v5-0006-Add-database-Oid-to-CkptSortItem.patch

From 7e54f2577dce04615b3082fe518490dbd2fa8ad7 Mon Sep 17 00:00:00 2001
From: Melanie Plageman <melanieplageman@gmail.com>
Date: Tue, 2 Sep 2025 15:22:11 -0400
Subject: [PATCH v5 6/9] Add database Oid to CkptSortItem

This is useful for checkpointer write combining -- which will be added
in a future commit.
---
 src/backend/storage/buffer/bufmgr.c | 8 ++++++++
 src/include/storage/buf_internals.h | 1 +
 2 files changed, 9 insertions(+)

diff --git a/src/backend/storage/buffer/bufmgr.c b/src/backend/storage/buffer/bufmgr.c
index 98c03ef1b1a..246f675333e 100644
--- a/src/backend/storage/buffer/bufmgr.c
+++ b/src/backend/storage/buffer/bufmgr.c
@@ -3371,6 +3371,7 @@ BufferSync(int flags)
 			item = &CkptBufferIds[num_to_scan++];
 			item->buf_id = buf_id;
 			item->tsId = bufHdr->tag.spcOid;
+			item->db_id = bufHdr->tag.dbOid;
 			item->relNumber = BufTagGetRelNumber(&bufHdr->tag);
 			item->forkNum = BufTagGetForkNum(&bufHdr->tag);
 			item->blockNum = bufHdr->tag.blockNum;
@@ -6691,6 +6692,13 @@ ckpt_buforder_comparator(const CkptSortItem *a, const CkptSortItem *b)
 		return -1;
 	else if (a->tsId > b->tsId)
 		return 1;
+
+	/* compare database */
+	if (a->db_id < b->db_id)
+		return -1;
+	else if (a->db_id > b->db_id)
+		return 1;
+
 	/* compare relation */
 	if (a->relNumber < b->relNumber)
 		return -1;
diff --git a/src/include/storage/buf_internals.h b/src/include/storage/buf_internals.h
index c082a50166f..99f17091a40 100644
--- a/src/include/storage/buf_internals.h
+++ b/src/include/storage/buf_internals.h
@@ -382,6 +382,7 @@ UnlockBufHdr(BufferDesc *desc, uint32 buf_state)
 typedef struct CkptSortItem
 {
 	Oid			tsId;
+	Oid			db_id;
 	RelFileNumber relNumber;
 	ForkNumber	forkNum;
 	BlockNumber blockNum;
-- 
2.43.0