Responsibility of OPTIMIZER is :

  1. Compiles the SQL statements

  2. Complies the list of packages into application plan

  3. Stored the application plan and packages into Directory

  4. Chooses the best access path from catalog tables


Correct Option: D
Explanation:

To answer this question, the user needs to know about the role of an optimizer in database management systems.

The optimizer is a component of a database management system (DBMS) that is responsible for generating the most efficient execution plan for a given SQL query.

Now let's go through each option and explain why it is right or wrong:

A. Compiles the SQL statements: This option is partially correct. The optimizer does not compile SQL statements, but it does analyze the query and generates an execution plan to execute the SQL statement.

B. Complies the list of packages into application plan: This option is incorrect. The job of the precompiler is to compile the list of packages into an application plan, not the optimizer.

C. Stored the application plan and packages into Directory: This option is incorrect. The job of the precompiler is to store the application plan and packages into a directory, not the optimizer.

D. Chooses the best access path from catalog tables: This option is correct. The optimizer analyzes the query and chooses the best access path from a set of possible access paths based on the metadata stored in the catalog tables.

Therefore, the correct answer is:

The Answer is: D

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