buf.h

PostgreSQL 8.2中增加了很多企业用户所需要的功能和性能上的提高,其开发团队说,该版本将加速更多企业向该数据库移植.核心开发成员之一Bruce Momjian表示,在新版PostgreSQL

/*-------------------------------------------------------------------------
 *
 * buf.h
 *	  Basic buffer manager data types.
 *
 *
 * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * $PostgreSQL: pgsql/src/include/storage/buf.h,v 1.20 2006/03/05 15:58:59 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */
#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)

#endif   /* BUF_H */