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diff --git a/src/include/nodes/tidbitmap.h b/src/include/nodes/tidbitmap.h
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+/*-------------------------------------------------------------------------
+ *
+ * tidbitmap.h
+ *	  PostgreSQL tuple-id (TID) bitmap package
+ *
+ * This module provides bitmap data structures that are spiritually
+ * similar to Bitmapsets, but are specially adapted to store sets of
+ * tuple identifiers (TIDs), or ItemPointers.  In particular, the division
+ * of an ItemPointer into BlockNumber and OffsetNumber is catered for.
+ * Also, since we wish to be able to store very large tuple sets in
+ * memory with this data structure, we support "lossy" storage, in which
+ * we no longer remember individual tuple offsets on a page but only the
+ * fact that a particular page needs to be visited.
+ *
+ *
+ * Copyright (c) 2003-2021, PostgreSQL Global Development Group
+ *
+ * src/include/nodes/tidbitmap.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef TIDBITMAP_H
+#define TIDBITMAP_H
+
+#include "storage/itemptr.h"
+#include "utils/dsa.h"
+
+
+/*
+ * Actual bitmap representation is private to tidbitmap.c.  Callers can
+ * do IsA(x, TIDBitmap) on it, but nothing else.
+ */
+typedef struct TIDBitmap TIDBitmap;
+
+/* Likewise, TBMIterator is private */
+typedef struct TBMIterator TBMIterator;
+typedef struct TBMSharedIterator TBMSharedIterator;
+
+/* Result structure for tbm_iterate */
+typedef struct TBMIterateResult
+{
+	BlockNumber blockno;		/* page number containing tuples */
+	int			ntuples;		/* -1 indicates lossy result */
+	bool		recheck;		/* should the tuples be rechecked? */
+	/* Note: recheck is always true if ntuples < 0 */
+	OffsetNumber offsets[FLEXIBLE_ARRAY_MEMBER];
+} TBMIterateResult;
+
+/* function prototypes in nodes/tidbitmap.c */
+
+extern TIDBitmap *tbm_create(long maxbytes, dsa_area *dsa);
+extern void tbm_free(TIDBitmap *tbm);
+extern void tbm_free_shared_area(dsa_area *dsa, dsa_pointer dp);
+
+extern void tbm_add_tuples(TIDBitmap *tbm,
+						   const ItemPointer tids, int ntids,
+						   bool recheck);
+extern void tbm_add_page(TIDBitmap *tbm, BlockNumber pageno);
+
+extern void tbm_union(TIDBitmap *a, const TIDBitmap *b);
+extern void tbm_intersect(TIDBitmap *a, const TIDBitmap *b);
+
+extern bool tbm_is_empty(const TIDBitmap *tbm);
+
+extern TBMIterator *tbm_begin_iterate(TIDBitmap *tbm);
+extern dsa_pointer tbm_prepare_shared_iterate(TIDBitmap *tbm);
+extern TBMIterateResult *tbm_iterate(TBMIterator *iterator);
+extern TBMIterateResult *tbm_shared_iterate(TBMSharedIterator *iterator);
+extern void tbm_end_iterate(TBMIterator *iterator);
+extern void tbm_end_shared_iterate(TBMSharedIterator *iterator);
+extern TBMSharedIterator *tbm_attach_shared_iterate(dsa_area *dsa,
+													dsa_pointer dp);
+extern long tbm_calculate_entries(double maxbytes);
+
+#endif							/* TIDBITMAP_H */