Allow comma-separted namespace options

[choplin]

Description

Currently, schema-importer accepts multiple --namespace options to specify multiple namespaces, like below.

$ schema-importer --namespace ns1 --namespace --ns2

However, other Scalar tools employ a comma-separated style to specify multiple options.

$ schema-importer --namespace ns1,ns2

To keep consistency among the products, we should also allow a comma-separated style for schema-importer.

Considerations

• Should we keep multiple options after implementing a comma-separated style or obsolete it?
• Should be the name of the comma-separated style option --namespace as well?

[kota2and3kan]

Thank you for considering this improvement!

Should we keep multiple options after implementing a comma-separated style or obsolete it?

I will create the Helm Chart based on the current implementation (i.e., multiple options). So, I want schema-importer to keep multiple options in v3.x.

However, I think it's OK if it obsoletes multiple options in v4.x in the future (i.e., the backward incompatible update is acceptable in a major release).

Should be the name of the comma-separated style option --namespace as well?

I think there is no problem if we use the same name.
However, this is a very minor thing, but it might be better to use --namespaces (plural form) because this option can accept several namespaces.

---

FYI:

The following configurations related to the namespace in other ScalarDB tools adopt the comma-separated style.

• Multi-storage Transactions (scalar.db.multi_storage.namespace_mapping)
• ScalarDB GraphQL (scalar.db.graphql.namespaces)