This page describes how a Pub/Sub subscription retains published messages and how to configure this behavior. You might change the default settings for the following reasons:
- To adjust how long unacknowledged messages remain available to a subscription before they are deleted.
- To enable replaying previously-acknowledged messages.
Overview
When you create a subscription, Pub/Sub begins retaining published messages on behalf of the subscription. By default, Pub/Sub discards a message from a subscription as soon as the message is acknowledged, and retains unacknowledged messages for 7 days.
You can set the retention duration when you create or update the subscription. The minimum retention duration is 10 minutes, and the maximum is 31 days.
You can also enable the subscription to retain acknowledged messages, up to the configured retention duration. Retaining acknowledged messages lets you replay previously-acknowledged messages for as long as they are retained. For more information about replaying messages, see Replay and purge messages with seek.
If a subscription is configured to retain acknowledged messages, storage costs for the acknowledged messages retained by the subscription are billed to the subscription's project.
If you also enable message retention on the subscription's topic, then messages are deleted from the subscription only when their age exceeds the maximum of the subscription retention and topic retention durations. For more information, see Enable topic message retention.
Configure message retention
To create a subscription that retains acknowledged messages, perform the following steps:
Console
In the Cloud de Confiance console, go to the Pub/Sub subscriptions page.
Click Create subscription.
In the Subscription ID field, enter an ID for your subscription.
In the Message retention duration section, select the number of days, hours, and minutes to retain messages.
Select the Retain acknowledged messages checkbox.
Click Create subscription.
gcloud
Use the
gcloud pubsub subscriptions create:
gcloud pubsub subscriptions create SUBSCRIPTION_ID \
--message-retention-duration=5d \
--retain-acked-messages
Replace SUBSCRIPTION_ID with the ID of the
subscription.
If you omit the --message-retention-duration flag, messages are retained for
the default duration of 7 days.
To update the message retention settings on an existing subscription, perform the following steps:
Console
Select your subscription from the Pub/Sub subscriptions page.
Click Edit at the top of the subscription details page.
In the Message retention duration section, update the number of days, hours, and minutes to retain messages.
Select or clear the Retain acknowledged messages checkbox.
Click Update to save the changes to the subscription.
gcloud
Use the
gcloud pubsub subscriptions update
command:
gcloud pubsub subscriptions update SUBSCRIPTION_ID \
--message-retention-duration=1d \
--retain-acked-messages
To disable retention of acknowledged messages, use the update command with
the --no-retain-acked-messages flag:
gcloud pubsub subscriptions update SUBSCRIPTION_ID \
--no-retain-acked-messages