Add the ability to limit query resource usage

[russorat]

from our community: Is there any way to set query RAM limits, timeouts, ... to prevent a too complex query endangering the entire instance?

Using this issue to start the discussion and planning of this type of capability.

• Ideally, they could be configured per org by an admin of the system.
• Initially, the 3 vectors could be limit by memory usage, by time, by number of results.
• Once queries trigger one of these limits, they would be cancelled and an error message returned to the user.

[jsternberg]

The memory and parallelism limits for queries are part of OSS, but they aren't exposed as part of the configuration file so these limits are just set to the maximum values. This is because we were still evolving the parameters and didn't want to create configuration values that we would later deprecate or remove.

If we have decided on the current parameters, we can expose them. We should still work on exposing it in a way that would allow us to change in the future.