ODA database selection and planning

SKA needs to make technical decisions on OSO database infrastructure and deployment so that we have an operational database for long-term storage of OSO entities by AA0.5.

To summarise ODA requirements, the database(s) must support:

• long-term storage of various data types: versioned JSON documents, possibly relational tables when JSON schemas mature or performance requires, and binary attachments.
• replication to all SKA sites. AA0.5 will not require multi-master capabilities, so this requirement does not need to be satisfied by the initial deployment.
• Transaction support (or equivalent) for storing multiple entities of different data types as a single atomic operation.
• Python is SKA's preferred language, so the operational database(s) must also be easily accessed by Python clients.
• Ease of migration. Initially, the motivation is so that we can migrate from the prototype DB to an alternative if necessary, though eventually this becomes a firmer requirement so that data can be migrated to new technologies over the lifetime of the SKA.

Identify the most suitable technology/technologies for the SKA use case and create a deployment plan so that we are positioned to begin infrastructure deployment and initial ODA implementation. The choice of database(s) need not be permanent, and can be reviewed once we have some experience with the chosen database.