| 摘要 |
Techniques are described to allow a query to be registered as a persistent stored entity within the database, and to generate notifications as and when the query result changes continuously as long as the query continues to be registered with the database. According to one aspect, for a table referenced in a query, a filter condition is generated based, at least in part, on a predicate of the query. Then, the database server determines whether the filter condition is satisfied by either a before image of a row, or an after image of the row, that was modified by a transaction. If the filter condition is satisfied by either the before image or the after image, then the query is added to a first set of queries whose result sets may have been affected by the transaction. From among the first set of queries, a second set of queries that have result sets that were actually affected by the transaction is determined. Notifications are then sent based on the second set of queries.
|
