InfluxQL miscellaneous functions
Use InfluxQL miscellaneous functions to perform different operations in InfluxQL queries.
fill()
Fills null field values returned from empty time windows in GROUP BY time()
queries with a specified fill value.
Supported only in the GROUP BY clause.
fill(behavior)
Arguments
-
behavior: Defines the behavior of the fill operation. If no
FILLclause is included, the default behavior isfill(null).The following options are available:
- numeric literal: Replaces null values with the specified numeric literal.
- linear: Uses linear interpolation between existing values to replace null values.
- none: Removes rows with null field values.
- null: Keeps null values and associated timestamps.
- previous: Replaces null values with the most recent non-null value.
Examples
The following example uses the Bitcoin price sample dataset.
SELECT
MEAN(price)
FROM bitcoin
WHERE
code = 'USD'
AND time >= '2023-05-01T00:00:00Z'
AND time < '2023-05-01T02:00:00Z'
GROUP BY
time(30m)
fill(0)
| time | mean |
|---|---|
| 2023-05-01T00:00:00Z | 29319.9092 |
| 2023-05-01T00:30:00Z | 29307.4416 |
| 2023-05-01T01:00:00Z | 0 |
| 2023-05-01T01:30:00Z | 29263.2886 |
SELECT
MEAN(price)
FROM bitcoin
WHERE
code = 'USD'
AND time >= '2023-05-01T00:00:00Z'
AND time < '2023-05-01T02:00:00Z'
GROUP BY
time(30m)
fill(linear)
| time | mean |
|---|---|
| 2023-05-01T00:00:00Z | 29319.9092 |
| 2023-05-01T00:30:00Z | 29307.4416 |
| 2023-05-01T01:00:00Z | 29285.3651 |
| 2023-05-01T01:30:00Z | 29263.2886 |
SELECT
MEAN(price)
FROM bitcoin
WHERE
code = 'USD'
AND time >= '2023-05-01T00:00:00Z'
AND time < '2023-05-01T02:00:00Z'
GROUP BY
time(30m)
fill(none)
| time | mean |
|---|---|
| 2023-05-01T00:00:00Z | 29319.9092 |
| 2023-05-01T00:30:00Z | 29307.4416 |
| 2023-05-01T01:30:00Z | 29263.2886 |
SELECT
MEAN(price)
FROM bitcoin
WHERE
code = 'USD'
AND time >= '2023-05-01T00:00:00Z'
AND time < '2023-05-01T02:00:00Z'
GROUP BY
time(30m)
fill(null)
| time | mean |
|---|---|
| 2023-05-01T00:00:00Z | 29319.9092 |
| 2023-05-01T00:30:00Z | 29307.4416 |
| 2023-05-01T01:00:00Z | |
| 2023-05-01T01:30:00Z | 29263.2886 |
SELECT
MEAN(price)
FROM bitcoin
WHERE
code = 'USD'
AND time >= '2023-05-01T00:00:00Z'
AND time < '2023-05-01T02:00:00Z'
GROUP BY
time(30m)
fill(previous)
| time | mean |
|---|---|
| 2023-05-01T00:00:00Z | 29319.9092 |
| 2023-05-01T00:30:00Z | 29307.4416 |
| 2023-05-01T01:00:00Z | 29307.4416 |
| 2023-05-01T01:30:00Z | 29263.2886 |
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