Understanding the Basics
Selecting Data
- Basic Query:
SELECT "field_key" FROM "measurement_name" - With Time Filter:
SELECT "field_key" FROM "measurement_name" WHERE $timeFilter
Filtering
- Specific Time Range:
WHERE time >= '2023-01-01T00:00:00Z' AND time <= '2023-01-02T00:00:00Z' - Relative Time:
WHERE time > now() - 1h - Tags:
WHERE "tag_key" = 'tag_value' - Fields:
WHERE "field_key" > 100
Grouping Data
- Time Intervals:
GROUP BY time(10m) - Tags:
GROUP BY "tag_key" - Time and Tags:
GROUP BY time(10m), "tag_key"
Aggregations and Calculations
Common Aggregations
- Count:
SELECT COUNT("field_key") FROM "measurement_name" - Sum:
SELECT SUM("field_key") FROM "measurement_name" - Mean:
SELECT MEAN("field_key") FROM "measurement_name" - Min/Max:
SELECT MIN("field_key"), MAX("field_key") FROM "measurement_name"
Selectors (Return a single point)
- First/Last:
SELECT FIRST("field_key"), LAST("field_key") FROM "measurement_name" - Top/Bottom:
SELECT TOP("field_key", 5), BOTTOM("field_key", 5) FROM "measurement_name"
Transformations
- Difference:
SELECT DIFFERENCE(FIRST("field_key")) FROM "measurement_name" - Moving Average:
SELECT MOVING_AVERAGE("field_key", 5) FROM "measurement_name" - Cumulative Sum:
SELECT CUMULATIVE_SUM("field_key") FROM "measurement_name"
Advanced Techniques
Joining Data (Merge)
SELECT * FROM "measurement_one" INNER JOIN "measurement_two" ON "measurement_one"."tag_key" = "measurement_two"."tag_key"
Subqueries
SELECT MEAN("usage") FROM (SELECT SUM("field_key") AS "usage" FROM "measurement_name" GROUP BY time(1h))
Data Exploration
- Show Databases:
SHOW DATABASES - Show Measurements:
SHOW MEASUREMENTS - Show Field Keys:
SHOW FIELD KEYS FROM "measurement_name" - Show Tag Keys:
SHOW TAG KEYS FROM "measurement_name"
Grafana-Specific Tips
- Using
$timeFilter: Grafana replaces$timeFilterwith the dashboard’s current time range, ensuring queries are automatically scoped to the visible window. - Template Variables: Use Grafana template variables to create dynamic dashboards. You can incorporate variables in your InfluxQL queries like so:
WHERE "tag_key" = '$variable_name'. - Annotations: Use InfluxQL to create annotations in Grafana by selecting the time and text columns, e.g.,
SELECT time, "event_text" FROM "annotations" WHERE $timeFilter. - Debugging Queries: Utilize Grafana’s Query Inspector feature to debug and optimize your InfluxQL queries. This can be especially helpful for understanding how Grafana applies
$timeFilterand other variables to your queries.