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29 lines
1.2 KiB
Plaintext
29 lines
1.2 KiB
Plaintext
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<Chapter>
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<Title>The <ProductName>Postgres</ProductName> Rule System</Title>
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<Para>
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Production rule systems are conceptually simple, but
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there are many subtle points involved in actually using
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them. Consequently, we will not attempt to explain the
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actual syntax and operation of the <ProductName>Postgres</ProductName> rule system
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here. Instead, you should read
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<XRef LinkEnd="STON90b" EndTerm="[STON90b]"> to understand
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some of these points and the theoretical foundations of
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the <ProductName>Postgres</ProductName> rule system before trying to use rules.
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The discussion in this section is intended to provide
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an overview of the <ProductName>Postgres</ProductName> rule system and point the
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user at helpful references and examples.
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The "query rewrite" rule system modifies queries to
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take rules into consideration, and then passes the modified
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query to the query optimizer for execution. It
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is very powerful, and can be used for many things such
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as query language procedures, views, and versions. The
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power of this rule system is discussed in
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<XRef LinkEnd="ONG90" EndTerm="[ONG90]">
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as well as
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<XRef LinkEnd="STON90b" EndTerm="[STON90b]">.
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</Para>
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</Chapter>
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