large_object.h

关系型数据库 Postgresql 6.5.2

/*-------------------------------------------------------------------------
 *
 * large_object.h
 *	  file of info for Postgres large objects. POSTGRES 4.2 supports
 *	  zillions of large objects (internal, external, jaquith, inversion).
 *	  Now we only support inversion.
 *
 * Copyright (c) 1994, Regents of the University of California
 *
 * $Id: large_object.h,v 1.10 1999/02/13 23:22:06 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#ifndef LARGE_OBJECT_H
#define LARGE_OBJECT_H

#include <sys/types.h>

#include <access/relscan.h>

/*
 * This structure will eventually have lots more stuff associated with it.
 */
typedef struct LargeObjectDesc
{
	Relation	heap_r;			/* heap relation */
	Relation	index_r;		/* index relation on seqno attribute */
	IndexScanDesc iscan;		/* index scan we're using */
	TupleDesc	hdesc;			/* heap relation tuple desc */
	TupleDesc	idesc;			/* index relation tuple desc */
	uint32		lowbyte;		/* low byte on the current page */
	uint32		highbyte;		/* high byte on the current page */
	uint32		offset;			/* current seek pointer */
	ItemPointerData htid;		/* tid of current heap tuple */

#define IFS_RDLOCK		(1 << 0)
#define IFS_WRLOCK		(1 << 1)
#define IFS_ATEOF		(1 << 2)

	u_long		flags;			/* locking info, etc */
} LargeObjectDesc;

/*
 * Function definitions...
 */

/* inversion stuff in inv_api.c */
extern LargeObjectDesc *inv_create(int flags);
extern LargeObjectDesc *inv_open(Oid lobjId, int flags);
extern void inv_close(LargeObjectDesc *obj_desc);
extern int	inv_destroy(Oid lobjId);
extern int	inv_seek(LargeObjectDesc *obj_desc, int offset, int whence);
extern int	inv_tell(LargeObjectDesc *obj_desc);
extern int	inv_read(LargeObjectDesc *obj_desc, char *buf, int nbytes);
extern int	inv_write(LargeObjectDesc *obj_desc, char *buf, int nbytes);

/* added for buffer leak prevention [ PA ] */
extern void inv_cleanindex(LargeObjectDesc *obj_desc);

#endif	 /* LARGE_OBJECT_H */