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Expose sequence page LSN via pg_get_sequence_data.

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This patch enhances the pg_get_sequence_data function to include the
page-level LSN (Log Sequence Number) of the sequence. This additional
metadata will be used by upcoming patches to support synchronization
of sequences during logical replication.

By exposing the LSN, we enable more accurate tracking of sequence
changes, which is essential for maintaining consistency across
replicated nodes.

Author: vignesh C <vignesh21@gmail.com>
Reviewed-by: shveta malik <shveta.malik@gmail.com>
Reviewed-by: Masahiko Sawada <sawada.mshk@gmail.com>
Reviewed-by: Hayato Kuroda <kuroda.hayato@fujitsu.com>
Reviewed-by: Amit Kapila <amit.kapila16@gmail.com>
Discussion: https://www.postgresql.org/message-id/CAA4eK1LC+KJiAkSrpE_NwvNdidw9F2os7GERUeSxSKv71gXysQ@mail.gmail.com
This commit is contained in:
Amit Kapila
2025-10-06 08:27:22 +00:00
parent 42c6b74d89
commit b93172ca59
5 changed files with 16 additions and 10 deletions
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10
src/backend/commands/sequence.c
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@@ -45,6 +45,7 @@
#include "utils/acl.h"
#include "utils/builtins.h"
#include "utils/lsyscache.h"
#include "utils/pg_lsn.h"
#include "utils/resowner.h"
#include "utils/syscache.h"
#include "utils/varlena.h"
@@ -1795,7 +1796,7 @@ pg_sequence_parameters(PG_FUNCTION_ARGS)
/*
* Return the sequence tuple.
* Return the sequence tuple along with its page LSN.
*
* This is primarily intended for use by pg_dump to gather sequence data
* without needing to individually query each sequence relation.
@@ -1803,7 +1804,7 @@ pg_sequence_parameters(PG_FUNCTION_ARGS)
Datum
pg_get_sequence_data(PG_FUNCTION_ARGS)
{
#define PG_GET_SEQUENCE_DATA_COLS 2
#define PG_GET_SEQUENCE_DATA_COLS 3
Oid relid = PG_GETARG_OID(0);
SeqTable elm;
Relation seqrel;
@@ -1818,6 +1819,8 @@ pg_get_sequence_data(PG_FUNCTION_ARGS)
INT8OID, -1, 0);
TupleDescInitEntry(resultTupleDesc, (AttrNumber) 2, "is_called",
BOOLOID, -1, 0);
TupleDescInitEntry(resultTupleDesc, (AttrNumber) 3, "page_lsn",
LSNOID, -1, 0);
resultTupleDesc = BlessTupleDesc(resultTupleDesc);
init_sequence(relid, &elm, &seqrel);
@@ -1833,11 +1836,14 @@ pg_get_sequence_data(PG_FUNCTION_ARGS)
Buffer buf;
HeapTupleData seqtuple;
Form_pg_sequence_data seq;
Page page;
seq = read_seq_tuple(seqrel, &buf, &seqtuple);
page = BufferGetPage(buf);
values[0] = Int64GetDatum(seq->last_value);
values[1] = BoolGetDatum(seq->is_called);
values[2] = LSNGetDatum(PageGetLSN(page));
UnlockReleaseBuffer(buf);
}