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rare

Table of contents

Description

Using rare command to find the least common tuple of values of all fields in the field list.

Note: A maximum of 10 results is returned for each distinct tuple of values of the group-by fields.

Syntax

rare <field-list> [by-clause]

rare <field-list> [rare-options] [by-clause] (available from 3.1.0+)

  • field-list: mandatory. comma-delimited list of field names.
  • by-clause: optional. one or more fields to group the results by.
  • rare-options: optional. options for the rare command. Supported syntax is [countfield=<string>] [showcount=<bool>].
  • showcount=<bool>: optional. whether to create a field in output that represent a count of the tuple of values. Default value is true.
  • countfield=<string>: optional. the name of the field that contains count. Default value is 'count'.

Example 1: Find the least common values in a field

The example finds least common gender of all the accounts.

PPL query:

os> source=accounts | rare gender;
fetched rows / total rows = 2/2
+--------+
| gender |
|--------|
| F      |
| M      |
+--------+

Example 2: Find the least common values organized by gender

The example finds least common age of all the accounts group by gender.

PPL query:

os> source=accounts | rare age by gender;
fetched rows / total rows = 4/4
+--------+-----+
| gender | age |
|--------+-----|
| F      | 28  |
| M      | 32  |
| M      | 33  |
| M      | 36  |
+--------+-----+

Example 3: Rare command with Calcite enabled

The example finds least common gender of all the accounts when plugins.calcite.enabled is true.

PPL query:

PPL> source=accounts | rare gender;
fetched row
+--------+-------+
| gender | count |
|--------+-------|
| F      | 1     |
| M      | 3     |
+--------+-------+

Example 4: Specify the count field option

The example specifies the count field when plugins.calcite.enabled is true.

PPL query:

PPL> source=accounts | rare countfield='cnt' gender;
fetched row
+--------+-----+
| gender | cnt |
|--------+-----|
| F      | 1   |
| M      | 3   |
+--------+-----+

Limitation

The rare command is not rewritten to OpenSearch DSL, it is only executed on the coordination node.
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