prometheus/docs/disabled_features.md

---
title: Disabled Features
sort_rank: 10
---

# Disabled Features

Here is a list of features that are disabled by default since they are breaking changes or are considered experimental.
Their behaviour can change in future releases which will be communicated via the [release changelog](https://github.com/prometheus/prometheus/blob/master/CHANGELOG.md).

You can enable them using the `--enable-feature` flag with a comma separated list of features.
They may be enabled by default in future versions.

## `@` Modifier in PromQL

`--enable-feature=promql-at-modifier`

This feature lets you specify the evaluation time for instant vector selectors,
range vector selectors, and subqueries. More details can be found [here](querying/basics.md#@-modifier).

## Remote Write Receiver

`--enable-feature=remote-write-receiver`

The remote write receiver allows Prometheus to accept remote write requests from other Prometheus servers. More details can be found [here](storage.md#overview).
-												'@ <timestamp>' modifier  (#8121)

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>
											
										
										
											2021-01-20 02:57:39 -08:00
+								---
 								title: Disabled Features
 								sort_rank: 10
 								---
 								# Disabled Features
 								Here is a list of features that are disabled by default since they are breaking changes or are considered experimental.
 								Their behaviour can change in future releases which will be communicated via the [release changelog](https://github.com/prometheus/prometheus/blob/master/CHANGELOG.md).
 								You can enable them using the `--enable-feature` flag with a comma separated list of features.
 								They may be enabled by default in future versions.
 								## `@` Modifier in PromQL
 								`--enable-feature=promql-at-modifier`
 								This feature lets you specify the evaluation time for instant vector selectors,
 								range vector selectors, and subqueries. More details can be found [here](querying/basics.md#@-modifier).
-												Various enhancements and refactorings for remote write receiver:

- Remove unrelated changes
- Refactor code out of the API module - that is already getting pretty crowded.
- Don't track reference for AddFast in remote write.  This has the potential to consume unlimited server-side memory if a malicious client pushes a different label set for every series.  For now, its easier and safer to always use the 'slow' path.
- Return 400 on out of order samples.
- Use remote.DecodeWriteRequest in the remote write adapters.
- Put this behing the 'remote-write-server' feature flag
- Add some (very) basic docs.
- Used named return & add test for commit error propagation

Signed-off-by: Tom Wilkie <tom.wilkie@gmail.com>

											
										
										
											2021-01-30 03:04:48 -08:00
 								## Remote Write Receiver
 								`--enable-feature=remote-write-receiver`
 								The remote write receiver allows Prometheus to accept remote write requests from other Prometheus servers. More details can be found [here](storage.md#overview).