We support JSON as a format for ad-hoc queries but it's probably good to deprecate it medium term as it has several issues that prevent representing results (of views and tables) in certain cases:

Here are a few known limitations for the JSON format that causes friction with users running into it:

• Numbers are represented/coerced to f64 which may lead to loss of precision in case types that do not fit f64 are used
• The SQL MAP type can contain non-string keys which is not supported in JSON
• It's valid SQL to have >1 column with the same name, in which case the JSON format will silently skip columns

Note that the other formats (text, parquet, and arrow-ipc) do not have these limitation.

As a default arrow-ipc should be used, it can be streamed over http/websocket and is a compact binary format made for data exchange.

We'll start by switching the default in our own libraries and printing a warning in fda.