Note: This article applies only to AAIA Legacy Documents. Legacy tables were removed from the VCdb in 2013! AceMapper still provides Legacy support, but only if the Legacy tables are found in the VCdb. You can use our RetroVCdb product to recreate the Legacy tables using current VCdb configurations.
What is the “Compression Threshold” for?
The threshold box on the Compression Settings dialog is used exclusively for re-compressing applications created from legacy. Compression works on one base vehicle at a time. It only compresses a base vehicle if it has at least one application with the threshold number or more attributes. If you set the threshold to 4, for example, compression will skip any base vehicles that don’t have applications with 4 or more attributes.
The only purpose of this feature is to save compression time after incrementally creating applications from legacy. The first time a legacy file is mapped to ACES, you can create and compress in a single step saving the time required for compression.
When an updated legacy file is imported and mapped, compression needs to be run as a separate step. To save time, we only want to try compressing newly created applications.
Applications created from legacy will initially have all of the legacy attributes (at least 14). Applications that have been compressed before will, in most cases, have fewer that 4 attributes. Setting a threshold to 4 tells compression not to try compressing applications that have already been compressed. (It doesn’t really hurt to re-compress applications. Nothing will change. But it will take more time).