Support for Variant/Dynamic/JSON types

[arnaudbriche]

Hi,

I'm just wondering if you are planning on supporting the new set of semi-structured data types.

[SpencerTorres]

This is how they are supported in clickhouse-go:

• Add Variant Type clickhouse-go#1453
• Add Dynamic Type clickhouse-go#1454
• Add JSON Type clickhouse-go#1455

I would like to add some support for them, but we would need to make sure it fits the performance goals of ch-go. There's some overhead for working with these types, and we need to find a user-friendly way to read/write this type of data.

[tanner-bruce]

Is it possible to write to a JSON type column via ch-go? We do not need to to query it through ch-go.

[SpencerTorres]

You may be able to use String, I think the server can automatically cast it. I haven't checked in a while though.

Adding Variant and Dynamic would need some discussion given their complexity, but JSON has support for string encoding. Perhaps we can add a JSONString type pretty easily since it's just String with a u64 prefix. You would need to handle marshal/unmarshal yourself though

[SpencerTorres]

Just in case String doesn't directly insert into JSON (and for easily reading JSON directly), I have added ColJSONStr in #1034. Check the PR description for some notes on usage.