Query optimizer concepts

Introduction to Query Optimization

Query Optimizer Concepts

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Introduction to Query Optimization The query optimizer (called simply the optimizer) is built-in data source software Decides the most effective method for an SQL declaration to gain access asked for information.

This area contains the following topics: 1. Goal of the Query Optimizer 2. Cost-Based Optimization 3. Performance Plans

Purpose of the Query Optimizer  

generate the best performance strategy for a SQL declaration.

The price calculations accounts for factors of query performance such

Introduction to Query Optimization

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Cost-Based Optimization SQL is a nonprocedural language, so the optimizer is free to combine, rearrange, and procedure in any order.

The information source maximizes each SQL declaration centered on research gathered about the utilized information.  l

When producing performance programs, the optimizer views different access routes and be a part of methods.

Execution Plans An execution plans reveals the expense of the entire strategy and each individual function.

The cost is an enclosed unit that the execution strategy only reveals to allow for strategy evaluations.

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Steps of Optimizer Components This representation represents a parsed query (from the parser) coming into the Query Transformer.

The modified question is then sent to the Estimator. Statistics are recovered from the Dictionary, then the query and estimates are sent to the Plan Generator.

The plan generator either returns the plan to the estimator or delivers the execution plan to the row source generator.

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