Updating Data

Abstract

We now investigate how the plan synthesis approaches can be applied to the problem of database updates. The general framework is a follows.

• 1. The user issues a request to add (insert) and remove (delete) sets of tuples to/from an instance of a logical relation.

• 2. This request is then translated to possibly multiple requests that modify all the access paths in the associated physical design.

Since modification requests must be consistency-preserving (i.e., the result of the modification must satisfy all integrity constraints in the schema) and this may require modifying the instances of several logical relations simultaneously, we henceforth assume that a modification request is specified by a set of such requests (perhaps trivially empty), one for each symbol in the logical design.