oracle cost
时间: 2023-10-03 14:05:09 浏览: 56
Oracle cost refers to the total cost of ownership (TCO) associated with using Oracle database software. This includes the cost of purchasing the software, as well as ongoing costs such as maintenance, support, upgrades, and licensing fees. The cost of Oracle can vary depending on factors such as the size and complexity of the database, the number of users, and the level of support required. However, Oracle is generally considered to be a high-end, enterprise-level database solution, and as such, can be quite expensive compared to other database options.
相关问题
oracle explain
Oracle Explain Plan is a tool used for analyzing and understanding how Oracle will execute a SQL statement. It provides information on the operations that will be performed by Oracle to fetch the requested data, the order in which the operations will be executed, and the expected cost of each operation.
The Explain Plan is generated by the Oracle Optimizer, which analyzes the SQL statement and determines the most efficient way to execute it. The optimizer considers factors such as the available indexes, the size of the tables, and the complexity of the query.
The Explain Plan can be obtained using the EXPLAIN PLAN statement or by using tools such as SQL Developer or Toad. The output of the Explain Plan includes the execution plan, the estimated number of rows, and the cost of each operation.
The execution plan provides a visual representation of the operations that Oracle will perform to execute the SQL statement. The estimated number of rows indicates the number of rows that Oracle expects to retrieve for each operation. The cost of each operation is an estimate of the resources required to execute the operation, including disk I/O, CPU time, and memory usage.
The Explain Plan is a valuable tool for optimizing SQL statements and improving the performance of Oracle databases. By analyzing the plan, database administrators and developers can identify potential bottlenecks and make changes to the SQL statement or database schema to improve performance.
oracle执行计划 怎么优化降低cost的耗费
优化 Oracle 执行计划以降低 cost 的耗费通常需要以下步骤:
1. 通过执行 `EXPLAIN PLAN` 命令来获取查询的当前执行计划,了解查询中每个步骤的成本和行数。
2. 通过使用 `SET AUTOTRACE ON` 命令来获取更详细的执行计划信息,包括实际执行的行数和缓存命中率等。
3. 确认索引是否被正确地使用。可以使用 `INDEX_STATS` 视图和 `DBMS_STATS` 包来收集索引统计信息,以便确定索引是否需要重新构建或重组。
4. 确认查询是否使用了正确的连接类型。如果使用了错误的连接类型,可能会导致 Oracle 执行计划成本过高。
5. 确认查询是否使用了正确的谓词。如果查询没有使用正确的谓词,可能会导致 Oracle 执行计划成本过高。
6. 确认查询是否使用了正确的优化器提示。可以使用 `/*+ ... */` 注释来为 Oracle 提供提示,以帮助它生成更好的执行计划。
7. 确认是否存在数据倾斜问题。如果数据倾斜导致一个或多个分区中的数据量过大,可能会导致 Oracle 执行计划成本过高。
8. 最后,可以考虑使用性能调整工具,如 AWR 报告、ASH 报告或 SQL 优化工具来辅助优化 Oracle 执行计划。
请注意,以上步骤只是一些基本的优化步骤。具体的优化步骤将取决于查询本身以及其它因素。