handling ecocomDP version compatibility

[mobb]

adding info for traits to the ecocomDP model will be a new version of the model. There are some issues with this to resolve.

table names and content

1. new model has a one table renamed. (variable_mapping to variable_attribute (current proposal) or maybe variable_info (may be less confusing). Does this create incompatibility with existing code?
2. new model has new columns added to some tables
   1. variable_attribute.Variable_type (optional)
   2. dataset_summary.Dataset_level_bio_organization (controlled vocab)
   3. dataset_summary.Observation_finest_level (controlled vocab)
   4. dataset_summary.Number of variables (calculated)

Instance packages

Presumably both original-flavor ecocomDP packages and trait-enabled packages will coexist. We should have a mechanism to tell these apart. the simplest might be to record the ecocomDP version in the metadata.

1. we need a numbering scheme. I think we can assume that original-flavor ecocomDP are v1
   1. can we assume that any non-assigned packages are also v.1? do we need a check for that?
2. what numbering scheme do we want to adopt?
   1. if trait-enabled packages are backward compatible, they could probably be v1.1.
   2. if not backward compatible (most likely) they should probably be v2
   3. where in metadata should we record the model version?

[clnsmth]

Thanks for raising this issue @mobb . A few thoughts ...

Table Names and Content

Changing variable_mapping to variable_attribute would create a backwards-breaking change. That's why I'm proposing we don't modify the original name of the table.

The new columns of the tables do not introduce backwards-incompatibilities. So we're good here.

Instance Packages

If we preserve backwards compatibility for the data model, the urgency on version numbering doesn't seem as urgent? The code will simply read whatever ecocomDP package is input and process the data to its full extent. If there is traits information, then any new features that support traits will be reflected, and vice versa for older ecocomDP package versions that don't contain any traits information.