mudhorn/prometheus
1
0
Fork 0
mirror of https://github.com/prometheus/prometheus.git synced 2024-09-19 23:37:31 -07:00
Code Issues Actions 7 Packages Projects Releases Wiki Activity

Update staleness documentation

Browse source 
Signed-off-by: Craig Ringer <craig.ringer@enterprisedb.com>
This commit is contained in:
Craig Ringer 2024-09-12 14:30:32 +12:00
parent 894df4c8be
commit fb0c8a927e
1 changed files with 10 additions and 5 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

15
docs/querying/basics.md
View file

@ -109,10 +109,14 @@ single sample value for each at a given timestamp (point in time). In the simpl
form, only a metric name is specified, which results in an instant vector
containing elements for all time series that have this metric name.
The value returned will be the most recent sample within the the time frame
specified by [the API call that submitted the query](api.md#instant-queries)
or by the [`@` modifier](#modifier). Time series where the most recent sample
is older than the [staleness threshold](#staleness) will not be returned.
The value returned will be that of the most recent sample prior to the query's
evaluation timestamp (in the case of an
[instant query](api.md#instant-queries))
or of the current resolution step within the query (in the case of a
[range query](api.md/#range-queries)).
The [`@` modifier](#modifier) allows overriding the timestamp relative to which
the selection takes place. Time series where the most recent sample is older
than the [staleness threshold](#staleness) will not be returned.
This example selects all time series that have the `http_requests_total` metric
name, returning the most recent sample for each:
@ -364,7 +368,8 @@ cases like aggregation (`sum`, `avg`, and so on), where multiple aggregated
time series do not precisely align in time. Because of their independence,
Prometheus needs to assign a value at those timestamps for each relevant time
series. It does so by taking the newest sample that is less than the lookback period ago.
The lookback period is 5 minutes by default.
The lookback period is 5 minutes by default, but can be
[set with the `--query.lookback-delta` flag](../command-line/prometheus.md)
If a target scrape or rule evaluation no longer returns a sample for a time
series that was previously present, this time series will be marked as stale.