It increases the size from 4 bytes to 8 bytes of file-header fields such as current transaction number (CTN), maximum TN and others that contain transaction numbers.

It resets the various trace counters and changes the database format to V5. This change does not upgrade the individual database blocks but sets the database format flag to V5.

It also initializes a counter of the current blocks that are still in V4 format. It decrements this counter each time an existing V4 format block is converted to V5 format. When the counter is 0, the entire database gets converted.