From cca186348929cd75f23ef1b25922386bf38cf99c Mon Sep 17 00:00:00 2001 From: Michael Paquier Date: Tue, 20 Dec 2022 13:36:27 +0900 Subject: [PATCH] Add pg_dissect_walfile_name() This function takes in input a WAL segment name and returns a tuple made of the segment sequence number (dependent on the WAL segment size of the cluster) and its timeline, as of a thin SQL wrapper around the existing XLogFromFileName(). This function has multiple usages, like being able to compile a LSN from a file name and an offset, or finding the timeline of a segment without having to do to some maths based on the first eight characters of the segment. Bump catalog version. Author: Bharath Rupireddy Reviewed-by: Nathan Bossart, Kyotaro Horiguchi, Maxim Orlov, Michael Paquier Discussion: https://postgr.es/m/CALj2ACWV=FCddsxcGbVOA=cvPyMr75YCFbSQT6g4KDj=gcJK4g@mail.gmail.com --- doc/src/sgml/func.sgml | 33 ++++++++++++ src/backend/access/transam/xlogfuncs.c | 53 ++++++++++++++++++++ src/include/catalog/catversion.h | 2 +- src/include/catalog/pg_proc.dat | 7 +++ src/test/regress/expected/misc_functions.out | 23 +++++++++ src/test/regress/sql/misc_functions.sql | 8 +++ 6 files changed, 125 insertions(+), 1 deletion(-) 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');