This is the db-file size, which is actual DB-implemenation detail, and
which will probably only grow up - depends on the particular db u
have. There are many strategies, like paging etc. e.g. some DBs
require a whole partition just for themselves - dont even think of
shrinking those...
See your db's doco about some way to purge, clean, vacuum the db to
get back the unused space.
> Hi All,
>
> at the end, I finally cracked the problem with the
> tree-structured database with SQLAlchemy. I still have however a
> problem.
> I am using a "physical" database, not an in-memory one. I have
> declared my Tables as follows:
>
> trees = Table('treenodes', metadata,
> Column('node_id', Integer,
> Sequence('treenode_id_seq',optional=False), primary_key=True),
> Column('parent_node_id', Integer,
> ForeignKey('treenodes.node_id'), nullable=True),
> Column('node_name', String(500), nullable=False),
> Column('formattedname', String(500), nullable=False),
> Column('data_ident', Integer,
> ForeignKey('treedata.data_id')) )
>
>
> treedata = Table("treedata", metadata,
> Column('data_id', Integer, primary_key=True),
> Column('value', String(100), nullable=False)
> )
>
> mapper(TreeNode, trees, properties=dict(id=trees.c.node_id,
> name=trees.c.node_name,
>
> parent_id=trees.c.parent_node_id, children=relation(TreeNode,
> cascade="all", backref=backref("parent",
> remote_side=[trees.c.node_id]),
>
> collection_class=NodeList),
>
> data=relation(mapper(TreeData, treedata,
> properties=dict(id=treedata.c.data_id)),
>
> cascade="all,delete,delete-orphan", lazy=False))
>
>
> Everything goes ok, I can save my data to a database file called
> MyDatabase.db. After saving few items, the database size is about
> 180 Kb. So far so good. But when I delete one or more items (also
> if I delete all the items) using:
>
> self.session.delete(bad_node)
> self.session.flush()
> self.session.clear()
>
> By printing the node names, I know that bad_node is no more there,
> but its data seems to still live in the database. I mean, even if I
> delete *all* the items, the database size is still 180 Kb, no
> matter how much I flush(), clear(), close() and reopen the
> database.
> I am sure I am missing something. Which is the usual approach to
> delete *permanently* things from a database?
>
> Thank you in advance for your suggestions.
>
> Andrea.
>
> "Imagination Is The Only Weapon In The War Against Reality."
> http://xoomer.virgilio.it/infinity77/
>
>
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