#include <db.h> int db_create(DB **dbp, DB_ENV *dbenv, u_int32_t flags);
The db_create() function creates a DB
structure that is the handle for a Berkeley DB database. This function allocates memory for the
structure, returning a pointer to the structure in the memory to which
dbp refers. To release the allocated memory and
discard the handle, call the
DB->close()
,
DB->remove()
,
DB->rename()
, or
DB->verify()
methods.
DB handles are free-threaded if the DB_THREAD flag is specified to the DB->open() method when the database is opened or if the database environment in which the database is opened is free-threaded. The handle should not be closed while any other handle that refers to the database is in use; for example, database handles must not be closed while cursor handles into the database remain open, or transactions that include operations on the database have not yet been committed or aborted. Once the DB->close() , DB->remove() , DB->rename() , or DB->verify() methods are called, the handle may not be accessed again, regardless of the method's return.
The DB handle contains a special field, app_private,
which is declared as type void *. This field is provided for the use
of the application program. It is initialized to NULL and is not further used by
Berkeley DB in any way.
The db_create function returns a non-zero error value on failure
and 0 on success.
If the dbenv parameter is NULL, the database is standalone; that is, it is not part of any Berkeley DB environment. Since it is not part of any environment, any DB_CONFIG file in the application’s current working directory is ignored.
If the dbenv parameter is not NULL, the database is created within the specified Berkeley DB environment. The database access methods automatically make calls to the other subsystems in Berkeley DB, based on the enclosing environment. For example, if the environment has been configured to use locking, the access methods will automatically acquire the correct locks when reading and writing pages of the database.
The flags parameter must be set to 0 or the following value:
Instead of creating a standalone database, create a database intended to be accessed via applications running under an X/Open conformant Transaction Manager. The database will be opened in the environment specified by the OPENINFO parameter of the GROUPS section of the ubbconfig file. See the XA Introduction section in the Berkeley DB Reference Guide for more information.
The db_create() function may fail and return one of the following non-zero
errors: