grafana/public/app/plugins/datasource/influxdb/query_help.md

Alias patterns

• replaced with measurement name
• $measurement = replaced with measurement name
• $1 - $9 = replaced with part of measurement name (if you separate your measurement name with dots)
• $col = replaced with column name
• $tag_exampletag = replaced with the value of the exampletag tag
• You can also use tag_exampletag pattern replacement syntax

Stacking and fill

• When stacking is enabled it is important that points align
• If there are missing points for one series it can cause gaps or missing bars
• You must use fill(0), and select a group by time low limit
• Use the group by time option below your queries and specify for example 10s if your metrics are written every 10 seconds
• This will insert zeros for series that are missing measurements and will make stacking work properly

Group by time

• Group by time is important, otherwise the query could return many thousands of datapoints that will slow down Grafana
• Leave the group by time field empty for each query and it will be calculated based on time range and pixel width of the graph
• If you use fill(0) or fill(null) set a low limit for the auto group by time interval
• The low limit can only be set in the group by time option below your queries
• Example: 60s if you write metrics to InfluxDB every 60 seconds

Documentation links:

Grafana's InfluxDB Documentation

Official InfluxDB Documentation