* fix(promql): align timestamp() and label_join with Prometheus semantics
- timestamp() over a selector reports the selected sample's timestamp, without adding the offset.
- timestamp() over any other expression reports the evaluation time instead of the input value.
- label_join that overwrites an existing label rejects duplicate label sets at runtime.
Signed-off-by: Dennis Zhuang <killme2008@gmail.com>
* fix(promql): align label_replace and label_join edge cases with Prometheus
- label_replace leaves non-matching series unchanged instead of copying the source value into the destination label.
- label_replace may overwrite an existing label; duplicate label sets are rejected at runtime like label_join.
- label_join with no source labels removes the destination label, and an empty source label name is rejected.
- Empty label values produced by these functions are NULL, the same as an absent label.
Signed-off-by: Dennis Zhuang <killme2008@gmail.com>
* fix(promql): join absent labels as empty strings in label_join
concat_ws skips NULL arguments together with their separator, so a label that is absent (NULL) dropped its separator, e.g. label_join(label_join(vector(1), "a", "", "missing"), "b", "-", "a", "a") lost b="-". Read every source label as coalesce(label, '') like label_replace does.
Signed-off-by: Dennis Zhuang <killme2008@gmail.com>
* fix(promql): skip rows without a sample in timestamp()
timestamp() replaced the input fields with the timestamp before the empty-value filter ran, so a row whose fields were all NULL got a timestamp, e.g. timestamp(-m) for a NULL sample. Filter such rows before the projection, for both the selector and the evaluation-time paths.
Signed-off-by: Dennis Zhuang <killme2008@gmail.com>
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Signed-off-by: Dennis Zhuang <killme2008@gmail.com>
dennis zhuang
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