Databases ========= .. module:: pyrseas.database The :mod:`database` module defines :class:`Database`. Database -------- A :class:`Database` is initialized with a :class:`~pyrseas.dbconn.DbConnection` object. It consists of one or two :class:`Dicts`. A :class:`Dicts` object holds various dictionary objects derived from :class:`~pyrseas.dbobject.DbObjectDict`, e.g., :class:`~pyrseas.dbobject.schema.SchemaDict`, :class:`~pyrseas.dbobject.table.ClassDict`, and :class:`~pyrseas.dbobject.column.ColumnDict`. The key for each dictionary is a Python tuple (or a single value in the case of :class:`SchemaDict`). For example, the :class:`~pyrseas.dbobject.table.ClassDict` dictionary is indexed by (`schema name`, `table name`). In addition, object instances in each dictionary are linked to related objects in other dictionaries, e.g., columns are linked to the tables where they belong. The :attr:`db` :class:`Dicts` object --always present-- defines the database schemas, including their tables and other objects, by querying the system catalogs. The :attr:`ndb` :class:`Dicts` object defines the schemas based on the :obj:`input_map` supplied to the :meth:`diff_map` method. The :meth:`to_map` method returns and the :meth:`diff_map` method takes as input, a dictionary as shown below. It uses 'schema `schema_name`' as the key for each schema. The value corresponding to each 'schema `schema_name`' is another dictionary using 'sequences', 'tables', etc., as keys and more dictionaries as values. For example:: {'schema public': {'sequence seq1': { ... }, 'sequence seq2': { ... }, 'table t1': { ... }, 'table t2': { ... }, 'table t3': { ... }, 'view v1': { ... } }, 'schema s1': { ... }, 'schema s2': { ... } } Refer to :class:`~pyrseas.dbobject.table.Sequence`, :class:`~pyrseas.dbobject.table.Table` and :class:`~pyrseas.dbobject.table.View` for details on the lower level dictionaries. .. autoclass:: Database Methods :meth:`from_catalog` and :meth:`from_map` are for internal use. Methods :meth:`to_map` and :meth:`diff_map` are the external API. .. automethod:: Database.from_catalog .. automethod:: Database.from_map .. automethod:: Database.to_map .. automethod:: Database.diff_map