x/neutron-classifier
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Docs: Design motivation for the database schema

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Sean M. Collins
2015-11-03 13:17:12 -05:00
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doc/source/usage.rst
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@@ -5,3 +5,44 @@ Usage
To use neutron-classifier in a project:: To use neutron-classifier in a project::
import neutron_classifier import neutron_classifier
Design
------
Creating a single database table, with columns for each kind of
attribute that can be classified is not ideal, since the number
of columns in the table will grow as more classifiers are introduced.
Instead of one table with a large number of rows, classifiers are
implemented as SQLAlchemy classes. Since there are a myriad of ways to
classify packets, an attempt was made to try and group attributes into
logical groupings (transport layer, IP layer, etc). In the database,
classifiers are implemented using `joined table inheritance`_ where
rows are inserted into the classifier table, and additional attributes
for each classifier that fit into the logical groupings (transport
layer, IP layer, etc) are inserted into the inheritance tables.
For example - a classifier that matches the following tuple
(source_ip_prefix, destination_ip_prefix) has a row inserted in the
main 'classifiers' table, and a row inserted into the 'ip_classifiers'
table with the IP layer classification attributes.
The motivation for this is to break classifiers out into separate
tables, so adding new classifiers is as simple as creating a new table
with the specific attributes for that table.
::
2015-10-30 23:25:24,249 INFO sqlalchemy.engine.base.Engine BEGIN (implicit)
2015-10-30 23:25:24,250 INFO sqlalchemy.engine.base.Engine INSERT INTO classifiers (id, classifier_type) VALUES (?, ?)
2015-10-30 23:25:24,250 INFO sqlalchemy.engine.base.Engine ('7244cbba-03af-4a10-8995-10c75725d7c1', 'ipclassifier')
2015-10-30 23:25:24,250 INFO sqlalchemy.engine.base.Engine INSERT INTO ip_classifiers (id, source_ip_prefix, destination_ip_prefix) VALUES (?, ?, ?)
2015-10-30 23:25:24,250 INFO sqlalchemy.engine.base.Engine ('7244cbba-03af-4a10-8995-10c75725d7c1', 'fddf:cb3b:bc4::/48', 'fd70:fbb6:449e::/48')
2015-10-30 23:25:24,251 INFO sqlalchemy.engine.base.Engine INSERT INTO classifier_groups (tenant_id, id, name, description, service) VALUES (?, ?, ?, ?, ?)
2015-10-30 23:25:24,251 INFO sqlalchemy.engine.base.Engine ('bc66b697-f145-41b1-8770-5c825d205f88', '0c8c9f51-4d4b-47d9-a030-ddc3cf86418e', 'test classifier', 'ensure all data inserted correctly', 'neutron-fwaas')
2015-10-30 23:25:24,252 INFO sqlalchemy.engine.base.Engine INSERT INTO classifier_chains (id, classifier_group_id, classifier_id, sequence) VALUES (?, ?, ?, ?)
2015-10-30 23:25:24,252 INFO sqlalchemy.engine.base.Engine ('099a754f-1e91-42db-853d-9a385ddef39d', '0c8c9f51-4d4b-47d9-a030-ddc3cf86418e', '7244cbba-03af-4a10-8995-10c75725d7c1', 1)
2015-10-30 23:25:24,253 INFO sqlalchemy.engine.base.Engine COMMIT
.. _joined table inheritance: http://docs.sqlalchemy.org/en/rel_1_0/orm/extensions/declarative/inheritance.html#joined-table-inheritance