where

This page explains how to use the where operator in APL.

The where operator in APL is used to filter rows based on specified conditions. You can use the where operator to return only the records that meet the criteria you define. It’s a foundational operator in querying datasets, helping you focus on specific data by applying conditions to filter out unwanted rows. This is useful when working with large datasets, logs, traces, or security events, allowing you to extract meaningful information quickly.

For users of other query languages

If you come from other query languages, this section explains how to adjust your existing queries to achieve the same results in APL.

Splunk SPL users

In Splunk SPL, the where operator filters events based on boolean expressions. APL’s where operator functions similarly, allowing you to filter rows that satisfy a condition.

ANSI SQL users

In ANSI SQL, the WHERE clause filters rows in a SELECT query based on a condition. APL’s where operator behaves similarly, but the syntax reflects APL’s specific dataset structures.

Usage

Syntax

| where condition

Parameters

• condition: A Boolean expression that specifies the filtering condition. The where operator returns only the rows that satisfy this condition.

Returns

The where operator returns a filtered dataset containing only the rows where the condition evaluates to true.

Use case examples

• Log analysis
• OpenTelemetry traces
• Security logs

In this use case, you filter HTTP logs to focus on records where the HTTP status is 404 (Not Found).

Query

['sample-http-logs']
| where status == '404'

Run in Playground

Output

_time	id	status	method	uri	req_duration_ms	geo.city	geo.country
2024-10-17 10:20:00	12345	404	GET	/notfound.html	120	Seattle	US

This query filters out all HTTP requests except those that resulted in a 404 error, making it easy to investigate pages that were not found.

where * has

The * has pattern in APL is a dynamic and powerful tool within the where operator. It offers you the flexibility to search for specific substrings across all fields in a dataset without the need to specify each field name individually. This becomes especially advantageous when dealing with datasets that have numerous or dynamically named fields.

where * has is an expensive operation because it searches all fields. For a more efficient query, explicitly list the fields in which you want to search. For example: where firstName has "miguel" or lastName has "miguel".

Basic where * has usage

Find events where any field contains a specific substring.

['sample-http-logs'] 
| where * has "GET"

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Combine multiple substrings

Find events where any field contains one of multiple substrings.

['sample-http-logs'] 
| where * has "GET" or * has "text"

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Use * has with other operators

Find events where any field contains a substring, and another specific field equals a certain value.

['sample-http-logs'] 
| where * has "css" and req_duration_ms == 1

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Advanced chaining

Filter data based on several conditions, including fields containing certain substrings, then summarize by another specific criterion.

['sample-http-logs']
| where * has "GET" and * has "css"
| summarize Count=count() by method, content_type, server_datacenter

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Use with aggregations

Find the average of a specific field for events where any field contains a certain substring.

['sample-http-logs']
| where * has "Japan"
| summarize avg(req_duration_ms)

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String case transformation

The has operator is case insensitive. Use has if you’re unsure about the case of the substring in the dataset. For the case-sensitive operator, use has_cs.

['sample-http-logs']
| where * has "mexico"
| summarize avg(req_duration_ms)

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List of related operators

• count: Use count to return the number of records that match specific criteria.
• distinct: Use distinct to return unique values in a dataset, complementing filtering.
• take: Use take to return a specific number of records, typically in combination with where for pagination.