Learning PostgreSQL 10 - Second Edition: A beginner's guide to building high-performance PostgreSQL database solutions by Salahaldin Juba & Andrey Volkov

Author:Salahaldin Juba & Andrey Volkov [Juba, Salahaldin]
Language: eng
Format: azw3
Publisher: Packt Publishing
Published: 2017-11-30T16:00:00+00:00

Function planner-related parameters

Function planer related parameters helps in giving the planner information about the function execution cost, this helps the planner to generate a good execution plans. The following three parameters are used by the planner to determine the cost of executing the function, the number of rows that are expected to be returned, and whether the function pushes down when evaluating predicates. These parameters are:

Leakproof: Leakproof means that the function has no side effects. It does not reveal any information about its argument. For example, it does not throw error messages about its argument. This parameter affects views with the security_barrier parameter.

Cost: Declares the execution cost per row; the default value for the C language function is 1, and for PL/pgSQL it is 100. The cost is used by the planner to determine the best execution plan.

Rows: The estimated number of rows returned by the function if the function is set-returning. The default value is 1000.

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