Are there tradeoffs with AllowDirect: true?

[jgaskins]

Is there ever a reason to avoid AllowDirect: true when creating a stream? Are there tradeoffs being made?

Just trying to understand why it's optional and, from what I can tell, not the default (other than for KV).

[derekcollison]

Used for internal usage only atm.

[jgaskins]

I maintain a NATS client, so the internal usage is what I'm actually trying to understand. 😄 I looked at the ADR for the DIRECT.GET API and I see that the server sets it based on whether max_msgs_per_subject is set (presumably the reason this became a required setting for KV to distribute reads), but I haven't been able to uncover why it isn't set for all streams. I assume there are tradeoffs involved.

[derekcollison]

My answer is wrong, I thought you were talking about direct consumers which is a whole different thing.

Yes you can edit a stream to enable.

[kolypto]

I grepped the code for AllowDirect and found that it influences the way clusters work: probably allocating more resources because of unoptimized access?

I'd assume that keeping it AllowDirect: false is easier on server resources