MySQL-specific implementation. Should be used in conjunction with a {@link MySQLJDBCDataModel}. This implementation stores item-item diffs in a MySQL database and encapsulates some other slope-one-specific operations that are needed on the preference data in the database. It assumes the database has a schema like:
| item_id_a | item_id_b | average_diff | count |
|---|---|---|---|
| 123 | 234 | 0.5 | 5 |
| 123 | 789 | -1.33 | 3 |
| 234 | 789 | 2.1 | 1 |
item_id_a and item_id_b should have types compatible with the long primitive type. average_diff must be compatible with float and count must be compatible with int.
The following command sets up a suitable table in MySQL:
CREATE TABLE taste_slopeone_diffs ( item_id_a BIGINT NOT NULL, item_id_b BIGINT NOT NULL, average_diff FLOAT NOT NULL, count INT NOT NULL, PRIMARY KEY (item_id_a, item_id_b), INDEX (item_id_a), INDEX (item_id_b) )
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