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db_include/access/toast_internals.h

@@ -0,0 +1,63 @@
+/*-------------------------------------------------------------------------
+ *
+ * toast_internals.h
+ *	  Internal definitions for the TOAST system.
+ *
+ * Copyright (c) 2000-2021, PostgreSQL Global Development Group
+ *
+ * src/include/access/toast_internals.h
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef TOAST_INTERNALS_H
+#define TOAST_INTERNALS_H
+
+#include "access/toast_compression.h"
+#include "storage/lockdefs.h"
+#include "utils/relcache.h"
+#include "utils/snapshot.h"
+
+/*
+ *	The information at the start of the compressed toast data.
+ */
+typedef struct toast_compress_header
+{
+	int32		vl_len_;		/* varlena header (do not touch directly!) */
+	uint32		tcinfo;			/* 2 bits for compression method and 30 bits
+								 * external size; see va_extinfo */
+} toast_compress_header;
+
+/*
+ * Utilities for manipulation of header information for compressed
+ * toast entries.
+ */
+#define TOAST_COMPRESS_EXTSIZE(ptr) \
+	(((toast_compress_header *) (ptr))->tcinfo & VARLENA_EXTSIZE_MASK)
+#define TOAST_COMPRESS_METHOD(ptr) \
+	(((toast_compress_header *) (ptr))->tcinfo >> VARLENA_EXTSIZE_BITS)
+
+#define TOAST_COMPRESS_SET_SIZE_AND_COMPRESS_METHOD(ptr, len, cm_method) \
+	do { \
+		Assert((len) > 0 && (len) <= VARLENA_EXTSIZE_MASK); \
+		Assert((cm_method) == TOAST_PGLZ_COMPRESSION_ID || \
+			   (cm_method) == TOAST_LZ4_COMPRESSION_ID); \
+		((toast_compress_header *) (ptr))->tcinfo = \
+			(len) | ((uint32) (cm_method) << VARLENA_EXTSIZE_BITS); \
+	} while (0)
+
+extern Datum toast_compress_datum(Datum value, char cmethod);
+extern Oid	toast_get_valid_index(Oid toastoid, LOCKMODE lock);
+
+extern void toast_delete_datum(Relation rel, Datum value, bool is_speculative);
+extern Datum toast_save_datum(Relation rel, Datum value,
+							  struct varlena *oldexternal, int options);
+
+extern int	toast_open_indexes(Relation toastrel,
+							   LOCKMODE lock,
+							   Relation **toastidxs,
+							   int *num_indexes);
+extern void toast_close_indexes(Relation *toastidxs, int num_indexes,
+								LOCKMODE lock);
+extern void init_toast_snapshot(Snapshot toast_snapshot);
+
+#endif							/* TOAST_INTERNALS_H */