From afc270f37cd082fb6e9f4ad694ea4cb123d98062 Mon Sep 17 00:00:00 2001
From: "Andrey V. Lepikhov" <a.lepikhov@postgrespro.ru>
Date: Tue, 5 Feb 2019 08:11:47 +0500
Subject: [PATCH 1/4] Relation-into-WAL-function

---
 src/backend/access/spgist/spgutils.c      |  1 +
 src/backend/access/transam/generic_xlog.c | 39 +++++++++++++++++++++++
 src/include/access/generic_xlog.h         |  3 ++
 3 files changed, 43 insertions(+)

diff --git a/src/backend/access/spgist/spgutils.c b/src/backend/access/spgist/spgutils.c
index 8e63c1fad2..b782bc2338 100644
--- a/src/backend/access/spgist/spgutils.c
+++ b/src/backend/access/spgist/spgutils.c
@@ -550,6 +550,7 @@ SpGistInitBuffer(Buffer b, uint16 f)
 {
 	Assert(BufferGetPageSize(b) == BLCKSZ);
 	SpGistInitPage(BufferGetPage(b), f);
+	MarkBufferDirty(b);
 }
 
 /*
diff --git a/src/backend/access/transam/generic_xlog.c b/src/backend/access/transam/generic_xlog.c
index 5b00b7275b..643da48345 100644
--- a/src/backend/access/transam/generic_xlog.c
+++ b/src/backend/access/transam/generic_xlog.c
@@ -542,3 +542,42 @@ generic_mask(char *page, BlockNumber blkno)
 
 	mask_unused_space(page);
 }
+
+/*
+ * Function to write generic xlog for every existing block of a relation.
+ * Caller is responsible for locking the relation exclusively.
+ */
+void
+generic_log_relation(Relation rel)
+{
+	BlockNumber blkno;
+	BlockNumber nblocks = RelationGetNumberOfBlocks(rel);
+
+	for (blkno = 0; blkno < nblocks; )
+	{
+		GenericXLogState	*state;
+		Buffer				buffer[MAX_GENERIC_XLOG_PAGES];
+		int					i,
+							blocks_pack;
+
+		CHECK_FOR_INTERRUPTS();
+
+		blocks_pack = ((nblocks-blkno) < MAX_GENERIC_XLOG_PAGES) ?
+						(nblocks-blkno) : MAX_GENERIC_XLOG_PAGES;
+
+		state = GenericXLogStart(rel);
+
+		for (i = 0 ; i < blocks_pack; i++)
+		{
+			buffer[i] = ReadBuffer(rel, blkno);
+			LockBuffer(buffer[i], BUFFER_LOCK_EXCLUSIVE);
+			GenericXLogRegisterBuffer(state, buffer[i], GENERIC_XLOG_FULL_IMAGE);
+			blkno++;
+		}
+
+		GenericXLogFinish(state);
+
+		for (i = 0 ; i < blocks_pack; i++)
+			UnlockReleaseBuffer(buffer[i]);
+	}
+}
diff --git a/src/include/access/generic_xlog.h b/src/include/access/generic_xlog.h
index cb5b5b713a..e3bbf014cc 100644
--- a/src/include/access/generic_xlog.h
+++ b/src/include/access/generic_xlog.h
@@ -42,4 +42,7 @@ extern const char *generic_identify(uint8 info);
 extern void generic_desc(StringInfo buf, XLogReaderState *record);
 extern void generic_mask(char *pagedata, BlockNumber blkno);
 
+/* other utils */
+extern void generic_log_relation(Relation rel);
+
 #endif							/* GENERIC_XLOG_H */
-- 
2.17.1