** Oracle Optimizer Explained: A Step-by-Step Guide to Efficient SQL Query Execution

The Oracle Optimizer is a crucial component of the Oracle database, responsible for generating optimal query execution plans. This process involves several steps, including syntax validation, query rewriting, cost estimation, and plan selection. The optimizer uses various techniques such as predicate pushdown, view merging, and subquery unnesting to ensure efficient data retrieval while minimizing resource consumption.

The steps involved in the Oracle Optimizer include:

1. Parsing: Validates syntax and semantics of the SQL statement.
2. Transformation: Rewrites the query into a more efficient equivalent version.
3. Cost Estimation: Estimates the cost of different query operations based on available statistics.
4. Plan Selection: Chooses the best execution plan from enumerated plans.

By understanding these steps, developers and DBAs can effectively analyze and optimize SQL queries for better performance.

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Source: https://dev.to/mrcaption49/oracle-optimizer-3fgc