diff --git a/docs/APDB.md b/docs/APDB.md index 8437c3a1..57564f9c 100644 --- a/docs/APDB.md +++ b/docs/APDB.md @@ -11,8 +11,8 @@ The versioning system of the APDB is outlined in [DMTN-269](https://dmtn-269.lss The deployed database schema is a product of the [schema in sdm_schemas](../python/lsst/sdm_schemas/schemas/apdb.yaml) and processing by tools in the [dax_apdb](https://github.com/lsst/dax_apdb) repository. Compatibility of the client executable with the actual database schema is determined by the version number in `apdb.yaml` and that which is stored in the database metadata. -Backward compatibility in the context of the APDB implies that a client using an interface derived from a schema with a higher `MINOR` version number will be able to read and write into a database with a lower `MINOR` version -- in other words, an existing APDB need not be migrated to match newer clients. -But a client using a lower `MINOR` version number will not be compatible with a database that contains the changes from a higher version. +Backward compatibility in the context of the APDB implies that a client using a schema with a higher minor version will be able to read and write into a database with a lower minor version -- in other words, an existing database instance need not be migrated to match the newer client interface. +But a client using a schema with a lower minor version will be incompatible with a database that has a higher version number. There may be cases where significant schema changes may still be compatible if the client can handle them transparently. Typical Schema Changes