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Oracle SQL Processing

sql processing use the following main components to execute a SQL query

• The parser checks both syntax and semantic analysis
• The Optimizer uses costing methods, cost-based optimizer(CBO), or internal rules, rule-based optimizer(RBO), to determine the most efficient way of producing the result of the query.
• The Row Source Generator receives the optimal plan from the optimizer and outputs the execution plan for the SQL statement.( execution plan defines how oracle finds or writes the data. For example, an important decision that Oracle has to take is if it uses indexes or not. And if there are more indexes, which of these is used.)
• The SQL Execution Engine operates on the execution plan associated with a SQL statement and then produces the results of the query.

posted by James Pei @ 4:19 PM