This mostly handles the cases mentioned in #16576. However, there are
some related changes in here, too:
- Some line formatting to avoid lines longer than 80 characters.
- Establish in basics.md that histograms have a counter vs. gauge
"flavor" that is also stored in the sample and not just by
convention as for float samples.
- Add the documentation of the unary minus, which was missing so far.
This require a bit of restructuring.
- Cleaned up a few references to "Prometheus" that should better refer
to "PromQL" (and "Prometheus's query language" → "PromQL" etc.).
I decided to not explain in all detail when and how PromQL detects an
incompatible counter reset. The spec is linked from basics.md, so the
minority that might be interested in this can still look it up.
Signed-off-by: beorn7 <beorn@grafana.com>
This is also meant to document the actual implementation, but
see #13934 for the current state.
This also improves and streamlines some parts of the documentation
that are not strictly native histogram related, but are colocated with
them. In particular, the section about aggregation operators got
restructured quite a bit, including the removal of a quite verbose
example for `limit_ratio` (which was just too long an this location
and also a bit questionabl in its usefulness).
Signed-off-by: beorn7 <beorn@grafana.com>
Put a scalar to query, it can be graphed.
So the doc says "an expression that returns an instant vector is the only type which can be graphed." is not correct?
And also, a query_range, which used for graph, always return a range vector <https://promlabs.com/blog/2020/06/18/the-anatomy-of-a-promql-query/#range-queries> , so it's confusing to read the above statement.
Signed-off-by: Viet Hung Nguyen <hvn@familug.org>
This unifies the documentation of float literals and time durations
and updates all references to the old definitions.
Signed-off-by: beorn7 <beorn@grafana.com>
The instant vector documentation does not explain which metric samples are selected - in particular, it makes no reference to staleness.
It's confusing when reading the docs to understand how exactly Prometheus selects the metrics to report: the most recent sample older than the search timestamp specified in the API request, so long as that metric is not "stale".
Signed-off-by: Craig Ringer <craig.ringer@enterprisedb.com>
I often see people ask questions that indicate they don't understand
this point, and launching into "instant vector" and "range vector" is
likely to point them in the wrong direction.
Remove the admonishment that the reader mustn't confuse these things.
Remove mention of "inferred sample timestamps" that is never explained.
Signed-off-by: Bryan Boreham <bjboreham@gmail.com>
Split out the note about regex-matching into a separate paragraph to
make it more obvious. Move it up, closer to the definition.
Signed-off-by: SuperQ <superq@gmail.com>
This follows the line of argument that the invariant of not looking
ahead of the query time was merely emerging behavior and not a
documented stable feature. Any query that looks ahead of the query
time was simply invalid before the introduction of the negative offset
and the @ modifier.
Signed-off-by: beorn7 <beorn@grafana.com>
This commit adds `@ <timestamp>` modifier as per this design doc: https://docs.google.com/document/d/1uSbD3T2beM-iX4-Hp7V074bzBRiRNlqUdcWP6JTDQSs/edit.
An example query:
```
rate(process_cpu_seconds_total[1m])
and
topk(7, rate(process_cpu_seconds_total[1h] @ 1234))
```
which ranks based on last 1h rate and w.r.t. unix timestamp 1234 but actually plots the 1m rate.
Signed-off-by: Ganesh Vernekar <cs15btech11018@iith.ac.in>
Substring matching for labels doesn't work anymore.
These parts are misleading, and contradict with the rest of the
documentation.
Signed-off-by: Semyon Slepov <slepovss@gmail.com>
