Introduction to Oracle In-Memory Undo features

The following articles mainly talk about Oracle In-Memory Undo. I found a piece of information about Oracle In-Memory Undo on a reputable website for you to share. I hope you will gain some benefits after browsing the following content. The following is an introduction to the text.

I have read a technical document All About of Oracle's In-Memory Undo In the boring pre-sales demonstration. I remember talking About Oracle In-Memory Undo (IMU) a few years ago, most of them are based on speculation. This is the first detail.
Oracle has applied for a patent for the IMU feature launched at 10 Gb ). As one of the most important components, the efficiency of Undo is directly related to the capabilities of the entire database. The old Block-based Segment (Segment refers to the concept of the storage layer) Management Mode of Undo. Changes of UNDO itself must be recorded in the Redo Log Buffer, while IMU avoids this operation (because it is memory rather than storage), thus reducing the amount of Redo generated.

In addition, because the read consistency overhead is directly stored in the memory instead of dependent on the storage segment, the overall consumption is greatly reduced, and the CPU load is also effectively reduced. Its application model should be said to be an OLTP suitable for consistent read with a large demand.

Oracle 10g uses IMU by default. The implicit parameter _ in_memory_undo can be used to disable this feature. Because it is an implicit parameter, it also reflects that this feature is not so mature. Searching Metalink involves a lot of IMU bugs. Once UNOD bugs are encountered, it may be difficult to solve non-stop DB bugs. Therefore, for systems with high availability requirements, we still need to think twice before using this feature.

 

The above content is an introduction to Oracle In-Memory Undo. I hope you will get something better.

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