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Query Optimization and Processing - (BCA / B.Tech)

Query Optimization & Processing in RDBMS:

Query Optimization and Processing is a crucial process in database systems used to improve the performance of SQL queries and execute them efficiently. This process consists of several steps and techniques to ensure that a user's query is completed in the shortest possible time using the fewest resources.

Query Processing Steps:

Query processing is the procedure through which an SQL query goes through various stages to return a result in the form of data. This process mainly involves three steps:

Parsing: In this step, the SQL query is verified for syntax and semantics. It ensures the query is written correctly and has no syntax errors. The query is broken down, and a parse tree is created to represent its structure.
Query Optimization: This is a critical step where the database system evaluates various possible execution plans and selects the most efficient one. This involves logical optimization (simplifying the query logic) and physical optimization (deciding on indexes, join algorithms, etc.), often based on a cost model.
Query Execution: In this final step, the selected execution plan is actually implemented, the data is retrieved from the database, and the final result is returned to the user.

Query Optimization Techniques:

The goal of query optimization is to make the execution of an SQL query faster and more efficient. Common techniques include join optimization (reordering joins), using indexes to speed up data retrieval, and employing cost-based optimization to choose the plan with the lowest estimated cost (in terms of CPU time, I/O, etc.).

Query Optimization and Processing

Query Optimization & Processing in RDBMS:

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