# Db::sync

`

###

    #include <db_cxx.h>

    int
    Db::sync(u_int32_t flags);

# Description

The Db::sync method flushes any cached information to disk.

If the database is in memory only, the Db::sync method has no effect and will always succeed.

The flags parameter is currently unused, and must be set to 0.

See Db::close for a discussion of Berkeley DB and cached data.

The Db::sync method either returns a non-zero error value or throws an exception that encapsulates a non-zero error value on failure, 0 on success, and DB_INCOMPLETE if the underlying database still has dirty pages in the cache. (The only reason for a return of DB_INCOMPLETE is if another thread of control was writing pages in the underlying database file at the same time as the Db::sync method was being called. For this reason, a return of DB_INCOMPLETE can normally be ignored, or, in cases where it is a possible return value, there may be no reason to call Db::sync.)

# Errors

The Db::sync method may fail and throw an exception or return a non-zero error for the following conditions:

EINVAL
  An invalid flag value or parameter was specified.

The Db::sync method may fail and throw an exception or return a non-zero error for errors specified for other Berkeley DB and C library or system methods. If a catastrophic error has occurred, the Db::sync method may fail and either return DB_RUNRECOVERY or throw an exception encapsulating DB_RUNRECOVERY, in which case all subsequent Berkeley DB calls will fail in the same way.

### Class

Db

# See Also

Db::close, Db::cursor, Db::del, Db::err, Db::fd, Db::get, Db::get_byteswapped, Db::get_type, Db::join, Db::key_range, Db::open, Db::put, Db::remove, Db::set_bt_compare, Db::set_bt_minkey, Db::set_bt_prefix, Db::set_cachesize, Db::set_dup_compare, Db::set_errcall, Db::set_errfile, Db::set_errpfx, Db::set_flags, Db::set_h_ffactor, Db::set_h_hash, Db::set_h_nelem, Db::set_lorder, Db::set_malloc, Db::set_pagesize, Db::set_paniccall, Db::set_realloc, Db::set_re_delim, Db::set_re_len, Db::set_re_pad, Db::set_re_source, Db::stat, Db::sync, Db::upgrade and Db::verify.`

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