Database Management
Reference Manual
Introduction to Database Concepts
:
Database Sessions
: Merge Changes
Merge Changes
As a result of storing all changes, AVEVA E3D™ databases will grow relatively quickly. You may compress a DB to reduce its size by merging multiple sessions together using the MERGE CHANGES command in ADMIN. You may compress all sessions, or a range of sessions.
Any sessions used in stamps will always be preserved. Thus before compressing a DB you should create stamps to preserve any comparison points that might be needed. Sessions 1,2 and the last session are also always preserved. Thus for the previous example, if you decide to do a MERGE CHANGES on a database having set a stamp on session 10, the resultant DB will look like:
It can be seen that as well as sessions 10, sessions 1,2 and 39 are kept. The changes in session 10 now hold the accumulated changes for sessions 3-10, and Session 39 actually holds the accumulated changes for sessions 11 to 39.
The MERGE CHANGES command is discussed in the ADMIN manual.
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