fillnull

Description

Replaces null values with a specified value. Null values are field values that are missing in a particular result but present in another result. Use the fillnull command to replace null field values with a string. You can replace the null values in one or more fields. You can specify a string to fill the null field values or use the default, field value which is zero ( 0 ).

Syntax

The required syntax is in bold.

fillnull

[value=<string>]

[<field-list>]

Required arguments

None.

Optional arguments

field-list

Syntax: <field>...

Description: A space-delimited list of one or more fields. If you specify a field list, all of the fields in that list are filled in with the value you specify. If you specify a field that didn't previously exist, the field is created. If you do not specify a field list, the value is applied to all fields.

value

Syntax: value=<string>

Description: Specify a string value to replace null values. If you do not specify a value, the default value is applied to the <field-list>.

Default: 0

Usage

The fillnull command is a distributable streaming command when a field-list is specified. When no field-list is specified, fillnull is a dataset processing command. See Command types.

Examples

1. Fill all empty field values with the default value

Your search has produced the following search results:

_time	ACCESSORIES	ARCADE	SHOOTER	SIMULATION	SPORTS	STRATEGY	TEE
2021-03-17	5	17	6	3	5	32
2021-03-16		63	39	30	22	127	56
2021-03-15	65	94	38	42		128	60

You can fill all of empty field values with a zero ( 0 ) by adding the fillnull command to the end of your search.

... | fillnull

The search results will look like this:

_time	ACCESSORIES	ARCADE	SHOOTER	SIMULATION	SPORTS	STRATEGY	TEE
2021-03-17	5	17	6	3	5	32	0
2021-03-16	0	63	39	30	22	127	56
2021-03-15	65	94	38	42	0	128	60

2. Fill all empty fields with the string "NULL"

For the current search results, fill all empty field values with the string "NULL".

... | fillnull value=NULL

Using the search results from the previous example, adding value=NULL to the end of your search changes the results to this:

_time	ACCESSORIES	ARCADE	SHOOTER	SIMULATION	SPORTS	STRATEGY	TEE
2021-03-17	5	17	6	3	5	32	NULL
2021-03-16	NULL	63	39	30	22	127	56
2021-03-15	65	94	38	42	NULL	128	60

3. Fill the specified fields with the string "unknown"

Your search has produced the following search results:

_time	host	average_kbps	instanenous_kbps	kbps
2021/02/14 12:00	danube.sample.com		1.865	3.420
2021/02/14 11:53	mekong.buttercupgames.com	0.710	0.164	1.256
2021/02/14 11:47	danube.sample.com	1.325		2.230
2021/02/14 11:42	yangtze.buttercupgames.com	2.249	0.000	2.249
2021/02/14 11:39		2.874	3.841	1.906
2021/02/14 11:33	nile.example.net	2.023	0.915

You can fill all empty field values in the "host" and "kbps" fields with the string "unknown" by adding the fillnull command to your search.

... | fillnull value=unknown host kbps

_time	host	average_kbps	instanenous_kbps	kbps
2021/02/14 12:00	danube.sample.com		1.865	3.420
2021/02/14 11:53	mekong.buttercupgames.com	0.710	0.164	1.256
2021/02/14 11:47	danube.sample.com	1.325		2.230
2021/02/14 11:42	yangtze.buttercupgames.com	2.249	0.000	2.249
2021/02/14 11:39	unknown	2.874	3.841	1.906
2021/02/14 11:33	nile.example.net	2.023	0.915	unknown

if you specify a field that does not exist, the field is created and the value you specify is added to the new field.

For example if you specify bytes in the field list, the bytes field is created and filled with the string "unknown".

... | fillnull value=unknown host kbps bytes

_time	host	average_kbps	instanenous_kbps	kbps	bytes
2021/02/14 12:00	danube.sample.com		1.865	3.420	unknown
2021/02/14 11:53	mekong.buttercupgames.com	0.710	0.164	1.256	unknown
2021/02/14 11:47	danube.sample.com	1.325		2.230	unknown
2021/02/14 11:42	yangtze.buttercupgames.com	2.249	0.000	2.249	unknown
2021/02/14 11:39	unknown	2.874	3.841	1.906	unknown
2021/02/14 11:33	nile.example.net	2.023	0.915	unknown	unknown

4. Use the fillnull command with the timechart command

Build a time series chart of web events by host and fill all empty fields with the string "NULL".

sourcetype="web" | timechart count by host | fillnull value=NULL

See also

filldown
streamstats