1 files changed, 46 insertions, 0 deletions
diff --git a/src/include/storage/buf.h b/src/include/storage/buf.h
new file mode 100644
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--- /dev/null
+++ b/src/include/storage/buf.h
@@ -0,0 +1,46 @@
+/*-------------------------------------------------------------------------
+ *
+ * buf.h
+ *	  Basic buffer manager data types.
+ *
+ *
+ * Portions Copyright (c) 1996-2020, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/storage/buf.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef BUF_H
+#define BUF_H
+
+/*
+ * Buffer identifiers.
+ *
+ * Zero is invalid, positive is the index of a shared buffer (1..NBuffers),
+ * negative is the index of a local buffer (-1 .. -NLocBuffer).
+ */
+typedef int Buffer;
+
+#define InvalidBuffer	0
+
+/*
+ * BufferIsInvalid
+ *		True iff the buffer is invalid.
+ */
+#define BufferIsInvalid(buffer) ((buffer) == InvalidBuffer)
+
+/*
+ * BufferIsLocal
+ *		True iff the buffer is local (not visible to other backends).
+ */
+#define BufferIsLocal(buffer)	((buffer) < 0)
+
+/*
+ * Buffer access strategy objects.
+ *
+ * BufferAccessStrategyData is private to freelist.c
+ */
+typedef struct BufferAccessStrategyData *BufferAccessStrategy;
+
+#endif							/* BUF_H */