diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 1cd8b11334..1f63dc6dba 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -26098,6 +26098,22 @@ LOG: Grand total: 1651920 bytes in 201 blocks; 622360 free (88 chunks); 1029560
+
+
+
+ pg_dissect_walfile_name
+
+ pg_dissect_walfile_name ( file_name text )
+ record
+ ( segno numeric,
+ timeline_id bigint )
+
+
+ Extracts the file sequence number and timeline ID from a WAL file
+ name.
+
+
+
@@ -26155,6 +26171,23 @@ postgres=# SELECT * FROM pg_walfile_name_offset((pg_backup_stop()).lsn);
needs to be archived.
+
+ pg_dissect_walfile_name is useful to compute a
+ LSN from a file offset and WAL file name, for example:
+
+postgres=# \set file_name '000000010000000100C000AB'
+postgres=# \set offset 256
+postgres=# SELECT '0/0'::pg_lsn + pd.segno * ps.setting::int + :offset AS lsn
+ FROM pg_dissect_walfile_name(:'file_name') pd,
+ pg_show_all_settings() ps
+ WHERE ps.name = 'wal_segment_size';
+ lsn
+---------------
+ C001/AB000100
+(1 row)
+
+
+
diff --git a/src/backend/access/transam/xlogfuncs.c b/src/backend/access/transam/xlogfuncs.c
index 487d5d9cac..0a31837ef1 100644
--- a/src/backend/access/transam/xlogfuncs.c
+++ b/src/backend/access/transam/xlogfuncs.c
@@ -432,6 +432,59 @@ pg_walfile_name(PG_FUNCTION_ARGS)
PG_RETURN_TEXT_P(cstring_to_text(xlogfilename));
}
+/*
+ * Extract the sequence number and the timeline ID from given a WAL file
+ * name.
+ */
+Datum
+pg_dissect_walfile_name(PG_FUNCTION_ARGS)
+{
+#define PG_DISSECT_WALFILE_NAME_COLS 2
+ char *fname = text_to_cstring(PG_GETARG_TEXT_PP(0));
+ char *fname_upper;
+ char *p;
+ TimeLineID tli;
+ XLogSegNo segno;
+ Datum values[PG_DISSECT_WALFILE_NAME_COLS] = {0};
+ bool isnull[PG_DISSECT_WALFILE_NAME_COLS] = {0};
+ TupleDesc tupdesc;
+ HeapTuple tuple;
+ char buf[256];
+ Datum result;
+
+ fname_upper = pstrdup(fname);
+
+ /* Capitalize WAL file name. */
+ for (p = fname_upper; *p; p++)
+ *p = pg_toupper((unsigned char) *p);
+
+ if (!IsXLogFileName(fname_upper))
+ ereport(ERROR,
+ (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
+ errmsg("invalid WAL file name \"%s\"", fname)));
+
+ XLogFromFileName(fname_upper, &tli, &segno, wal_segment_size);
+
+ if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
+ elog(ERROR, "return type must be a row type");
+
+ /* Convert to numeric. */
+ snprintf(buf, sizeof buf, UINT64_FORMAT, segno);
+ values[0] = DirectFunctionCall3(numeric_in,
+ CStringGetDatum(buf),
+ ObjectIdGetDatum(0),
+ Int32GetDatum(-1));
+
+ values[1] = Int64GetDatum(tli);
+
+ tuple = heap_form_tuple(tupdesc, values, isnull);
+ result = HeapTupleGetDatum(tuple);
+
+ PG_RETURN_DATUM(result);
+
+#undef PG_DISSECT_WALFILE_NAME_COLS
+}
+
/*
* pg_wal_replay_pause - Request to pause recovery
*
diff --git a/src/include/catalog/catversion.h b/src/include/catalog/catversion.h
index 094f59f82d..091ad94c5e 100644
--- a/src/include/catalog/catversion.h
+++ b/src/include/catalog/catversion.h
@@ -57,6 +57,6 @@
*/
/* yyyymmddN */
-#define CATALOG_VERSION_NO 202212191
+#define CATALOG_VERSION_NO 202212201
#endif
diff --git a/src/include/catalog/pg_proc.dat b/src/include/catalog/pg_proc.dat
index d763419c0d..98d90d9338 100644
--- a/src/include/catalog/pg_proc.dat
+++ b/src/include/catalog/pg_proc.dat
@@ -6372,6 +6372,13 @@
{ oid => '2851', descr => 'wal filename, given a wal location',
proname => 'pg_walfile_name', prorettype => 'text', proargtypes => 'pg_lsn',
prosrc => 'pg_walfile_name' },
+{ oid => '8205',
+ descr => 'sequence number and timeline ID given a wal filename',
+ proname => 'pg_dissect_walfile_name', provolatile => 's',
+ prorettype => 'record', proargtypes => 'text',
+ proallargtypes => '{text,numeric,int8}', proargmodes => '{i,o,o}',
+ proargnames => '{file_name,segno,timeline_id}',
+ prosrc => 'pg_dissect_walfile_name' },
{ oid => '3165', descr => 'difference in bytes, given two wal locations',
proname => 'pg_wal_lsn_diff', prorettype => 'numeric',
diff --git a/src/test/regress/expected/misc_functions.out b/src/test/regress/expected/misc_functions.out
index 88bb696ded..2907f779a7 100644
--- a/src/test/regress/expected/misc_functions.out
+++ b/src/test/regress/expected/misc_functions.out
@@ -619,3 +619,26 @@ SELECT count(*) > 0 AS ok FROM pg_control_system();
t
(1 row)
+-- pg_dissect_walfile_name
+SELECT * FROM pg_dissect_walfile_name(NULL);
+ segno | timeline_id
+-------+-------------
+ |
+(1 row)
+
+SELECT * FROM pg_dissect_walfile_name('invalid');
+ERROR: invalid WAL file name "invalid"
+SELECT segno > 0 AS ok_segno, timeline_id
+ FROM pg_dissect_walfile_name('000000010000000100000000');
+ ok_segno | timeline_id
+----------+-------------
+ t | 1
+(1 row)
+
+SELECT segno > 0 AS ok_segno, timeline_id
+ FROM pg_dissect_walfile_name('ffffffFF00000001000000af');
+ ok_segno | timeline_id
+----------+-------------
+ t | 4294967295
+(1 row)
+
diff --git a/src/test/regress/sql/misc_functions.sql b/src/test/regress/sql/misc_functions.sql
index b07e9e8dbb..0c3d75fd1a 100644
--- a/src/test/regress/sql/misc_functions.sql
+++ b/src/test/regress/sql/misc_functions.sql
@@ -229,3 +229,11 @@ SELECT count(*) > 0 AS ok FROM pg_control_checkpoint();
SELECT count(*) > 0 AS ok FROM pg_control_init();
SELECT count(*) > 0 AS ok FROM pg_control_recovery();
SELECT count(*) > 0 AS ok FROM pg_control_system();
+
+-- pg_dissect_walfile_name
+SELECT * FROM pg_dissect_walfile_name(NULL);
+SELECT * FROM pg_dissect_walfile_name('invalid');
+SELECT segno > 0 AS ok_segno, timeline_id
+ FROM pg_dissect_walfile_name('000000010000000100000000');
+SELECT segno > 0 AS ok_segno, timeline_id
+ FROM pg_dissect_walfile_name('ffffffFF00000001000000af');