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PL/SQL Optimizer and Performance Tuning

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Questions and Answers

What can be done if the overhead of the PL/SQL optimizer makes compilation of very large applications too slow?

Set the compilation parameter PLSQL_OPTIMIZE_LEVEL=3
Disable the PL/SQL optimizer
Set the compilation parameter PLSQL_OPTIMIZE_LEVEL=1 (correct)
Enable the PL/SQL optimizer at a higher level

When is dynamic SQL useful in PL/SQL programs?

When avoiding any run-time generation of SQL statements
When knowing at compile time the full text of a SQL statement
When writing fixed SQL statements
When knowing at compile time the number and data types of input and output variables of a dynamic SQL statement (correct)

What is the most common cause of slowness in PL/SQL programs?

Using appropriate indexes
Inefficient use of bulk SQL
Slow SQL statements (correct)
Query hints in SQL statements

What is native dynamic SQL?

A methodology for generating and running SQL statements at run time (B) Signup and view all the answers

How can you minimize the performance overhead of communication between PL/SQL and SQL?

Use set of PL/SQL features known as bulk SQL (A) Signup and view all the answers

In what cases is dynamic SQL particularly useful?

When writing general-purpose and flexible programs like ad hoc query systems (B) Signup and view all the answers

What is the purpose of tuning loops in PL/SQL applications?

To optimize the loops themselves and the code inside them (A) Signup and view all the answers

Why should functions not be invoked unnecessarily in queries?

To make the invocation as efficient as possible (A) Signup and view all the answers

What is the advantage of using data types like PLS_INTEGER, BINARY_FLOAT, and BINARY_DOUBLE?

They use hardware arithmetic for better performance (A) Signup and view all the answers

What does the FORALL statement in PL/SQL do?

Sends DML statements from PL/SQL to SQL in batches rather than one at a time (C) Signup and view all the answers

What is the purpose of bulk SQL in PL/SQL?

To minimize the performance overhead of communication between PL/SQL and SQL (A) Signup and view all the answers

Why should one avoid using data types in the NUMBER family?

To use hardware arithmetic for better performance (B) Signup and view all the answers

How can short-circuit evaluation be utilized in logical expressions in PL/SQL?

By putting least expensive conditional tests first in logical expressions (C) Signup and view all the answers

What is bulk binding in bulk SQL?

It binds an entire collection of values at once (D) Signup and view all the answers

What are obstacles to scaling up RDBMS as mentioned in the text?

Scaling Relational Databases Is Hard because todays business is digital. (A) Signup and view all the answers

What is an important consideration when using conditional expressions in PL/SQL?

Put least expensive conditional tests first to take advantage of short-circuit evaluation. (D) Signup and view all the answers

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