* Postgres transaction log manager record pointer and
* timeline number definitions
*
- * Portions Copyright (c) 1996-2008, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
- * $PostgreSQL: pgsql/src/include/access/xlogdefs.h,v 1.22 2008/05/17 17:24:57 tgl Exp $
+ * src/include/access/xlogdefs.h
*/
#ifndef XLOG_DEFS_H
#define XLOG_DEFS_H
/*
* Pointer to a location in the XLOG. These pointers are 64 bits wide,
* because we don't want them ever to overflow.
- *
- * NOTE: xrecoff == 0 is used to indicate an invalid pointer. This is OK
- * because we use page headers in the XLOG, so no XLOG record can start
- * right at the beginning of a file.
- *
- * NOTE: the "log file number" is somewhat misnamed, since the actual files
- * making up the XLOG are much smaller than 4Gb. Each actual file is an
- * XLogSegSize-byte "segment" of a logical log file having the indicated
- * xlogid. The log file number and segment number together identify a
- * physical XLOG file. Segment number and offset within the physical file
- * are computed from xrecoff div and mod XLogSegSize.
*/
-typedef struct XLogRecPtr
-{
- uint32 xlogid; /* log file #, 0 based */
- uint32 xrecoff; /* byte offset of location in log file */
-} XLogRecPtr;
-
-#define XLogRecPtrIsInvalid(r) ((r).xrecoff == 0)
-
+typedef uint64 XLogRecPtr;
/*
- * Macros for comparing XLogRecPtrs
- *
- * Beware of passing expressions with side-effects to these macros,
- * since the arguments may be evaluated multiple times.
+ * Zero is used indicate an invalid pointer. Bootstrap skips the first possible
+ * WAL segment, initializing the first WAL page at XLOG_SEG_SIZE, so no XLOG
+ * record can begin at zero.
*/
-#define XLByteLT(a, b) \
- ((a).xlogid < (b).xlogid || \
- ((a).xlogid == (b).xlogid && (a).xrecoff < (b).xrecoff))
-
-#define XLByteLE(a, b) \
- ((a).xlogid < (b).xlogid || \
- ((a).xlogid == (b).xlogid && (a).xrecoff <= (b).xrecoff))
-
-#define XLByteEQ(a, b) \
- ((a).xlogid == (b).xlogid && (a).xrecoff == (b).xrecoff)
+#define InvalidXLogRecPtr 0
+#define XLogRecPtrIsInvalid(r) ((r) == InvalidXLogRecPtr)
+/*
+ * XLogSegNo - physical log file sequence number.
+ */
+typedef uint64 XLogSegNo;
/*
* TimeLineID (TLI) - identifies different database histories to prevent
*/
typedef uint32 TimeLineID;
+/*
+ * Replication origin id - this is located in this file to avoid having to
+ * include origin.h in a bunch of xlog related places.
+ */
+typedef uint16 RepOriginId;
+
/*
* Because O_DIRECT bypasses the kernel buffers, and because we never
- * read those buffers except during crash recovery, it is a win to use
- * it in all cases where we sync on each write(). We could allow O_DIRECT
- * with fsync(), but because skipping the kernel buffer forces writes out
- * quickly, it seems best just to use it for O_SYNC. It is hard to imagine
- * how fsync() could be a win for O_DIRECT compared to O_SYNC and O_DIRECT.
- * Also, O_DIRECT is never enough to force data to the drives, it merely
- * tries to bypass the kernel cache, so we still need O_SYNC or fsync().
+ * read those buffers except during crash recovery or if wal_level != minimal,
+ * it is a win to use it in all cases where we sync on each write(). We could
+ * allow O_DIRECT with fsync(), but it is unclear if fsync() could process
+ * writes not buffered in the kernel. Also, O_DIRECT is never enough to force
+ * data to the drives, it merely tries to bypass the kernel cache, so we still
+ * need O_SYNC/O_DSYNC.
*/
#ifdef O_DIRECT
#define PG_O_DIRECT O_DIRECT
/*
* This chunk of hackery attempts to determine which file sync methods
* are available on the current platform, and to choose an appropriate
- * default method. We assume that fsync() is always available, and that
+ * default method. We assume that fsync() is always available, and that
* configure determined whether fdatasync() is.
*/
#if defined(O_SYNC)
-#define BARE_OPEN_SYNC_FLAG O_SYNC
+#define OPEN_SYNC_FLAG O_SYNC
#elif defined(O_FSYNC)
-#define BARE_OPEN_SYNC_FLAG O_FSYNC
-#endif
-#ifdef BARE_OPEN_SYNC_FLAG
-#define OPEN_SYNC_FLAG (BARE_OPEN_SYNC_FLAG | PG_O_DIRECT)
+#define OPEN_SYNC_FLAG O_FSYNC
#endif
#if defined(O_DSYNC)
#if defined(OPEN_SYNC_FLAG)
/* O_DSYNC is distinct? */
-#if O_DSYNC != BARE_OPEN_SYNC_FLAG
-#define OPEN_DATASYNC_FLAG (O_DSYNC | PG_O_DIRECT)
+#if O_DSYNC != OPEN_SYNC_FLAG
+#define OPEN_DATASYNC_FLAG O_DSYNC
#endif
#else /* !defined(OPEN_SYNC_FLAG) */
/* Win32 only has O_DSYNC */
-#define OPEN_DATASYNC_FLAG (O_DSYNC | PG_O_DIRECT)
+#define OPEN_DATASYNC_FLAG O_DSYNC
#endif
#endif
-#if defined(OPEN_DATASYNC_FLAG)
+#if defined(PLATFORM_DEFAULT_SYNC_METHOD)
+#define DEFAULT_SYNC_METHOD PLATFORM_DEFAULT_SYNC_METHOD
+#elif defined(OPEN_DATASYNC_FLAG)
#define DEFAULT_SYNC_METHOD SYNC_METHOD_OPEN_DSYNC
#elif defined(HAVE_FDATASYNC)
#define DEFAULT_SYNC_METHOD SYNC_METHOD_FDATASYNC
-#elif defined(HAVE_FSYNC_WRITETHROUGH_ONLY)
-#define DEFAULT_SYNC_METHOD SYNC_METHOD_FSYNC_WRITETHROUGH
#else
#define DEFAULT_SYNC_METHOD SYNC_METHOD_FSYNC
#endif
-/*
- * Limitation of buffer-alignment for direct IO depends on OS and filesystem,
- * but XLOG_BLCKSZ is assumed to be enough for it.
- */
-#ifdef O_DIRECT
-#define ALIGNOF_XLOG_BUFFER XLOG_BLCKSZ
-#else
-#define ALIGNOF_XLOG_BUFFER ALIGNOF_BUFFER
-#endif
-
#endif /* XLOG_DEFS_H */
projects / postgresql / blobdiff