Prefix for non-FHIR fields

[niquola]

We have to decide on the prefix we will use for non-FHIR elements.
Options:

• $
• sof_
• _

[niquola]

TODO: Determine a standard prefix or suffix for elements added in level 1 and level 2 transformations. This probably needs to be alphabetical since an underscore is used in FHIR JSON for primitive extensions and databases like BigQuery only allow a-z and underscore as the first character of a field name (https://cloud.google.com/bigquery/docs/schemas#:~:text=A%20column%20name%20must%20contain). Maybe sof_ for sql on fhir?

by @gotdan

[niquola]

I'd generally lean toward:
Leave .id in place
Add new normalized value in $id(if "$" is the desired convention for normalization. If not... define some conventional prefix for all > normalizations and use it here.)
I don't know, I'd look at _ because it's not used in FHIR element names and is valid in SQL column names (but that's not a hard requirement).

by @jmandel

[niquola]

Binary formats and strict schemas limitations may influence prefix choice. TODO: take a look at restrictions in Avro, ProtoBuf, ClickHouse, Snowflake etc.

[niquola]

Avro, for example:

• start with [A-Za-z_]
• subsequently contain only [A-Za-z0-9_]

Looks like sof_ style is the safest choice.

[vadi2]

And what does it stand for?

[jmandel]

"sql on fhir" ?

[jmandel]

There's also the potential for __ which FHIR does not use. But I like the explicitness of the acronym.

[niquola]

Yep, it's nice. In the case of Avro it will not work :(