v18-0003-Move-pg_get_wal_record_info-functionality-from-p.patch

From e1cbde65108376c61377f12089bdc3990b53330e Mon Sep 17 00:00:00 2001
From: Hayato Kuroda <kuroda.hayato@fujitsu.com>
Date: Tue, 1 Aug 2023 14:04:04 +0000
Subject: [PATCH v18 3/4] Move pg_get_wal_record_info functionality from
 pg_walinspect to core

Upgrade of publications required pg_get_wal_record_info to check that there are
no WAL records other than CHECKPOINT_SHUTDOWN WAL record to be consumed. Hence
moved pg_get_wal_record_info functionality as pg_get_wal_record_content
to core so that it can be called from pg_upgrade.
---
 contrib/pg_walinspect/Makefile                |   2 +-
 contrib/pg_walinspect/meson.build             |   1 +
 .../pg_walinspect/pg_walinspect--1.1--1.2.sql |  31 +++
 contrib/pg_walinspect/pg_walinspect.c         | 180 +-----------------
 contrib/pg_walinspect/pg_walinspect.control   |   2 +-
 src/backend/access/transam/xlogfuncs.c        |  50 +++++
 src/backend/access/transam/xlogutils.c        | 173 +++++++++++++++++
 src/backend/catalog/system_functions.sql      |   4 +
 src/include/access/xlogutils.h                |   6 +
 src/include/catalog/pg_proc.dat               |   9 +
 src/test/regress/expected/misc_functions.out  |  18 ++
 src/test/regress/sql/misc_functions.sql       |  16 ++
 12 files changed, 313 insertions(+), 179 deletions(-)
 create mode 100644 contrib/pg_walinspect/pg_walinspect--1.1--1.2.sql

diff --git a/contrib/pg_walinspect/Makefile b/contrib/pg_walinspect/Makefile
index 22090f7716..5cc7d81b42 100644
--- a/contrib/pg_walinspect/Makefile
+++ b/contrib/pg_walinspect/Makefile
@@ -7,7 +7,7 @@ OBJS = \
 PGFILEDESC = "pg_walinspect - functions to inspect contents of PostgreSQL Write-Ahead Log"
 
 EXTENSION = pg_walinspect
-DATA = pg_walinspect--1.0.sql pg_walinspect--1.0--1.1.sql
+DATA = pg_walinspect--1.0.sql pg_walinspect--1.0--1.1.sql pg_walinspect--1.1--1.2.sql
 
 REGRESS = pg_walinspect oldextversions
 
diff --git a/contrib/pg_walinspect/meson.build b/contrib/pg_walinspect/meson.build
index 80059f6119..8f7a99a493 100644
--- a/contrib/pg_walinspect/meson.build
+++ b/contrib/pg_walinspect/meson.build
@@ -20,6 +20,7 @@ install_data(
   'pg_walinspect.control',
   'pg_walinspect--1.0.sql',
   'pg_walinspect--1.0--1.1.sql',
+  'pg_walinspect--1.1--1.2.sql',
   kwargs: contrib_data_args,
 )
 
diff --git a/contrib/pg_walinspect/pg_walinspect--1.1--1.2.sql b/contrib/pg_walinspect/pg_walinspect--1.1--1.2.sql
new file mode 100644
index 0000000000..48e2da3034
--- /dev/null
+++ b/contrib/pg_walinspect/pg_walinspect--1.1--1.2.sql
@@ -0,0 +1,31 @@
+/* contrib/pg_walinspect/pg_walinspect--1.1--1.2.sql */
+
+-- complain if script is sourced in psql, rather than via ALTER EXTENSION
+\echo Use "ALTER EXTENSION pg_walinspect UPDATE TO '1.2'" to load this file. \quit
+
+-- The function is now in the backend and callers should update to use those.
+
+ALTER EXTENSION pg_walinspect DROP FUNCTION pg_get_wal_record_info;
+DROP FUNCTION pg_get_wal_record_info(pg_lsn);
+
+--
+-- pg_get_wal_record_info()
+--
+CREATE FUNCTION pg_get_wal_record_info(IN in_lsn pg_lsn,
+    OUT start_lsn pg_lsn,
+    OUT end_lsn pg_lsn,
+    OUT prev_lsn pg_lsn,
+    OUT xid xid,
+    OUT resource_manager text,
+    OUT record_type text,
+    OUT record_length int4,
+    OUT main_data_length int4,
+    OUT fpi_length int4,
+    OUT description text,
+    OUT block_ref text
+)
+AS 'pg_get_wal_record_content'
+LANGUAGE INTERNAL STRICT PARALLEL SAFE;
+
+REVOKE EXECUTE ON FUNCTION pg_get_wal_record_info(pg_lsn) FROM PUBLIC;
+GRANT EXECUTE ON FUNCTION pg_get_wal_record_info(pg_lsn) TO pg_read_server_files;
diff --git a/contrib/pg_walinspect/pg_walinspect.c b/contrib/pg_walinspect/pg_walinspect.c
index 796a74f322..8cba14e789 100644
--- a/contrib/pg_walinspect/pg_walinspect.c
+++ b/contrib/pg_walinspect/pg_walinspect.c
@@ -39,11 +39,6 @@ PG_FUNCTION_INFO_V1(pg_get_wal_stats);
 PG_FUNCTION_INFO_V1(pg_get_wal_stats_till_end_of_wal);
 
 static void ValidateInputLSNs(XLogRecPtr start_lsn, XLogRecPtr *end_lsn);
-static XLogRecPtr GetCurrentLSN(void);
-static XLogReaderState *InitXLogReaderState(XLogRecPtr lsn);
-static XLogRecord *ReadNextXLogRecord(XLogReaderState *xlogreader);
-static void GetWALRecordInfo(XLogReaderState *record, Datum *values,
-							 bool *nulls, uint32 ncols);
 static void GetWALRecordsInfo(FunctionCallInfo fcinfo,
 							  XLogRecPtr start_lsn,
 							  XLogRecPtr end_lsn);
@@ -62,178 +57,6 @@ static void GetWalStats(FunctionCallInfo fcinfo,
 static void GetWALBlockInfo(FunctionCallInfo fcinfo, XLogReaderState *record,
 							bool show_data);
 
-/*
- * Return the LSN up to which the server has WAL.
- */
-static XLogRecPtr
-GetCurrentLSN(void)
-{
-	XLogRecPtr	curr_lsn;
-
-	/*
-	 * We determine the current LSN of the server similar to how page_read
-	 * callback read_local_xlog_page_no_wait does.
-	 */
-	if (!RecoveryInProgress())
-		curr_lsn = GetFlushRecPtr(NULL);
-	else
-		curr_lsn = GetXLogReplayRecPtr(NULL);
-
-	Assert(!XLogRecPtrIsInvalid(curr_lsn));
-
-	return curr_lsn;
-}
-
-/*
- * Initialize WAL reader and identify first valid LSN.
- */
-static XLogReaderState *
-InitXLogReaderState(XLogRecPtr lsn)
-{
-	XLogReaderState *xlogreader;
-	ReadLocalXLogPageNoWaitPrivate *private_data;
-	XLogRecPtr	first_valid_record;
-
-	/*
-	 * Reading WAL below the first page of the first segments isn't allowed.
-	 * This is a bootstrap WAL page and the page_read callback fails to read
-	 * it.
-	 */
-	if (lsn < XLOG_BLCKSZ)
-		ereport(ERROR,
-				(errmsg("could not read WAL at LSN %X/%X",
-						LSN_FORMAT_ARGS(lsn))));
-
-	private_data = (ReadLocalXLogPageNoWaitPrivate *)
-		palloc0(sizeof(ReadLocalXLogPageNoWaitPrivate));
-
-	xlogreader = XLogReaderAllocate(wal_segment_size, NULL,
-									XL_ROUTINE(.page_read = &read_local_xlog_page_no_wait,
-											   .segment_open = &wal_segment_open,
-											   .segment_close = &wal_segment_close),
-									private_data);
-
-	if (xlogreader == NULL)
-		ereport(ERROR,
-				(errcode(ERRCODE_OUT_OF_MEMORY),
-				 errmsg("out of memory"),
-				 errdetail("Failed while allocating a WAL reading processor.")));
-
-	/* first find a valid recptr to start from */
-	first_valid_record = XLogFindNextRecord(xlogreader, lsn);
-
-	if (XLogRecPtrIsInvalid(first_valid_record))
-		ereport(ERROR,
-				(errmsg("could not find a valid record after %X/%X",
-						LSN_FORMAT_ARGS(lsn))));
-
-	return xlogreader;
-}
-
-/*
- * Read next WAL record.
- *
- * By design, to be less intrusive in a running system, no slot is allocated
- * to reserve the WAL we're about to read. Therefore this function can
- * encounter read errors for historical WAL.
- *
- * We guard against ordinary errors trying to read WAL that hasn't been
- * written yet by limiting end_lsn to the flushed WAL, but that can also
- * encounter errors if the flush pointer falls in the middle of a record. In
- * that case we'll return NULL.
- */
-static XLogRecord *
-ReadNextXLogRecord(XLogReaderState *xlogreader)
-{
-	XLogRecord *record;
-	char	   *errormsg;
-
-	record = XLogReadRecord(xlogreader, &errormsg);
-
-	if (record == NULL)
-	{
-		ReadLocalXLogPageNoWaitPrivate *private_data;
-
-		/* return NULL, if end of WAL is reached */
-		private_data = (ReadLocalXLogPageNoWaitPrivate *)
-			xlogreader->private_data;
-
-		if (private_data->end_of_wal)
-			return NULL;
-
-		if (errormsg)
-			ereport(ERROR,
-					(errcode_for_file_access(),
-					 errmsg("could not read WAL at %X/%X: %s",
-							LSN_FORMAT_ARGS(xlogreader->EndRecPtr), errormsg)));
-		else
-			ereport(ERROR,
-					(errcode_for_file_access(),
-					 errmsg("could not read WAL at %X/%X",
-							LSN_FORMAT_ARGS(xlogreader->EndRecPtr))));
-	}
-
-	return record;
-}
-
-/*
- * Output values that make up a row describing caller's WAL record.
- *
- * This function leaks memory.  Caller may need to use its own custom memory
- * context.
- *
- * Keep this in sync with GetWALBlockInfo.
- */
-static void
-GetWALRecordInfo(XLogReaderState *record, Datum *values,
-				 bool *nulls, uint32 ncols)
-{
-	const char *record_type;
-	RmgrData	desc;
-	uint32		fpi_len = 0;
-	StringInfoData rec_desc;
-	StringInfoData rec_blk_ref;
-	int			i = 0;
-
-	desc = GetRmgr(XLogRecGetRmid(record));
-	record_type = desc.rm_identify(XLogRecGetInfo(record));
-
-	if (record_type == NULL)
-		record_type = psprintf("UNKNOWN (%x)", XLogRecGetInfo(record) & ~XLR_INFO_MASK);
-
-	initStringInfo(&rec_desc);
-	desc.rm_desc(&rec_desc, record);
-
-	if (XLogRecHasAnyBlockRefs(record))
-	{
-		initStringInfo(&rec_blk_ref);
-		XLogRecGetBlockRefInfo(record, false, true, &rec_blk_ref, &fpi_len);
-	}
-
-	values[i++] = LSNGetDatum(record->ReadRecPtr);
-	values[i++] = LSNGetDatum(record->EndRecPtr);
-	values[i++] = LSNGetDatum(XLogRecGetPrev(record));
-	values[i++] = TransactionIdGetDatum(XLogRecGetXid(record));
-	values[i++] = CStringGetTextDatum(desc.rm_name);
-	values[i++] = CStringGetTextDatum(record_type);
-	values[i++] = UInt32GetDatum(XLogRecGetTotalLen(record));
-	values[i++] = UInt32GetDatum(XLogRecGetDataLen(record));
-	values[i++] = UInt32GetDatum(fpi_len);
-
-	if (rec_desc.len > 0)
-		values[i++] = CStringGetTextDatum(rec_desc.data);
-	else
-		nulls[i++] = true;
-
-	if (XLogRecHasAnyBlockRefs(record))
-		values[i++] = CStringGetTextDatum(rec_blk_ref.data);
-	else
-		nulls[i++] = true;
-
-	Assert(i == ncols);
-}
-
-
 /*
  * Output one or more rows in rsinfo tuple store, each describing a single
  * block reference from caller's WAL record. (Should only be called with
@@ -454,6 +277,9 @@ pg_get_wal_block_info(PG_FUNCTION_ARGS)
 
 /*
  * Get WAL record info.
+ *
+ * Note that this function have been removed in newer versions in 1.2, but they
+ * are kept around for compatibility.
  */
 Datum
 pg_get_wal_record_info(PG_FUNCTION_ARGS)
diff --git a/contrib/pg_walinspect/pg_walinspect.control b/contrib/pg_walinspect/pg_walinspect.control
index efa3cb2cfe..5f574b865b 100644
--- a/contrib/pg_walinspect/pg_walinspect.control
+++ b/contrib/pg_walinspect/pg_walinspect.control
@@ -1,5 +1,5 @@
 # pg_walinspect extension
 comment = 'functions to inspect contents of PostgreSQL Write-Ahead Log'
-default_version = '1.1'
+default_version = '1.2'
 module_pathname = '$libdir/pg_walinspect'
 relocatable = true
diff --git a/src/backend/access/transam/xlogfuncs.c b/src/backend/access/transam/xlogfuncs.c
index 5044ff0643..71ee1069f6 100644
--- a/src/backend/access/transam/xlogfuncs.c
+++ b/src/backend/access/transam/xlogfuncs.c
@@ -754,3 +754,53 @@ pg_promote(PG_FUNCTION_ARGS)
 						   wait_seconds)));
 	PG_RETURN_BOOL(false);
 }
+
+/*
+ * Get WAL record content.
+ */
+Datum
+pg_get_wal_record_content(PG_FUNCTION_ARGS)
+{
+#define PG_GET_WAL_RECORD_CONTENT_COLS 11
+	Datum		result;
+	Datum		values[PG_GET_WAL_RECORD_CONTENT_COLS] = {0};
+	bool		nulls[PG_GET_WAL_RECORD_CONTENT_COLS] = {0};
+	XLogRecPtr	lsn;
+	XLogRecPtr	curr_lsn;
+	XLogReaderState *xlogreader;
+	TupleDesc	tupdesc;
+	HeapTuple	tuple;
+
+	lsn = PG_GETARG_LSN(0);
+	curr_lsn = GetCurrentLSN();
+
+	if (lsn > curr_lsn)
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("WAL input LSN must be less than current LSN"),
+				 errdetail("Current WAL LSN on the database system is at %X/%X.",
+						   LSN_FORMAT_ARGS(curr_lsn))));
+
+	/* Build a tuple descriptor for our result type. */
+	if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
+		elog(ERROR, "return type must be a row type");
+
+	xlogreader = InitXLogReaderState(lsn);
+
+	if (!ReadNextXLogRecord(xlogreader))
+		ereport(ERROR,
+				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+				 errmsg("could not read WAL at %X/%X",
+						LSN_FORMAT_ARGS(xlogreader->EndRecPtr))));
+
+	GetWALRecordInfo(xlogreader, values, nulls, PG_GET_WAL_RECORD_CONTENT_COLS);
+
+	pfree(xlogreader->private_data);
+	XLogReaderFree(xlogreader);
+
+	tuple = heap_form_tuple(tupdesc, values, nulls);
+	result = HeapTupleGetDatum(tuple);
+
+	PG_RETURN_DATUM(result);
+#undef PG_GET_WAL_RECORD_CONTENT_COLS
+}
diff --git a/src/backend/access/transam/xlogutils.c b/src/backend/access/transam/xlogutils.c
index e174a2a891..f637028b8e 100644
--- a/src/backend/access/transam/xlogutils.c
+++ b/src/backend/access/transam/xlogutils.c
@@ -28,8 +28,10 @@
 #include "pgstat.h"
 #include "storage/fd.h"
 #include "storage/smgr.h"
+#include "utils/builtins.h"
 #include "utils/guc.h"
 #include "utils/hsearch.h"
+#include "utils/pg_lsn.h"
 #include "utils/rel.h"
 
 
@@ -1048,3 +1050,174 @@ WALReadRaiseError(WALReadError *errinfo)
 						errinfo->wre_req)));
 	}
 }
+
+/*
+ * Return the LSN up to which the server has WAL.
+ */
+XLogRecPtr
+GetCurrentLSN(void)
+{
+	XLogRecPtr	curr_lsn;
+
+	/*
+	 * We determine the current LSN of the server similar to how page_read
+	 * callback read_local_xlog_page_no_wait does.
+	 */
+	if (!RecoveryInProgress())
+		curr_lsn = GetFlushRecPtr(NULL);
+	else
+		curr_lsn = GetXLogReplayRecPtr(NULL);
+
+	Assert(!XLogRecPtrIsInvalid(curr_lsn));
+
+	return curr_lsn;
+}
+
+/*
+ * Initialize WAL reader and identify first valid LSN.
+ */
+XLogReaderState *
+InitXLogReaderState(XLogRecPtr lsn)
+{
+	XLogReaderState *xlogreader;
+	ReadLocalXLogPageNoWaitPrivate *private_data;
+	XLogRecPtr	first_valid_record;
+
+	/*
+	 * Reading WAL below the first page of the first segments isn't allowed.
+	 * This is a bootstrap WAL page and the page_read callback fails to read
+	 * it.
+	 */
+	if (lsn < XLOG_BLCKSZ)
+		ereport(ERROR,
+				(errmsg("could not read WAL at LSN %X/%X",
+						LSN_FORMAT_ARGS(lsn))));
+
+	private_data = (ReadLocalXLogPageNoWaitPrivate *)
+		palloc0(sizeof(ReadLocalXLogPageNoWaitPrivate));
+
+	xlogreader = XLogReaderAllocate(wal_segment_size, NULL,
+									XL_ROUTINE(.page_read = &read_local_xlog_page_no_wait,
+											   .segment_open = &wal_segment_open,
+											   .segment_close = &wal_segment_close),
+									private_data);
+
+	if (xlogreader == NULL)
+		ereport(ERROR,
+				(errcode(ERRCODE_OUT_OF_MEMORY),
+				 errmsg("out of memory"),
+				 errdetail("Failed while allocating a WAL reading processor.")));
+
+	/* first find a valid recptr to start from */
+	first_valid_record = XLogFindNextRecord(xlogreader, lsn);
+
+	if (XLogRecPtrIsInvalid(first_valid_record))
+		ereport(ERROR,
+				(errmsg("could not find a valid record after %X/%X",
+						LSN_FORMAT_ARGS(lsn))));
+
+	return xlogreader;
+}
+
+/*
+ * Read next WAL record.
+ *
+ * By design, to be less intrusive in a running system, no slot is allocated
+ * to reserve the WAL we're about to read. Therefore this function can
+ * encounter read errors for historical WAL.
+ *
+ * We guard against ordinary errors trying to read WAL that hasn't been
+ * written yet by limiting end_lsn to the flushed WAL, but that can also
+ * encounter errors if the flush pointer falls in the middle of a record. In
+ * that case we'll return NULL.
+ */
+XLogRecord *
+ReadNextXLogRecord(XLogReaderState *xlogreader)
+{
+	XLogRecord *record;
+	char	   *errormsg;
+
+	record = XLogReadRecord(xlogreader, &errormsg);
+
+	if (record == NULL)
+	{
+		ReadLocalXLogPageNoWaitPrivate *private_data;
+
+		/* return NULL, if end of WAL is reached */
+		private_data = (ReadLocalXLogPageNoWaitPrivate *)
+			xlogreader->private_data;
+
+		if (private_data->end_of_wal)
+			return NULL;
+
+		if (errormsg)
+			ereport(ERROR,
+					(errcode_for_file_access(),
+					 errmsg("could not read WAL at %X/%X: %s",
+							LSN_FORMAT_ARGS(xlogreader->EndRecPtr), errormsg)));
+		else
+			ereport(ERROR,
+					(errcode_for_file_access(),
+					 errmsg("could not read WAL at %X/%X",
+							LSN_FORMAT_ARGS(xlogreader->EndRecPtr))));
+	}
+
+	return record;
+}
+
+/*
+ * Output values that make up a row describing caller's WAL record.
+ *
+ * This function leaks memory.  Caller may need to use its own custom memory
+ * context.
+ *
+ * Keep this in sync with GetWALBlockInfo.
+ */
+void
+GetWALRecordInfo(XLogReaderState *record, Datum *values,
+				 bool *nulls, uint32 ncols)
+{
+	const char *record_type;
+	RmgrData	desc;
+	uint32		fpi_len = 0;
+	StringInfoData rec_desc;
+	StringInfoData rec_blk_ref;
+	int			i = 0;
+
+	desc = GetRmgr(XLogRecGetRmid(record));
+	record_type = desc.rm_identify(XLogRecGetInfo(record));
+
+	if (record_type == NULL)
+		record_type = psprintf("UNKNOWN (%x)", XLogRecGetInfo(record) & ~XLR_INFO_MASK);
+
+	initStringInfo(&rec_desc);
+	desc.rm_desc(&rec_desc, record);
+
+	if (XLogRecHasAnyBlockRefs(record))
+	{
+		initStringInfo(&rec_blk_ref);
+		XLogRecGetBlockRefInfo(record, false, true, &rec_blk_ref, &fpi_len);
+	}
+
+	values[i++] = LSNGetDatum(record->ReadRecPtr);
+	values[i++] = LSNGetDatum(record->EndRecPtr);
+	values[i++] = LSNGetDatum(XLogRecGetPrev(record));
+	values[i++] = TransactionIdGetDatum(XLogRecGetXid(record));
+	values[i++] = CStringGetTextDatum(desc.rm_name);
+	values[i++] = CStringGetTextDatum(record_type);
+	values[i++] = UInt32GetDatum(XLogRecGetTotalLen(record));
+	values[i++] = UInt32GetDatum(XLogRecGetDataLen(record));
+	values[i++] = UInt32GetDatum(fpi_len);
+
+	if (rec_desc.len > 0)
+		values[i++] = CStringGetTextDatum(rec_desc.data);
+	else
+		nulls[i++] = true;
+
+	if (XLogRecHasAnyBlockRefs(record))
+		values[i++] = CStringGetTextDatum(rec_blk_ref.data);
+	else
+		nulls[i++] = true;
+
+	Assert(i == ncols);
+}
diff --git a/src/backend/catalog/system_functions.sql b/src/backend/catalog/system_functions.sql
index 07c0d89c4f..0186d594fb 100644
--- a/src/backend/catalog/system_functions.sql
+++ b/src/backend/catalog/system_functions.sql
@@ -616,6 +616,8 @@ REVOKE EXECUTE ON FUNCTION pg_backup_stop(boolean) FROM public;
 
 REVOKE EXECUTE ON FUNCTION pg_create_restore_point(text) FROM public;
 
+REVOKE EXECUTE ON FUNCTION pg_get_wal_record_content(pg_lsn) FROM public;
+
 REVOKE EXECUTE ON FUNCTION pg_switch_wal() FROM public;
 
 REVOKE EXECUTE ON FUNCTION pg_log_standby_snapshot() FROM public;
@@ -726,6 +728,8 @@ REVOKE EXECUTE ON FUNCTION pg_ls_replslotdir(text) FROM PUBLIC;
 -- We also set up some things as accessible to standard roles.
 --
 
+GRANT EXECUTE ON FUNCTION pg_get_wal_record_content(pg_lsn) TO pg_read_server_files;
+
 GRANT EXECUTE ON FUNCTION pg_ls_logdir() TO pg_monitor;
 
 GRANT EXECUTE ON FUNCTION pg_ls_waldir() TO pg_monitor;
diff --git a/src/include/access/xlogutils.h b/src/include/access/xlogutils.h
index 5b77b11f50..95ad84ac6f 100644
--- a/src/include/access/xlogutils.h
+++ b/src/include/access/xlogutils.h
@@ -115,4 +115,10 @@ extern void XLogReadDetermineTimeline(XLogReaderState *state,
 
 extern void WALReadRaiseError(WALReadError *errinfo);
 
+extern XLogRecPtr GetCurrentLSN(void);
+extern XLogReaderState *InitXLogReaderState(XLogRecPtr lsn);
+extern XLogRecord *ReadNextXLogRecord(XLogReaderState *xlogreader);
+extern void GetWALRecordInfo(XLogReaderState *record, Datum *values,
+							 bool *nulls, uint32 ncols);
+
 #endif
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index 6996073989..ffe146ba84 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6489,6 +6489,15 @@
   proargnames => '{rm_id, rm_name, rm_builtin}',
   prosrc => 'pg_get_wal_resource_managers' },
 
+
+{ oid => '8045', descr => 'Info of the WAL conent',
+  proname => 'pg_get_wal_record_content', prorows => '1', proretset => 't',
+  provolatile => 's', prorettype => 'record', proargtypes => 'pg_lsn',
+  proallargtypes => '{pg_lsn,pg_lsn,pg_lsn,pg_lsn,xid,text,text,int4,int4,int4,text,text}',
+  proargmodes => '{i,o,o,o,o,o,o,o,o,o,o,o}',
+  proargnames => '{in_lsn,start_lsn,end_lsn,prev_lsn,xid,resource_manager,record_type,record_length,main_data_length,fpi_length,description,block_ref}',
+  prosrc => 'pg_get_wal_record_content' },
+
 { oid => '2621', descr => 'reload configuration files',
   proname => 'pg_reload_conf', provolatile => 'v', prorettype => 'bool',
   proargtypes => '', prosrc => 'pg_reload_conf' },
diff --git a/src/test/regress/expected/misc_functions.out b/src/test/regress/expected/misc_functions.out
index c669948370..bf2d1a5f9b 100644
--- a/src/test/regress/expected/misc_functions.out
+++ b/src/test/regress/expected/misc_functions.out
@@ -642,3 +642,21 @@ SELECT segment_number > 0 AS ok_segment_number, timeline_id
  t                 |  4294967295
 (1 row)
 
+-- pg_get_wal_record_content
+CREATE TABLE sample_tbl(col1 int, col2 int);
+SELECT pg_current_wal_lsn() AS wal_lsn \gset
+INSERT INTO sample_tbl SELECT * FROM generate_series(1, 2);
+-- Mask DETAIL messages as these could refer to current LSN positions.
+\set VERBOSITY terse
+-- Invalid input LSN.
+SELECT * FROM pg_get_wal_record_content('0/0');
+ERROR:  could not read WAL at LSN 0/0
+-- LSNs with the highest value possible.
+SELECT * FROM pg_get_wal_record_content('FFFFFFFF/FFFFFFFF');
+ERROR:  WAL input LSN must be less than current LSN
+SELECT COUNT(*) >= 1 AS ok FROM pg_get_wal_record_content(:'wal_lsn');
+ ok 
+----
+ t
+(1 row)
+
diff --git a/src/test/regress/sql/misc_functions.sql b/src/test/regress/sql/misc_functions.sql
index b57f01f3e9..4ff19b4927 100644
--- a/src/test/regress/sql/misc_functions.sql
+++ b/src/test/regress/sql/misc_functions.sql
@@ -237,3 +237,19 @@ SELECT segment_number > 0 AS ok_segment_number, timeline_id
   FROM pg_split_walfile_name('000000010000000100000000');
 SELECT segment_number > 0 AS ok_segment_number, timeline_id
   FROM pg_split_walfile_name('ffffffFF00000001000000af');
+
+-- pg_get_wal_record_content
+CREATE TABLE sample_tbl(col1 int, col2 int);
+SELECT pg_current_wal_lsn() AS wal_lsn \gset
+INSERT INTO sample_tbl SELECT * FROM generate_series(1, 2);
+
+-- Mask DETAIL messages as these could refer to current LSN positions.
+\set VERBOSITY terse
+
+-- Invalid input LSN.
+SELECT * FROM pg_get_wal_record_content('0/0');
+
+-- LSNs with the highest value possible.
+SELECT * FROM pg_get_wal_record_content('FFFFFFFF/FFFFFFFF');
+
+SELECT COUNT(*) >= 1 AS ok FROM pg_get_wal_record_content(:'wal_lsn');
-- 
2.27.0