Berkeley DB: log_archive
Description: Berkeley DB: An embedded database programmatic toolkit.
Keywords: embedded,database,programmatic,toolkit,b+tree,btree,hash,hashing,transaction,transactions,locking,logging,access method,access methods,java,C,C++

# log_archive |

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    #include <db.h>

    int
    log_archive(DB_ENV *env, char *(*listp)[], u_int32_t flags);

# Description

The log_archive function creates a NULL-terminated array of log or database filenames, and copies a pointer to them into the user-specified memory location listp.

By default, log_archive returns the names of all of the log files that are no longer in use (for example, that are no longer involved in active transactions), and that may safely be archived for catastrophic recovery and then removed from the system. If there are no filenames to return, the memory location to which listp refers will be set to NULL.

Arrays of log filenames are created in allocated memory. If application-specific allocation routines have been declared (see DB_ENV->set_alloc for more information), they are used to allocate the memory; otherwise, the library function malloc(3) is used. The caller is responsible for deallocating the memory. To deallocate the memory, free the memory reference; references inside the returned memory need not be individually freed.

The flags value must be set to 0 or by bitwise inclusively OR'ing together one or more of the following values:

DB_ARCH_ABS
  All pathnames are returned as absolute pathnames, instead of relative to the database home directory.

DB_ARCH_DATA
  Return the database files that need to be archived in order to recover the database from catastrophic failure. If any of the database files have not been accessed during the lifetime of the current log files, log_archive will not include them in this list. It is also possible that some of the files referred to by the log have since been deleted from the system.

DB_ARCH_LOG
  Return all the log filenames, regardless of whether or not they are in use.

The DB_ARCH_DATA and DB_ARCH_LOG flags are mutually exclusive.

See the db_archive manual page for more information on database archival procedures.

The log_archive function is the underlying function used by the db_archive utility. See the db_archive utility source code for an example of using log_archive in a IEEE/ANSI Std 1003.1 (POSIX) environment.

The log_archive function returns a non-zero error value on failure and 0 on success.

# Bugs

In a threaded application (that is, one where the environment was created with the DB_THREAD flag specified), calling log_archive with the DB_ARCH_DATA flag will fail, returning EINVAL. To work around this problem, reopen the log explicitly without specifying DB_THREAD. This restriction is expected to be removed in a future version of Berkeley DB.

# Errors

The log_archive function may fail and return a non-zero error for the following conditions:

EINVAL
  An invalid flag value or parameter was specified.

  The log was corrupted.

The log_archive function may fail and return a non-zero error for errors specified for other Berkeley DB and C library or system functions. If a catastrophic error has occurred, the log_archive function may fail and return DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way.

# See Also

DB_ENV->set_lg_bsize, DB_ENV->set_lg_dir, DB_ENV->set_lg_max, DB_ENV->set_lg_regionmax, log_archive, log_compare, log_file, log_flush, log_get, log_put, log_register, log_stat, and log_unregister.`

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