Add new columns to table schema

Arbitrary context as key-value pairs. How to use the context is custom to the specific implementation.

On a request, it carries caller-provided context to the implementation. On a response, it carries implementation-provided context back to the caller.

REST NAMESPACE ONLY Context entries are mapped to and from HTTP headers using the header. prefix:

• On a request, any entry whose key starts with header. is sent as an HTTP request header with the prefix stripped. For example, the entry {"header.Authorization": "Bearer abc"} is sent as the request header Authorization: Bearer abc.
• On a response, every HTTP response header is returned as an entry whose key is the header name prefixed with header.. For example, the response header x-request-id: abc123 is returned as the entry {"header.x-request-id": "abc123"}.

Arbitrary context as key-value pairs. How to use the context is custom to the specific implementation.

On a request, it carries caller-provided context to the implementation. On a response, it carries implementation-provided context back to the caller.

REST NAMESPACE ONLY Context entries are mapped to and from HTTP headers using the header. prefix:

• On a request, any entry whose key starts with header. is sent as an HTTP request header with the prefix stripped. For example, the entry {"header.Authorization": "Bearer abc"} is sent as the request header Authorization: Bearer abc.
• On a response, every HTTP response header is returned as an entry whose key is the header name prefixed with header.. For example, the response header x-request-id: abc123 is returned as the entry {"header.x-request-id": "abc123"}.