Allows wildcard queries for metric names in PromQL.

[killme2008]

What type of enhancement is this?

API improvement

What does the enhancement do?

GreptimeDB currently supports only the equal matcher for metric names, such as {__name__ = 'up'}, and does not support other matchers like != or ~=.

For instance:

 count by(__name__)({__name__=~"go_.*"})

I believe GreptimeDB should also support regex(and not regex) matchers, but the != matcher will not be implemented due to performance concerns.

The regex matcher will query the tables from the metric engine's internal metadata, and join the results from each metric table to return the response. Of course, we must limit the table number to return at one time to avoid OOM error.

Implementation challenges

No response