How Crash Recovery Works? : Part 3

In the last post we saw how the log is written during the operation of a database system. In this post we will go over the actual recovery mechanism and how the log is used. Why recovery? As we discussed in our first post on this topic, a recovery algorithm ensures that all the changes...

How Crash Recovery Works? : Part 2

Continuing where we left off in the last post, we saw why database systems use logs for recovery. Besides logs there are other supporting data structures that are needed for recovery. Broadly speaking there are three data structures that are part of a recovery mechanism (We’ll discuss the ARIES mechanism here) LogTransaction TableDirty Page Table...

How Crash Recovery Works? : Part 1

We hear terms like ‘recovery is slow’ , ‘system is in recovery mode’ and I felt that I don’t understand enough about what "recovery" entails. In an attempt to understand it, I did some dabbling in reading and wanted to condense it here on my blog.