Adding upstream version 14.5.upstream/14.5upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

20 files changed, 2804 insertions, 0 deletions

diff --git a/src/include/replication/backup_manifest.h b/src/include/replication/backup_manifest.h
new file mode 100644
index 0000000..0991089
--- /dev/null
+++ b/src/include/replication/backup_manifest.h
@@ -0,0 +1,53 @@
+/*-------------------------------------------------------------------------
+ *
+ * backup_manifest.h
+ *	  Routines for generating a backup manifest.
+ *
+ * Portions Copyright (c) 2010-2021, PostgreSQL Global Development Group
+ *
+ * src/include/replication/backup_manifest.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef BACKUP_MANIFEST_H
+#define BACKUP_MANIFEST_H
+
+#include "access/xlogdefs.h"
+#include "common/checksum_helper.h"
+#include "pgtime.h"
+#include "storage/buffile.h"
+
+typedef enum manifest_option
+{
+	MANIFEST_OPTION_YES,
+	MANIFEST_OPTION_NO,
+	MANIFEST_OPTION_FORCE_ENCODE
+} backup_manifest_option;
+
+typedef struct backup_manifest_info
+{
+	BufFile    *buffile;
+	pg_checksum_type checksum_type;
+	pg_cryptohash_ctx *manifest_ctx;
+	uint64		manifest_size;
+	bool		force_encode;
+	bool		first_file;
+	bool		still_checksumming;
+} backup_manifest_info;
+
+extern void InitializeBackupManifest(backup_manifest_info *manifest,
+									 backup_manifest_option want_manifest,
+									 pg_checksum_type manifest_checksum_type);
+extern void AddFileToBackupManifest(backup_manifest_info *manifest,
+									const char *spcoid,
+									const char *pathname, size_t size,
+									pg_time_t mtime,
+									pg_checksum_context *checksum_ctx);
+extern void AddWALInfoToBackupManifest(backup_manifest_info *manifest,
+									   XLogRecPtr startptr,
+									   TimeLineID starttli, XLogRecPtr endptr,
+									   TimeLineID endtli);
+extern void SendBackupManifest(backup_manifest_info *manifest);
+extern void FreeBackupManifest(backup_manifest_info *manifest);
+
+#endif
diff --git a/src/include/replication/basebackup.h b/src/include/replication/basebackup.h
new file mode 100644
index 0000000..379eb41
--- /dev/null
+++ b/src/include/replication/basebackup.h
@@ -0,0 +1,39 @@
+/*-------------------------------------------------------------------------
+ *
+ * basebackup.h
+ *	  Exports from replication/basebackup.c.
+ *
+ * Portions Copyright (c) 2010-2021, PostgreSQL Global Development Group
+ *
+ * src/include/replication/basebackup.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef _BASEBACKUP_H
+#define _BASEBACKUP_H
+
+#include "nodes/replnodes.h"
+
+/*
+ * Minimum and maximum values of MAX_RATE option in BASE_BACKUP command.
+ */
+#define MAX_RATE_LOWER	32
+#define MAX_RATE_UPPER	1048576
+
+/*
+ * Information about a tablespace
+ *
+ * In some usages, "path" can be NULL to denote the PGDATA directory itself.
+ */
+typedef struct
+{
+	char	   *oid;			/* tablespace's OID, as a decimal string */
+	char	   *path;			/* full path to tablespace's directory */
+	char	   *rpath;			/* relative path if it's within PGDATA, else
+								 * NULL */
+	int64		size;			/* total size as sent; -1 if not known */
+} tablespaceinfo;
+
+extern void SendBaseBackup(BaseBackupCmd *cmd);
+
+#endif							/* _BASEBACKUP_H */
diff --git a/src/include/replication/decode.h b/src/include/replication/decode.h
new file mode 100644
index 0000000..6991808
--- /dev/null
+++ b/src/include/replication/decode.h
@@ -0,0 +1,20 @@
+/*-------------------------------------------------------------------------
+ * decode.h
+ *	   PostgreSQL WAL to logical transformation
+ *
+ * Portions Copyright (c) 2012-2021, PostgreSQL Global Development Group
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef DECODE_H
+#define DECODE_H
+
+#include "access/xlogreader.h"
+#include "access/xlogrecord.h"
+#include "replication/logical.h"
+#include "replication/reorderbuffer.h"
+
+void		LogicalDecodingProcessRecord(LogicalDecodingContext *ctx,
+										 XLogReaderState *record);
+
+#endif
diff --git a/src/include/replication/logical.h b/src/include/replication/logical.h
new file mode 100644
index 0000000..25490f2
--- /dev/null
+++ b/src/include/replication/logical.h
@@ -0,0 +1,137 @@
+/*-------------------------------------------------------------------------
+ * logical.h
+ *	   PostgreSQL logical decoding coordination
+ *
+ * Copyright (c) 2012-2021, PostgreSQL Global Development Group
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef LOGICAL_H
+#define LOGICAL_H
+
+#include "access/xlog.h"
+#include "access/xlogreader.h"
+#include "replication/output_plugin.h"
+#include "replication/slot.h"
+
+struct LogicalDecodingContext;
+
+typedef void (*LogicalOutputPluginWriterWrite) (struct LogicalDecodingContext *lr,
+												XLogRecPtr Ptr,
+												TransactionId xid,
+												bool last_write
+);
+
+typedef LogicalOutputPluginWriterWrite LogicalOutputPluginWriterPrepareWrite;
+
+typedef void (*LogicalOutputPluginWriterUpdateProgress) (struct LogicalDecodingContext *lr,
+														 XLogRecPtr Ptr,
+														 TransactionId xid
+);
+
+typedef struct LogicalDecodingContext
+{
+	/* memory context this is all allocated in */
+	MemoryContext context;
+
+	/* The associated replication slot */
+	ReplicationSlot *slot;
+
+	/* infrastructure pieces for decoding */
+	XLogReaderState *reader;
+	struct ReorderBuffer *reorder;
+	struct SnapBuild *snapshot_builder;
+
+	/*
+	 * Marks the logical decoding context as fast forward decoding one. Such a
+	 * context does not have plugin loaded so most of the following properties
+	 * are unused.
+	 */
+	bool		fast_forward;
+
+	/* Are we processing the end LSN of a transaction? */
+	bool		end_xact;
+
+	OutputPluginCallbacks callbacks;
+	OutputPluginOptions options;
+
+	/*
+	 * User specified options
+	 */
+	List	   *output_plugin_options;
+
+	/*
+	 * User-Provided callback for writing/streaming out data.
+	 */
+	LogicalOutputPluginWriterPrepareWrite prepare_write;
+	LogicalOutputPluginWriterWrite write;
+	LogicalOutputPluginWriterUpdateProgress update_progress;
+
+	/*
+	 * Output buffer.
+	 */
+	StringInfo	out;
+
+	/*
+	 * Private data pointer of the output plugin.
+	 */
+	void	   *output_plugin_private;
+
+	/*
+	 * Private data pointer for the data writer.
+	 */
+	void	   *output_writer_private;
+
+	/*
+	 * Does the output plugin support streaming, and is it enabled?
+	 */
+	bool		streaming;
+
+	/*
+	 * Does the output plugin support two-phase decoding, and is it enabled?
+	 */
+	bool		twophase;
+
+	/*
+	 * State for writing output.
+	 */
+	bool		accept_writes;
+	bool		prepared_write;
+	XLogRecPtr	write_location;
+	TransactionId write_xid;
+} LogicalDecodingContext;
+
+
+extern void CheckLogicalDecodingRequirements(void);
+
+extern LogicalDecodingContext *CreateInitDecodingContext(const char *plugin,
+														 List *output_plugin_options,
+														 bool need_full_snapshot,
+														 XLogRecPtr restart_lsn,
+														 XLogReaderRoutine *xl_routine,
+														 LogicalOutputPluginWriterPrepareWrite prepare_write,
+														 LogicalOutputPluginWriterWrite do_write,
+														 LogicalOutputPluginWriterUpdateProgress update_progress);
+extern LogicalDecodingContext *CreateDecodingContext(XLogRecPtr start_lsn,
+													 List *output_plugin_options,
+													 bool fast_forward,
+													 XLogReaderRoutine *xl_routine,
+													 LogicalOutputPluginWriterPrepareWrite prepare_write,
+													 LogicalOutputPluginWriterWrite do_write,
+													 LogicalOutputPluginWriterUpdateProgress update_progress);
+extern void DecodingContextFindStartpoint(LogicalDecodingContext *ctx);
+extern bool DecodingContextReady(LogicalDecodingContext *ctx);
+extern void FreeDecodingContext(LogicalDecodingContext *ctx);
+
+extern void LogicalIncreaseXminForSlot(XLogRecPtr lsn, TransactionId xmin);
+extern void LogicalIncreaseRestartDecodingForSlot(XLogRecPtr current_lsn,
+												  XLogRecPtr restart_lsn);
+extern void LogicalConfirmReceivedLocation(XLogRecPtr lsn);
+
+extern bool filter_prepare_cb_wrapper(LogicalDecodingContext *ctx,
+									  TransactionId xid, const char *gid);
+extern bool filter_by_origin_cb_wrapper(LogicalDecodingContext *ctx, RepOriginId origin_id);
+extern void ResetLogicalStreamingState(void);
+extern void UpdateDecodingStats(LogicalDecodingContext *ctx);
+
+#endif
diff --git a/src/include/replication/logicallauncher.h b/src/include/replication/logicallauncher.h
new file mode 100644
index 0000000..301e494
--- /dev/null
+++ b/src/include/replication/logicallauncher.h
@@ -0,0 +1,29 @@
+/*-------------------------------------------------------------------------
+ *
+ * logicallauncher.h
+ *	  Exports for logical replication launcher.
+ *
+ * Portions Copyright (c) 2016-2021, PostgreSQL Global Development Group
+ *
+ * src/include/replication/logicallauncher.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef LOGICALLAUNCHER_H
+#define LOGICALLAUNCHER_H
+
+extern int	max_logical_replication_workers;
+extern int	max_sync_workers_per_subscription;
+
+extern void ApplyLauncherRegister(void);
+extern void ApplyLauncherMain(Datum main_arg);
+
+extern Size ApplyLauncherShmemSize(void);
+extern void ApplyLauncherShmemInit(void);
+
+extern void ApplyLauncherWakeupAtCommit(void);
+extern void AtEOXact_ApplyLauncher(bool isCommit);
+
+extern bool IsLogicalLauncher(void);
+
+#endif							/* LOGICALLAUNCHER_H */
diff --git a/src/include/replication/logicalproto.h b/src/include/replication/logicalproto.h
new file mode 100644
index 0000000..55b90c0
--- /dev/null
+++ b/src/include/replication/logicalproto.h
@@ -0,0 +1,177 @@
+/*-------------------------------------------------------------------------
+ *
+ * logicalproto.h
+ *		logical replication protocol
+ *
+ * Copyright (c) 2015-2021, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *		src/include/replication/logicalproto.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef LOGICAL_PROTO_H
+#define LOGICAL_PROTO_H
+
+#include "replication/reorderbuffer.h"
+#include "utils/rel.h"
+
+/*
+ * Protocol capabilities
+ *
+ * LOGICALREP_PROTO_VERSION_NUM is our native protocol.
+ * LOGICALREP_PROTO_MAX_VERSION_NUM is the greatest version we can support.
+ * LOGICALREP_PROTO_MIN_VERSION_NUM is the oldest version we
+ * have backwards compatibility for. The client requests protocol version at
+ * connect time.
+ *
+ * LOGICALREP_PROTO_STREAM_VERSION_NUM is the minimum protocol version with
+ * support for streaming large transactions.
+ */
+#define LOGICALREP_PROTO_MIN_VERSION_NUM 1
+#define LOGICALREP_PROTO_VERSION_NUM 1
+#define LOGICALREP_PROTO_STREAM_VERSION_NUM 2
+#define LOGICALREP_PROTO_MAX_VERSION_NUM LOGICALREP_PROTO_STREAM_VERSION_NUM
+
+/*
+ * Logical message types
+ *
+ * Used by logical replication wire protocol.
+ *
+ * Note: though this is an enum, the values are used to identify message types
+ * in logical replication protocol, which uses a single byte to identify a
+ * message type. Hence the values should be single-byte wide and preferably
+ * human-readable characters.
+ */
+typedef enum LogicalRepMsgType
+{
+	LOGICAL_REP_MSG_BEGIN = 'B',
+	LOGICAL_REP_MSG_COMMIT = 'C',
+	LOGICAL_REP_MSG_ORIGIN = 'O',
+	LOGICAL_REP_MSG_INSERT = 'I',
+	LOGICAL_REP_MSG_UPDATE = 'U',
+	LOGICAL_REP_MSG_DELETE = 'D',
+	LOGICAL_REP_MSG_TRUNCATE = 'T',
+	LOGICAL_REP_MSG_RELATION = 'R',
+	LOGICAL_REP_MSG_TYPE = 'Y',
+	LOGICAL_REP_MSG_MESSAGE = 'M',
+	LOGICAL_REP_MSG_STREAM_START = 'S',
+	LOGICAL_REP_MSG_STREAM_END = 'E',
+	LOGICAL_REP_MSG_STREAM_COMMIT = 'c',
+	LOGICAL_REP_MSG_STREAM_ABORT = 'A'
+} LogicalRepMsgType;
+
+/*
+ * This struct stores a tuple received via logical replication.
+ * Keep in mind that the columns correspond to the *remote* table.
+ */
+typedef struct LogicalRepTupleData
+{
+	/* Array of StringInfos, one per column; some may be unused */
+	StringInfoData *colvalues;
+	/* Array of markers for null/unchanged/text/binary, one per column */
+	char	   *colstatus;
+	/* Length of above arrays */
+	int			ncols;
+} LogicalRepTupleData;
+
+/* Possible values for LogicalRepTupleData.colstatus[colnum] */
+/* These values are also used in the on-the-wire protocol */
+#define LOGICALREP_COLUMN_NULL		'n'
+#define LOGICALREP_COLUMN_UNCHANGED	'u'
+#define LOGICALREP_COLUMN_TEXT		't'
+#define LOGICALREP_COLUMN_BINARY	'b' /* added in PG14 */
+
+typedef uint32 LogicalRepRelId;
+
+/* Relation information */
+typedef struct LogicalRepRelation
+{
+	/* Info coming from the remote side. */
+	LogicalRepRelId remoteid;	/* unique id of the relation */
+	char	   *nspname;		/* schema name */
+	char	   *relname;		/* relation name */
+	int			natts;			/* number of columns */
+	char	  **attnames;		/* column names */
+	Oid		   *atttyps;		/* column types */
+	char		replident;		/* replica identity */
+	char		relkind;		/* remote relation kind */
+	Bitmapset  *attkeys;		/* Bitmap of key columns */
+} LogicalRepRelation;
+
+/* Type mapping info */
+typedef struct LogicalRepTyp
+{
+	Oid			remoteid;		/* unique id of the remote type */
+	char	   *nspname;		/* schema name of remote type */
+	char	   *typname;		/* name of the remote type */
+} LogicalRepTyp;
+
+/* Transaction info */
+typedef struct LogicalRepBeginData
+{
+	XLogRecPtr	final_lsn;
+	TimestampTz committime;
+	TransactionId xid;
+} LogicalRepBeginData;
+
+typedef struct LogicalRepCommitData
+{
+	XLogRecPtr	commit_lsn;
+	XLogRecPtr	end_lsn;
+	TimestampTz committime;
+} LogicalRepCommitData;
+
+extern void logicalrep_write_begin(StringInfo out, ReorderBufferTXN *txn);
+extern void logicalrep_read_begin(StringInfo in,
+								  LogicalRepBeginData *begin_data);
+extern void logicalrep_write_commit(StringInfo out, ReorderBufferTXN *txn,
+									XLogRecPtr commit_lsn);
+extern void logicalrep_read_commit(StringInfo in,
+								   LogicalRepCommitData *commit_data);
+extern void logicalrep_write_origin(StringInfo out, const char *origin,
+									XLogRecPtr origin_lsn);
+extern char *logicalrep_read_origin(StringInfo in, XLogRecPtr *origin_lsn);
+extern void logicalrep_write_insert(StringInfo out, TransactionId xid,
+									Relation rel, HeapTuple newtuple,
+									bool binary);
+extern LogicalRepRelId logicalrep_read_insert(StringInfo in, LogicalRepTupleData *newtup);
+extern void logicalrep_write_update(StringInfo out, TransactionId xid,
+									Relation rel, HeapTuple oldtuple,
+									HeapTuple newtuple, bool binary);
+extern LogicalRepRelId logicalrep_read_update(StringInfo in,
+											  bool *has_oldtuple, LogicalRepTupleData *oldtup,
+											  LogicalRepTupleData *newtup);
+extern void logicalrep_write_delete(StringInfo out, TransactionId xid,
+									Relation rel, HeapTuple oldtuple,
+									bool binary);
+extern LogicalRepRelId logicalrep_read_delete(StringInfo in,
+											  LogicalRepTupleData *oldtup);
+extern void logicalrep_write_truncate(StringInfo out, TransactionId xid,
+									  int nrelids, Oid relids[],
+									  bool cascade, bool restart_seqs);
+extern List *logicalrep_read_truncate(StringInfo in,
+									  bool *cascade, bool *restart_seqs);
+extern void logicalrep_write_message(StringInfo out, TransactionId xid, XLogRecPtr lsn,
+									 bool transactional, const char *prefix, Size sz, const char *message);
+extern void logicalrep_write_rel(StringInfo out, TransactionId xid,
+								 Relation rel);
+extern LogicalRepRelation *logicalrep_read_rel(StringInfo in);
+extern void logicalrep_write_typ(StringInfo out, TransactionId xid,
+								 Oid typoid);
+extern void logicalrep_read_typ(StringInfo out, LogicalRepTyp *ltyp);
+extern void logicalrep_write_stream_start(StringInfo out, TransactionId xid,
+										  bool first_segment);
+extern TransactionId logicalrep_read_stream_start(StringInfo in,
+												  bool *first_segment);
+extern void logicalrep_write_stream_stop(StringInfo out);
+extern void logicalrep_write_stream_commit(StringInfo out, ReorderBufferTXN *txn,
+										   XLogRecPtr commit_lsn);
+extern TransactionId logicalrep_read_stream_commit(StringInfo out,
+												   LogicalRepCommitData *commit_data);
+extern void logicalrep_write_stream_abort(StringInfo out, TransactionId xid,
+										  TransactionId subxid);
+extern void logicalrep_read_stream_abort(StringInfo in, TransactionId *xid,
+										 TransactionId *subxid);
+
+#endif							/* LOGICAL_PROTO_H */
diff --git a/src/include/replication/logicalrelation.h b/src/include/replication/logicalrelation.h
new file mode 100644
index 0000000..10f9149
--- /dev/null
+++ b/src/include/replication/logicalrelation.h
@@ -0,0 +1,50 @@
+/*-------------------------------------------------------------------------
+ *
+ * logicalrelation.h
+ *	  Relation definitions for logical replication relation mapping.
+ *
+ * Portions Copyright (c) 2016-2021, PostgreSQL Global Development Group
+ *
+ * src/include/replication/logicalrelation.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef LOGICALRELATION_H
+#define LOGICALRELATION_H
+
+#include "access/attmap.h"
+#include "replication/logicalproto.h"
+
+typedef struct LogicalRepRelMapEntry
+{
+	LogicalRepRelation remoterel;	/* key is remoterel.remoteid */
+
+	/*
+	 * Validity flag -- when false, revalidate all derived info at next
+	 * logicalrep_rel_open.  (While the localrel is open, we assume our lock
+	 * on that rel ensures the info remains good.)
+	 */
+	bool		localrelvalid;
+
+	/* Mapping to local relation. */
+	Oid			localreloid;	/* local relation id */
+	Relation	localrel;		/* relcache entry (NULL when closed) */
+	AttrMap    *attrmap;		/* map of local attributes to remote ones */
+	bool		updatable;		/* Can apply updates/deletes? */
+
+	/* Sync state. */
+	char		state;
+	XLogRecPtr	statelsn;
+} LogicalRepRelMapEntry;
+
+extern void logicalrep_relmap_update(LogicalRepRelation *remoterel);
+extern void logicalrep_partmap_reset_relmap(LogicalRepRelation *remoterel);
+
+extern LogicalRepRelMapEntry *logicalrep_rel_open(LogicalRepRelId remoteid,
+												  LOCKMODE lockmode);
+extern LogicalRepRelMapEntry *logicalrep_partition_open(LogicalRepRelMapEntry *root,
+														Relation partrel, AttrMap *map);
+extern void logicalrep_rel_close(LogicalRepRelMapEntry *rel,
+								 LOCKMODE lockmode);
+
+#endif							/* LOGICALRELATION_H */
diff --git a/src/include/replication/logicalworker.h b/src/include/replication/logicalworker.h
new file mode 100644
index 0000000..2ad61a0
--- /dev/null
+++ b/src/include/replication/logicalworker.h
@@ -0,0 +1,19 @@
+/*-------------------------------------------------------------------------
+ *
+ * logicalworker.h
+ *	  Exports for logical replication workers.
+ *
+ * Portions Copyright (c) 2016-2021, PostgreSQL Global Development Group
+ *
+ * src/include/replication/logicalworker.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef LOGICALWORKER_H
+#define LOGICALWORKER_H
+
+extern void ApplyWorkerMain(Datum main_arg);
+
+extern bool IsLogicalWorker(void);
+
+#endif							/* LOGICALWORKER_H */
diff --git a/src/include/replication/message.h b/src/include/replication/message.h
new file mode 100644
index 0000000..d3fb324
--- /dev/null
+++ b/src/include/replication/message.h
@@ -0,0 +1,41 @@
+/*-------------------------------------------------------------------------
+ * message.h
+ *	   Exports from replication/logical/message.c
+ *
+ * Copyright (c) 2013-2021, PostgreSQL Global Development Group
+ *
+ * src/include/replication/message.h
+ *-------------------------------------------------------------------------
+ */
+#ifndef PG_LOGICAL_MESSAGE_H
+#define PG_LOGICAL_MESSAGE_H
+
+#include "access/xlog.h"
+#include "access/xlogdefs.h"
+#include "access/xlogreader.h"
+
+/*
+ * Generic logical decoding message wal record.
+ */
+typedef struct xl_logical_message
+{
+	Oid			dbId;			/* database Oid emitted from */
+	bool		transactional;	/* is message transactional? */
+	Size		prefix_size;	/* length of prefix */
+	Size		message_size;	/* size of the message */
+	/* payload, including null-terminated prefix of length prefix_size */
+	char		message[FLEXIBLE_ARRAY_MEMBER];
+} xl_logical_message;
+
+#define SizeOfLogicalMessage	(offsetof(xl_logical_message, message))
+
+extern XLogRecPtr LogLogicalMessage(const char *prefix, const char *message,
+									size_t size, bool transactional);
+
+/* RMGR API*/
+#define XLOG_LOGICAL_MESSAGE	0x00
+void		logicalmsg_redo(XLogReaderState *record);
+void		logicalmsg_desc(StringInfo buf, XLogReaderState *record);
+const char *logicalmsg_identify(uint8 info);
+
+#endif							/* PG_LOGICAL_MESSAGE_H */
diff --git a/src/include/replication/origin.h b/src/include/replication/origin.h
new file mode 100644
index 0000000..cd0b3e1
--- /dev/null
+++ b/src/include/replication/origin.h
@@ -0,0 +1,73 @@
+/*-------------------------------------------------------------------------
+ * origin.h
+ *	   Exports from replication/logical/origin.c
+ *
+ * Copyright (c) 2013-2021, PostgreSQL Global Development Group
+ *
+ * src/include/replication/origin.h
+ *-------------------------------------------------------------------------
+ */
+#ifndef PG_ORIGIN_H
+#define PG_ORIGIN_H
+
+#include "access/xlog.h"
+#include "access/xlogdefs.h"
+#include "access/xlogreader.h"
+#include "catalog/pg_replication_origin.h"
+
+typedef struct xl_replorigin_set
+{
+	XLogRecPtr	remote_lsn;
+	RepOriginId node_id;
+	bool		force;
+} xl_replorigin_set;
+
+typedef struct xl_replorigin_drop
+{
+	RepOriginId node_id;
+} xl_replorigin_drop;
+
+#define XLOG_REPLORIGIN_SET		0x00
+#define XLOG_REPLORIGIN_DROP		0x10
+
+#define InvalidRepOriginId 0
+#define DoNotReplicateId PG_UINT16_MAX
+
+extern PGDLLIMPORT RepOriginId replorigin_session_origin;
+extern PGDLLIMPORT XLogRecPtr replorigin_session_origin_lsn;
+extern PGDLLIMPORT TimestampTz replorigin_session_origin_timestamp;
+
+/* API for querying & manipulating replication origins */
+extern RepOriginId replorigin_by_name(const char *name, bool missing_ok);
+extern RepOriginId replorigin_create(const char *name);
+extern void replorigin_drop_by_name(const char *name, bool missing_ok, bool nowait);
+extern bool replorigin_by_oid(RepOriginId roident, bool missing_ok,
+							  char **roname);
+
+/* API for querying & manipulating replication progress tracking */
+extern void replorigin_advance(RepOriginId node,
+							   XLogRecPtr remote_commit,
+							   XLogRecPtr local_commit,
+							   bool go_backward, bool wal_log);
+extern XLogRecPtr replorigin_get_progress(RepOriginId node, bool flush);
+
+extern void replorigin_session_advance(XLogRecPtr remote_commit,
+									   XLogRecPtr local_commit);
+extern void replorigin_session_setup(RepOriginId node);
+extern void replorigin_session_reset(void);
+extern XLogRecPtr replorigin_session_get_progress(bool flush);
+
+/* Checkpoint/Startup integration */
+extern void CheckPointReplicationOrigin(void);
+extern void StartupReplicationOrigin(void);
+
+/* WAL logging */
+void		replorigin_redo(XLogReaderState *record);
+void		replorigin_desc(StringInfo buf, XLogReaderState *record);
+const char *replorigin_identify(uint8 info);
+
+/* shared memory allocation */
+extern Size ReplicationOriginShmemSize(void);
+extern void ReplicationOriginShmemInit(void);
+
+#endif							/* PG_ORIGIN_H */
diff --git a/src/include/replication/output_plugin.h b/src/include/replication/output_plugin.h
new file mode 100644
index 0000000..810495e
--- /dev/null
+++ b/src/include/replication/output_plugin.h
@@ -0,0 +1,248 @@
+/*-------------------------------------------------------------------------
+ * output_plugin.h
+ *	   PostgreSQL Logical Decode Plugin Interface
+ *
+ * Copyright (c) 2012-2021, PostgreSQL Global Development Group
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef OUTPUT_PLUGIN_H
+#define OUTPUT_PLUGIN_H
+
+#include "replication/reorderbuffer.h"
+
+struct LogicalDecodingContext;
+struct OutputPluginCallbacks;
+
+typedef enum OutputPluginOutputType
+{
+	OUTPUT_PLUGIN_BINARY_OUTPUT,
+	OUTPUT_PLUGIN_TEXTUAL_OUTPUT
+} OutputPluginOutputType;
+
+/*
+ * Options set by the output plugin, in the startup callback.
+ */
+typedef struct OutputPluginOptions
+{
+	OutputPluginOutputType output_type;
+	bool		receive_rewrites;
+} OutputPluginOptions;
+
+/*
+ * Type of the shared library symbol _PG_output_plugin_init that is looked up
+ * when loading an output plugin shared library.
+ */
+typedef void (*LogicalOutputPluginInit) (struct OutputPluginCallbacks *cb);
+
+/*
+ * Callback that gets called in a user-defined plugin. ctx->private_data can
+ * be set to some private data.
+ *
+ * "is_init" will be set to "true" if the decoding slot just got defined. When
+ * the same slot is used from there one, it will be "false".
+ */
+typedef void (*LogicalDecodeStartupCB) (struct LogicalDecodingContext *ctx,
+										OutputPluginOptions *options,
+										bool is_init);
+
+/*
+ * Callback called for every (explicit or implicit) BEGIN of a successful
+ * transaction.
+ */
+typedef void (*LogicalDecodeBeginCB) (struct LogicalDecodingContext *ctx,
+									  ReorderBufferTXN *txn);
+
+/*
+ * Callback for every individual change in a successful transaction.
+ */
+typedef void (*LogicalDecodeChangeCB) (struct LogicalDecodingContext *ctx,
+									   ReorderBufferTXN *txn,
+									   Relation relation,
+									   ReorderBufferChange *change);
+
+/*
+ * Callback for every TRUNCATE in a successful transaction.
+ */
+typedef void (*LogicalDecodeTruncateCB) (struct LogicalDecodingContext *ctx,
+										 ReorderBufferTXN *txn,
+										 int nrelations,
+										 Relation relations[],
+										 ReorderBufferChange *change);
+
+/*
+ * Called for every (explicit or implicit) COMMIT of a successful transaction.
+ */
+typedef void (*LogicalDecodeCommitCB) (struct LogicalDecodingContext *ctx,
+									   ReorderBufferTXN *txn,
+									   XLogRecPtr commit_lsn);
+
+/*
+ * Called for the generic logical decoding messages.
+ */
+typedef void (*LogicalDecodeMessageCB) (struct LogicalDecodingContext *ctx,
+										ReorderBufferTXN *txn,
+										XLogRecPtr message_lsn,
+										bool transactional,
+										const char *prefix,
+										Size message_size,
+										const char *message);
+
+/*
+ * Filter changes by origin.
+ */
+typedef bool (*LogicalDecodeFilterByOriginCB) (struct LogicalDecodingContext *ctx,
+											   RepOriginId origin_id);
+
+/*
+ * Called to shutdown an output plugin.
+ */
+typedef void (*LogicalDecodeShutdownCB) (struct LogicalDecodingContext *ctx);
+
+/*
+ * Called before decoding of PREPARE record to decide whether this
+ * transaction should be decoded with separate calls to prepare and
+ * commit_prepared/rollback_prepared callbacks or wait till COMMIT PREPARED
+ * and sent as usual transaction.
+ */
+typedef bool (*LogicalDecodeFilterPrepareCB) (struct LogicalDecodingContext *ctx,
+											  TransactionId xid,
+											  const char *gid);
+
+/*
+ * Callback called for every BEGIN of a prepared trnsaction.
+ */
+typedef void (*LogicalDecodeBeginPrepareCB) (struct LogicalDecodingContext *ctx,
+											 ReorderBufferTXN *txn);
+
+/*
+ * Called for PREPARE record unless it was filtered by filter_prepare()
+ * callback.
+ */
+typedef void (*LogicalDecodePrepareCB) (struct LogicalDecodingContext *ctx,
+										ReorderBufferTXN *txn,
+										XLogRecPtr prepare_lsn);
+
+/*
+ * Called for COMMIT PREPARED.
+ */
+typedef void (*LogicalDecodeCommitPreparedCB) (struct LogicalDecodingContext *ctx,
+											   ReorderBufferTXN *txn,
+											   XLogRecPtr commit_lsn);
+
+/*
+ * Called for ROLLBACK PREPARED.
+ */
+typedef void (*LogicalDecodeRollbackPreparedCB) (struct LogicalDecodingContext *ctx,
+												 ReorderBufferTXN *txn,
+												 XLogRecPtr prepare_end_lsn,
+												 TimestampTz prepare_time);
+
+
+/*
+ * Called when starting to stream a block of changes from in-progress
+ * transaction (may be called repeatedly, if it's streamed in multiple
+ * chunks).
+ */
+typedef void (*LogicalDecodeStreamStartCB) (struct LogicalDecodingContext *ctx,
+											ReorderBufferTXN *txn);
+
+/*
+ * Called when stopping to stream a block of changes from in-progress
+ * transaction to a remote node (may be called repeatedly, if it's streamed
+ * in multiple chunks).
+ */
+typedef void (*LogicalDecodeStreamStopCB) (struct LogicalDecodingContext *ctx,
+										   ReorderBufferTXN *txn);
+
+/*
+ * Called to discard changes streamed to remote node from in-progress
+ * transaction.
+ */
+typedef void (*LogicalDecodeStreamAbortCB) (struct LogicalDecodingContext *ctx,
+											ReorderBufferTXN *txn,
+											XLogRecPtr abort_lsn);
+
+/*
+ * Called to prepare changes streamed to remote node from in-progress
+ * transaction. This is called as part of a two-phase commit.
+ */
+typedef void (*LogicalDecodeStreamPrepareCB) (struct LogicalDecodingContext *ctx,
+											  ReorderBufferTXN *txn,
+											  XLogRecPtr prepare_lsn);
+
+/*
+ * Called to apply changes streamed to remote node from in-progress
+ * transaction.
+ */
+typedef void (*LogicalDecodeStreamCommitCB) (struct LogicalDecodingContext *ctx,
+											 ReorderBufferTXN *txn,
+											 XLogRecPtr commit_lsn);
+
+/*
+ * Callback for streaming individual changes from in-progress transactions.
+ */
+typedef void (*LogicalDecodeStreamChangeCB) (struct LogicalDecodingContext *ctx,
+											 ReorderBufferTXN *txn,
+											 Relation relation,
+											 ReorderBufferChange *change);
+
+/*
+ * Callback for streaming generic logical decoding messages from in-progress
+ * transactions.
+ */
+typedef void (*LogicalDecodeStreamMessageCB) (struct LogicalDecodingContext *ctx,
+											  ReorderBufferTXN *txn,
+											  XLogRecPtr message_lsn,
+											  bool transactional,
+											  const char *prefix,
+											  Size message_size,
+											  const char *message);
+
+/*
+ * Callback for streaming truncates from in-progress transactions.
+ */
+typedef void (*LogicalDecodeStreamTruncateCB) (struct LogicalDecodingContext *ctx,
+											   ReorderBufferTXN *txn,
+											   int nrelations,
+											   Relation relations[],
+											   ReorderBufferChange *change);
+
+/*
+ * Output plugin callbacks
+ */
+typedef struct OutputPluginCallbacks
+{
+	LogicalDecodeStartupCB startup_cb;
+	LogicalDecodeBeginCB begin_cb;
+	LogicalDecodeChangeCB change_cb;
+	LogicalDecodeTruncateCB truncate_cb;
+	LogicalDecodeCommitCB commit_cb;
+	LogicalDecodeMessageCB message_cb;
+	LogicalDecodeFilterByOriginCB filter_by_origin_cb;
+	LogicalDecodeShutdownCB shutdown_cb;
+
+	/* streaming of changes at prepare time */
+	LogicalDecodeFilterPrepareCB filter_prepare_cb;
+	LogicalDecodeBeginPrepareCB begin_prepare_cb;
+	LogicalDecodePrepareCB prepare_cb;
+	LogicalDecodeCommitPreparedCB commit_prepared_cb;
+	LogicalDecodeRollbackPreparedCB rollback_prepared_cb;
+
+	/* streaming of changes */
+	LogicalDecodeStreamStartCB stream_start_cb;
+	LogicalDecodeStreamStopCB stream_stop_cb;
+	LogicalDecodeStreamAbortCB stream_abort_cb;
+	LogicalDecodeStreamPrepareCB stream_prepare_cb;
+	LogicalDecodeStreamCommitCB stream_commit_cb;
+	LogicalDecodeStreamChangeCB stream_change_cb;
+	LogicalDecodeStreamMessageCB stream_message_cb;
+	LogicalDecodeStreamTruncateCB stream_truncate_cb;
+} OutputPluginCallbacks;
+
+/* Functions in replication/logical/logical.c */
+extern void OutputPluginPrepareWrite(struct LogicalDecodingContext *ctx, bool last_write);
+extern void OutputPluginWrite(struct LogicalDecodingContext *ctx, bool last_write);
+extern void OutputPluginUpdateProgress(struct LogicalDecodingContext *ctx);
+
+#endif							/* OUTPUT_PLUGIN_H */
diff --git a/src/include/replication/pgoutput.h b/src/include/replication/pgoutput.h
new file mode 100644
index 0000000..51e7c03
--- /dev/null
+++ b/src/include/replication/pgoutput.h
@@ -0,0 +1,32 @@
+/*-------------------------------------------------------------------------
+ *
+ * pgoutput.h
+ *		Logical Replication output plugin
+ *
+ * Copyright (c) 2015-2021, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *		pgoutput.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef PGOUTPUT_H
+#define PGOUTPUT_H
+
+#include "nodes/pg_list.h"
+
+typedef struct PGOutputData
+{
+	MemoryContext context;		/* private memory context for transient
+								 * allocations */
+
+	/* client-supplied info: */
+	uint32		protocol_version;
+	List	   *publication_names;
+	List	   *publications;
+	bool		binary;
+	bool		streaming;
+	bool		messages;
+} PGOutputData;
+
+#endif							/* PGOUTPUT_H */
diff --git a/src/include/replication/reorderbuffer.h b/src/include/replication/reorderbuffer.h
new file mode 100644
index 0000000..ba257d8
--- /dev/null
+++ b/src/include/replication/reorderbuffer.h
@@ -0,0 +1,681 @@
+/*
+ * reorderbuffer.h
+ *	  PostgreSQL logical replay/reorder buffer management.
+ *
+ * Copyright (c) 2012-2021, PostgreSQL Global Development Group
+ *
+ * src/include/replication/reorderbuffer.h
+ */
+#ifndef REORDERBUFFER_H
+#define REORDERBUFFER_H
+
+#include "access/htup_details.h"
+#include "lib/ilist.h"
+#include "storage/sinval.h"
+#include "utils/hsearch.h"
+#include "utils/relcache.h"
+#include "utils/snapshot.h"
+#include "utils/timestamp.h"
+
+extern PGDLLIMPORT int logical_decoding_work_mem;
+
+/* an individual tuple, stored in one chunk of memory */
+typedef struct ReorderBufferTupleBuf
+{
+	/* position in preallocated list */
+	slist_node	node;
+
+	/* tuple header, the interesting bit for users of logical decoding */
+	HeapTupleData tuple;
+
+	/* pre-allocated size of tuple buffer, different from tuple size */
+	Size		alloc_tuple_size;
+
+	/* actual tuple data follows */
+} ReorderBufferTupleBuf;
+
+/* pointer to the data stored in a TupleBuf */
+#define ReorderBufferTupleBufData(p) \
+	((HeapTupleHeader) MAXALIGN(((char *) p) + sizeof(ReorderBufferTupleBuf)))
+
+/*
+ * Types of the change passed to a 'change' callback.
+ *
+ * For efficiency and simplicity reasons we want to keep Snapshots, CommandIds
+ * and ComboCids in the same list with the user visible INSERT/UPDATE/DELETE
+ * changes. Users of the decoding facilities will never see changes with
+ * *_INTERNAL_* actions.
+ *
+ * The INTERNAL_SPEC_INSERT and INTERNAL_SPEC_CONFIRM, and INTERNAL_SPEC_ABORT
+ * changes concern "speculative insertions", their confirmation, and abort
+ * respectively.  They're used by INSERT .. ON CONFLICT .. UPDATE.  Users of
+ * logical decoding don't have to care about these.
+ */
+enum ReorderBufferChangeType
+{
+	REORDER_BUFFER_CHANGE_INSERT,
+	REORDER_BUFFER_CHANGE_UPDATE,
+	REORDER_BUFFER_CHANGE_DELETE,
+	REORDER_BUFFER_CHANGE_MESSAGE,
+	REORDER_BUFFER_CHANGE_INVALIDATION,
+	REORDER_BUFFER_CHANGE_INTERNAL_SNAPSHOT,
+	REORDER_BUFFER_CHANGE_INTERNAL_COMMAND_ID,
+	REORDER_BUFFER_CHANGE_INTERNAL_TUPLECID,
+	REORDER_BUFFER_CHANGE_INTERNAL_SPEC_INSERT,
+	REORDER_BUFFER_CHANGE_INTERNAL_SPEC_CONFIRM,
+	REORDER_BUFFER_CHANGE_INTERNAL_SPEC_ABORT,
+	REORDER_BUFFER_CHANGE_TRUNCATE
+};
+
+/* forward declaration */
+struct ReorderBufferTXN;
+
+/*
+ * a single 'change', can be an insert (with one tuple), an update (old, new),
+ * or a delete (old).
+ *
+ * The same struct is also used internally for other purposes but that should
+ * never be visible outside reorderbuffer.c.
+ */
+typedef struct ReorderBufferChange
+{
+	XLogRecPtr	lsn;
+
+	/* The type of change. */
+	enum ReorderBufferChangeType action;
+
+	/* Transaction this change belongs to. */
+	struct ReorderBufferTXN *txn;
+
+	RepOriginId origin_id;
+
+	/*
+	 * Context data for the change. Which part of the union is valid depends
+	 * on action.
+	 */
+	union
+	{
+		/* Old, new tuples when action == *_INSERT|UPDATE|DELETE */
+		struct
+		{
+			/* relation that has been changed */
+			RelFileNode relnode;
+
+			/* no previously reassembled toast chunks are necessary anymore */
+			bool		clear_toast_afterwards;
+
+			/* valid for DELETE || UPDATE */
+			ReorderBufferTupleBuf *oldtuple;
+			/* valid for INSERT || UPDATE */
+			ReorderBufferTupleBuf *newtuple;
+		}			tp;
+
+		/*
+		 * Truncate data for REORDER_BUFFER_CHANGE_TRUNCATE representing one
+		 * set of relations to be truncated.
+		 */
+		struct
+		{
+			Size		nrelids;
+			bool		cascade;
+			bool		restart_seqs;
+			Oid		   *relids;
+		}			truncate;
+
+		/* Message with arbitrary data. */
+		struct
+		{
+			char	   *prefix;
+			Size		message_size;
+			char	   *message;
+		}			msg;
+
+		/* New snapshot, set when action == *_INTERNAL_SNAPSHOT */
+		Snapshot	snapshot;
+
+		/*
+		 * New command id for existing snapshot in a catalog changing tx. Set
+		 * when action == *_INTERNAL_COMMAND_ID.
+		 */
+		CommandId	command_id;
+
+		/*
+		 * New cid mapping for catalog changing transaction, set when action
+		 * == *_INTERNAL_TUPLECID.
+		 */
+		struct
+		{
+			RelFileNode node;
+			ItemPointerData tid;
+			CommandId	cmin;
+			CommandId	cmax;
+			CommandId	combocid;
+		}			tuplecid;
+
+		/* Invalidation. */
+		struct
+		{
+			uint32		ninvalidations; /* Number of messages */
+			SharedInvalidationMessage *invalidations;	/* invalidation message */
+		}			inval;
+	}			data;
+
+	/*
+	 * While in use this is how a change is linked into a transactions,
+	 * otherwise it's the preallocated list.
+	 */
+	dlist_node	node;
+} ReorderBufferChange;
+
+/* ReorderBufferTXN txn_flags */
+#define RBTXN_HAS_CATALOG_CHANGES 0x0001
+#define RBTXN_IS_SUBXACT          0x0002
+#define RBTXN_IS_SERIALIZED       0x0004
+#define RBTXN_IS_SERIALIZED_CLEAR 0x0008
+#define RBTXN_IS_STREAMED         0x0010
+#define RBTXN_HAS_PARTIAL_CHANGE  0x0020
+#define RBTXN_PREPARE             0x0040
+#define RBTXN_SKIPPED_PREPARE	  0x0080
+
+/* Does the transaction have catalog changes? */
+#define rbtxn_has_catalog_changes(txn) \
+( \
+	 ((txn)->txn_flags & RBTXN_HAS_CATALOG_CHANGES) != 0 \
+)
+
+/* Is the transaction known as a subxact? */
+#define rbtxn_is_known_subxact(txn) \
+( \
+	((txn)->txn_flags & RBTXN_IS_SUBXACT) != 0 \
+)
+
+/* Has this transaction been spilled to disk? */
+#define rbtxn_is_serialized(txn) \
+( \
+	((txn)->txn_flags & RBTXN_IS_SERIALIZED) != 0 \
+)
+
+/* Has this transaction ever been spilled to disk? */
+#define rbtxn_is_serialized_clear(txn) \
+( \
+	((txn)->txn_flags & RBTXN_IS_SERIALIZED_CLEAR) != 0 \
+)
+
+/* Has this transaction contains partial changes? */
+#define rbtxn_has_partial_change(txn) \
+( \
+	((txn)->txn_flags & RBTXN_HAS_PARTIAL_CHANGE) != 0 \
+)
+
+/*
+ * Has this transaction been streamed to downstream?
+ *
+ * (It's not possible to deduce this from nentries and nentries_mem for
+ * various reasons. For example, all changes may be in subtransactions in
+ * which case we'd have nentries==0 for the toplevel one, which would say
+ * nothing about the streaming. So we maintain this flag, but only for the
+ * toplevel transaction.)
+ */
+#define rbtxn_is_streamed(txn) \
+( \
+	((txn)->txn_flags & RBTXN_IS_STREAMED) != 0 \
+)
+
+/* Has this transaction been prepared? */
+#define rbtxn_prepared(txn) \
+( \
+	((txn)->txn_flags & RBTXN_PREPARE) != 0 \
+)
+
+/* prepare for this transaction skipped? */
+#define rbtxn_skip_prepared(txn) \
+( \
+	((txn)->txn_flags & RBTXN_SKIPPED_PREPARE) != 0 \
+)
+
+typedef struct ReorderBufferTXN
+{
+	/* See above */
+	bits32		txn_flags;
+
+	/* The transaction's transaction id, can be a toplevel or sub xid. */
+	TransactionId xid;
+
+	/* Xid of top-level transaction, if known */
+	TransactionId toplevel_xid;
+
+	/*
+	 * Global transaction id required for identification of prepared
+	 * transactions.
+	 */
+	char	   *gid;
+
+	/*
+	 * LSN of the first data carrying, WAL record with knowledge about this
+	 * xid. This is allowed to *not* be first record adorned with this xid, if
+	 * the previous records aren't relevant for logical decoding.
+	 */
+	XLogRecPtr	first_lsn;
+
+	/* ----
+	 * LSN of the record that lead to this xact to be prepared or committed or
+	 * aborted. This can be a
+	 * * plain commit record
+	 * * plain commit record, of a parent transaction
+	 * * prepared tansaction
+	 * * prepared transaction commit
+	 * * plain abort record
+	 * * prepared transaction abort
+	 *
+	 * This can also become set to earlier values than transaction end when
+	 * a transaction is spilled to disk; specifically it's set to the LSN of
+	 * the latest change written to disk so far.
+	 * ----
+	 */
+	XLogRecPtr	final_lsn;
+
+	/*
+	 * LSN pointing to the end of the commit record + 1.
+	 */
+	XLogRecPtr	end_lsn;
+
+	/* Toplevel transaction for this subxact (NULL for top-level). */
+	struct ReorderBufferTXN *toptxn;
+
+	/*
+	 * LSN of the last lsn at which snapshot information reside, so we can
+	 * restart decoding from there and fully recover this transaction from
+	 * WAL.
+	 */
+	XLogRecPtr	restart_decoding_lsn;
+
+	/* origin of the change that caused this transaction */
+	RepOriginId origin_id;
+	XLogRecPtr	origin_lsn;
+
+	/*
+	 * Commit or Prepare time, only known when we read the actual commit or
+	 * prepare record.
+	 */
+	TimestampTz commit_time;
+
+	/*
+	 * The base snapshot is used to decode all changes until either this
+	 * transaction modifies the catalog, or another catalog-modifying
+	 * transaction commits.
+	 */
+	Snapshot	base_snapshot;
+	XLogRecPtr	base_snapshot_lsn;
+	dlist_node	base_snapshot_node; /* link in txns_by_base_snapshot_lsn */
+
+	/*
+	 * Snapshot/CID from the previous streaming run. Only valid for already
+	 * streamed transactions (NULL/InvalidCommandId otherwise).
+	 */
+	Snapshot	snapshot_now;
+	CommandId	command_id;
+
+	/*
+	 * How many ReorderBufferChange's do we have in this txn.
+	 *
+	 * Changes in subtransactions are *not* included but tracked separately.
+	 */
+	uint64		nentries;
+
+	/*
+	 * How many of the above entries are stored in memory in contrast to being
+	 * spilled to disk.
+	 */
+	uint64		nentries_mem;
+
+	/*
+	 * List of ReorderBufferChange structs, including new Snapshots, new
+	 * CommandIds and command invalidation messages.
+	 */
+	dlist_head	changes;
+
+	/*
+	 * List of (relation, ctid) => (cmin, cmax) mappings for catalog tuples.
+	 * Those are always assigned to the toplevel transaction. (Keep track of
+	 * #entries to create a hash of the right size)
+	 */
+	dlist_head	tuplecids;
+	uint64		ntuplecids;
+
+	/*
+	 * On-demand built hash for looking up the above values.
+	 */
+	HTAB	   *tuplecid_hash;
+
+	/*
+	 * Hash containing (potentially partial) toast entries. NULL if no toast
+	 * tuples have been found for the current change.
+	 */
+	HTAB	   *toast_hash;
+
+	/*
+	 * non-hierarchical list of subtransactions that are *not* aborted. Only
+	 * used in toplevel transactions.
+	 */
+	dlist_head	subtxns;
+	uint32		nsubtxns;
+
+	/*
+	 * Stored cache invalidations. This is not a linked list because we get
+	 * all the invalidations at once.
+	 */
+	uint32		ninvalidations;
+	SharedInvalidationMessage *invalidations;
+
+	/* ---
+	 * Position in one of three lists:
+	 * * list of subtransactions if we are *known* to be subxact
+	 * * list of toplevel xacts (can be an as-yet unknown subxact)
+	 * * list of preallocated ReorderBufferTXNs (if unused)
+	 * ---
+	 */
+	dlist_node	node;
+
+	/*
+	 * Size of this transaction (changes currently in memory, in bytes).
+	 */
+	Size		size;
+
+	/* Size of top-transaction including sub-transactions. */
+	Size		total_size;
+
+	/* If we have detected concurrent abort then ignore future changes. */
+	bool		concurrent_abort;
+
+	/*
+	 * Private data pointer of the output plugin.
+	 */
+	void	   *output_plugin_private;
+} ReorderBufferTXN;
+
+/* so we can define the callbacks used inside struct ReorderBuffer itself */
+typedef struct ReorderBuffer ReorderBuffer;
+
+/* change callback signature */
+typedef void (*ReorderBufferApplyChangeCB) (ReorderBuffer *rb,
+											ReorderBufferTXN *txn,
+											Relation relation,
+											ReorderBufferChange *change);
+
+/* truncate callback signature */
+typedef void (*ReorderBufferApplyTruncateCB) (ReorderBuffer *rb,
+											  ReorderBufferTXN *txn,
+											  int nrelations,
+											  Relation relations[],
+											  ReorderBufferChange *change);
+
+/* begin callback signature */
+typedef void (*ReorderBufferBeginCB) (ReorderBuffer *rb,
+									  ReorderBufferTXN *txn);
+
+/* commit callback signature */
+typedef void (*ReorderBufferCommitCB) (ReorderBuffer *rb,
+									   ReorderBufferTXN *txn,
+									   XLogRecPtr commit_lsn);
+
+/* message callback signature */
+typedef void (*ReorderBufferMessageCB) (ReorderBuffer *rb,
+										ReorderBufferTXN *txn,
+										XLogRecPtr message_lsn,
+										bool transactional,
+										const char *prefix, Size sz,
+										const char *message);
+
+/* begin prepare callback signature */
+typedef void (*ReorderBufferBeginPrepareCB) (ReorderBuffer *rb,
+											 ReorderBufferTXN *txn);
+
+/* prepare callback signature */
+typedef void (*ReorderBufferPrepareCB) (ReorderBuffer *rb,
+										ReorderBufferTXN *txn,
+										XLogRecPtr prepare_lsn);
+
+/* commit prepared callback signature */
+typedef void (*ReorderBufferCommitPreparedCB) (ReorderBuffer *rb,
+											   ReorderBufferTXN *txn,
+											   XLogRecPtr commit_lsn);
+
+/* rollback  prepared callback signature */
+typedef void (*ReorderBufferRollbackPreparedCB) (ReorderBuffer *rb,
+												 ReorderBufferTXN *txn,
+												 XLogRecPtr prepare_end_lsn,
+												 TimestampTz prepare_time);
+
+/* start streaming transaction callback signature */
+typedef void (*ReorderBufferStreamStartCB) (
+											ReorderBuffer *rb,
+											ReorderBufferTXN *txn,
+											XLogRecPtr first_lsn);
+
+/* stop streaming transaction callback signature */
+typedef void (*ReorderBufferStreamStopCB) (
+										   ReorderBuffer *rb,
+										   ReorderBufferTXN *txn,
+										   XLogRecPtr last_lsn);
+
+/* discard streamed transaction callback signature */
+typedef void (*ReorderBufferStreamAbortCB) (
+											ReorderBuffer *rb,
+											ReorderBufferTXN *txn,
+											XLogRecPtr abort_lsn);
+
+/* prepare streamed transaction callback signature */
+typedef void (*ReorderBufferStreamPrepareCB) (
+											  ReorderBuffer *rb,
+											  ReorderBufferTXN *txn,
+											  XLogRecPtr prepare_lsn);
+
+/* commit streamed transaction callback signature */
+typedef void (*ReorderBufferStreamCommitCB) (
+											 ReorderBuffer *rb,
+											 ReorderBufferTXN *txn,
+											 XLogRecPtr commit_lsn);
+
+/* stream change callback signature */
+typedef void (*ReorderBufferStreamChangeCB) (
+											 ReorderBuffer *rb,
+											 ReorderBufferTXN *txn,
+											 Relation relation,
+											 ReorderBufferChange *change);
+
+/* stream message callback signature */
+typedef void (*ReorderBufferStreamMessageCB) (
+											  ReorderBuffer *rb,
+											  ReorderBufferTXN *txn,
+											  XLogRecPtr message_lsn,
+											  bool transactional,
+											  const char *prefix, Size sz,
+											  const char *message);
+
+/* stream truncate callback signature */
+typedef void (*ReorderBufferStreamTruncateCB) (
+											   ReorderBuffer *rb,
+											   ReorderBufferTXN *txn,
+											   int nrelations,
+											   Relation relations[],
+											   ReorderBufferChange *change);
+
+struct ReorderBuffer
+{
+	/*
+	 * xid => ReorderBufferTXN lookup table
+	 */
+	HTAB	   *by_txn;
+
+	/*
+	 * Transactions that could be a toplevel xact, ordered by LSN of the first
+	 * record bearing that xid.
+	 */
+	dlist_head	toplevel_by_lsn;
+
+	/*
+	 * Transactions and subtransactions that have a base snapshot, ordered by
+	 * LSN of the record which caused us to first obtain the base snapshot.
+	 * This is not the same as toplevel_by_lsn, because we only set the base
+	 * snapshot on the first logical-decoding-relevant record (eg. heap
+	 * writes), whereas the initial LSN could be set by other operations.
+	 */
+	dlist_head	txns_by_base_snapshot_lsn;
+
+	/*
+	 * one-entry sized cache for by_txn. Very frequently the same txn gets
+	 * looked up over and over again.
+	 */
+	TransactionId by_txn_last_xid;
+	ReorderBufferTXN *by_txn_last_txn;
+
+	/*
+	 * Callbacks to be called when a transactions commits.
+	 */
+	ReorderBufferBeginCB begin;
+	ReorderBufferApplyChangeCB apply_change;
+	ReorderBufferApplyTruncateCB apply_truncate;
+	ReorderBufferCommitCB commit;
+	ReorderBufferMessageCB message;
+
+	/*
+	 * Callbacks to be called when streaming a transaction at prepare time.
+	 */
+	ReorderBufferBeginCB begin_prepare;
+	ReorderBufferPrepareCB prepare;
+	ReorderBufferCommitPreparedCB commit_prepared;
+	ReorderBufferRollbackPreparedCB rollback_prepared;
+
+	/*
+	 * Callbacks to be called when streaming a transaction.
+	 */
+	ReorderBufferStreamStartCB stream_start;
+	ReorderBufferStreamStopCB stream_stop;
+	ReorderBufferStreamAbortCB stream_abort;
+	ReorderBufferStreamPrepareCB stream_prepare;
+	ReorderBufferStreamCommitCB stream_commit;
+	ReorderBufferStreamChangeCB stream_change;
+	ReorderBufferStreamMessageCB stream_message;
+	ReorderBufferStreamTruncateCB stream_truncate;
+
+	/*
+	 * Pointer that will be passed untouched to the callbacks.
+	 */
+	void	   *private_data;
+
+	/*
+	 * Saved output plugin option
+	 */
+	bool		output_rewrites;
+
+	/*
+	 * Private memory context.
+	 */
+	MemoryContext context;
+
+	/*
+	 * Memory contexts for specific types objects
+	 */
+	MemoryContext change_context;
+	MemoryContext txn_context;
+	MemoryContext tup_context;
+
+	XLogRecPtr	current_restart_decoding_lsn;
+
+	/* buffer for disk<->memory conversions */
+	char	   *outbuf;
+	Size		outbufsize;
+
+	/* memory accounting */
+	Size		size;
+
+	/*
+	 * Statistics about transactions spilled to disk.
+	 *
+	 * A single transaction may be spilled repeatedly, which is why we keep
+	 * two different counters. For spilling, the transaction counter includes
+	 * both toplevel transactions and subtransactions.
+	 */
+	int64		spillTxns;		/* number of transactions spilled to disk */
+	int64		spillCount;		/* spill-to-disk invocation counter */
+	int64		spillBytes;		/* amount of data spilled to disk */
+
+	/* Statistics about transactions streamed to the decoding output plugin */
+	int64		streamTxns;		/* number of transactions streamed */
+	int64		streamCount;	/* streaming invocation counter */
+	int64		streamBytes;	/* amount of data decoded */
+
+	/*
+	 * Statistics about all the transactions sent to the decoding output
+	 * plugin
+	 */
+	int64		totalTxns;		/* total number of transactions sent */
+	int64		totalBytes;		/* total amount of data decoded */
+};
+
+
+ReorderBuffer *ReorderBufferAllocate(void);
+void		ReorderBufferFree(ReorderBuffer *);
+
+ReorderBufferTupleBuf *ReorderBufferGetTupleBuf(ReorderBuffer *, Size tuple_len);
+void		ReorderBufferReturnTupleBuf(ReorderBuffer *, ReorderBufferTupleBuf *tuple);
+ReorderBufferChange *ReorderBufferGetChange(ReorderBuffer *);
+void		ReorderBufferReturnChange(ReorderBuffer *, ReorderBufferChange *, bool);
+
+Oid		   *ReorderBufferGetRelids(ReorderBuffer *, int nrelids);
+void		ReorderBufferReturnRelids(ReorderBuffer *, Oid *relids);
+
+void		ReorderBufferQueueChange(ReorderBuffer *, TransactionId,
+									 XLogRecPtr lsn, ReorderBufferChange *,
+									 bool toast_insert);
+void		ReorderBufferQueueMessage(ReorderBuffer *, TransactionId, Snapshot snapshot, XLogRecPtr lsn,
+									  bool transactional, const char *prefix,
+									  Size message_size, const char *message);
+void		ReorderBufferCommit(ReorderBuffer *, TransactionId,
+								XLogRecPtr commit_lsn, XLogRecPtr end_lsn,
+								TimestampTz commit_time, RepOriginId origin_id, XLogRecPtr origin_lsn);
+void		ReorderBufferFinishPrepared(ReorderBuffer *rb, TransactionId xid,
+										XLogRecPtr commit_lsn, XLogRecPtr end_lsn,
+										XLogRecPtr initial_consistent_point,
+										TimestampTz commit_time,
+										RepOriginId origin_id, XLogRecPtr origin_lsn,
+										char *gid, bool is_commit);
+void		ReorderBufferAssignChild(ReorderBuffer *, TransactionId, TransactionId, XLogRecPtr commit_lsn);
+void		ReorderBufferCommitChild(ReorderBuffer *, TransactionId, TransactionId,
+									 XLogRecPtr commit_lsn, XLogRecPtr end_lsn);
+void		ReorderBufferAbort(ReorderBuffer *, TransactionId, XLogRecPtr lsn);
+void		ReorderBufferAbortOld(ReorderBuffer *, TransactionId xid);
+void		ReorderBufferForget(ReorderBuffer *, TransactionId, XLogRecPtr lsn);
+void		ReorderBufferInvalidate(ReorderBuffer *, TransactionId, XLogRecPtr lsn);
+
+void		ReorderBufferSetBaseSnapshot(ReorderBuffer *, TransactionId, XLogRecPtr lsn, struct SnapshotData *snap);
+void		ReorderBufferAddSnapshot(ReorderBuffer *, TransactionId, XLogRecPtr lsn, struct SnapshotData *snap);
+void		ReorderBufferAddNewCommandId(ReorderBuffer *, TransactionId, XLogRecPtr lsn,
+										 CommandId cid);
+void		ReorderBufferAddNewTupleCids(ReorderBuffer *, TransactionId, XLogRecPtr lsn,
+										 RelFileNode node, ItemPointerData pt,
+										 CommandId cmin, CommandId cmax, CommandId combocid);
+void		ReorderBufferAddInvalidations(ReorderBuffer *, TransactionId, XLogRecPtr lsn,
+										  Size nmsgs, SharedInvalidationMessage *msgs);
+void		ReorderBufferImmediateInvalidation(ReorderBuffer *, uint32 ninvalidations,
+											   SharedInvalidationMessage *invalidations);
+void		ReorderBufferProcessXid(ReorderBuffer *, TransactionId xid, XLogRecPtr lsn);
+
+void		ReorderBufferXidSetCatalogChanges(ReorderBuffer *, TransactionId xid, XLogRecPtr lsn);
+bool		ReorderBufferXidHasCatalogChanges(ReorderBuffer *, TransactionId xid);
+bool		ReorderBufferXidHasBaseSnapshot(ReorderBuffer *, TransactionId xid);
+
+bool		ReorderBufferRememberPrepareInfo(ReorderBuffer *rb, TransactionId xid,
+											 XLogRecPtr prepare_lsn, XLogRecPtr end_lsn,
+											 TimestampTz prepare_time,
+											 RepOriginId origin_id, XLogRecPtr origin_lsn);
+void		ReorderBufferSkipPrepare(ReorderBuffer *rb, TransactionId xid);
+void		ReorderBufferPrepare(ReorderBuffer *rb, TransactionId xid, char *gid);
+ReorderBufferTXN *ReorderBufferGetOldestTXN(ReorderBuffer *);
+TransactionId ReorderBufferGetOldestXmin(ReorderBuffer *rb);
+
+void		ReorderBufferSetRestartPoint(ReorderBuffer *, XLogRecPtr ptr);
+
+void		StartupReorderBuffer(void);
+
+#endif
diff --git a/src/include/replication/slot.h b/src/include/replication/slot.h
new file mode 100644
index 0000000..c0fca56
--- /dev/null
+++ b/src/include/replication/slot.h
@@ -0,0 +1,227 @@
+/*-------------------------------------------------------------------------
+ * slot.h
+ *	   Replication slot management.
+ *
+ * Copyright (c) 2012-2021, PostgreSQL Global Development Group
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef SLOT_H
+#define SLOT_H
+
+#include "access/xlog.h"
+#include "access/xlogreader.h"
+#include "storage/condition_variable.h"
+#include "storage/lwlock.h"
+#include "storage/shmem.h"
+#include "storage/spin.h"
+#include "replication/walreceiver.h"
+
+/*
+ * Behaviour of replication slots, upon release or crash.
+ *
+ * Slots marked as PERSISTENT are crash-safe and will not be dropped when
+ * released. Slots marked as EPHEMERAL will be dropped when released or after
+ * restarts.  Slots marked TEMPORARY will be dropped at the end of a session
+ * or on error.
+ *
+ * EPHEMERAL is used as a not-quite-ready state when creating persistent
+ * slots.  EPHEMERAL slots can be made PERSISTENT by calling
+ * ReplicationSlotPersist().  For a slot that goes away at the end of a
+ * session, TEMPORARY is the appropriate choice.
+ */
+typedef enum ReplicationSlotPersistency
+{
+	RS_PERSISTENT,
+	RS_EPHEMERAL,
+	RS_TEMPORARY
+} ReplicationSlotPersistency;
+
+/*
+ * On-Disk data of a replication slot, preserved across restarts.
+ */
+typedef struct ReplicationSlotPersistentData
+{
+	/* The slot's identifier */
+	NameData	name;
+
+	/* database the slot is active on */
+	Oid			database;
+
+	/*
+	 * The slot's behaviour when being dropped (or restored after a crash).
+	 */
+	ReplicationSlotPersistency persistency;
+
+	/*
+	 * xmin horizon for data
+	 *
+	 * NB: This may represent a value that hasn't been written to disk yet;
+	 * see notes for effective_xmin, below.
+	 */
+	TransactionId xmin;
+
+	/*
+	 * xmin horizon for catalog tuples
+	 *
+	 * NB: This may represent a value that hasn't been written to disk yet;
+	 * see notes for effective_xmin, below.
+	 */
+	TransactionId catalog_xmin;
+
+	/* oldest LSN that might be required by this replication slot */
+	XLogRecPtr	restart_lsn;
+
+	/* restart_lsn is copied here when the slot is invalidated */
+	XLogRecPtr	invalidated_at;
+
+	/*
+	 * Oldest LSN that the client has acked receipt for.  This is used as the
+	 * start_lsn point in case the client doesn't specify one, and also as a
+	 * safety measure to jump forwards in case the client specifies a
+	 * start_lsn that's further in the past than this value.
+	 */
+	XLogRecPtr	confirmed_flush;
+
+	/*
+	 * LSN at which we found a consistent point at the time of slot creation.
+	 * This is also the point where we have exported a snapshot for the
+	 * initial copy.
+	 */
+	XLogRecPtr	initial_consistent_point;
+
+	/*
+	 * Allow decoding of prepared transactions?
+	 */
+	bool		two_phase;
+
+	/* plugin name */
+	NameData	plugin;
+} ReplicationSlotPersistentData;
+
+/*
+ * Shared memory state of a single replication slot.
+ *
+ * The in-memory data of replication slots follows a locking model based
+ * on two linked concepts:
+ * - A replication slot's in_use flag is switched when added or discarded using
+ * the LWLock ReplicationSlotControlLock, which needs to be hold in exclusive
+ * mode when updating the flag by the backend owning the slot and doing the
+ * operation, while readers (concurrent backends not owning the slot) need
+ * to hold it in shared mode when looking at replication slot data.
+ * - Individual fields are protected by mutex where only the backend owning
+ * the slot is authorized to update the fields from its own slot.  The
+ * backend owning the slot does not need to take this lock when reading its
+ * own fields, while concurrent backends not owning this slot should take the
+ * lock when reading this slot's data.
+ */
+typedef struct ReplicationSlot
+{
+	/* lock, on same cacheline as effective_xmin */
+	slock_t		mutex;
+
+	/* is this slot defined */
+	bool		in_use;
+
+	/* Who is streaming out changes for this slot? 0 in unused slots. */
+	pid_t		active_pid;
+
+	/* any outstanding modifications? */
+	bool		just_dirtied;
+	bool		dirty;
+
+	/*
+	 * For logical decoding, it's extremely important that we never remove any
+	 * data that's still needed for decoding purposes, even after a crash;
+	 * otherwise, decoding will produce wrong answers.  Ordinary streaming
+	 * replication also needs to prevent old row versions from being removed
+	 * too soon, but the worst consequence we might encounter there is
+	 * unwanted query cancellations on the standby.  Thus, for logical
+	 * decoding, this value represents the latest xmin that has actually been
+	 * written to disk, whereas for streaming replication, it's just the same
+	 * as the persistent value (data.xmin).
+	 */
+	TransactionId effective_xmin;
+	TransactionId effective_catalog_xmin;
+
+	/* data surviving shutdowns and crashes */
+	ReplicationSlotPersistentData data;
+
+	/* is somebody performing io on this slot? */
+	LWLock		io_in_progress_lock;
+
+	/* Condition variable signaled when active_pid changes */
+	ConditionVariable active_cv;
+
+	/* all the remaining data is only used for logical slots */
+
+	/*
+	 * When the client has confirmed flushes >= candidate_xmin_lsn we can
+	 * advance the catalog xmin.  When restart_valid has been passed,
+	 * restart_lsn can be increased.
+	 */
+	TransactionId candidate_catalog_xmin;
+	XLogRecPtr	candidate_xmin_lsn;
+	XLogRecPtr	candidate_restart_valid;
+	XLogRecPtr	candidate_restart_lsn;
+} ReplicationSlot;
+
+#define SlotIsPhysical(slot) ((slot)->data.database == InvalidOid)
+#define SlotIsLogical(slot) ((slot)->data.database != InvalidOid)
+
+/*
+ * Shared memory control area for all of replication slots.
+ */
+typedef struct ReplicationSlotCtlData
+{
+	/*
+	 * This array should be declared [FLEXIBLE_ARRAY_MEMBER], but for some
+	 * reason you can't do that in an otherwise-empty struct.
+	 */
+	ReplicationSlot replication_slots[1];
+} ReplicationSlotCtlData;
+
+/*
+ * Pointers to shared memory
+ */
+extern PGDLLIMPORT ReplicationSlotCtlData *ReplicationSlotCtl;
+extern PGDLLIMPORT ReplicationSlot *MyReplicationSlot;
+
+/* GUCs */
+extern PGDLLIMPORT int max_replication_slots;
+
+/* shmem initialization functions */
+extern Size ReplicationSlotsShmemSize(void);
+extern void ReplicationSlotsShmemInit(void);
+
+/* management of individual slots */
+extern void ReplicationSlotCreate(const char *name, bool db_specific,
+								  ReplicationSlotPersistency p, bool two_phase);
+extern void ReplicationSlotPersist(void);
+extern void ReplicationSlotDrop(const char *name, bool nowait);
+
+extern void ReplicationSlotAcquire(const char *name, bool nowait);
+extern void ReplicationSlotRelease(void);
+extern void ReplicationSlotCleanup(void);
+extern void ReplicationSlotSave(void);
+extern void ReplicationSlotMarkDirty(void);
+
+/* misc stuff */
+extern bool ReplicationSlotValidateName(const char *name, int elevel);
+extern void ReplicationSlotReserveWal(void);
+extern void ReplicationSlotsComputeRequiredXmin(bool already_locked);
+extern void ReplicationSlotsComputeRequiredLSN(void);
+extern XLogRecPtr ReplicationSlotsComputeLogicalRestartLSN(void);
+extern bool ReplicationSlotsCountDBSlots(Oid dboid, int *nslots, int *nactive);
+extern void ReplicationSlotsDropDBSlots(Oid dboid);
+extern bool InvalidateObsoleteReplicationSlots(XLogSegNo oldestSegno);
+extern ReplicationSlot *SearchNamedReplicationSlot(const char *name, bool need_lock);
+extern void ReplicationSlotNameForTablesync(Oid suboid, Oid relid, char *syncslotname, int szslot);
+extern void ReplicationSlotDropAtPubNode(WalReceiverConn *wrconn, char *slotname, bool missing_ok);
+
+extern void StartupReplicationSlots(void);
+extern void CheckPointReplicationSlots(void);
+
+extern void CheckSlotRequirements(void);
+
+#endif							/* SLOT_H */
diff --git a/src/include/replication/snapbuild.h b/src/include/replication/snapbuild.h
new file mode 100644
index 0000000..3604621
--- /dev/null
+++ b/src/include/replication/snapbuild.h
@@ -0,0 +1,93 @@
+/*-------------------------------------------------------------------------
+ *
+ * snapbuild.h
+ *	  Exports from replication/logical/snapbuild.c.
+ *
+ * Copyright (c) 2012-2021, PostgreSQL Global Development Group
+ *
+ * src/include/replication/snapbuild.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef SNAPBUILD_H
+#define SNAPBUILD_H
+
+#include "access/xlogdefs.h"
+#include "utils/snapmgr.h"
+
+typedef enum
+{
+	/*
+	 * Initial state, we can't do much yet.
+	 */
+	SNAPBUILD_START = -1,
+
+	/*
+	 * Collecting committed transactions, to build the initial catalog
+	 * snapshot.
+	 */
+	SNAPBUILD_BUILDING_SNAPSHOT = 0,
+
+	/*
+	 * We have collected enough information to decode tuples in transactions
+	 * that started after this.
+	 *
+	 * Once we reached this we start to collect changes. We cannot apply them
+	 * yet, because they might be based on transactions that were still
+	 * running when FULL_SNAPSHOT was reached.
+	 */
+	SNAPBUILD_FULL_SNAPSHOT = 1,
+
+	/*
+	 * Found a point after SNAPBUILD_FULL_SNAPSHOT where all transactions that
+	 * were running at that point finished. Till we reach that we hold off
+	 * calling any commit callbacks.
+	 */
+	SNAPBUILD_CONSISTENT = 2
+} SnapBuildState;
+
+/* forward declare so we don't have to expose the struct to the public */
+struct SnapBuild;
+typedef struct SnapBuild SnapBuild;
+
+/* forward declare so we don't have to include reorderbuffer.h */
+struct ReorderBuffer;
+
+/* forward declare so we don't have to include heapam_xlog.h */
+struct xl_heap_new_cid;
+struct xl_running_xacts;
+
+extern void CheckPointSnapBuild(void);
+
+extern SnapBuild *AllocateSnapshotBuilder(struct ReorderBuffer *cache,
+										  TransactionId xmin_horizon, XLogRecPtr start_lsn,
+										  bool need_full_snapshot,
+										  XLogRecPtr initial_consistent_point);
+extern void FreeSnapshotBuilder(SnapBuild *cache);
+
+extern void SnapBuildSnapDecRefcount(Snapshot snap);
+
+extern Snapshot SnapBuildInitialSnapshot(SnapBuild *builder);
+extern const char *SnapBuildExportSnapshot(SnapBuild *snapstate);
+extern void SnapBuildClearExportedSnapshot(void);
+extern void SnapBuildResetExportedSnapshotState(void);
+
+extern SnapBuildState SnapBuildCurrentState(SnapBuild *snapstate);
+extern Snapshot SnapBuildGetOrBuildSnapshot(SnapBuild *builder,
+											TransactionId xid);
+
+extern bool SnapBuildXactNeedsSkip(SnapBuild *snapstate, XLogRecPtr ptr);
+extern XLogRecPtr SnapBuildInitialConsistentPoint(SnapBuild *builder);
+
+extern void SnapBuildCommitTxn(SnapBuild *builder, XLogRecPtr lsn,
+							   TransactionId xid, int nsubxacts,
+							   TransactionId *subxacts);
+extern bool SnapBuildProcessChange(SnapBuild *builder, TransactionId xid,
+								   XLogRecPtr lsn);
+extern void SnapBuildProcessNewCid(SnapBuild *builder, TransactionId xid,
+								   XLogRecPtr lsn, struct xl_heap_new_cid *cid);
+extern void SnapBuildProcessRunningXacts(SnapBuild *builder, XLogRecPtr lsn,
+										 struct xl_running_xacts *running);
+extern void SnapBuildSerializationPoint(SnapBuild *builder, XLogRecPtr lsn);
+
+#endif							/* SNAPBUILD_H */
diff --git a/src/include/replication/syncrep.h b/src/include/replication/syncrep.h
new file mode 100644
index 0000000..4266afd
--- /dev/null
+++ b/src/include/replication/syncrep.h
@@ -0,0 +1,115 @@
+/*-------------------------------------------------------------------------
+ *
+ * syncrep.h
+ *	  Exports from replication/syncrep.c.
+ *
+ * Portions Copyright (c) 2010-2021, PostgreSQL Global Development Group
+ *
+ * IDENTIFICATION
+ *		src/include/replication/syncrep.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef _SYNCREP_H
+#define _SYNCREP_H
+
+#include "access/xlogdefs.h"
+#include "utils/guc.h"
+
+#define SyncRepRequested() \
+	(max_wal_senders > 0 && synchronous_commit > SYNCHRONOUS_COMMIT_LOCAL_FLUSH)
+
+/* SyncRepWaitMode */
+#define SYNC_REP_NO_WAIT		(-1)
+#define SYNC_REP_WAIT_WRITE		0
+#define SYNC_REP_WAIT_FLUSH		1
+#define SYNC_REP_WAIT_APPLY		2
+
+#define NUM_SYNC_REP_WAIT_MODE	3
+
+/* syncRepState */
+#define SYNC_REP_NOT_WAITING		0
+#define SYNC_REP_WAITING			1
+#define SYNC_REP_WAIT_COMPLETE		2
+
+/* syncrep_method of SyncRepConfigData */
+#define SYNC_REP_PRIORITY		0
+#define SYNC_REP_QUORUM		1
+
+/*
+ * SyncRepGetCandidateStandbys returns an array of these structs,
+ * one per candidate synchronous walsender.
+ */
+typedef struct SyncRepStandbyData
+{
+	/* Copies of relevant fields from WalSnd shared-memory struct */
+	pid_t		pid;
+	XLogRecPtr	write;
+	XLogRecPtr	flush;
+	XLogRecPtr	apply;
+	int			sync_standby_priority;
+	/* Index of this walsender in the WalSnd shared-memory array */
+	int			walsnd_index;
+	/* This flag indicates whether this struct is about our own process */
+	bool		is_me;
+} SyncRepStandbyData;
+
+/*
+ * Struct for the configuration of synchronous replication.
+ *
+ * Note: this must be a flat representation that can be held in a single
+ * chunk of malloc'd memory, so that it can be stored as the "extra" data
+ * for the synchronous_standby_names GUC.
+ */
+typedef struct SyncRepConfigData
+{
+	int			config_size;	/* total size of this struct, in bytes */
+	int			num_sync;		/* number of sync standbys that we need to
+								 * wait for */
+	uint8		syncrep_method; /* method to choose sync standbys */
+	int			nmembers;		/* number of members in the following list */
+	/* member_names contains nmembers consecutive nul-terminated C strings */
+	char		member_names[FLEXIBLE_ARRAY_MEMBER];
+} SyncRepConfigData;
+
+extern SyncRepConfigData *SyncRepConfig;
+
+/* communication variables for parsing synchronous_standby_names GUC */
+extern SyncRepConfigData *syncrep_parse_result;
+extern char *syncrep_parse_error_msg;
+
+/* user-settable parameters for synchronous replication */
+extern char *SyncRepStandbyNames;
+
+/* called by user backend */
+extern void SyncRepWaitForLSN(XLogRecPtr lsn, bool commit);
+
+/* called at backend exit */
+extern void SyncRepCleanupAtProcExit(void);
+
+/* called by wal sender */
+extern void SyncRepInitConfig(void);
+extern void SyncRepReleaseWaiters(void);
+
+/* called by wal sender and user backend */
+extern int	SyncRepGetCandidateStandbys(SyncRepStandbyData **standbys);
+
+/* called by checkpointer */
+extern void SyncRepUpdateSyncStandbysDefined(void);
+
+/* GUC infrastructure */
+extern bool check_synchronous_standby_names(char **newval, void **extra, GucSource source);
+extern void assign_synchronous_standby_names(const char *newval, void *extra);
+extern void assign_synchronous_commit(int newval, void *extra);
+
+/*
+ * Internal functions for parsing synchronous_standby_names grammar,
+ * in syncrep_gram.y and syncrep_scanner.l
+ */
+extern int	syncrep_yyparse(void);
+extern int	syncrep_yylex(void);
+extern void syncrep_yyerror(const char *str);
+extern void syncrep_scanner_init(const char *query_string);
+extern void syncrep_scanner_finish(void);
+
+#endif							/* _SYNCREP_H */
diff --git a/src/include/replication/walreceiver.h b/src/include/replication/walreceiver.h
new file mode 100644
index 0000000..4fd7c25
--- /dev/null
+++ b/src/include/replication/walreceiver.h
@@ -0,0 +1,469 @@
+/*-------------------------------------------------------------------------
+ *
+ * walreceiver.h
+ *	  Exports from replication/walreceiverfuncs.c.
+ *
+ * Portions Copyright (c) 2010-2021, PostgreSQL Global Development Group
+ *
+ * src/include/replication/walreceiver.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef _WALRECEIVER_H
+#define _WALRECEIVER_H
+
+#include "access/xlog.h"
+#include "access/xlogdefs.h"
+#include "getaddrinfo.h"		/* for NI_MAXHOST */
+#include "pgtime.h"
+#include "port/atomics.h"
+#include "replication/logicalproto.h"
+#include "replication/walsender.h"
+#include "storage/condition_variable.h"
+#include "storage/latch.h"
+#include "storage/spin.h"
+#include "utils/tuplestore.h"
+
+/* user-settable parameters */
+extern int	wal_receiver_status_interval;
+extern int	wal_receiver_timeout;
+extern bool hot_standby_feedback;
+
+/*
+ * MAXCONNINFO: maximum size of a connection string.
+ *
+ * XXX: Should this move to pg_config_manual.h?
+ */
+#define MAXCONNINFO		1024
+
+/* Can we allow the standby to accept replication connection from another standby? */
+#define AllowCascadeReplication() (EnableHotStandby && max_wal_senders > 0)
+
+/*
+ * Values for WalRcv->walRcvState.
+ */
+typedef enum
+{
+	WALRCV_STOPPED,				/* stopped and mustn't start up again */
+	WALRCV_STARTING,			/* launched, but the process hasn't
+								 * initialized yet */
+	WALRCV_STREAMING,			/* walreceiver is streaming */
+	WALRCV_WAITING,				/* stopped streaming, waiting for orders */
+	WALRCV_RESTARTING,			/* asked to restart streaming */
+	WALRCV_STOPPING				/* requested to stop, but still running */
+} WalRcvState;
+
+/* Shared memory area for management of walreceiver process */
+typedef struct
+{
+	/*
+	 * PID of currently active walreceiver process, its current state and
+	 * start time (actually, the time at which it was requested to be
+	 * started).
+	 */
+	pid_t		pid;
+	WalRcvState walRcvState;
+	ConditionVariable walRcvStoppedCV;
+	pg_time_t	startTime;
+
+	/*
+	 * receiveStart and receiveStartTLI indicate the first byte position and
+	 * timeline that will be received. When startup process starts the
+	 * walreceiver, it sets these to the point where it wants the streaming to
+	 * begin.
+	 */
+	XLogRecPtr	receiveStart;
+	TimeLineID	receiveStartTLI;
+
+	/*
+	 * flushedUpto-1 is the last byte position that has already been received,
+	 * and receivedTLI is the timeline it came from.  At the first startup of
+	 * walreceiver, these are set to receiveStart and receiveStartTLI. After
+	 * that, walreceiver updates these whenever it flushes the received WAL to
+	 * disk.
+	 */
+	XLogRecPtr	flushedUpto;
+	TimeLineID	receivedTLI;
+
+	/*
+	 * latestChunkStart is the starting byte position of the current "batch"
+	 * of received WAL.  It's actually the same as the previous value of
+	 * flushedUpto before the last flush to disk.  Startup process can use
+	 * this to detect whether it's keeping up or not.
+	 */
+	XLogRecPtr	latestChunkStart;
+
+	/*
+	 * Time of send and receive of any message received.
+	 */
+	TimestampTz lastMsgSendTime;
+	TimestampTz lastMsgReceiptTime;
+
+	/*
+	 * Latest reported end of WAL on the sender
+	 */
+	XLogRecPtr	latestWalEnd;
+	TimestampTz latestWalEndTime;
+
+	/*
+	 * connection string; initially set to connect to the primary, and later
+	 * clobbered to hide security-sensitive fields.
+	 */
+	char		conninfo[MAXCONNINFO];
+
+	/*
+	 * Host name (this can be a host name, an IP address, or a directory path)
+	 * and port number of the active replication connection.
+	 */
+	char		sender_host[NI_MAXHOST];
+	int			sender_port;
+
+	/*
+	 * replication slot name; is also used for walreceiver to connect with the
+	 * primary
+	 */
+	char		slotname[NAMEDATALEN];
+
+	/*
+	 * If it's a temporary replication slot, it needs to be recreated when
+	 * connecting.
+	 */
+	bool		is_temp_slot;
+
+	/* set true once conninfo is ready to display (obfuscated pwds etc) */
+	bool		ready_to_display;
+
+	/*
+	 * Latch used by startup process to wake up walreceiver after telling it
+	 * where to start streaming (after setting receiveStart and
+	 * receiveStartTLI), and also to tell it to send apply feedback to the
+	 * primary whenever specially marked commit records are applied. This is
+	 * normally mapped to procLatch when walreceiver is running.
+	 */
+	Latch	   *latch;
+
+	slock_t		mutex;			/* locks shared variables shown above */
+
+	/*
+	 * Like flushedUpto, but advanced after writing and before flushing,
+	 * without the need to acquire the spin lock.  Data can be read by another
+	 * process up to this point, but shouldn't be used for data integrity
+	 * purposes.
+	 */
+	pg_atomic_uint64 writtenUpto;
+
+	/*
+	 * force walreceiver reply?  This doesn't need to be locked; memory
+	 * barriers for ordering are sufficient.  But we do need atomic fetch and
+	 * store semantics, so use sig_atomic_t.
+	 */
+	sig_atomic_t force_reply;	/* used as a bool */
+} WalRcvData;
+
+extern WalRcvData *WalRcv;
+
+typedef struct
+{
+	bool		logical;		/* True if this is logical replication stream,
+								 * false if physical stream.  */
+	char	   *slotname;		/* Name of the replication slot or NULL. */
+	XLogRecPtr	startpoint;		/* LSN of starting point. */
+
+	union
+	{
+		struct
+		{
+			TimeLineID	startpointTLI;	/* Starting timeline */
+		}			physical;
+		struct
+		{
+			uint32		proto_version;	/* Logical protocol version */
+			List	   *publication_names;	/* String list of publications */
+			bool		binary; /* Ask publisher to use binary */
+			bool		streaming;	/* Streaming of large transactions */
+		}			logical;
+	}			proto;
+} WalRcvStreamOptions;
+
+struct WalReceiverConn;
+typedef struct WalReceiverConn WalReceiverConn;
+
+/*
+ * Status of walreceiver query execution.
+ *
+ * We only define statuses that are currently used.
+ */
+typedef enum
+{
+	WALRCV_ERROR,				/* There was error when executing the query. */
+	WALRCV_OK_COMMAND,			/* Query executed utility or replication
+								 * command. */
+	WALRCV_OK_TUPLES,			/* Query returned tuples. */
+	WALRCV_OK_COPY_IN,			/* Query started COPY FROM. */
+	WALRCV_OK_COPY_OUT,			/* Query started COPY TO. */
+	WALRCV_OK_COPY_BOTH			/* Query started COPY BOTH replication
+								 * protocol. */
+} WalRcvExecStatus;
+
+/*
+ * Return value for walrcv_exec, returns the status of the execution and
+ * tuples if any.
+ */
+typedef struct WalRcvExecResult
+{
+	WalRcvExecStatus status;
+	int			sqlstate;
+	char	   *err;
+	Tuplestorestate *tuplestore;
+	TupleDesc	tupledesc;
+} WalRcvExecResult;
+
+/* WAL receiver - libpqwalreceiver hooks */
+
+/*
+ * walrcv_connect_fn
+ *
+ * Establish connection to a cluster.  'logical' is true if the
+ * connection is logical, and false if the connection is physical.
+ * 'appname' is a name associated to the connection, to use for example
+ * with fallback_application_name or application_name.  Returns the
+ * details about the connection established, as defined by
+ * WalReceiverConn for each WAL receiver module.  On error, NULL is
+ * returned with 'err' including the error generated.
+ */
+typedef WalReceiverConn *(*walrcv_connect_fn) (const char *conninfo,
+											   bool logical,
+											   const char *appname,
+											   char **err);
+
+/*
+ * walrcv_check_conninfo_fn
+ *
+ * Parse and validate the connection string given as of 'conninfo'.
+ */
+typedef void (*walrcv_check_conninfo_fn) (const char *conninfo);
+
+/*
+ * walrcv_get_conninfo_fn
+ *
+ * Returns a user-displayable conninfo string.  Note that any
+ * security-sensitive fields should be obfuscated.
+ */
+typedef char *(*walrcv_get_conninfo_fn) (WalReceiverConn *conn);
+
+/*
+ * walrcv_get_senderinfo_fn
+ *
+ * Provide information of the WAL sender this WAL receiver is connected
+ * to, as of 'sender_host' for the host of the sender and 'sender_port'
+ * for its port.
+ */
+typedef void (*walrcv_get_senderinfo_fn) (WalReceiverConn *conn,
+										  char **sender_host,
+										  int *sender_port);
+
+/*
+ * walrcv_identify_system_fn
+ *
+ * Run IDENTIFY_SYSTEM on the cluster connected to and validate the
+ * identity of the cluster.  Returns the system ID of the cluster
+ * connected to.  'primary_tli' is the timeline ID of the sender.
+ */
+typedef char *(*walrcv_identify_system_fn) (WalReceiverConn *conn,
+											TimeLineID *primary_tli);
+
+/*
+ * walrcv_server_version_fn
+ *
+ * Returns the version number of the cluster connected to.
+ */
+typedef int (*walrcv_server_version_fn) (WalReceiverConn *conn);
+
+/*
+ * walrcv_readtimelinehistoryfile_fn
+ *
+ * Fetch from cluster the timeline history file for timeline 'tli'.
+ * Returns the name of the timeline history file as of 'filename', its
+ * contents as of 'content' and its 'size'.
+ */
+typedef void (*walrcv_readtimelinehistoryfile_fn) (WalReceiverConn *conn,
+												   TimeLineID tli,
+												   char **filename,
+												   char **content,
+												   int *size);
+
+/*
+ * walrcv_startstreaming_fn
+ *
+ * Start streaming WAL data from given streaming options.  Returns true
+ * if the connection has switched successfully to copy-both mode and false
+ * if the server received the command and executed it successfully, but
+ * didn't switch to copy-mode.
+ */
+typedef bool (*walrcv_startstreaming_fn) (WalReceiverConn *conn,
+										  const WalRcvStreamOptions *options);
+
+/*
+ * walrcv_endstreaming_fn
+ *
+ * Stop streaming of WAL data.  Returns the next timeline ID of the cluster
+ * connected to in 'next_tli', or 0 if there was no report.
+ */
+typedef void (*walrcv_endstreaming_fn) (WalReceiverConn *conn,
+										TimeLineID *next_tli);
+
+/*
+ * walrcv_receive_fn
+ *
+ * Receive a message available from the WAL stream.  'buffer' is a pointer
+ * to a buffer holding the message received.  Returns the length of the data,
+ * 0 if no data is available yet ('wait_fd' is a socket descriptor which can
+ * be waited on before a retry), and -1 if the cluster ended the COPY.
+ */
+typedef int (*walrcv_receive_fn) (WalReceiverConn *conn,
+								  char **buffer,
+								  pgsocket *wait_fd);
+
+/*
+ * walrcv_send_fn
+ *
+ * Send a message of size 'nbytes' to the WAL stream with 'buffer' as
+ * contents.
+ */
+typedef void (*walrcv_send_fn) (WalReceiverConn *conn,
+								const char *buffer,
+								int nbytes);
+
+/*
+ * walrcv_create_slot_fn
+ *
+ * Create a new replication slot named 'slotname'.  'temporary' defines
+ * if the slot is temporary.  'snapshot_action' defines the behavior wanted
+ * for an exported snapshot (see replication protocol for more details).
+ * 'lsn' includes the LSN position at which the created slot became
+ * consistent.  Returns the name of the exported snapshot for a logical
+ * slot, or NULL for a physical slot.
+ */
+typedef char *(*walrcv_create_slot_fn) (WalReceiverConn *conn,
+										const char *slotname,
+										bool temporary,
+										CRSSnapshotAction snapshot_action,
+										XLogRecPtr *lsn);
+
+/*
+ * walrcv_get_backend_pid_fn
+ *
+ * Returns the PID of the remote backend process.
+ */
+typedef pid_t (*walrcv_get_backend_pid_fn) (WalReceiverConn *conn);
+
+/*
+ * walrcv_exec_fn
+ *
+ * Send generic queries (and commands) to the remote cluster.  'nRetTypes'
+ * is the expected number of returned attributes, and 'retTypes' an array
+ * including their type OIDs.  Returns the status of the execution and
+ * tuples if any.
+ */
+typedef WalRcvExecResult *(*walrcv_exec_fn) (WalReceiverConn *conn,
+											 const char *query,
+											 const int nRetTypes,
+											 const Oid *retTypes);
+
+/*
+ * walrcv_disconnect_fn
+ *
+ * Disconnect with the cluster.
+ */
+typedef void (*walrcv_disconnect_fn) (WalReceiverConn *conn);
+
+typedef struct WalReceiverFunctionsType
+{
+	walrcv_connect_fn walrcv_connect;
+	walrcv_check_conninfo_fn walrcv_check_conninfo;
+	walrcv_get_conninfo_fn walrcv_get_conninfo;
+	walrcv_get_senderinfo_fn walrcv_get_senderinfo;
+	walrcv_identify_system_fn walrcv_identify_system;
+	walrcv_server_version_fn walrcv_server_version;
+	walrcv_readtimelinehistoryfile_fn walrcv_readtimelinehistoryfile;
+	walrcv_startstreaming_fn walrcv_startstreaming;
+	walrcv_endstreaming_fn walrcv_endstreaming;
+	walrcv_receive_fn walrcv_receive;
+	walrcv_send_fn walrcv_send;
+	walrcv_create_slot_fn walrcv_create_slot;
+	walrcv_get_backend_pid_fn walrcv_get_backend_pid;
+	walrcv_exec_fn walrcv_exec;
+	walrcv_disconnect_fn walrcv_disconnect;
+} WalReceiverFunctionsType;
+
+extern PGDLLIMPORT WalReceiverFunctionsType *WalReceiverFunctions;
+
+#define walrcv_connect(conninfo, logical, appname, err) \
+	WalReceiverFunctions->walrcv_connect(conninfo, logical, appname, err)
+#define walrcv_check_conninfo(conninfo) \
+	WalReceiverFunctions->walrcv_check_conninfo(conninfo)
+#define walrcv_get_conninfo(conn) \
+	WalReceiverFunctions->walrcv_get_conninfo(conn)
+#define walrcv_get_senderinfo(conn, sender_host, sender_port) \
+	WalReceiverFunctions->walrcv_get_senderinfo(conn, sender_host, sender_port)
+#define walrcv_identify_system(conn, primary_tli) \
+	WalReceiverFunctions->walrcv_identify_system(conn, primary_tli)
+#define walrcv_server_version(conn) \
+	WalReceiverFunctions->walrcv_server_version(conn)
+#define walrcv_readtimelinehistoryfile(conn, tli, filename, content, size) \
+	WalReceiverFunctions->walrcv_readtimelinehistoryfile(conn, tli, filename, content, size)
+#define walrcv_startstreaming(conn, options) \
+	WalReceiverFunctions->walrcv_startstreaming(conn, options)
+#define walrcv_endstreaming(conn, next_tli) \
+	WalReceiverFunctions->walrcv_endstreaming(conn, next_tli)
+#define walrcv_receive(conn, buffer, wait_fd) \
+	WalReceiverFunctions->walrcv_receive(conn, buffer, wait_fd)
+#define walrcv_send(conn, buffer, nbytes) \
+	WalReceiverFunctions->walrcv_send(conn, buffer, nbytes)
+#define walrcv_create_slot(conn, slotname, temporary, snapshot_action, lsn) \
+	WalReceiverFunctions->walrcv_create_slot(conn, slotname, temporary, snapshot_action, lsn)
+#define walrcv_get_backend_pid(conn) \
+	WalReceiverFunctions->walrcv_get_backend_pid(conn)
+#define walrcv_exec(conn, exec, nRetTypes, retTypes) \
+	WalReceiverFunctions->walrcv_exec(conn, exec, nRetTypes, retTypes)
+#define walrcv_disconnect(conn) \
+	WalReceiverFunctions->walrcv_disconnect(conn)
+
+static inline void
+walrcv_clear_result(WalRcvExecResult *walres)
+{
+	if (!walres)
+		return;
+
+	if (walres->err)
+		pfree(walres->err);
+
+	if (walres->tuplestore)
+		tuplestore_end(walres->tuplestore);
+
+	if (walres->tupledesc)
+		FreeTupleDesc(walres->tupledesc);
+
+	pfree(walres);
+}
+
+/* prototypes for functions in walreceiver.c */
+extern void WalReceiverMain(void) pg_attribute_noreturn();
+extern void ProcessWalRcvInterrupts(void);
+
+/* prototypes for functions in walreceiverfuncs.c */
+extern Size WalRcvShmemSize(void);
+extern void WalRcvShmemInit(void);
+extern void ShutdownWalRcv(void);
+extern bool WalRcvStreaming(void);
+extern bool WalRcvRunning(void);
+extern void RequestXLogStreaming(TimeLineID tli, XLogRecPtr recptr,
+								 const char *conninfo, const char *slotname,
+								 bool create_temp_slot);
+extern XLogRecPtr GetWalRcvFlushRecPtr(XLogRecPtr *latestChunkStart, TimeLineID *receiveTLI);
+extern XLogRecPtr GetWalRcvWriteRecPtr(void);
+extern int	GetReplicationApplyDelay(void);
+extern int	GetReplicationTransferLatency(void);
+extern void WalRcvForceReply(void);
+
+#endif							/* _WALRECEIVER_H */
diff --git a/src/include/replication/walsender.h b/src/include/replication/walsender.h
new file mode 100644
index 0000000..8281069
--- /dev/null
+++ b/src/include/replication/walsender.h
@@ -0,0 +1,74 @@
+/*-------------------------------------------------------------------------
+ *
+ * walsender.h
+ *	  Exports from replication/walsender.c.
+ *
+ * Portions Copyright (c) 2010-2021, PostgreSQL Global Development Group
+ *
+ * src/include/replication/walsender.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef _WALSENDER_H
+#define _WALSENDER_H
+
+#include <signal.h>
+
+/*
+ * What to do with a snapshot in create replication slot command.
+ */
+typedef enum
+{
+	CRS_EXPORT_SNAPSHOT,
+	CRS_NOEXPORT_SNAPSHOT,
+	CRS_USE_SNAPSHOT
+} CRSSnapshotAction;
+
+/* global state */
+extern bool am_walsender;
+extern bool am_cascading_walsender;
+extern bool am_db_walsender;
+extern bool wake_wal_senders;
+
+/* user-settable parameters */
+extern int	max_wal_senders;
+extern int	wal_sender_timeout;
+extern bool log_replication_commands;
+
+extern void InitWalSender(void);
+extern bool exec_replication_command(const char *query_string);
+extern void WalSndErrorCleanup(void);
+extern void WalSndResourceCleanup(bool isCommit);
+extern void WalSndSignals(void);
+extern Size WalSndShmemSize(void);
+extern void WalSndShmemInit(void);
+extern void WalSndWakeup(void);
+extern void WalSndInitStopping(void);
+extern void WalSndWaitStopping(void);
+extern void HandleWalSndInitStopping(void);
+extern void WalSndRqstFileReload(void);
+
+/*
+ * Remember that we want to wakeup walsenders later
+ *
+ * This is separated from doing the actual wakeup because the writeout is done
+ * while holding contended locks.
+ */
+#define WalSndWakeupRequest() \
+	do { wake_wal_senders = true; } while (0)
+
+/*
+ * wakeup walsenders if there is work to be done
+ */
+#define WalSndWakeupProcessRequests()		\
+	do										\
+	{										\
+		if (wake_wal_senders)				\
+		{									\
+			wake_wal_senders = false;		\
+			if (max_wal_senders > 0)		\
+				WalSndWakeup();				\
+		}									\
+	} while (0)
+
+#endif							/* _WALSENDER_H */
diff --git a/src/include/replication/walsender_private.h b/src/include/replication/walsender_private.h
new file mode 100644
index 0000000..07abf26
--- /dev/null
+++ b/src/include/replication/walsender_private.h
@@ -0,0 +1,128 @@
+/*-------------------------------------------------------------------------
+ *
+ * walsender_private.h
+ *	  Private definitions from replication/walsender.c.
+ *
+ * Portions Copyright (c) 2010-2021, PostgreSQL Global Development Group
+ *
+ * src/include/replication/walsender_private.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef _WALSENDER_PRIVATE_H
+#define _WALSENDER_PRIVATE_H
+
+#include "access/xlog.h"
+#include "nodes/nodes.h"
+#include "replication/syncrep.h"
+#include "storage/latch.h"
+#include "storage/shmem.h"
+#include "storage/spin.h"
+
+typedef enum WalSndState
+{
+	WALSNDSTATE_STARTUP = 0,
+	WALSNDSTATE_BACKUP,
+	WALSNDSTATE_CATCHUP,
+	WALSNDSTATE_STREAMING,
+	WALSNDSTATE_STOPPING
+} WalSndState;
+
+/*
+ * Each walsender has a WalSnd struct in shared memory.
+ *
+ * This struct is protected by its 'mutex' spinlock field, except that some
+ * members are only written by the walsender process itself, and thus that
+ * process is free to read those members without holding spinlock.  pid and
+ * needreload always require the spinlock to be held for all accesses.
+ */
+typedef struct WalSnd
+{
+	pid_t		pid;			/* this walsender's PID, or 0 if not active */
+
+	WalSndState state;			/* this walsender's state */
+	XLogRecPtr	sentPtr;		/* WAL has been sent up to this point */
+	bool		needreload;		/* does currently-open file need to be
+								 * reloaded? */
+
+	/*
+	 * The xlog locations that have been written, flushed, and applied by
+	 * standby-side. These may be invalid if the standby-side has not offered
+	 * values yet.
+	 */
+	XLogRecPtr	write;
+	XLogRecPtr	flush;
+	XLogRecPtr	apply;
+
+	/* Measured lag times, or -1 for unknown/none. */
+	TimeOffset	writeLag;
+	TimeOffset	flushLag;
+	TimeOffset	applyLag;
+
+	/*
+	 * The priority order of the standby managed by this WALSender, as listed
+	 * in synchronous_standby_names, or 0 if not-listed.
+	 */
+	int			sync_standby_priority;
+
+	/* Protects shared variables shown above. */
+	slock_t		mutex;
+
+	/*
+	 * Pointer to the walsender's latch. Used by backends to wake up this
+	 * walsender when it has work to do. NULL if the walsender isn't active.
+	 */
+	Latch	   *latch;
+
+	/*
+	 * Timestamp of the last message received from standby.
+	 */
+	TimestampTz replyTime;
+} WalSnd;
+
+extern WalSnd *MyWalSnd;
+
+/* There is one WalSndCtl struct for the whole database cluster */
+typedef struct
+{
+	/*
+	 * Synchronous replication queue with one queue per request type.
+	 * Protected by SyncRepLock.
+	 */
+	SHM_QUEUE	SyncRepQueue[NUM_SYNC_REP_WAIT_MODE];
+
+	/*
+	 * Current location of the head of the queue. All waiters should have a
+	 * waitLSN that follows this value. Protected by SyncRepLock.
+	 */
+	XLogRecPtr	lsn[NUM_SYNC_REP_WAIT_MODE];
+
+	/*
+	 * Are any sync standbys defined?  Waiting backends can't reload the
+	 * config file safely, so checkpointer updates this value as needed.
+	 * Protected by SyncRepLock.
+	 */
+	bool		sync_standbys_defined;
+
+	WalSnd		walsnds[FLEXIBLE_ARRAY_MEMBER];
+} WalSndCtlData;
+
+extern WalSndCtlData *WalSndCtl;
+
+
+extern void WalSndSetState(WalSndState state);
+
+/*
+ * Internal functions for parsing the replication grammar, in repl_gram.y and
+ * repl_scanner.l
+ */
+extern int	replication_yyparse(void);
+extern int	replication_yylex(void);
+extern void replication_yyerror(const char *str) pg_attribute_noreturn();
+extern void replication_scanner_init(const char *query_string);
+extern void replication_scanner_finish(void);
+extern bool replication_scanner_is_replication_command(void);
+
+extern Node *replication_parse_result;
+
+#endif							/* _WALSENDER_PRIVATE_H */
diff --git a/src/include/replication/worker_internal.h b/src/include/replication/worker_internal.h
new file mode 100644
index 0000000..179eb43
--- /dev/null
+++ b/src/include/replication/worker_internal.h
@@ -0,0 +1,99 @@
+/*-------------------------------------------------------------------------
+ *
+ * worker_internal.h
+ *	  Internal headers shared by logical replication workers.
+ *
+ * Portions Copyright (c) 2016-2021, PostgreSQL Global Development Group
+ *
+ * src/include/replication/worker_internal.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef WORKER_INTERNAL_H
+#define WORKER_INTERNAL_H
+
+#include <signal.h>
+
+#include "access/xlogdefs.h"
+#include "catalog/pg_subscription.h"
+#include "datatype/timestamp.h"
+#include "storage/lock.h"
+#include "storage/spin.h"
+
+
+typedef struct LogicalRepWorker
+{
+	/* Time at which this worker was launched. */
+	TimestampTz launch_time;
+
+	/* Indicates if this slot is used or free. */
+	bool		in_use;
+
+	/* Increased every time the slot is taken by new worker. */
+	uint16		generation;
+
+	/* Pointer to proc array. NULL if not running. */
+	PGPROC	   *proc;
+
+	/* Database id to connect to. */
+	Oid			dbid;
+
+	/* User to use for connection (will be same as owner of subscription). */
+	Oid			userid;
+
+	/* Subscription id for the worker. */
+	Oid			subid;
+
+	/* Used for initial table synchronization. */
+	Oid			relid;
+	char		relstate;
+	XLogRecPtr	relstate_lsn;
+	slock_t		relmutex;
+
+	/* Stats. */
+	XLogRecPtr	last_lsn;
+	TimestampTz last_send_time;
+	TimestampTz last_recv_time;
+	XLogRecPtr	reply_lsn;
+	TimestampTz reply_time;
+} LogicalRepWorker;
+
+/* Main memory context for apply worker. Permanent during worker lifetime. */
+extern MemoryContext ApplyContext;
+
+/* libpqreceiver connection */
+extern struct WalReceiverConn *LogRepWorkerWalRcvConn;
+
+/* Worker and subscription objects. */
+extern Subscription *MySubscription;
+extern LogicalRepWorker *MyLogicalRepWorker;
+
+extern bool in_remote_transaction;
+
+extern void logicalrep_worker_attach(int slot);
+extern LogicalRepWorker *logicalrep_worker_find(Oid subid, Oid relid,
+												bool only_running);
+extern List *logicalrep_workers_find(Oid subid, bool only_running);
+extern void logicalrep_worker_launch(Oid dbid, Oid subid, const char *subname,
+									 Oid userid, Oid relid);
+extern void logicalrep_worker_stop(Oid subid, Oid relid);
+extern void logicalrep_worker_wakeup(Oid subid, Oid relid);
+extern void logicalrep_worker_wakeup_ptr(LogicalRepWorker *worker);
+
+extern int	logicalrep_sync_worker_count(Oid subid);
+
+extern void ReplicationOriginNameForTablesync(Oid suboid, Oid relid,
+											  char *originname, int szorgname);
+extern char *LogicalRepSyncTableStart(XLogRecPtr *origin_startpos);
+
+void		process_syncing_tables(XLogRecPtr current_lsn);
+void		invalidate_syncing_table_states(Datum arg, int cacheid,
+											uint32 hashvalue);
+
+static inline bool
+am_tablesync_worker(void)
+{
+	return OidIsValid(MyLogicalRepWorker->relid);
+}
+
+#endif							/* WORKER_INTERNAL_H */