Oracle nolock
时间: 2023-12-24 09:04:11 浏览: 31
Oracle does not have a direct equivalent to the NOLOCK hint in SQL Server. However, Oracle provides several mechanisms to achieve similar functionality:
1. READ ONLY transactions: By setting a transaction to READ ONLY, Oracle ensures that the transaction does not acquire any locks on data. This can be achieved by setting the transaction isolation level to READ ONLY or by specifying the READ ONLY keyword when starting a transaction.
2. Snapshot isolation: Oracle provides a snapshot isolation feature that allows transactions to read data as of a specific point in time. This feature ensures that the transaction does not acquire any locks on data and reads a consistent view of the data.
3. Multi-version concurrency control (MVCC): Oracle uses MVCC to provide read consistency without acquiring locks on data. In MVCC, each transaction reads a consistent view of the data without blocking other transactions.
4. Query hints: Oracle provides query hints that can be used to control the behavior of queries. For example, the /*+ NOLOCK */ hint can be used to bypass locks on data.
Overall, Oracle provides several mechanisms to achieve similar functionality to the NOLOCK hint in SQL Server. However, it is important to carefully consider the implications of using these mechanisms as they can affect the consistency and integrity of data.