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This guide describes administration of the Sedna XML Database Management System (Sedna for short). Sedna has the following components.
Governor serves as a “control center” of the system. All other components register at the Governor. The Governor knows which other components (e.g. databases and sessions) are running in the system and controls them. Other components cannot function properly if the Governor is not running so you must start it to use Sedna. Besides, Governor is responsible for handling remote client’s requests. For each request it creates a session which keeps the direct connection with client. Then the client interacts with the system via session.
Session keeps the client’s settings and allows client to run a sequence of transactions. The transactions within a session are strictly serial, that is one transaction ends before next one starts, there is only one active transaction per session. Transaction provides functionality required for execution of the client’s queries. The query execution consists of several steps: (1) parsing of the query and translation of the query into its logical representation, (2) processing of the logical representation by optimizer that produces the optimal query execution plan, (3) execution of the optimal query plan and passing results to the client. Transaction is rolled back if error is occurred during its execution.
Storage manager manages a database and provides memory management functionality to the executor. There is an instance of storage manager for each database run.
All the components described above are implemented as operating system processes.
One can run sessions via Sedna client applications (See Sedna Programmer’s Guide how to use Sedna APIs) or via Sedna interactive terminal (see 2.4). In both cases, first of all the Governor and storage managers (one for each databases required) components should be run.
There are a set of command line utilities that allow you to administrate all aspects of Sedna. These utilities are described in detail in the following section.