What did you do?

load 20m
  series{label="a", idx="1"} 2 _
  series{label="a", idx="2"} _ 4

eval instant at 0 label_replace(series, "idx", "replaced", "idx", ".*")
  series{label="a", idx="replaced"} 2

eval instant at 20m label_replace(series, "idx", "replaced", "idx", ".*")
  series{label="a", idx="replaced"} 4

eval range from 0 to 20m step 20m label_replace(series, "idx", "replaced", "idx", ".*")
  series{label="a", idx="replaced"} 2 4

What did you expect to see?

I expected the tests to pass.

What did you see instead? Under which circumstances?

At the individual instants I get the expected result, but with the range query it fails with:

error evaluating query "label_replace(series, \"idx\", \"replaced\", \"idx\", \".*\")" (line 11): vector cannot contain metrics with the same labelset

System information

No response

Prometheus version

No response

Prometheus configuration file

No response

Alertmanager version

No response

Alertmanager configuration file

No response

Logs

No response