Skip Headers

Oracle® Database Reference 10g Release 2 (10.2) Part Number B14237-02 |
Home | Book List | Contents | Index | Master Index | Feedback

Previous | Next
| View PDF

# OPTIMIZER_MODE

Property | Description
--- | ---
Parameter type | String
Syntax | `OPTIMIZER_MODE =` `{ first_rows_[1 | 10 | 100 | 1000] | first_rows | all_rows }`
Default value | `all_rows`
Modifiable | `ALTER SESSION`, `ALTER SYSTEM`

`OPTIMIZER_MODE` establishes the default behavior for choosing an optimization approach for the instance.

Values:

- `first_rows_``n`

  The optimizer uses a cost-based approach and optimizes with a goal of best response time to return the first `n` rows (where `n` = 1, 10, 100, 1000).

- `first_rows`

  The optimizer uses a mix of costs and heuristics to find a best plan for fast delivery of the first few rows.

- `all_rows`

  The optimizer uses a cost-based approach for all SQL statements in the session and optimizes with a goal of best throughput (minimum resource use to complete the entire statement).

  See Also: Oracle Database Performance Tuning Guide for more information on setting this parameter Oracle Database Concepts and Oracle Database Performance Tuning Guide for more information about the optimizer