This reverts commit 5a3abfa041.
Reason for revert: exemplars aren't in wide use because they have numerous issues which prevent their adoption (see below).
Adding support for examplars into VictoriaMetrics introduces non-trivial code changes. These code changes need to be supported forever
once the release of VictoriaMetrics with exemplar support is published. That's why I don't think this is a good feature despite
that the source code of the reverted commit has an excellent quality. See https://docs.victoriametrics.com/goals/ .
Issues with Prometheus exemplars:
- Prometheus still has only experimental support for exemplars after more than three years since they were introduced.
It stores exemplars in memory, so they are lost after Prometheus restart. This doesn't look like production-ready feature.
See 0a2f3b3794/content/docs/instrumenting/exposition_formats.md (L153-L159)
and https://prometheus.io/docs/prometheus/latest/feature_flags/#exemplars-storage
- It is very non-trivial to expose exemplars alongside metrics in your application, since the official Prometheus SDKs
for metrics' exposition ( https://prometheus.io/docs/instrumenting/clientlibs/ ) either have very hard-to-use API
for exposing histograms or do not have this API at all. For example, try figuring out how to expose exemplars
via https://pkg.go.dev/github.com/prometheus/client_golang@v1.19.1/prometheus .
- It looks like exemplars are supported for Histogram metric types only -
see https://pkg.go.dev/github.com/prometheus/client_golang@v1.19.1/prometheus#Timer.ObserveDurationWithExemplar .
Exemplars aren't supported for Counter, Gauge and Summary metric types.
- Grafana has very poor support for Prometheus exemplars. It looks like it supports exemplars only when the query
contains histogram_quantile() function. It queries exemplars via special Prometheus API -
https://prometheus.io/docs/prometheus/latest/querying/api/#querying-exemplars - (which is still marked as experimental, btw.)
and then displays all the returned exemplars on the graph as special dots. The issue is that this doesn't work
in production in most cases when the histogram_quantile() is calculated over thousands of histogram buckets
exposed by big number of application instances. Every histogram bucket may expose an exemplar on every timestamp shown on the graph.
This makes the graph unusable, since it is litterally filled with thousands of exemplar dots.
Neither Prometheus API nor Grafana doesn't provide the ability to filter out unneeded exemplars.
- Exemplars are usually connected to traces. While traces are good for some
I doubt exemplars will become production-ready in the near future because of the issues outlined above.
Alternative to exemplars:
Exemplars are marketed as a silver bullet for the correlation between metrics, traces and logs -
just click the exemplar dot on some graph in Grafana and instantly see the corresponding trace or log entry!
This doesn't work as expected in production as shown above. Are there better solutions, which work in production?
Yes - just use time-based and label-based correlation between metrics, traces and logs. Assign the same `job`
and `instance` labels to metrics, logs and traces, so you can quickly find the needed trace or log entry
by these labes on the time range with the anomaly on metrics' graph.
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/pull/5982
- Export streamaggr.LoadFromData() function, so it could be used in tests outside the lib/streamaggr package.
This allows removing a hack with creation of temporary files at TestRemoteWriteContext_TryPush_ImmutableTimeseries.
- Move common code for mustParsePromMetrics() function into lib/prompbmarshal package,
so it could be used in tests for building []prompbmarshal.TimeSeries from string.
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/6205
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/pull/6206
Move the code responsible for relabelCtx clearing into deferred function.
This allows making more clear the remoteWriteCtx.TryPush code.
This is a follow-up for 879771808b
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/6205
While at it, clarify the description of the bugfix at docs/CHANGELOG.md
Use metricsql.IsLikelyInvalid() function for determining whether the given query is likely invalid,
e.g. there is high change the query is incorrectly written, so it will return unexpected results.
The query is invalid most of the time if it passes something other than series selector into rollup function.
For example:
- rate(sum(foo))
- rate(foo + bar)
- rate(foo > bar)
Improtant note: the query is considered valid if it misses the lookbehind window in square brackes inside rollup function,
e.g. rate(foo), since this is very convenient MetricsQL extention to PromQL, and this query returns the expected results
most of the time.
Other unsafe query types can be added in the future into metricsql.IsLikelyInvalid().
TODO: probably, the -search.disableImplicitConversion command-line flag must be set by default in the future releases of VictoriaMetrics.
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/issues/4338
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/pull/6180
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/pull/6450
- Clarify docs for `Ignore aggregation intervals on start` feature.
- Make more clear the code dealing with ignoreFirstIntervals at aggregator.runFlusher() functions.
It is better from readability and maintainability PoV using distinct a.flush() calls
for distinct cases instead of merging them into a single a.flush() call.
- Take into account the first incomplete interval when tracking the number of skipped aggregation intervals,
since this behaviour is easier to understand by the end users.
Updates https://github.com/VictoriaMetrics/VictoriaMetrics/pull/6137
Previously the in-memory buffer could remain unflushed for long periods of time under low ingestion rate.
The ingested logs weren't visible for search during this time.
### Describe Your Changes
Removed snap packages support as it requires time for maintenance and
it's not popular at all
### Checklist
The following checks are **mandatory**:
- [ ] My change adheres [VictoriaMetrics contributing
guidelines](https://docs.victoriametrics.com/contributing/).
---------
Signed-off-by: hagen1778 <roman@victoriametrics.com>
Co-authored-by: hagen1778 <roman@victoriametrics.com>
(cherry picked from commit 0a42c8fd8b)
Signed-off-by: hagen1778 <roman@victoriametrics.com>
### Describe Your Changes
- added stale metrics counters for input and output samples
- added labels for aggregator metrics =>
`name="{rwctx}:{aggrId}:{aggrSuffix}"`
- rwctx - global or number starting from 1
- aggrid - aggregator id starting from 1
- aggrSuffix - <interval>_(by|without)_label1_label2_labeln
e.g: `name="global:1:1m_without_instance_pod"`
### Checklist
The following checks are **mandatory**:
- [ ] My change adheres [VictoriaMetrics contributing
guidelines](https://docs.victoriametrics.com/contributing/).
---------
Signed-off-by: hagen1778 <roman@victoriametrics.com>
Co-authored-by: hagen1778 <roman@victoriametrics.com>
(cherry picked from commit 861852f262)
Signed-off-by: hagen1778 <roman@victoriametrics.com>
The set of log fields in the found logs may differ from the set of log fields present in the log stream.
So compare only the log fields in the found logs when searching for the matching log entry in the log stream.
While at it, return _stream field in the delimiter log entry, since this field is used by VictoriaLogs Web UI
for grouping logs by log streams.
