Oracle supports a mechanism called Multi-Version ReadConsistency which is implemented by undo data in the undo segments.
Oracle支持一种称为Multi - Version Read Consistency的机制,这是用undo段中的undo数据实现的。
2
If the business requires greater availability but readconsistency is not a premium, then an asynchronous option may be a more cost-effective approach.
如果业务要求更高的可用性,并且读一致性不是很重要,那么选择异步可能是更经济的方法。
3
That's also a costly option, however, because every time you iterate across the contents of the collection, you have to synchronize all operations, including read and write, to ensure consistency.