Chapter 41. The Rule System

Chapter 41. The Rule System
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Table of Contents

41.1. The Query Tree

41.2. Views and the Rule System

41.2.1. How SELECT Rules Work
41.2.2. View Rules in Non-SELECT Statements
41.2.3. The Power of Views in PostgreSQL
41.2.4. Updating a View

41.3. Materialized Views

41.4. Rules on INSERT, UPDATE, and DELETE

41.4.1. How Update Rules Work
41.4.2. Cooperation with Views

41.5. Rules and Privileges

41.6. Rules and Command Status

41.7. Rules Versus Triggers

+ This chapter discusses the rule system in + PostgreSQL. Production rule systems + are conceptually simple, but there are many subtle points + involved in actually using them. +

+ Some other database systems define active database rules, which + are usually stored procedures and triggers. In + PostgreSQL, these can be implemented + using functions and triggers as well. +

+ The rule system (more precisely speaking, the query rewrite rule + system) is totally different from stored procedures and triggers. + It modifies queries to take rules into consideration, and then + passes the modified query to the query planner for planning and + execution. It is very powerful, and can be used for many things + such as query language procedures, views, and versions. The + theoretical foundations and the power of this rule system are + also discussed in [ston90b] and [ong90]. +

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40.5. A Table Rewrite Event Trigger Example	Home	41.1. The Query Tree