+/*-------------------------------------------------------------------------
+ *
+ * xlog.c
+ *
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ * $Header: /cvsroot/pgsql/src/backend/access/transam/xlog.c,v 1.6 1999/10/24 20:42:27 tgl Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <sys/time.h>
#include "postgres.h"
+
#include "access/xlog.h"
#include "access/xact.h"
+#include "catalog/catversion.h"
#include "storage/sinval.h"
#include "storage/proc.h"
#include "storage/spin.h"
DBState state; /* */
/*
- * following data used to make sure that configurations for this DB
- * do not conflict with the backend
+ * this data is used to make sure that configuration of this DB
+ * is compatible with the current backend
*/
uint32 blcksz; /* block size for this DB */
- uint32 relseg_size; /* segmented file's block number */
- /* MORE DATA FOLLOWS AT THE END OF THIS STRUCTURE
+ uint32 relseg_size; /* blocks per segment of large relation */
+ uint32 catalog_version_no; /* internal version number */
+
+ /*
+ * MORE DATA FOLLOWS AT THE END OF THIS STRUCTURE
* - locations of data dirs
*/
} ControlFileData;
ControlFile->state = DB_SHUTDOWNED;
ControlFile->blcksz = BLCKSZ;
ControlFile->relseg_size = RELSEG_SIZE;
+ ControlFile->catalog_version_no = CATALOG_VERSION_NO;
if (write(fd, buffer, BLCKSZ) != BLCKSZ)
elog(STOP, "BootStrapXLOG failed to write control file: %d", errno);
elog(STOP, "BootStrapXLOG failed to fsync control file: %d", errno);
close(fd);
-
- return;
-
}
static char*
!XRecOffIsValid(ControlFile->checkPoint.xrecoff))
elog(STOP, "Control file context is broken");
+ /* Check for incompatible database */
if (ControlFile->blcksz != BLCKSZ)
- elog(STOP, "database was initialized in BLCKSZ(%d), but the backend was compiled in BLCKSZ(%d)",ControlFile->blcksz,BLCKSZ);
-
+ elog(STOP, "database was initialized with BLCKSZ %d,\n\tbut the backend was compiled with BLCKSZ %d.\n\tlooks like you need to initdb.",
+ ControlFile->blcksz, BLCKSZ);
if (ControlFile->relseg_size != RELSEG_SIZE)
- elog(STOP, "database was initialized in RELSEG_SIZE(%d), but the backend was compiled in RELSEG_SIZE(%d)",ControlFile->relseg_size, RELSEG_SIZE);
+ elog(STOP, "database was initialized with RELSEG_SIZE %d,\n\tbut the backend was compiled with RELSEG_SIZE %d.\n\tlooks like you need to initdb.",
+ ControlFile->relseg_size, RELSEG_SIZE);
+ if (ControlFile->catalog_version_no != CATALOG_VERSION_NO)
+ elog(STOP, "database was initialized with CATALOG_VERSION_NO %d,\n\tbut the backend was compiled with CATALOG_VERSION_NO %d.\n\tlooks like you need to initdb.",
+ ControlFile->catalog_version_no, CATALOG_VERSION_NO);
if (ControlFile->state == DB_SHUTDOWNED)
elog(LOG, "Data Base System was shutdowned at %s",
--- /dev/null
+/*-------------------------------------------------------------------------
+ *
+ * catversion.h
+ * "Catalog version number" for Postgres.
+ *
+ * The catalog version number is used to flag incompatible changes in
+ * the Postgres system catalogs. Whenever anyone changes the format of
+ * a system catalog relation, or adds, deletes, or modifies standard
+ * catalog entries in such a way that an updated backend wouldn't work
+ * with an old database (or vice versa), the catalog version number
+ * should be changed. The version number stored in pg_control by initdb
+ * is checked against the version number compiled into the backend at
+ * startup time, so that a backend can refuse to run in an incompatible
+ * database.
+ *
+ * The point of this feature is to provide a finer grain of compatibility
+ * checking than is possible from looking at the major version number
+ * stored in PG_VERSION. It shouldn't matter to end users, but during
+ * development cycles we usually make quite a few incompatible changes
+ * to the contents of the system catalogs, and we don't want to bump the
+ * major version number for each one. What we can do instead is bump
+ * this internal version number. This should save some grief for
+ * developers who might otherwise waste time tracking down "bugs" that
+ * are really just code-vs-database incompatibilities.
+ *
+ * The rule for developers is: if you commit a change that requires
+ * an initdb, you should update the catalog version number (as well as
+ * notifying the pghackers mailing list, which has been the informal
+ * practice for a long time).
+ *
+ * The catalog version number is placed here since modifying files in
+ * include/catalog is the most common kind of initdb-forcing change.
+ * But it could be used to protect any kind of incompatible change in
+ * database contents or layout, such as altering tuple headers.
+ *
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ * $Id: catversion.h,v 1.1 1999/10/24 20:42:26 tgl Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#ifndef CATVERSION_H
+#define CATVERSION_H
+
+/*
+ * We could use anything we wanted for version numbers, but I recommend
+ * following the "YYYYMMDDN" style often used for DNS zone serial numbers.
+ * YYYYMMDD are the date of the change, and N is the number of the change
+ * on that day. (Hopefully we'll never commit ten independent sets of
+ * catalog changes on the same day...)
+ */
+
+#define CATALOG_VERSION_NO 199910241
+
+#endif
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