From 1b86460bb25aef99a39034e5bf6be581cdccfb88 Mon Sep 17 00:00:00 2001 From: Melanie Plageman Date: Tue, 5 Dec 2023 07:29:39 -0500 Subject: [PATCH v4 1/6] Record LSN at postmaster startup The insert_lsn at postmaster startup can be used along with PgStartTime as seed values for a timeline mapping LSNs to time. Future commits will add such a structure for LSN <-> time conversions. A start LSN allows for such conversions before even inserting a value into the timeline. The current time and current insert LSN can be used along with PgStartTime and PgStartLSN. This is WIP, as I'm not sure if I did this in the right place. --- src/backend/access/transam/xlog.c | 2 ++ src/backend/postmaster/postmaster.c | 2 ++ src/include/utils/builtins.h | 3 +++ 3 files changed, 7 insertions(+) diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c index 330e058c5f2..6fff1f52084 100644 --- a/src/backend/access/transam/xlog.c +++ b/src/backend/access/transam/xlog.c @@ -142,6 +142,8 @@ bool XLOG_DEBUG = false; int wal_segment_size = DEFAULT_XLOG_SEG_SIZE; +XLogRecPtr PgStartLSN = InvalidXLogRecPtr; + /* * Number of WAL insertion locks to use. A higher value allows more insertions * to happen concurrently, but adds some CPU overhead to flushing the WAL, diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c index bf0241aed0c..f1b60fe6cee 100644 --- a/src/backend/postmaster/postmaster.c +++ b/src/backend/postmaster/postmaster.c @@ -117,6 +117,7 @@ #include "storage/proc.h" #include "tcop/backend_startup.h" #include "tcop/tcopprot.h" +#include "utils/builtins.h" #include "utils/datetime.h" #include "utils/memutils.h" #include "utils/pidfile.h" @@ -1345,6 +1346,7 @@ PostmasterMain(int argc, char *argv[]) * Remember postmaster startup time */ PgStartTime = GetCurrentTimestamp(); + PgStartLSN = GetXLogInsertRecPtr(); /* * Report postmaster status in the postmaster.pid file, to allow pg_ctl to diff --git a/src/include/utils/builtins.h b/src/include/utils/builtins.h index 359c570f23e..16a7a058bc7 100644 --- a/src/include/utils/builtins.h +++ b/src/include/utils/builtins.h @@ -17,6 +17,7 @@ #include "fmgr.h" #include "nodes/nodes.h" #include "utils/fmgrprotos.h" +#include "access/xlogdefs.h" /* Sign + the most decimal digits an 8-byte number could have */ #define MAXINT8LEN 20 @@ -85,6 +86,8 @@ extern void generate_operator_clause(fmStringInfo buf, Oid opoid, const char *rightop, Oid rightoptype); +extern PGDLLIMPORT XLogRecPtr PgStartLSN; + /* varchar.c */ extern int bpchartruelen(char *s, int len); -- 2.34.1