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Berkeley DB: Db::upgrade
Db::upgrade
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#include <db_cxx.h>
int
Db::upgrade(const char *file, u_int32_t flags);
Description: Db::upgrade
The Db::upgrade method upgrades all of the databases included in the
file file, if necessary. If no upgrade is necessary,
Db::upgrade always returns success.
Database upgrades are done in place and are destructive. For example,
if pages need to be allocated and no disk space is available, the
database may be left corrupted. Backups should be made before databases
are upgraded. See Upgrading databases
for more information.
Unlike all other database operations, Db::upgrade may only be done
on a system with the same byte-order as the database.
The Db::upgrade method
either returns a non-zero error value
or throws an exception that encapsulates a non-zero error value on
failure, and returns 0 on success.
Parameters
- file
- The file parameter is the physical file containing the databases
to be upgraded.
- flags
- The flags parameter must be set to 0 or
the following value:
- DB_DUPSORT
- This flag is only meaningful when upgrading databases from
releases before the Berkeley DB 3.1 release.
As part of the upgrade from the Berkeley DB 3.0 release to the 3.1 release,
the on-disk format of duplicate data items changed. To correctly
upgrade the format requires applications to specify whether duplicate
data items in the database are sorted or not. Specifying the
DB_DUPSORT flag informs Db::upgrade that the duplicates
are sorted; otherwise they are assumed to be unsorted. Incorrectly
specifying the value of this flag may lead to database corruption.
Further, because the Db::upgrade method upgrades a physical file
(including all the databases it contains), it is not possible to use
Db::upgrade to upgrade files in which some of the databases it
includes have sorted duplicate data items, and some of the databases it
includes have unsorted duplicate data items. If the file does not have
more than a single database, if the databases do not support duplicate
data items, or if all of the databases that support duplicate data items
support the same style of duplicates (either sorted or unsorted),
Db::upgrade will work correctly as long as the
DB_DUPSORT flag is correctly specified. Otherwise, the file
cannot be upgraded using Db::upgrade; it must be upgraded
manually by dumping and reloading the databases.
Environment Variables
If the database was opened within a database environment, the
environment variable DB_HOME may be used as the path of the
database environment home.
Db::upgrade is affected by any database directory specified using
the DbEnv::set_data_dir method, or by setting the "set_data_dir" string
in the environment's DB_CONFIG file.
Errors
The Db::upgrade method
may fail and throw
DbException,
encapsulating one of the following non-zero errors, or return one of
the following non-zero errors:
- DB_OLD_VERSION
- The database cannot be upgraded by this version of the Berkeley DB software.
- EINVAL
- If the database is not in the same byte-order as the system; or if an
invalid flag value or parameter was specified.
Class
Db
See Also
Databases and Related Methods
Copyright (c) 1996-2004 Sleepycat Software, Inc. - All rights reserved.
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