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This topic explains how to use LaunchDarkly’s observability search feature to query and filter data across your application. The search functionality allows you to find specific sessions, errors, logs, and traces by composing queries with different properties and attributes.
The session replay search pane, with options expanded.

The session replay search pane, with options expanded.

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Compose search queries

Compose your search query with one or more expressions. Each expression can be a comparison between a key and a value, or a logical combination of other expressions. Here are some examples of search queries:
Find sessions associated with a specific feature flag.
Enter a search value without a key to search on a default key. For logs, the default key is the message, and for traces it is the span_name.
You can also filter for custom attributes you send in sessions, logs, and traces.

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Keys and values

Keys are identifiers, which can include any combination of alphanumeric characters, underscores (_), periods (.), dashes (-), and wildcards, which are indicated by asterisks (*). Values are strings with any character. To use spaces or special characters, you must enclose the string in quotes (", '). You can use wildcards (*) in values to match on part of a pattern. For example:
  • span_name=gorm.* matches all span_name values that start with gorm.
  • span_name=*.Query matches all span_name values that end with .Query
  • span_name=*orm* matches all values that contain orm
If you want to use a value with a space or special character, you must wrap the value in quotations.

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Regex expressions

You can search with regex expressions by using the matches query operator: =/[your regex here]/. For example:
  • clickTextContent=/\w.+\w/ matches all clickTextContent that start and end with any word
  • browser_version=/\d\.\d\.\d/ matches all browser_version values in the form [0-9].[0-9].[0-9]
If you want to use a regex expression with a space or special character, you must wrap the value in quotations. For example:
  • tag="/\w \w/"
  • visited-url="/https://app.launchdarkly.com/\d/.+/"

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Comparisons

Use operators to compare two different elements in your search query. The following operators are supported:
  • =: Equals
  • !=: Does not equal
  • <: Less than
  • <=: Less than or equal to
  • >: Greater than
  • >=: Greater than or equal to

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Exist and does not exist

You can search if a key exists or does not exist with the exists operator. For example, to return all the traces with a connected session, use the following query:
exists also works with the not keyword. For example, when you only want the root level spans when searching traces, use this query:
You can combine expressions with the logical operators AND, OR, and NOT:
  • AND: Both expressions must be true
  • OR: At least one of the expressions must be true
  • NOT: The following expression must be false
Filters are combined with an implicit AND unless you specify OR. For example:
This is equivalent to:
You can also use parentheses ( AND ) to group values in an expression. For example:
You can also use parentheses to group values in an expression:
The search functionality on the Traces page returns individual spans that make up traces. Span functions help you filter results to show only those spans for traces that contain or don’t contain spans that match one or more conditions. The following span functions are available when you search on the Traces page:
  • any_span( expression ) limits results to spans where the trace contains at least one span that matches the expression.
  • any_span2() and any_span3() operate in the same way as any_span(). The unique function names let you require different spans in the trace to satisfy different conditions in the same query. To learn more, read Using multiple span aliases.
  • no_span( expression ) limits results to spans where the trace contains no spans that match the inner expression.
  • child_span( expression ) limits results to spans that have at least one direct child span matching the expression.
  • parent_span( expression ) limits results to spans where the direct parent span matches the expression.
  • root_span( expression ) limits results to spans where the trace’s root span matches the expression.
Span functions wrap a normal search expression in parentheses. Inside the parentheses, you can use any of the existing operators, including comparisons, EXISTS, AND, OR, and NOT. Here is an example that returns spans whose trace contains at least one span from the auth-service:
Here is an example that returns spans whose trace contains at least one error in an auth-service span:
Here is an example that returns spans whose trace contains no spans with errors:
Here is an example that returns spans that have a direct child span that lasts longer than one second:
Here is an example that returns spans where the direct parent span belongs to the auth-service:
Here is an example that returns spans where the trace’s root span is named checkout:

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Using multiple span aliases

If you call any_span() more than once in a query, the conditions accumulate against the same span. For example, this query requires a single span in the trace to match both conditions:
To require that different spans in the trace satisfy each condition, use any_span2() or any_span3() for the second condition. Here is an example that returns spans whose trace contains at least one checkout span and another, different span that contains errors:

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Combining span functions with regular search expressions

You can combine span functions with regular search expressions in the same query. Regular expressions filter the displayed spans by their own properties, while span functions filter the displayed spans by conditions that apply to the same trace. Here is an example:
This query returns spans in the production environment whose trace also contains at least one auth-service span that lasts longer than one second.

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Limitations

You can only use span functions as top-level filters in a query. Span functions have the following restrictions:
  • You cannot wrap span functions in parentheses.
  • All span functions at the top level of a query are joined with an implicit AND operator. You cannot combine span functions using AND, OR, or NOT outside of the function call.
These restrictions apply to the span function itself. Inside the parentheses, the inner expression supports the full set of search operators, including AND, OR, NOT, EXISTS, and grouping.

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Saved searches

Saved searches are a set of search filters that apply to sessions or errors. Saved searches are useful if you want to quickly view sessions or errors that relate to a certain population of your end users. To save a search, click the Save button below the search bar. The searches you build are reflected in the URL parameters when you’re accessing sessions through the LaunchDarkly UI. You can share these URLs with others to deep link to search results, or create them programmatically.

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Session-specific searching

To learn more about search terms and defaults specific to session replays, read Search in the Session replay topic. LaunchDarkly flattens the nested properties of the track events your application records. This lets you query each individual property. To learn more, read Search by track event properties.

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Configure error views

You can configure the Errors page to display different subsets of errors. Use the date dropdown to select a time range, and search in the search bar to filter the errors.