# eXtremeSQL Administrative Functions

> Please use the links in the table below to view the eXtremeSQL aggregate functions:

> backup(<dbsFile>, <logFile>, <nThreads>) | Copy .dbs and .log files to dbsFile and logFile accordingly using nThreads threads. (Supported only for disk-based databases:
> config(name, value) | Sets a new configuration parameter value and returns the old value. If `value` is null, then the parameter is not changed and only the current value is returned. The following parameters are currently supported: `batch.buf.size [integer]` - size of buffer (number of elements) used for batch insert `bulk.page.write [boolean]` - bulk page write mode: instead of writing indidual dirty page thrown away from page pool, sort ad write all dirty page (for disk database only) `mursiw.commit.optimization [boolean]` - release transactions lock as soon as possible (for disk database only) `index.optimistic.lock.threshold [integer]` - maximum number of active write transactions when optimistic locking of B-Tree indexes can be performed `allocation.bitmap.caching.priority [integer]` - disk page pool priority for allocation bitmap pages `index.caching.priority [integer]` - disk page pool priority for index pages `object.caching.priority [integer]` - disk page pool priority for object pages
> save_dictionary(<filename>) | Saves the database metadata in xSQL config format (JSON) to <filename>
> save_metadata(<filename>) | Saves the database metadata in xSQL config format (JSON) to <filename>
> save_snapshot(<filename>) | Saves the database image (calling C API `mco_db_save()`) to specified <filename>
> set_free_memory_threshold(<size>) | Set the limit for free database memory. If the limit is reached, the current transaction is aborted (rolled back). xSQL sets the threshold to 4Mb by default. This function changes the limit only for the current connection.
> tl_save(<snapshotName>) | Saves a database snapshot to <snapshotName> and truncates the log. This function is available only for databases created by xSQL with TL support enabled. Returns error code (0 means OK)
> tl_start(<snapshotName>) | Starts Transaction Logging (TL). This function is available only for databases created by xSQL with TL support enabled. <snapshotName> is the file name to save the initial database snapshot. Returns error code (0 means OK)
> tl_stop() | Stops Transaction Logging (TL). This function is available only for databases created by xSQL with TL support enabled. Returns error code (0 means OK)