Oracle Performance Optimization Operations: summary

These articles of Oracle Performance optimization operations can be used in conjunction with each other. And the various methods of interaction, close contact.

This connection is both consistent and may bring conflict, when the conflict occurs, the need to choose according to the actual situation, there is no fixed pattern.

The final determinant of SQL optimization is the level of mastery of Oracle Foundation.

In addition, it is worth noting that Oracle's execution plan for SQL statements changes over time and as data accumulates and changes.

For example: The cost-based optimization method, with the increase in the amount of data, the optimizer may incorrectly select the index and use a full table scan.

This may be because the statistical information is outdated, the data volume changes greatly after the failure of the timely analysis of the table;

However, if you do not use a reasonable index after parsing the table, it is necessary to use the hint hint for the SQL statement, forcing a reasonable index.

However, this hint hint can not be abused, because this method is too complex, lack of versatility and adaptability, but also increase the cost of maintenance;

Relatively speaking, the method is "all-in-one", which is based on the right shift of functions, the removal of "in, or,<>, are not NULL", the decomposition of complex SQL statements, etc.

Can be assured of the use of bold.

At the same time, optimization is not "once and for all", it must be adjusted as the situation changes.

When the database design changes, including changing the table structure: field and index additions, deletions or renaming, etc.;

Business logic changes: such as query mode, value range changes and so on.

In this case, the original optimization must also be adjusted to meet the demand for efficiency.

Oracle Performance Optimization Operations: summary