */
-	snprintf(path, sizeof(path), SNAPSHOT_EXPORT_DIR "/%08X-%08X-%d",
+	snprintf(path, sizeof(path), PG_SNAPSHOTS_DIR "/%08X-%08X-%d",
 			 MyProc->backendId, MyProc->lxid, list_length(exportedSnapshots) + 1);
 
 	/*
@@ -1321,10 +1319,10 @@ ExportSnapshot(Snapshot snapshot)
 	/*
 	 * The basename of the file is what we return from pg_export_snapshot().
 	 * It's already in path in a textual format and we know that the path
-	 * starts with SNAPSHOT_EXPORT_DIR.  Skip over the prefix and the slash
+	 * starts with PG_SNAPSHOTS_DIR.  Skip over the prefix and the slash
 	 * and pstrdup it so as not to return the address of a local variable.
 	 */
-	return pstrdup(path + strlen(SNAPSHOT_EXPORT_DIR) + 1);
+	return pstrdup(path + strlen(PG_SNAPSHOTS_DIR) + 1);
 }
 
 /*
@@ -1423,7 +1421,7 @@ parseVxidFromText(const char *prefix, char **s, const char *filename,
 /*
  * ImportSnapshot
  *		Import a previously exported snapshot.  The argument should be a
- *		filename in SNAPSHOT_EXPORT_DIR.  Load the snapshot from that file.
+ *		filename in PG_SNAPSHOTS_DIR.  Load the snapshot from that file.
  *		This is called by "SET TRANSACTION SNAPSHOT 'foo'".
  */
 void
@@ -1474,7 +1472,7 @@ ImportSnapshot(const char *idstr)
 				 errmsg("invalid snapshot identifier: \"%s\"", idstr)));
 
 	/* OK, read the file */
-	snprintf(path, MAXPGPATH, SNAPSHOT_EXPORT_DIR "/%s", idstr);
+	snprintf(path, MAXPGPATH, PG_SNAPSHOTS_DIR "/%s", idstr);
 
 	f = AllocateFile(path, PG_BINARY_R);
 	if (!f)
@@ -1615,7 +1613,7 @@ XactHasExportedSnapshots(void)
 void
 DeleteAllExportedSnapshotFiles(void)
 {
-	char		buf[MAXPGPATH + sizeof(SNAPSHOT_EXPORT_DIR)];
+	char		buf[MAXPGPATH + sizeof(PG_SNAPSHOTS_DIR)];
 	DIR		   *s_dir;
 	struct dirent *s_de;
 
@@ -1624,15 +1622,15 @@ DeleteAllExportedSnapshotFiles(void)
 	 * LOG level.  Since we're running in the startup process, ERROR level
 	 * would prevent database start, and it's not important enough for that.
 	 */
-	s_dir = AllocateDir(SNAPSHOT_EXPORT_DIR);
+	s_dir = AllocateDir(PG_SNAPSHOTS_DIR);
 
-	while ((s_de = ReadDirExtended(s_dir, SNAPSHOT_EXPORT_DIR, LOG)) != NULL)
+	while ((s_de = ReadDirExtended(s_dir, PG_SNAPSHOTS_DIR, LOG)) != NULL)
 	{
 		if (strcmp(s_de->d_name, ".") == 0 ||
 			strcmp(s_de->d_name, "..") == 0)
 			continue;
 
-		snprintf(buf, sizeof(buf), SNAPSHOT_EXPORT_DIR "/%s", s_de->d_name);
+		snprintf(buf, sizeof(buf), PG_SNAPSHOTS_DIR "/%s", s_de->d_name);
 
 		if (unlink(buf) != 0)
 			ereport(LOG,
diff --git a/src/bin/initdb/initdb.c b/src/bin/initdb/initdb.c
index 0d75bd7..6b061c9 100644
--- a/src/bin/initdb/initdb.c
+++ b/src/bin/initdb/initdb.c
@@ -1188,7 +1188,7 @@ setup_config(void)
 	autoconflines[1] = pg_strdup("# It will be overwritten by the ALTER SYSTEM command.\n");
 	autoconflines[2] = NULL;
 
-	sprintf(path, "%s/postgresql.auto.conf", pg_data);
+	sprintf(path, "%s/%s", pg_data, PG_AUTOCONF_FILENAME);
 
 	writefile(path, autoconflines);
 	if (chmod(path, S_IRUSR | S_IWUSR) != 0)
@@ -2756,7 +2756,7 @@ create_xlog_or_symlink(void)
 	char	   *subdirloc;
 
 	/* form name of the place for the subdirectory or symlink */
-	subdirloc = psprintf("%s/pg_wal", pg_data);
+	subdirloc = psprintf("%s/%s", pg_data, XLOGDIR);
 
 	if (xlog_dir)
 	{
@@ -2931,7 +2931,7 @@ initialize_data_directory(void)
 	/*
 	 * Make the per-database PG_VERSION for template1 only after init'ing it
 	 */
-	write_version_file("base/1");
+	write_version_file(PG_BASE_DIR "/1");
 
 	/*
 	 * Create the stuff we don't need to use bootstrap mode for, using a
diff --git a/src/bin/pg_ctl/pg_ctl.c b/src/bin/pg_ctl/pg_ctl.c
index 9bc830b0..7dc15b1 100644
--- a/src/bin/pg_ctl/pg_ctl.c
+++ b/src/bin/pg_ctl/pg_ctl.c
@@ -26,6 +26,7 @@
 #include "catalog/pg_control.h"
 #include "common/controldata_utils.h"
 #include "getopt_long.h"
+#include "pg_paths.h"
 #include "utils/pidfile.h"
 
 #ifdef WIN32					/* on Unix, we don't need libpq */
@@ -2401,9 +2402,11 @@ main(int argc, char **argv)
 
 	if (pg_data)
 	{
-		snprintf(postopts_file, MAXPGPATH, "%s/postmaster.opts", pg_data);
+		snprintf(postopts_file, MAXPGPATH, "%s/%s", pg_data,
+				 POSTMASTER_OPTS_FILE);
 		snprintf(version_file, MAXPGPATH, "%s/PG_VERSION", pg_data);
-		snprintf(pid_file, MAXPGPATH, "%s/postmaster.pid", pg_data);
+		snprintf(pid_file, MAXPGPATH, "%s/%s", pg_data,
+				 POSTMASTER_PID_FILE);
 		snprintf(backup_file, MAXPGPATH, "%s/backup_label", pg_data);
 	}
 
diff --git a/src/bin/pg_resetwal/pg_resetwal.c b/src/bin/pg_resetwal/pg_resetwal.c
index a132cf2..673683a 100644
--- a/src/bin/pg_resetwal/pg_resetwal.c
+++ b/src/bin/pg_resetwal/pg_resetwal.c
@@ -55,6 +55,7 @@
 #include "common/restricted_token.h"
 #include "storage/large_object.h"
 #include "pg_getopt.h"
+#include "pg_paths.h"
 
 
 static ControlFileData ControlFile; /* pg_control values */
@@ -334,12 +335,12 @@ main(int argc, char *argv[])
 	 * Check for a postmaster lock file --- if there is one, refuse to
 	 * proceed, on grounds we might be interfering with a live installation.
 	 */
-	if ((fd = open("postmaster.pid", O_RDONLY, 0)) < 0)
+	if ((fd = open(POSTMASTER_PID_FILE, O_RDONLY, 0)) < 0)
 	{
 		if (errno != ENOENT)
 		{
 			fprintf(stderr, _("%s: could not open file \"%s\" for reading: %s\n"),
-					progname, "postmaster.pid", strerror(errno));
+					progname, POSTMASTER_PID_FILE, strerror(errno));
 			exit(1);
 		}
 	}
@@ -347,7 +348,7 @@ main(int argc, char *argv[])
 	{
 		fprintf(stderr, _("%s: lock file \"%s\" exists\n"
 						  "Is a server running?  If not, delete the lock file and try again.\n"),
-				progname, "postmaster.pid");
+				progname, POSTMASTER_PID_FILE);
 		exit(1);
 	}
 
diff --git a/src/bin/pg_rewind/copy_fetch.c b/src/bin/pg_rewind/copy_fetch.c
index 04db409..3a44da3 100644
--- a/src/bin/pg_rewind/copy_fetch.c
+++ b/src/bin/pg_rewind/copy_fetch.c
@@ -22,6 +22,7 @@
 #include "pg_rewind.h"
 
 #include "catalog/catalog.h"
+#include "pg_paths.h"
 
 static void recurse_dir(const char *datadir, const char *path,
 			process_file_callback_t callback);
@@ -131,8 +132,8 @@ recurse_dir(const char *datadir, const char *parentpath,
 			 * to process all the tablespaces.  We also follow a symlink if
 			 * it's for pg_wal.  Symlinks elsewhere are ignored.
 			 */
-			if ((parentpath && strcmp(parentpath, "pg_tblspc") == 0) ||
-				strcmp(path, "pg_wal") == 0)
+			if ((parentpath && strcmp(parentpath, PG_TABLESPACE_DIR) == 0) ||
+				strcmp(path, XLOGDIR) == 0)
 				recurse_dir(datadir, path, callback);
 #else
 			pg_fatal("\"%s\" is a symbolic link, but symbolic links are not supported on this platform\n",
diff --git a/src/bin/pg_rewind/filemap.c b/src/bin/pg_rewind/filemap.c
index 6122f17..d34f032 100644
--- a/src/bin/pg_rewind/filemap.c
+++ b/src/bin/pg_rewind/filemap.c
@@ -21,6 +21,7 @@
 #include "common/string.h"
 #include "catalog/catalog.h"
 #include "catalog/pg_tablespace.h"
+#include "pg_paths.h"
 #include "storage/fd.h"
 
 filemap_t  *filemap = NULL;
@@ -74,8 +75,8 @@ process_source_file(const char *path, file_type_t type, size_t newsize,
 	/*
 	 * Completely ignore some special files in source and destination.
 	 */
-	if (strcmp(path, "postmaster.pid") == 0 ||
-		strcmp(path, "postmaster.opts") == 0)
+	if (strcmp(path, POSTMASTER_PID_FILE) == 0 ||
+		strcmp(path, POSTMASTER_OPTS_FILE) == 0)
 		return;
 
 	/*
@@ -83,7 +84,7 @@ process_source_file(const char *path, file_type_t type, size_t newsize,
 	 * don't want to mess with the symlink itself, nor complain if it's a
 	 * symlink in source but not in target or vice versa.
 	 */
-	if (strcmp(path, "pg_wal") == 0 && type == FILE_TYPE_SYMLINK)
+	if (strcmp(path, XLOGDIR) == 0 && type == FILE_TYPE_SYMLINK)
 		type = FILE_TYPE_DIRECTORY;
 
 	/*
@@ -120,7 +121,7 @@ process_source_file(const char *path, file_type_t type, size_t newsize,
 	switch (type)
 	{
 		case FILE_TYPE_DIRECTORY:
-			if (exists && !S_ISDIR(statbuf.st_mode) && strcmp(path, "pg_wal") != 0)
+			if (exists && !S_ISDIR(statbuf.st_mode) && strcmp(path, XLOGDIR) != 0)
 			{
 				/* it's a directory in source, but not in target. Strange.. */
 				pg_fatal("\"%s\" is not a directory\n", localpath);
@@ -289,14 +290,14 @@ process_target_file(const char *path, file_type_t type, size_t oldsize,
 	/*
 	 * Completely ignore some special files
 	 */
-	if (strcmp(path, "postmaster.pid") == 0 ||
-		strcmp(path, "postmaster.opts") == 0)
+	if (strcmp(path, POSTMASTER_PID_FILE) == 0 ||
+		strcmp(path, POSTMASTER_OPTS_FILE) == 0)
 		return;
 
 	/*
 	 * Like in process_source_file, pretend that xlog is always a  directory.
 	 */
-	if (strcmp(path, "pg_wal") == 0 && type == FILE_TYPE_SYMLINK)
+	if (strcmp(path, XLOGDIR) == 0 && type == FILE_TYPE_SYMLINK)
 		type = FILE_TYPE_DIRECTORY;
 
 	key.path = (char *) path;
@@ -585,7 +586,7 @@ isRelDataFile(const char *path)
 	segNo = 0;
 	matched = false;
 
-	nmatch = sscanf(path, "global/%u.%u", &rnode.relNode, &segNo);
+	nmatch = sscanf(path, PG_GLOBAL_DIR "/%u.%u", &rnode.relNode, &segNo);
 	if (nmatch == 1 || nmatch == 2)
 	{
 		rnode.spcNode = GLOBALTABLESPACE_OID;
@@ -594,7 +595,7 @@ isRelDataFile(const char *path)
 	}
 	else
 	{
-		nmatch = sscanf(path, "base/%u/%u.%u",
+		nmatch = sscanf(path, PG_BASE_DIR "/%u/%u.%u",
 						&rnode.dbNode, &rnode.relNode, &segNo);
 		if (nmatch == 2 || nmatch == 3)
 		{
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index 72ab2f8..56aabfd 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -210,11 +210,11 @@ main(int argc, char **argv)
 	 * Ok, we have all the options and we're ready to start. Read in all the
 	 * information we need from both clusters.
 	 */
-	buffer = slurpFile(datadir_target, "global/pg_control", &size);
+	buffer = slurpFile(datadir_target, XLOG_CONTROL_FILE, &size);
 	digestControlFile(&ControlFile_target, buffer, size);
 	pg_free(buffer);
 
-	buffer = fetchFile("global/pg_control", &size);
+	buffer = fetchFile(XLOG_CONTROL_FILE, &size);
 	digestControlFile(&ControlFile_source, buffer, size);
 	pg_free(buffer);
 
@@ -675,7 +675,7 @@ updateControlFile(ControlFileData *ControlFile)
 	memset(buffer, 0, PG_CONTROL_FILE_SIZE);
 	memcpy(buffer, ControlFile, sizeof(ControlFileData));
 
-	open_target_file("global/pg_control", false);
+	open_target_file(XLOG_CONTROL_FILE, false);
 
 	write_target_range(buffer, 0, PG_CONTROL_FILE_SIZE);
 
diff --git a/src/bin/pg_upgrade/controldata.c b/src/bin/pg_upgrade/controldata.c
index 0fe98a5..7dce5ec 100644
--- a/src/bin/pg_upgrade/controldata.c
+++ b/src/bin/pg_upgrade/controldata.c
@@ -13,6 +13,8 @@
 
 #include <ctype.h>
 
+#include "pg_paths.h"
+
 /*
  * get_control_data()
  *
@@ -614,15 +616,18 @@ disable_old_cluster(void)
 	/* rename pg_control so old server cannot be accidentally started */
 	prep_status("Adding \".old\" suffix to old global/pg_control");
 
-	snprintf(old_path, sizeof(old_path), "%s/global/pg_control", old_cluster.pgdata);
-	snprintf(new_path, sizeof(new_path), "%s/global/pg_control.old", old_cluster.pgdata);
+	snprintf(old_path, sizeof(old_path), "%s/%s", old_cluster.pgdata,
+			 XLOG_CONTROL_FILE);
+	snprintf(new_path, sizeof(new_path), "%s/%s.old", old_cluster.pgdata,
+			 XLOG_CONTROL_FILE);
 	if (pg_mv_file(old_path, new_path) != 0)
 		pg_fatal("Unable to rename %s to %s.\n", old_path, new_path);
 	check_ok();
 
 	pg_log(PG_REPORT, "\n"
 		   "If you want to start the old cluster, you will need to remove\n"
-		   "the \".old\" suffix from %s/global/pg_control.old.\n"
+		   "the \".old\" suffix from %s/%s.old.\n"
 		   "Because \"link\" mode was used, the old cluster cannot be safely\n"
-		   "started once the new cluster has been started.\n\n", old_cluster.pgdata);
+		   "started once the new cluster has been started.\n\n",
+		   old_cluster.pgdata, XLOG_CONTROL_FILE);
 }
diff --git a/src/bin/pg_upgrade/exec.c b/src/bin/pg_upgrade/exec.c
index 9122e27..4138455 100644
--- a/src/bin/pg_upgrade/exec.c
+++ b/src/bin/pg_upgrade/exec.c
@@ -11,6 +11,7 @@
 
 #include <fcntl.h>
 
+#include "pg_paths.h"
 #include "pg_upgrade.h"
 
 static void check_data_dir(ClusterInfo *cluster);
@@ -219,7 +220,8 @@ pid_lock_file_exists(const char *datadir)
 	char		path[MAXPGPATH];
 	int			fd;
 
-	snprintf(path, sizeof(path), "%s/postmaster.pid", datadir);
+	snprintf(path, sizeof(path), "%s/%s", datadir,
+			 POSTMASTER_PID_FILE);
 
 	if ((fd = open(path, O_RDONLY, 0)) < 0)
 	{
@@ -331,12 +333,12 @@ check_data_dir(ClusterInfo *cluster)
 	cluster->major_version = get_major_server_version(cluster);
 
 	check_single_dir(pg_data, "");
-	check_single_dir(pg_data, "base");
-	check_single_dir(pg_data, "global");
-	check_single_dir(pg_data, "pg_multixact");
-	check_single_dir(pg_data, "pg_subtrans");
-	check_single_dir(pg_data, "pg_tblspc");
-	check_single_dir(pg_data, "pg_twophase");
+	check_single_dir(pg_data, PG_BASE_DIR);
+	check_single_dir(pg_data, PG_GLOBAL_DIR);
+	check_single_dir(pg_data, PG_MULTIXACT_DIR);
+	check_single_dir(pg_data, PG_SUBTRANS_DIR);
+	check_single_dir(pg_data, PG_TABLESPACE_DIR);
+	check_single_dir(pg_data, PG_TWOPHASE_DIR);
 
 	/* pg_xlog has been renamed to pg_wal in v10 */
 	if (GET_MAJOR_VERSION(cluster->major_version) < 1000)
diff --git a/src/bin/pg_upgrade/option.c b/src/bin/pg_upgrade/option.c
index 9dbc922..6d96c78 100644
--- a/src/bin/pg_upgrade/option.c
+++ b/src/bin/pg_upgrade/option.c
@@ -15,6 +15,7 @@
 #endif
 
 #include "getopt_long.h"
+#include "pg_paths.h"
 #include "utils/pidfile.h"
 
 #include "pg_upgrade.h"
@@ -474,8 +475,8 @@ get_sock_dir(ClusterInfo *cluster, bool live_check)
 			FILE	   *fp;
 			int			lineno;
 
-			snprintf(filename, sizeof(filename), "%s/postmaster.pid",
-					 cluster->pgdata);
+			snprintf(filename, sizeof(filename), "%s/%s",
+					 cluster->pgdata, POSTMASTER_PID_FILE);
 			if ((fp = fopen(filename, "r")) == NULL)
 				pg_fatal("could not open file \"%s\": %s\n",
 						 filename, strerror(errno));
diff --git a/src/bin/pg_upgrade/pg_upgrade.c b/src/bin/pg_upgrade/pg_upgrade.c
index d124127..f11d772 100644
--- a/src/bin/pg_upgrade/pg_upgrade.c
+++ b/src/bin/pg_upgrade/pg_upgrade.c
@@ -40,6 +40,7 @@
 #include "catalog/pg_class.h"
 #include "common/restricted_token.h"
 #include "fe_utils/string_utils.h"
+#include "pg_paths.h"
 
 #ifdef HAVE_LANGINFO_H
 #include <langinfo.h>
@@ -483,8 +484,8 @@ copy_xact_xlog_xid(void)
 	if (old_cluster.controldata.cat_ver >= MULTIXACT_FORMATCHANGE_CAT_VER &&
 		new_cluster.controldata.cat_ver >= MULTIXACT_FORMATCHANGE_CAT_VER)
 	{
-		copy_subdir_files("pg_multixact/offsets", "pg_multixact/offsets");
-		copy_subdir_files("pg_multixact/members", "pg_multixact/members");
+		copy_subdir_files(PG_MULTIXACT_OFFSETS_DIR, PG_MULTIXACT_OFFSETS_DIR);
+		copy_subdir_files(PG_MULTIXACT_MEMBERS_DIR, PG_MULTIXACT_MEMBERS_DIR);
 
 		prep_status("Setting next multixact ID and offset for new cluster");
 
@@ -508,7 +509,7 @@ copy_xact_xlog_xid(void)
 		 * the new multi-xid value.  "members" starts at zero so no need to
 		 * remove it.
 		 */
-		remove_new_subdir("pg_multixact/offsets", false);
+		remove_new_subdir(PG_MULTIXACT_OFFSETS_DIR, false);
 
 		prep_status("Setting oldest multixact ID in new cluster");
 
diff --git a/src/common/controldata_utils.c b/src/common/controldata_utils.c
index f12a188..a93a567 100644
--- a/src/common/controldata_utils.c
+++ b/src/common/controldata_utils.c
@@ -26,6 +26,7 @@
 
 #include "catalog/pg_control.h"
 #include "common/controldata_utils.h"
+#include "pg_paths.h"
 #include "port/pg_crc32c.h"
 
 /*
@@ -48,7 +49,8 @@ get_controlfile(const char *DataDir, const char *progname, bool *crc_ok_p)
 	AssertArg(crc_ok_p);
 
 	ControlFile = palloc(sizeof(ControlFileData));
-	snprintf(ControlFilePath, MAXPGPATH, "%s/global/pg_control", DataDir);
+	snprintf(ControlFilePath, MAXPGPATH, "%s/%s", DataDir,
+			 XLOG_CONTROL_FILE);
 
 	if ((fd = open(ControlFilePath, O_RDONLY | PG_BINARY, 0)) == -1)
 #ifndef FRONTEND
diff --git a/src/common/relpath.c b/src/common/relpath.c
index d98050c..e34aa4c 100644
--- a/src/common/relpath.c
+++ b/src/common/relpath.c
@@ -21,6 +21,7 @@
 #include "catalog/catalog.h"
 #include "catalog/pg_tablespace.h"
 #include "common/relpath.h"
+#include "pg_paths.h"
 #include "storage/backendid.h"
 
 
@@ -111,17 +112,17 @@ GetDatabasePath(Oid dbNode, Oid spcNode)
 	{
 		/* Shared system relations live in {datadir}/global */
 		Assert(dbNode == 0);
-		return pstrdup("global");
+		return pstrdup(PG_GLOBAL_DIR);
 	}
 	else if (spcNode == DEFAULTTABLESPACE_OID)
 	{
 		/* The default tablespace is {datadir}/base */
-		return psprintf("base/%u", dbNode);
+		return psprintf(PG_BASE_DIR "/%u", dbNode);
 	}
 	else
 	{
 		/* All other tablespaces are accessed via symlinks */
-		return psprintf("pg_tblspc/%u/%s/%u",
+		return psprintf(PG_TABLESPACE_DIR "/%u/%s/%u",
 						spcNode, TABLESPACE_VERSION_DIRECTORY, dbNode);
 	}
 }
@@ -147,10 +148,11 @@ GetRelationPath(Oid dbNode, Oid spcNode, Oid relNode,
 		Assert(dbNode == 0);
 		Assert(backendId == InvalidBackendId);
 		if (forkNumber != MAIN_FORKNUM)
-			path = psprintf("global/%u_%s",
+			path = psprintf("%s/%u_%s",
+							PG_GLOBAL_DIR,
 							relNode, forkNames[forkNumber]);
 		else
-			path = psprintf("global/%u", relNode);
+			path = psprintf("%s/%u", PG_GLOBAL_DIR, relNode);
 	}
 	else if (spcNode == DEFAULTTABLESPACE_OID)
 	{
@@ -158,22 +160,22 @@ GetRelationPath(Oid dbNode, Oid spcNode, Oid relNode,
 		if (backendId == InvalidBackendId)
 		{
 			if (forkNumber != MAIN_FORKNUM)
-				path = psprintf("base/%u/%u_%s",
-								dbNode, relNode,
+				path = psprintf("%s/%u/%u_%s",
+								PG_BASE_DIR, dbNode, relNode,
 								forkNames[forkNumber]);
 			else
-				path = psprintf("base/%u/%u",
-								dbNode, relNode);
+				path = psprintf("%s/%u/%u",
+								PG_BASE_DIR, dbNode, relNode);
 		}
 		else
 		{
 			if (forkNumber != MAIN_FORKNUM)
-				path = psprintf("base/%u/t%d_%u_%s",
-								dbNode, backendId, relNode,
+				path = psprintf("%s/%u/t%d_%u_%s",
+								PG_BASE_DIR, dbNode, backendId, relNode,
 								forkNames[forkNumber]);
 			else
-				path = psprintf("base/%u/t%d_%u",
-								dbNode, backendId, relNode);
+				path = psprintf("%s/%u/t%d_%u",
+								PG_BASE_DIR, dbNode, backendId, relNode);
 		}
 	}
 	else

From b01fbf41f6d9d3b1fe211c8ea2a929ce36d1e658 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Mon, 5 Feb 2018 15:01:42 +0900
Subject: [PATCH 3/5] Add backup_label, pg_internal.init and tablespace_map to
 pg_paths.h

Those are going to be used in the list of files to be excluded from base
backups which is made available to the frontends.
---
 src/bin/pg_ctl/pg_ctl.c       |  3 ++-
 src/bin/pg_rewind/pg_rewind.c |  2 +-
 src/include/access/xlog.h     |  7 -------
 src/include/pg_paths.h        | 17 +++++++++++++++++
 src/include/utils/relcache.h  |  5 -----
 5 files changed, 20 insertions(+), 14 deletions(-)

diff --git a/src/bin/pg_ctl/pg_ctl.c b/src/bin/pg_ctl/pg_ctl.c
index 7dc15b13b0..7f9106a527 100644
--- a/src/bin/pg_ctl/pg_ctl.c
+++ b/src/bin/pg_ctl/pg_ctl.c
@@ -2407,7 +2407,8 @@ main(int argc, char **argv)
 		snprintf(version_file, MAXPGPATH, "%s/PG_VERSION", pg_data);
 		snprintf(pid_file, MAXPGPATH, "%s/%s", pg_data,
 				 POSTMASTER_PID_FILE);
-		snprintf(backup_file, MAXPGPATH, "%s/backup_label", pg_data);
+		snprintf(backup_file, MAXPGPATH, "%s/%s", pg_data,
+				 BACKUP_LABEL_FILE);
 	}
 
 	switch (ctl_command)
diff --git a/src/bin/pg_rewind/pg_rewind.c b/src/bin/pg_rewind/pg_rewind.c
index 56aabfd4af..bbd514f6f1 100644
--- a/src/bin/pg_rewind/pg_rewind.c
+++ b/src/bin/pg_rewind/pg_rewind.c
@@ -597,7 +597,7 @@ createBackupLabel(XLogRecPtr startpoint, TimeLineID starttli, XLogRecPtr checkpo
 		pg_fatal("backup label buffer too small\n");	/* shouldn't happen */
 
 	/* TODO: move old file out of the way, if any. */
-	open_target_file("backup_label", true); /* BACKUP_LABEL_FILE */
+	open_target_file(BACKUP_LABEL_FILE, true);
 	write_target_range(buf, 0, len);
 	close_target_file();
 }
diff --git a/src/include/access/xlog.h b/src/include/access/xlog.h
index 421ba6d775..ca4cbc811a 100644
--- a/src/include/access/xlog.h
+++ b/src/include/access/xlog.h
@@ -318,11 +318,4 @@ extern XLogRecPtr do_pg_stop_backup(char *labelfile, bool waitforarchive,
 extern void do_pg_abort_backup(void);
 extern SessionBackupState get_backup_status(void);
 
-/* File path names (all relative to $PGDATA) */
-#define BACKUP_LABEL_FILE		"backup_label"
-#define BACKUP_LABEL_OLD		"backup_label.old"
-
-#define TABLESPACE_MAP			"tablespace_map"
-#define TABLESPACE_MAP_OLD		"tablespace_map.old"
-
 #endif							/* XLOG_H */
diff --git a/src/include/pg_paths.h b/src/include/pg_paths.h
index a4746e75e4..f033f8f390 100644
--- a/src/include/pg_paths.h
+++ b/src/include/pg_paths.h
@@ -13,6 +13,23 @@
 #ifndef PG_PATHS_H
 #define PG_PATHS_H
 
+/*
+ * Backup label file names used in base backups.
+ */
+#define BACKUP_LABEL_FILE       "backup_label"
+#define BACKUP_LABEL_OLD        "backup_label.old"
+
+/*
+ * Tablespace map files used in base backups.
+ */
+#define TABLESPACE_MAP          "tablespace_map"
+#define TABLESPACE_MAP_OLD      "tablespace_map.old"
+
+/*
+ * Name of relcache init file(s), used to speed up backend startup
+ */
+#define RELCACHE_INIT_FILENAME	"pg_internal.init"
+
 /*
  * Name of files saving meta-data information about the log
  * files currently in use by the syslogger
diff --git a/src/include/utils/relcache.h b/src/include/utils/relcache.h
index 8a546aba28..7a884cb26a 100644
--- a/src/include/utils/relcache.h
+++ b/src/include/utils/relcache.h
@@ -18,11 +18,6 @@
 #include "nodes/bitmapset.h"
 
 
-/*
- * Name of relcache init file(s), used to speed up backend startup
- */
-#define RELCACHE_INIT_FILENAME	"pg_internal.init"
-
 typedef struct RelationData *Relation;
 
 /* ----------------
-- 
2.16.1

From 7aaafd2631386bb2bd7e628334a8409fbb648402 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Mon, 5 Feb 2018 14:43:10 +0900
Subject: [PATCH 4/5] Move base backup filter lists into their own header file

This list is for now consumed only by the backend-side base backup code,
which is used to filter out a set of paths and/or files which cannot be
included in base backup data sent to clients.

A follow-up patch will make use of that in pg_rewind itself.
---
 src/backend/replication/basebackup.c       | 82 ++-------------------------
 src/include/replication/basebackup_paths.h | 89 ++++++++++++++++++++++++++++++
 2 files changed, 94 insertions(+), 77 deletions(-)
 create mode 100644 src/include/replication/basebackup_paths.h

diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c
index 2e764ab293..2ea2306cfa 100644
--- a/src/backend/replication/basebackup.c
+++ b/src/backend/replication/basebackup.c
@@ -28,6 +28,7 @@
 #include "pgstat.h"
 #include "postmaster/syslogger.h"
 #include "replication/basebackup.h"
+#include "replication/basebackup_paths.h"
 #include "replication/walsender.h"
 #include "replication/walsender_private.h"
 #include "storage/dsm_impl.h"
@@ -98,79 +99,6 @@ static TimeOffset elapsed_min_unit;
 /* The last check of the transfer rate. */
 static TimestampTz throttled_last;
 
-/*
- * The contents of these directories are removed or recreated during server
- * start so they are not included in backups.  The directories themselves are
- * kept and included as empty to preserve access permissions.
- */
-static const char *excludeDirContents[] =
-{
-	/*
-	 * Skip temporary statistics files. PG_STAT_TMP_DIR must be skipped even
-	 * when stats_temp_directory is set because PGSS_TEXT_FILE is always
-	 * created there.
-	 */
-	PG_STAT_TMP_DIR,
-
-	/*
-	 * It is generally not useful to backup the contents of this directory
-	 * even if the intention is to restore to another master. See backup.sgml
-	 * for a more detailed description.
-	 */
-	PG_REPLSLOT_DIR,
-
-	/* Contents removed on startup, see dsm_cleanup_for_mmap(). */
-	PG_DYNSHMEM_DIR,
-
-	/* Contents removed on startup, see AsyncShmemInit(). */
-	PG_NOTIFY_DIR,
-
-	/*
-	 * Old contents are loaded for possible debugging but are not required for
-	 * normal operation, see OldSerXidInit().
-	 */
-	PG_SERIAL_DIR,
-
-	/* Contents removed on startup, see DeleteAllExportedSnapshotFiles(). */
-	PG_SNAPSHOTS_DIR,
-
-	/* Contents zeroed on startup, see StartupSUBTRANS(). */
-	PG_SUBTRANS_DIR,
-
-	/* end of list */
-	NULL
-};
-
-/*
- * List of files excluded from backups.
- */
-static const char *excludeFiles[] =
-{
-	/* Skip auto conf temporary file. */
-	PG_AUTOCONF_FILENAME_TMP,
-
-	/* Skip current log file temporary file */
-	LOG_METAINFO_DATAFILE_TMP,
-
-	/* Skip relation cache because it is rebuilt on startup */
-	RELCACHE_INIT_FILENAME,
-
-	/*
-	 * If there's a backup_label or tablespace_map file, it belongs to a
-	 * backup started by the user with pg_start_backup().  It is *not* correct
-	 * for this backup.  Our backup_label/tablespace_map is injected into the
-	 * tar separately.
-	 */
-	BACKUP_LABEL_FILE,
-	TABLESPACE_MAP,
-
-	POSTMASTER_PID_FILE,
-	POSTMASTER_OPTS_FILE,
-
-	/* end of list */
-	NULL
-};
-
 /*
  * Called when ERROR or FATAL happens in perform_base_backup() after
  * we have started the backup - make sure we end it!
@@ -995,9 +923,9 @@ sendDir(const char *path, int basepathlen, bool sizeonly, List *tablespaces,
 
 		/* Scan for files that should be excluded */
 		excludeFound = false;
-		for (excludeIdx = 0; excludeFiles[excludeIdx] != NULL; excludeIdx++)
+		for (excludeIdx = 0; backupExcludeFiles[excludeIdx] != NULL; excludeIdx++)
 		{
-			if (strcmp(de->d_name, excludeFiles[excludeIdx]) == 0)
+			if (strcmp(de->d_name, backupExcludeFiles[excludeIdx]) == 0)
 			{
 				elog(DEBUG1, "file \"%s\" excluded from backup", de->d_name);
 				excludeFound = true;
@@ -1028,9 +956,9 @@ sendDir(const char *path, int basepathlen, bool sizeonly, List *tablespaces,
 
 		/* Scan for directories whose contents should be excluded */
 		excludeFound = false;
-		for (excludeIdx = 0; excludeDirContents[excludeIdx] != NULL; excludeIdx++)
+		for (excludeIdx = 0; backupExcludeDirs[excludeIdx] != NULL; excludeIdx++)
 		{
-			if (strcmp(de->d_name, excludeDirContents[excludeIdx]) == 0)
+			if (strcmp(de->d_name, backupExcludeDirs[excludeIdx]) == 0)
 			{
 				elog(DEBUG1, "contents of directory \"%s\" excluded from backup", de->d_name);
 				size += _tarWriteDir(pathbuf, basepathlen, &statbuf, sizeonly);
diff --git a/src/include/replication/basebackup_paths.h b/src/include/replication/basebackup_paths.h
new file mode 100644
index 0000000000..64c9f20333
--- /dev/null
+++ b/src/include/replication/basebackup_paths.h
@@ -0,0 +1,89 @@
+/*-------------------------------------------------------------------------
+ *
+ * basebackup_paths.h
+ *	  Filter lists when working on base backups. Can be used by both
+ *	  frontends and backends.
+ *
+ * Portions Copyright (c) 2018, PostgreSQL Global Development Group
+ *
+ * src/include/replication/basebackup_paths.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef _BASEBACKUP_PATHS_H
+#define _BASEBACKUP_PATHS_H
+
+/*
+ * The contents of these directories are removed or recreated during server
+ * start so they are not included in backups.  The directories themselves are
+ * kept and included as empty to preserve access permissions.
+ */
+static const char *backupExcludeDirs[] =
+{
+	/*
+	 * Skip temporary statistics files. PG_STAT_TMP_DIR must be skipped even
+	 * when stats_temp_directory is set because PGSS_TEXT_FILE is always
+	 * created there.
+	 */
+	PG_STAT_TMP_DIR,
+
+	/*
+	 * It is generally not useful to backup the contents of this directory
+	 * even if the intention is to restore to another master. See backup.sgml
+	 * for a more detailed description.
+	 */
+	PG_REPLSLOT_DIR,
+
+	/* Contents removed on startup, see dsm_cleanup_for_mmap(). */
+	PG_DYNSHMEM_DIR,
+
+	/* Contents removed on startup, see AsyncShmemInit(). */
+	PG_NOTIFY_DIR,
+
+	/*
+	 * Old contents are loaded for possible debugging but are not required for
+	 * normal operation, see OldSerXidInit().
+	 */
+	PG_SERIAL_DIR,
+
+	/* Contents removed on startup, see DeleteAllExportedSnapshotFiles(). */
+	PG_SNAPSHOTS_DIR,
+
+	/* Contents zeroed on startup, see StartupSUBTRANS(). */
+	PG_SUBTRANS_DIR,
+
+	/* end of list */
+	NULL
+};
+
+/*
+ * List of files excluded from base backups.
+ */
+static const char *backupExcludeFiles[] =
+{
+	/* Skip auto conf temporary file. */
+	PG_AUTOCONF_FILENAME_TMP,
+
+	/* Skip current log file temporary file */
+	LOG_METAINFO_DATAFILE_TMP,
+
+	/* Skip relation cache because it is rebuilt on startup */
+	RELCACHE_INIT_FILENAME,
+
+	/*
+	 * If there's a backup_label or tablespace_map file, it belongs to a
+	 * backup started by the user with pg_start_backup().  It is *not* correct
+	 * for this backup.  Our backup_label/tablespace_map is injected into the
+	 * tar separately.
+	 */
+	BACKUP_LABEL_FILE,
+	TABLESPACE_MAP,
+
+	POSTMASTER_PID_FILE,
+	POSTMASTER_OPTS_FILE,
+
+	/* end of list */
+	NULL
+};
+
+#endif							/* _BASEBACKUP_PATHS_H */
-- 
2.16.1

From 9ac82aebd2de8d3821633fcbc0838bd872f2e423 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Mon, 5 Feb 2018 15:48:35 +0900
Subject: [PATCH 5/5] Use filtering list of base backups in pg_rewind to
 exclude more content

After being rewound, a standby to-be-recycled needs to perform recovery
from the last checkpoint where WAL forked after a promotion, which leads
it to automatically remove some files which may have been copied from
the source cluster. Make use of the same filtering list as base backups
to find out what is this data and then remove it. This reduces the
amount of data transferred during a rewind without changing the
usefulness of the operation. This takes advantage of the
newly-introduced basebackup_paths.h to allow pg_rewind to have access to
this data.

Documentation is updated to take into account what is filtered out.
---
 doc/src/sgml/ref/pg_rewind.sgml | 12 ++++++++-
 src/bin/pg_rewind/filemap.c     | 60 +++++++++++++++++++++++++++++++++++------
 2 files changed, 63 insertions(+), 9 deletions(-)

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 8e49249826..ccd0ae505e 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -231,7 +231,17 @@ PostgreSQL documentation
      <para>
       Copy all other files such as <filename>pg_xact</filename> and
       configuration files from the source cluster to the target cluster
-      (everything except the relation files).
+      (everything except the relation files). Similarly to base backups,
+      the contents of the directories <filename>pg_dynshmem/</filename>,
+      <filename>pg_notify/</filename>, <filename>pg_replslot/</filename>,
+      <filename>pg_serial/</filename>, <filename>pg_snapshots/</filename>,
+      <filename>pg_stat_tmp/</filename>, and
+      <filename>pg_subtrans/</filename> are omitted from the data copied
+      from the source cluster. Any file or directory beginning with
+      <filename>pgsql_tmp</filename> is omitted, as well as are
+      <filename>pg_internal.init</filename>,
+      <filename>postmaster.opts</filename> and
+      <filename>postmaster.pid</filename>.
      </para>
     </step>
     <step>
diff --git a/src/bin/pg_rewind/filemap.c b/src/bin/pg_rewind/filemap.c
index 1c462c1041..0a6426e6c2 100644
--- a/src/bin/pg_rewind/filemap.c
+++ b/src/bin/pg_rewind/filemap.c
@@ -21,6 +21,7 @@
 #include "common/string.h"
 #include "catalog/pg_tablespace.h"
 #include "pg_paths.h"
+#include "replication/basebackup_paths.h"
 #include "storage/fd.h"
 
 filemap_t  *filemap = NULL;
@@ -68,15 +69,37 @@ process_source_file(const char *path, file_type_t type, size_t newsize,
 	file_action_t action = FILE_ACTION_NONE;
 	size_t		oldsize = 0;
 	file_entry_t *entry;
+	int			excludeIdx;
 
 	Assert(map->array == NULL);
 
 	/*
-	 * Completely ignore some special files in source and destination.
+	 * Completely ignore some special files in source and destination.  This
+	 * filters willingly any files matching an entry in the list of files to
+	 * filter out.
 	 */
-	if (strcmp(path, POSTMASTER_PID_FILE) == 0 ||
-		strcmp(path, POSTMASTER_OPTS_FILE) == 0)
-		return;
+	for (excludeIdx = 0; backupExcludeFiles[excludeIdx] != NULL; excludeIdx++)
+	{
+		if (strstr(path, backupExcludeFiles[excludeIdx]) != NULL)
+		{
+			pg_log(PG_DEBUG, "file \"%s\" excluded from source file list\n",
+				   path);
+			return;
+		}
+	}
+
+	/*
+	 * ... And ignore some directories.
+	 */
+	for (excludeIdx = 0; backupExcludeDirs[excludeIdx] != NULL; excludeIdx++)
+	{
+		if (strcmp(path, backupExcludeDirs[excludeIdx]) == 0)
+		{
+			pg_log(PG_DEBUG, "directory \"%s\" excluded from source file list\n",
+				   path);
+			return;
+		}
+	}
 
 	/*
 	 * Pretend that pg_wal is a directory, even if it's really a symlink. We
@@ -259,6 +282,7 @@ process_target_file(const char *path, file_type_t type, size_t oldsize,
 	file_entry_t *key_ptr;
 	filemap_t  *map = filemap;
 	file_entry_t *entry;
+	int			excludeIdx;
 
 	snprintf(localpath, sizeof(localpath), "%s/%s", datadir_target, path);
 	if (lstat(localpath, &statbuf) < 0)
@@ -287,11 +311,31 @@ process_target_file(const char *path, file_type_t type, size_t oldsize,
 	}
 
 	/*
-	 * Completely ignore some special files
+	 * Completely ignore some special files.  This filters willingly any files
+	 * matching an entry in the list of files to filter out.
 	 */
-	if (strcmp(path, POSTMASTER_PID_FILE) == 0 ||
-		strcmp(path, POSTMASTER_OPTS_FILE) == 0)
-		return;
+	for (excludeIdx = 0; backupExcludeFiles[excludeIdx] != NULL; excludeIdx++)
+	{
+		if (strstr(path, backupExcludeFiles[excludeIdx]) != NULL)
+		{
+			pg_log(PG_DEBUG, "file \"%s\" excluded from target file list\n",
+				   path);
+			return;
+		}
+	}
+
+	/*
+	 * ... And ignore some directories.
+	 */
+	for (excludeIdx = 0; backupExcludeDirs[excludeIdx] != NULL; excludeIdx++)
+	{
+		if (strcmp(path, backupExcludeDirs[excludeIdx]) == 0)
+		{
+			pg_log(PG_DEBUG, "directory \"%s\" excluded from target file list\n",
+				   path);
+			return;
+		}
+	}
 
 	/*
 	 * Like in process_source_file, pretend that xlog is always a  directory.
-- 
2.16.1

diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 0598212..a7b64bd 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -6460,14 +6460,16 @@ StartupXLOG(void)
 				if (!ReadRecord(xlogreader, checkPoint.redo, LOG, false))
 					ereport(FATAL,
 							(errmsg("could not find redo location referenced by checkpoint record"),
-							 errhint("If you are not restoring from a backup, try removing the file \"%s/backup_label\".", DataDir)));
+							 errhint("If you are not restoring from a backup, try removing the file \"%s/%s\".", 
+									 DataDir, BACKUP_LABEL_FILE)));
 			}
 		}
 		else
 		{
 			ereport(FATAL,
 					(errmsg("could not locate required checkpoint record"),
-					 errhint("If you are not restoring from a backup, try removing the file \"%s/backup_label\".", DataDir)));
+					 errhint("If you are not restoring from a backup, try removing the file \"%s/%s\".",
+							 DataDir, BACKUP_LABEL_FILE)));
 			wasShutdown = false;	/* keep compiler quiet */
 		}
 
diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c
index 6a202fb..22dcbaa 100644
--- a/src/backend/replication/basebackup.c
+++ b/src/backend/replication/basebackup.c
@@ -590,7 +590,7 @@ parse_basebackup_options(List *options, basebackup_options *opt)
 			opt->maxrate = (uint32) maxrate;
 			o_maxrate = true;
 		}
-		else if (strcmp(defel->defname, "tablespace_map") == 0)
+		else if (strcmp(defel->defname, TABLESPACE_MAP) == 0)
 		{
 			if (o_tablespace_map)
 				ereport(ERROR,

From ba4502c9711c7b7933a5ef2186e895c0ae6b4616 Mon Sep 17 00:00:00 2001
From: Michael Paquier <michael@paquier.xyz>
Date: Mon, 5 Feb 2018 15:48:35 +0900
Subject: [PATCH] Add exclude list similar to base backups in pg_rewind

After being rewound, a standby to-be-recycled needs to perform recovery
from the last checkpoint where WAL forked after a promotion, which leads
it to automatically remove some files which may have been copied from
the source cluster. This makes use of the same filtering list as base
backups to find out what is this data and then remove it. This reduces
the amount of data transferred during a rewind without changing the
usefulness of the operation.

Documentation is updated to take into account what is filtered out.
---
 doc/src/sgml/ref/pg_rewind.sgml      |  14 +++-
 src/backend/replication/basebackup.c |   3 +
 src/bin/pg_rewind/filemap.c          | 144 ++++++++++++++++++++++++++++++++---
 3 files changed, 148 insertions(+), 13 deletions(-)

diff --git a/doc/src/sgml/ref/pg_rewind.sgml b/doc/src/sgml/ref/pg_rewind.sgml
index 8e49249826..520d843f0e 100644
--- a/doc/src/sgml/ref/pg_rewind.sgml
+++ b/doc/src/sgml/ref/pg_rewind.sgml
@@ -231,7 +231,19 @@ PostgreSQL documentation
      <para>
       Copy all other files such as <filename>pg_xact</filename> and
       configuration files from the source cluster to the target cluster
-      (everything except the relation files).
+      (everything except the relation files). Similarly to base backups,
+      the contents of the directories <filename>pg_dynshmem/</filename>,
+      <filename>pg_notify/</filename>, <filename>pg_replslot/</filename>,
+      <filename>pg_serial/</filename>, <filename>pg_snapshots/</filename>,
+      <filename>pg_stat_tmp/</filename>, and
+      <filename>pg_subtrans/</filename> are omitted from the data copied
+      from the source cluster. Any file or directory beginning with
+      <filename>pgsql_tmp</filename> is omitted, as well as are
+      <filename>backup_label</filename>,
+      <filename>tablespace_map</filename>,
+      <filename>pg_internal.init</filename>,
+      <filename>postmaster.opts</filename> and
+      <filename>postmaster.pid</filename>.
      </para>
     </step>
     <step>
diff --git a/src/backend/replication/basebackup.c b/src/backend/replication/basebackup.c
index e4c45c5025..902a553ffa 100644
--- a/src/backend/replication/basebackup.c
+++ b/src/backend/replication/basebackup.c
@@ -103,6 +103,9 @@ static TimestampTz throttled_last;
  * The contents of these directories are removed or recreated during server
  * start so they are not included in backups.  The directories themselves are
  * kept and included as empty to preserve access permissions.
+ *
+ * Note: this list should be kept in sync with the filter lists in pg_rewind's
+ * filemap.c.
  */
 static const char *excludeDirContents[] =
 {
diff --git a/src/bin/pg_rewind/filemap.c b/src/bin/pg_rewind/filemap.c
index 6122f177fe..67b01cbdfe 100644
--- a/src/bin/pg_rewind/filemap.c
+++ b/src/bin/pg_rewind/filemap.c
@@ -31,6 +31,83 @@ static char *datasegpath(RelFileNode rnode, ForkNumber forknum,
 static int	path_cmp(const void *a, const void *b);
 static int	final_filemap_cmp(const void *a, const void *b);
 static void filemap_list_to_array(filemap_t *map);
+static bool is_path_excluded(const char *path, const char *type);
+
+/*
+ * The contents of these directories are removed or recreated during server
+ * start so they are not included in data processed by pg_rewind.
+ *
+ * Note: those lists should be kept in sync with what basebackup.c provides.
+ * Some of the values, contrary to what basebackup.c uses, are hardcoded as
+ * they are defined in backend-only headers.  So this list is maintained
+ * with a best effort in mind.
+ */
+static const char *excludeDirContents[] =
+{
+	/*
+	 * Skip temporary statistics files. PG_STAT_TMP_DIR must be skipped even
+	 * when stats_temp_directory is set because PGSS_TEXT_FILE is always
+	 * created there.
+	 */
+	"pg_stat_tmp",	/* defined as PG_STAT_TMP_DIR */
+
+	/*
+	 * It is generally not useful to backup the contents of this directory
+	 * even if the intention is to restore to another master. See backup.sgml
+	 * for a more detailed description.
+	 */
+	"pg_replslot",
+
+	/* Contents removed on startup, see dsm_cleanup_for_mmap(). */
+	"pg_dynshmem",	/* defined as PG_DYNSHMEM_DIR */
+
+	/* Contents removed on startup, see AsyncShmemInit(). */
+	"pg_notify",
+
+	/*
+	 * Old contents are loaded for possible debugging but are not required for
+	 * normal operation, see OldSerXidInit().
+	 */
+	"pg_serial",
+
+	/* Contents removed on startup, see DeleteAllExportedSnapshotFiles(). */
+	"pg_snapshots",
+
+	/* Contents zeroed on startup, see StartupSUBTRANS(). */
+	"pg_subtrans",
+
+	/* end of list */
+	NULL
+};
+
+/*
+ * List of files excluded from filemap processing.
+ */
+static const char *excludeFiles[] =
+{
+	/* Skip auto conf temporary file. */
+	"postgresql.auto.conf.tmp", /* defined as PG_AUTOCONF_FILENAME */
+
+	/* Skip current log file temporary file */
+	"current_logfiles.tmp",		/* defined as LOG_METAINFO_DATAFILE_TMP */
+
+	/* Skip relation cache because it is rebuilt on startup */
+	"pg_internal.init",			/* defined as RELCACHE_INIT_FILENAME */
+
+	/*
+	 * If there's a backup_label or tablespace_map file, it belongs to a
+	 * backup started by the user with pg_start_backup().  It is *not* correct
+	 * for this backup.  Our backup_label is written later on separately.
+	 */
+	"backup_label",				/* defined as BACKUP_LABEL_FILE */
+	"tablespace_map",			/* defined as TABLESPACE_MAP */
+
+	"postmaster.pid",
+	"postmaster.opts",
+
+	/* end of list */
+	NULL
+};
 
 /*
  * Create a new file map (stored in the global pointer "filemap").
@@ -71,11 +148,8 @@ process_source_file(const char *path, file_type_t type, size_t newsize,
 
 	Assert(map->array == NULL);
 
-	/*
-	 * Completely ignore some special files in source and destination.
-	 */
-	if (strcmp(path, "postmaster.pid") == 0 ||
-		strcmp(path, "postmaster.opts") == 0)
+	/* ignore any path matching the exclusion filters */
+	if (is_path_excluded(path, "source"))
 		return;
 
 	/*
@@ -260,6 +334,14 @@ process_target_file(const char *path, file_type_t type, size_t oldsize,
 	filemap_t  *map = filemap;
 	file_entry_t *entry;
 
+	/*
+	 * Ignore any path matching the exclusion filters.  This is not actually
+	 * mandatory for target files, but this does not hurt and let's be
+	 * consistent with the source processing.
+	 */
+	if (is_path_excluded(path, "target"))
+		return;
+
 	snprintf(localpath, sizeof(localpath), "%s/%s", datadir_target, path);
 	if (lstat(localpath, &statbuf) < 0)
 	{
@@ -286,13 +368,6 @@ process_target_file(const char *path, file_type_t type, size_t oldsize,
 		qsort(map->array, map->narray, sizeof(file_entry_t *), path_cmp);
 	}
 
-	/*
-	 * Completely ignore some special files
-	 */
-	if (strcmp(path, "postmaster.pid") == 0 ||
-		strcmp(path, "postmaster.opts") == 0)
-		return;
-
 	/*
 	 * Like in process_source_file, pretend that xlog is always a  directory.
 	 */
@@ -412,6 +487,51 @@ process_block_change(ForkNumber forknum, RelFileNode rnode, BlockNumber blkno)
 	}
 }
 
+/*
+ * Completely ignore some special files in source and destination.  This
+ * filters willingly any files matching an entry in the list of files to
+ * filter out.  The input path is a relative path from a data directory,
+ * so comparisons need to compromise with that and do not check for
+ * slashes before the compared names.  This does not matter in practice
+ * as files listed in the exclusion list do not have names mapping with
+ * existing PostgreSQL internal paths.
+ */
+static bool
+is_path_excluded(const char *path, const char *type)
+{
+	char	localpath[MAXPGPATH];
+	int		excludeIdx;
+
+	/* check individual files... */
+	for (excludeIdx = 0; excludeFiles[excludeIdx] != NULL; excludeIdx++)
+	{
+		if (strstr(path, excludeFiles[excludeIdx]) != NULL)
+		{
+			pg_log(PG_DEBUG, "entry \"%s\" excluded from %s file list\n",
+				   path, type);
+			return true;
+		}
+	}
+
+	/*
+	 * ... And check some directories.  Note that this includes any contents
+	 * within the directories themselves.
+	 */
+	for (excludeIdx = 0; excludeDirContents[excludeIdx] != NULL; excludeIdx++)
+	{
+		snprintf(localpath, sizeof(localpath), "%s/",
+				 excludeDirContents[excludeIdx]);
+		if (strstr(path, localpath) != NULL)
+		{
+			pg_log(PG_DEBUG, "entry \"%s\" excluded from %s file list\n",
+				   path, type);
+			return true;
+		}
+	}
+
+	return false;
+}
+
 /*
  * Convert the linked list of entries in map->first/last to the array,
  * map->array.
-- 
2.16.3

*** a/src/backend/replication/basebackup.c
--- b/src/backend/replication/basebackup.c
***************
*** 103,108 **** static TimestampTz throttled_last;
--- 103,111 ----
   * The contents of these directories are removed or recreated during server
   * start so they are not included in backups.  The directories themselves are
   * kept and included as empty to preserve access permissions.
+  *
+  * Note: this list should be kept in sync with the filter lists in pg_rewind's
+  * filemap.c.
   */
  static const char *excludeDirContents[] =
  {
*** a/src/bin/pg_rewind/filemap.c
--- b/src/bin/pg_rewind/filemap.c
***************
*** 31,36 **** static char *datasegpath(RelFileNode rnode, ForkNumber forknum,
--- 31,113 ----
  static int	path_cmp(const void *a, const void *b);
  static int	final_filemap_cmp(const void *a, const void *b);
  static void filemap_list_to_array(filemap_t *map);
+ static bool check_file_excluded(const char *path, const char *type);
+ 
+ /*
+  * The contents of these directories are removed or recreated during server
+  * start so they are not included in data processed by pg_rewind.
+  *
+  * Note: those lists should be kept in sync with what basebackup.c provides.
+  * Some of the values, contrary to what basebackup.c uses, are hardcoded as
+  * they are defined in backend-only headers.  So this list is maintained
+  * with a best effort in mind.
+  */
+ static const char *excludeDirContents[] =
+ {
+ 	/*
+ 	 * Skip temporary statistics files. PG_STAT_TMP_DIR must be skipped even
+ 	 * when stats_temp_directory is set because PGSS_TEXT_FILE is always
+ 	 * created there.
+ 	 */
+ 	"pg_stat_tmp",	/* defined as PG_STAT_TMP_DIR */
+ 
+ 	/*
+ 	 * It is generally not useful to backup the contents of this directory
+ 	 * even if the intention is to restore to another master. See backup.sgml
+ 	 * for a more detailed description.
+ 	 */
+ 	"pg_replslot",
+ 
+ 	/* Contents removed on startup, see dsm_cleanup_for_mmap(). */
+ 	"pg_dynshmem",	/* defined as PG_DYNSHMEM_DIR */
+ 
+ 	/* Contents removed on startup, see AsyncShmemInit(). */
+ 	"pg_notify",
+ 
+ 	/*
+ 	 * Old contents are loaded for possible debugging but are not required for
+ 	 * normal operation, see OldSerXidInit().
+ 	 */
+ 	"pg_serial",
+ 
+ 	/* Contents removed on startup, see DeleteAllExportedSnapshotFiles(). */
+ 	"pg_snapshots",
+ 
+ 	/* Contents zeroed on startup, see StartupSUBTRANS(). */
+ 	"pg_subtrans",
+ 
+ 	/* end of list */
+ 	NULL
+ };
+ 
+ /*
+  * List of files excluded from filemap processing.
+  */
+ static const char *excludeFiles[] =
+ {
+ 	/* Skip auto conf temporary file. */
+ 	"postgresql.auto.conf.tmp", /* defined as PG_AUTOCONF_FILENAME */
+ 
+ 	/* Skip current log file temporary file */
+ 	"current_logfiles.tmp",		/* defined as LOG_METAINFO_DATAFILE_TMP */
+ 
+ 	/* Skip relation cache because it is rebuilt on startup */
+ 	"pg_internal.init",			/* defined as RELCACHE_INIT_FILENAME */
+ 
+ 	/*
+ 	 * If there's a backup_label or tablespace_map file, it belongs to a
+ 	 * backup started by the user with pg_start_backup().  It is *not* correct
+ 	 * for this backup.  Our backup_label is written later on separately.
+ 	 */
+ 	"backup_label",				/* defined as BACKUP_LABEL_FILE */
+ 	"tablespace_map",			/* defined as TABLESPACE_MAP */
+ 
+ 	"postmaster.pid",
+ 	"postmaster.opts",
+ 
+ 	/* end of list */
+ 	NULL
+ };
  
  /*
   * Create a new file map (stored in the global pointer "filemap").
***************
*** 71,81 **** process_source_file(const char *path, file_type_t type, size_t newsize,
  
  	Assert(map->array == NULL);
  
! 	/*
! 	 * Completely ignore some special files in source and destination.
! 	 */
! 	if (strcmp(path, "postmaster.pid") == 0 ||
! 		strcmp(path, "postmaster.opts") == 0)
  		return;
  
  	/*
--- 148,155 ----
  
  	Assert(map->array == NULL);
  
! 	/* ignore any path matching the exclusion filters */
! 	if (check_file_excluded(path, "source"))
  		return;
  
  	/*
***************
*** 260,265 **** process_target_file(const char *path, file_type_t type, size_t oldsize,
--- 334,347 ----
  	filemap_t  *map = filemap;
  	file_entry_t *entry;
  
+ 	/*
+ 	 * Ignore any path matching the exclusion filters.  This is not actually
+ 	 * mandatory for target files, but this does not hurt and let's be
+ 	 * consistent with the source processing.
+ 	 */
+ 	if (check_file_excluded(path, "target"))
+ 		return;
+ 
  	snprintf(localpath, sizeof(localpath), "%s/%s", datadir_target, path);
  	if (lstat(localpath, &statbuf) < 0)
  	{
***************
*** 287,299 **** process_target_file(const char *path, file_type_t type, size_t oldsize,
  	}
  
  	/*
- 	 * Completely ignore some special files
- 	 */
- 	if (strcmp(path, "postmaster.pid") == 0 ||
- 		strcmp(path, "postmaster.opts") == 0)
- 		return;
- 
- 	/*
  	 * Like in process_source_file, pretend that xlog is always a  directory.
  	 */
  	if (strcmp(path, "pg_wal") == 0 && type == FILE_TYPE_SYMLINK)
--- 369,374 ----
***************
*** 413,418 **** process_block_change(ForkNumber forknum, RelFileNode rnode, BlockNumber blkno)
--- 488,538 ----
  }
  
  /*
+  * Is this the path of file that pg_rewind can skip copying?
+  */
+ static bool
+ check_file_excluded(const char *path, const char *type)
+ {
+ 	char	localpath[MAXPGPATH];
+ 	int		excludeIdx;
+ 	const char	*filename;
+ 
+ 	/* check individual files... */
+ 	for (excludeIdx = 0; excludeFiles[excludeIdx] != NULL; excludeIdx++)
+ 	{
+ 		filename = last_dir_separator(path);
+ 		if (filename == NULL)
+ 			filename = path;
+ 		else
+ 			filename++;
+ 		if (strcmp(filename, excludeFiles[excludeIdx]) == 0)
+ 		{
+ 			pg_log(PG_DEBUG, "entry \"%s\" excluded from %s file list\n",
+ 				   path, type);
+ 			return true;
+ 		}
+ 	}
+ 
+ 	/*
+ 	 * ... And check some directories.  Note that this includes any contents
+ 	 * within the directories themselves.
+ 	 */
+ 	for (excludeIdx = 0; excludeDirContents[excludeIdx] != NULL; excludeIdx++)
+ 	{
+ 		snprintf(localpath, sizeof(localpath), "%s/",
+ 				 excludeDirContents[excludeIdx]);
+ 		if (strstr(path, localpath) == path)
+ 		{
+ 			pg_log(PG_DEBUG, "entry \"%s\" excluded from %s file list\n",
+ 				   path, type);
+ 			return true;
+ 		}
+ 	}
+ 
+ 	return false;
+ }
+ 
+ /*
   * Convert the linked list of entries in map->first/last to the array,
   * map->array.
   */