opensearch-docs-cn/_observability-plugin/ppl/commands.md

layout	title	parent	nav_order
default	Commands	Piped processing language	4

Commands

Start a PPL query with a search command to reference a table to search from. You can have the commands that follow in any order.

In the following example, the search command refers to an accounts index as the source, then uses fields and where commands for the conditions:

search source=accounts
| where age > 18
| fields firstname, lastname

In the below examples, we represent required arguments in angle brackets < > and optional arguments in square brackets [ ]. {: .note }

search

Use the search command to retrieve a document from an index. You can only use the search command as the first command in the PPL query.

Syntax

search source=<index> [boolean-expression]

Field	Description	Required
search	Specify search keywords.	Yes
index	Specify which index to query from.	No
bool-expression	Specify an expression that evaluates to a boolean value.	No

Example 1: Get all documents

To get all documents from the accounts index:

search source=accounts;

account_number	firstname	address	balance	gender	city	employer	state	age	email	lastname
1	Amber	880 Holmes Lane	39225	M	Brogan	Pyrami	IL	32	amberduke@pyrami.com	Duke
6	Hattie	671 Bristol Street	5686	M	Dante	Netagy	TN	36	hattiebond@netagy.com	Bond
13	Nanette	789 Madison Street	32838	F	Nogal	Quility	VA	28	null	Bates
18	Dale	467 Hutchinson Court	4180	M	Orick	null	MD	33	daleadams@boink.com	Adams

Example 2: Get documents that match a condition

To get all documents from the accounts index that have either account_number equal to 1 or have gender as F:

search source=accounts account_number=1 or gender=\"F\";

account_number	firstname	address	balance	gender	city	employer	state	age	email	lastname
1	Amber	880 Holmes Lane	39225	M	Brogan	Pyrami	IL	32	amberduke@pyrami.com	Duke
13	Nanette	789 Madison Street	32838	F	Nogal	Quility	VA	28	null	Bates

dedup

The dedup (data deduplication) command removes duplicate documents defined by a field from the search result.

Syntax

dedup [int] <field-list> [keepempty=<bool>] [consecutive=<bool>]

Field	Description	Type	Required	Default
int	Retain the specified number of duplicate events for each combination. The number must be greater than 0. If you do not specify a number, only the first occurring event is kept and all other duplicates are removed from the results.	string	No	1
keepempty	If true, keep the document if any field in the field list has a null value or a field missing.	nested list of objects	No	False
consecutive	If true, remove only consecutive events with duplicate combinations of values.	Boolean	No	False
field-list	Specify a comma-delimited field list. At least one field is required.	String or comma-separated list of strings	Yes	-

Example 1: Dedup by one field

To remove duplicate documents with the same gender:

search source=accounts | dedup gender | fields account_number, gender;

account_number	gender
1	M
13	F

Example 2: Keep two duplicate documents

To keep two duplicate documents with the same gender:

search source=accounts | dedup 2 gender | fields account_number, gender;

account_number	gender
1	M
6	M
13	F

Example 3: Keep or ignore an empty field by default

To keep two duplicate documents with a null field value:

search source=accounts | dedup email keepempty=true | fields account_number, email;

account_number	email
1	amberduke@pyrami.com
6	hattiebond@netagy.com
13	null
18	daleadams@boink.com

To remove duplicate documents with the null field value:

search source=accounts | dedup email | fields account_number, email;

account_number	email
1	amberduke@pyrami.com
6	hattiebond@netagy.com
18	daleadams@boink.com

Example 4: Dedup of consecutive documents

To remove duplicates of consecutive documents:

search source=accounts | dedup gender consecutive=true | fields account_number, gender;

account_number	gender
1	M
13	F
18	M

eval

The eval command evaluates an expression and appends its result to the search result.

Syntax

eval <field>=<expression> ["," <field>=<expression> ]...

Field	Description	Required
field	If a field name does not exist, a new field is added. If the field name already exists, it's overwritten.	Yes
expression	Specify any supported expression.	Yes

Example 1: Create a new field

To create a new doubleAge field for each document. doubleAge is the result of age multiplied by 2:

search source=accounts | eval doubleAge = age * 2 | fields age, doubleAge;

age	doubleAge
32	64
36	72
28	56
33	66

Example 2: Overwrite the existing field

To overwrite the age field with age plus 1:

search source=accounts | eval age = age + 1 | fields age;

age
33
37
29
34

Example 3: Create a new field with a field defined with the eval command

To create a new field ddAge. ddAge is the result of doubleAge multiplied by 2, where doubleAge is defined in the eval command:

search source=accounts | eval doubleAge = age * 2, ddAge = doubleAge * 2 | fields age, doubleAge, ddAge;

| age | doubleAge | ddAge :--- | :--- | | 32 | 64 | 128 | 36 | 72 | 144 | 28 | 56 | 112 | 33 | 66 | 132

fields

Use the fields command to keep or remove fields from a search result.

Syntax

fields [+|-] <field-list>

Field	Description	Required	Default
index	Plus (+) keeps only fields specified in the field list. Minus (-) removes all fields specified in the field list.	No	+
field list	Specify a comma-delimited list of fields.	Yes	No default

Example 1: Select specified fields from result

To get account_number, firstname, and lastname fields from a search result:

search source=accounts | fields account_number, firstname, lastname;

| account_number | firstname | lastname :--- | :--- | | 1 | Amber | Duke | 6 | Hattie | Bond | 13 | Nanette | Bates | 18 | Dale | Adams

Example 2: Remove specified fields from a search result

To remove the account_number field from the search results:

search source=accounts | fields account_number, firstname, lastname | fields - account_number;

firstname	lastname
Amber	Duke
Hattie	Bond
Nanette	Bates
Dale	Adams

rename

Use the rename command to rename one or more fields in the search result.

Syntax

rename <source-field> AS <target-field>["," <source-field> AS <target-field>]...

Field	Description	Required
source-field	The name of the field that you want to rename.	Yes
target-field	The name you want to rename to.	Yes

Example 1: Rename one field

Rename the account_number field as an:

search source=accounts | rename account_number as an | fields an;

an
1
6
13
18

Example 2: Rename multiple fields

Rename the account_number field as an and employer as emp:

search source=accounts | rename account_number as an, employer as emp | fields an, emp;

an	emp
1	Pyrami
6	Netagy
13	Quility
18	null

sort

Use the sort command to sort search results by a specified field.

Syntax

sort [count] <[+|-] sort-field>...

Field | Description | Required | Default :--- | :--- |:--- count | The maximum number results to return from the sorted result. If count=0, all results are returned. | No | 1000 [+|-] | Use plus [+] to sort by ascending order and minus [-] to sort by descending order. | No | Ascending order sort-field | Specify the field that you want to sort by. | Yes | -

Example 1: Sort by one field

To sort all documents by the age field in ascending order:

search source=accounts | sort age | fields account_number, age;

account_number	age
13	28
1	32
18	33
6	36

Example 2: Sort by one field and return all results

To sort all documents by the age field in ascending order and specify count as 0 to get back all results:

search source=accounts | sort 0 age | fields account_number, age;

account_number	age
13	28
1	32
18	33
6	36

Example 3: Sort by one field in descending order

To sort all documents by the age field in descending order:

search source=accounts | sort - age | fields account_number, age;

account_number	age
6	36
18	33
1	32
13	28

Example 4: Specify the number of sorted documents to return

To sort all documents by the age field in ascending order and specify count as 2 to get back two results:

search source=accounts | sort 2 age | fields account_number, age;

account_number	age
13	28
1	32

Example 5: Sort by multiple fields

To sort all documents by the gender field in ascending order and age field in descending order:

search source=accounts | sort + gender, - age | fields account_number, gender, age;

account_number	gender	age
13	F	28
6	M	36
18	M	33
1	M	32

stats

Use the stats command to aggregate from search results.

The following table lists the aggregation functions and also indicates how each one handles null or missing values:

Function	NULL	MISSING
COUNT	Not counted	Not counted
SUM	Ignore	Ignore
AVG	Ignore	Ignore
MAX	Ignore	Ignore
MIN	Ignore	Ignore

Syntax

stats <aggregation>... [by-clause]...

Field | Description | Required | Default :--- | :--- |:--- aggregation | Specify a statistical aggregation function. The argument of this function must be a field. | Yes | 1000 by-clause | Specify one or more fields to group the results by. If not specified, the stats command returns only one row, which is the aggregation over the entire result set. | No | -

Example 1: Calculate the average value of a field

To calculate the average age of all documents:

search source=accounts | stats avg(age);

avg(age)
32.25

Example 2: Calculate the average value of a field by group

To calculate the average age grouped by gender:

search source=accounts | stats avg(age) by gender;

gender	avg(age)
F	28.0
M	33.666666666666664

Example 3: Calculate the average and sum of a field by group

To calculate the average and sum of age grouped by gender:

search source=accounts | stats avg(age), sum(age) by gender;

| gender | avg(age) | sum(age) :--- | :--- | | F | 28 | 28 | M | 33.666666666666664 | 101

Example 4: Calculate the maximum value of a field

To calculate the maximum age:

search source=accounts | stats max(age);

max(age)
36

Example 5: Calculate the maximum and minimum value of a field by group

To calculate the maximum and minimum age values grouped by gender:

search source=accounts | stats max(age), min(age) by gender;

gender	min(age)	max(age)
F	28	28
M	32	36

where

Use the where command with a bool expression to filter the search result. The where command only returns the result when the bool expression evaluates to true.

Syntax

where <boolean-expression>

Field	Description	Required
bool-expression	An expression that evaluates to a boolean value.	No

Example 1: Filter result set with a condition

To get all documents from the accounts index where account_number is 1 or gender is F:

search source=accounts | where account_number=1 or gender=\"F\" | fields account_number, gender;

account_number	gender
1	M
13	F

head

Use the head command to return the first N number of results in a specified search order.

Syntax

head [N]

Field | Description | Required | Default :--- | :--- |:--- N | Specify the number of results to return. | No | 10

Example 1: Get the first 10 results

To get the first 10 results:

search source=accounts | fields firstname, age | head;

firstname	age
Amber	32
Hattie	36
Nanette	28

Example 2: Get the first N results

To get the first two results:

search source=accounts | fields firstname, age | head 2;

firstname	age
Amber	32
Hattie	36

rare

Use the rare command to find the least common values of all fields in a field list. A maximum of 10 results are returned for each distinct set of values of the group-by fields.

Syntax

rare <field-list> [by-clause]

Field	Description	Required
field-list	Specify a comma-delimited list of field names.	No
by-clause	Specify one or more fields to group the results by.	No

Example 1: Find the least common values in a field

To find the least common values of gender:

search source=accounts | rare gender;

gender
F
M

Example 2: Find the least common values grouped by gender

To find the least common age grouped by gender:

search source=accounts | rare age by gender;

gender	age
F	28
M	32
M	33

top

Use the top command to find the most common values of all fields in the field list.

Syntax

top [N] <field-list> [by-clause]

Field	Description	Default
N	Specify the number of results to return.	10
field-list	Specify a comma-delimited list of field names.	-
by-clause	Specify one or more fields to group the results by.	-

Example 1: Find the most common values in a field

To find the most common genders:

search source=accounts | top gender;

gender
M
F

Example 2: Find the most common value in a field

To find the most common gender:

search source=accounts | top 1 gender;

gender
M

Example 2: Find the most common values grouped by gender

To find the most common age grouped by gender:

search source=accounts | top 1 age by gender;

gender	age
F	28
M	32

match

Use the match command to search documents that match a string, number, date, or boolean value for a given field.

Syntax

match(field_expression, query_expression[, option=<option_value>]*)

You can specify the following options:

• analyzer
• auto_generate_synonyms_phrase
• fuzziness
• max_expansions
• prefix_length
• fuzzy_transpositions
• fuzzy_rewrite
• lenient
• operator
• minimum_should_match
• zero_terms_query
• boost

Example 1: Search the message field:

GET my_index/_search
{
  "query": {
    "match": {
      "message": "this is a test"
    }
  }
}

PPL query:

search source=my_index | match field=message query="this is a test"

Example 2: Search the message field with the operator parameter:

GET my_index/_search
{
  "query": {
    "match": {
      "message": {
        "query": "this is a test",
        "operator": "and"
      }
    }
  }
}

PPL query:

search source=my_index | match field=message query="this is a test" operator=and

Example 3: Search the message field with the operator and zero_terms_query parameters:

GET my_index/_search
{
  "query": {
    "match": {
      "message": {
        "query": "to be or not to be",
        "operator": "and",
        "zero_terms_query": "all"
      }
    }
  }
}

PPL query:

search source=my_index | where match(message, "this is a test", operator=and, zero_terms_query=all)