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modify segno. for pg_walfile_name() and pg_walfile_name_offset()

2023年11月25日 00:44:09 +0000 (19:44 -0500)

committer Bruce Momjian <bruce@momjian.us>

2023年11月25日 00:44:09 +0000 (19:44 -0500)

Previously these functions returned the previous segment number if the
LSN was on a segment boundary. We now always return the current segment
number for an LSN.

Docs updated to reflect this change. Regression tests added, author
Andres Freund.

Also mentioned in thread https://postgr.es/m/flat/20220204225057.GA1535307%40nathanxps13#d964275c9540d8395e138efc0a75f7e8

BACKWARD INCOMPATIBILITY

Reported-by: Kyotaro Horiguchi
Discussion: https://postgr.es/m/20190726.172120.101752680.horikyota.ntt@gmail.com

Co-authored-by: Kyotaro Horiguchi
Backpatch-through: master

doc/src/sgml/func.sgml patch | blob | blame | history

src/backend/access/transam/xlogfuncs.c patch | blob | blame | history

src/test/regress/expected/misc_functions.out patch | blob | blame | history

src/test/regress/sql/misc_functions.sql patch | blob | blame | history

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml

index 053fbc5ef2cc142e5d43379f53033ecc2a6d95f2..20da3ed0334886b7f1abba86d74b00c692af669f 100644 (file)

--- a/doc/src/sgml/func.sgml

+++ b/doc/src/sgml/func.sgml

@@ -27075,11 +27075,6 @@ postgres=# SELECT * FROM pg_walfile_name_offset((pg_backup_stop()).lsn);

(1 row)

</programlisting>

Similarly, <function>pg_walfile_name</function> extracts just the write-ahead log file name.

- When the given write-ahead log location is exactly at a write-ahead log file boundary, both

- these functions return the name of the preceding write-ahead log file.

- This is usually the desired behavior for managing write-ahead log archiving

- behavior, since the preceding file is the last one that currently

- needs to be archived.

</para>

<para>

diff --git a/src/backend/access/transam/xlogfuncs.c b/src/backend/access/transam/xlogfuncs.c

index 45a70668b1cce4fd8e901978adcf4f81b4d372ee..45452d937c7bd4178d0a5dc5fb1bc0deee9b46d5 100644 (file)

--- a/src/backend/access/transam/xlogfuncs.c

+++ b/src/backend/access/transam/xlogfuncs.c

@@ -374,10 +374,6 @@ pg_last_wal_replay_lsn(PG_FUNCTION_ARGS)

* Compute an xlog file name and decimal byte offset given a WAL location,

* such as is returned by pg_backup_stop() or pg_switch_wal().

- *

- * Note that a location exactly at a segment boundary is taken to be in

- * the previous segment. This is usually the right thing, since the

- * expected usage is to determine which xlog file(s) are ready to archive.

Datum

pg_walfile_name_offset(PG_FUNCTION_ARGS)

@@ -414,7 +410,7 @@ pg_walfile_name_offset(PG_FUNCTION_ARGS)

* xlogfilename

- XLByteToPrevSeg(locationpoint, xlogsegno, wal_segment_size);

+ XLByteToSeg(locationpoint, xlogsegno, wal_segment_size);

XLogFileName(xlogfilename, GetWALInsertionTimeLine(), xlogsegno,

wal_segment_size);

@@ -457,7 +453,7 @@ pg_walfile_name(PG_FUNCTION_ARGS)

errhint("%s cannot be executed during recovery.",

"pg_walfile_name()")));

- XLByteToPrevSeg(locationpoint, xlogsegno, wal_segment_size);

+ XLByteToSeg(locationpoint, xlogsegno, wal_segment_size);

XLogFileName(xlogfilename, GetWALInsertionTimeLine(), xlogsegno,

wal_segment_size);

diff --git a/src/test/regress/expected/misc_functions.out b/src/test/regress/expected/misc_functions.out

index c66994837087176eed215df7d044299f7b2f20c5..930213407733e11acd89b34f60cfa1a95e8c7e62 100644 (file)

--- a/src/test/regress/expected/misc_functions.out

+++ b/src/test/regress/expected/misc_functions.out

@@ -619,7 +619,7 @@ SELECT count(*) > 0 AS ok FROM pg_control_system();

(1 row)

--- pg_split_walfile_name

+-- pg_split_walfile_name, pg_walfile_name & pg_walfile_name_offset

SELECT * FROM pg_split_walfile_name(NULL);

segment_number | timeline_id

----------------+-------------

@@ -642,3 +642,31 @@ SELECT segment_number > 0 AS ok_segment_number, timeline_id

t | 4294967295

(1 row)

+SELECT setting::int8 AS segment_size

+FROM pg_settings

+WHERE name = 'wal_segment_size'

+\gset

+SELECT segment_number, file_offset

+FROM pg_walfile_name_offset('0/0'::pg_lsn + :segment_size),

+ pg_split_walfile_name(file_name);

+ segment_number | file_offset

+----------------+-------------

+ 1 | 0

+(1 row)

+SELECT segment_number, file_offset

+FROM pg_walfile_name_offset('0/0'::pg_lsn + :segment_size + 1),

+ pg_split_walfile_name(file_name);

+ segment_number | file_offset

+----------------+-------------

+ 1 | 1

+(1 row)

+SELECT segment_number, file_offset = :segment_size - 1

+FROM pg_walfile_name_offset('0/0'::pg_lsn + :segment_size - 1),

+ pg_split_walfile_name(file_name);

+ segment_number | ?column?

+----------------+----------

+ 0 | t

+(1 row)

diff --git a/src/test/regress/sql/misc_functions.sql b/src/test/regress/sql/misc_functions.sql

index b57f01f3e95913b924f4c1e8b99459ac23003c90..d3dc591173d29f6f9b5558ed0f8ce89829a4244c 100644 (file)

--- a/src/test/regress/sql/misc_functions.sql

+++ b/src/test/regress/sql/misc_functions.sql

@@ -230,10 +230,23 @@ 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_split_walfile_name

+-- pg_split_walfile_name, pg_walfile_name & pg_walfile_name_offset

SELECT * FROM pg_split_walfile_name(NULL);

SELECT * FROM pg_split_walfile_name('invalid');

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');

+SELECT setting::int8 AS segment_size

+FROM pg_settings

+WHERE name = 'wal_segment_size'

+\gset

+SELECT segment_number, file_offset

+FROM pg_walfile_name_offset('0/0'::pg_lsn + :segment_size),

+ pg_split_walfile_name(file_name);

+SELECT segment_number, file_offset

+FROM pg_walfile_name_offset('0/0'::pg_lsn + :segment_size + 1),

+ pg_split_walfile_name(file_name);

+SELECT segment_number, file_offset = :segment_size - 1

+FROM pg_walfile_name_offset('0/0'::pg_lsn + :segment_size - 1),

+ pg_split_walfile_name(file_name);

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