Control which sessions to record

If you get thousands or millions of visitors a day, you can't watch every replay. PostHog gives you a few knobs to keep only the useful sessions and keep costs low.

Trigger groups

Sessions are recorded when they meet the conditions of a trigger group. These rules decide when a session recording begins and ends.

Trigger groups

Configure custom recording triggers with individual sampling rates per group. Recording will start if any of the recording trigger groups match.

Group name

e.g., Error Tracking, Feature Testing

Sample rate (%)

100

Minimum duration (seconds)

No minimum

Match type

ANY condition matches

Conditions

Event triggers

Add event

URL patterns (regex)

Matches if the user visits a matching URL at any point during the session. For more control, use a $pageview event trigger with property filters.

Add URL

Feature flag

Add flag

No conditions added yet. A trigger group will match all sessions if there are no conditions.

Fig. 1 – One trigger group: the conditions that start a recording, and the sample rate and minimum duration that thin it.

The controls

Every trigger group is built from the same five controls. Conditions decide which sessions match; sample rate and minimum duration thin what's left.

Control	Reach for it when
Sample rate	Select N% of sessions to record at random.
Minimum duration	Discard sessions that are too short or are bounces.
Event triggers	Only sessions where something specific happened, like someone visiting the pricing page.
URL patterns	Only record sessions that match your URL patterns, like checkout.
Feature flag	You're rolling something out and want the sessions of the people who got it.

How groups play together

It can be difficult to understand exactly how these rules play together. A few things hold in every case:

Groups are combined with OR logic, so a session records if it matches any of them
Inside a group, the match type decides whether a session needs any of the conditions or all of them
The sample rate is applied last to the matching set of sessions.

Examples

Each example below combines trigger groups. Hand the prompt to PostHog AI and it sets the group up for you.

Example	How it works	Set it up
Record every checkout session, and 5% of everything else	Two groups. The first has a URL pattern for your checkout path and a 100% sample rate. The second has no conditions at all and a 5% sample rate. The first group catches checkouts, the second groups applies a 5% sample on everything else.	Set up
Record sessions where a paying customer hit an exception	One group, match type set to all: an event trigger on your exception event, plus a feature flag you've rolled out to paying customers.	Set up
Record marketing-site visits, but not bounces	One group with URL patterns for your marketing pages and a minimum duration of 10 seconds. Sessions shorter than that are never recorded.	Set up

Sane defaults

If you don't know what to set yet, start here:

Record 100% of sessions. Turn the sample rate down once you know how much you're actually recording, not before. Be realistic about how many you plan to watch.
Set a minimum duration of 2 seconds or more. A one-second bounce is billed like any other recording with nothing in it to watch, this will reduce junk volume.