Create a Google Cloud Pub/Sub BigQuery subscription to write messages directly into a BigQuery table

Steps

1. Create or identify an existing BigQuery table whose schema is compatible with your Pub/Sub message structure (or plan to use the topic schema if you want Pub/Sub to write structured columns automatically)
2. Grant the Pub/Sub service account the roles/bigquery.dataEditor role (and roles/bigquery.metadataViewer if needed) on the target BigQuery dataset so it can write rows
3. Create a subscription of type BigQuery subscription, specifying the target project, dataset, and table, via the Cloud Console, gcloud pubsub subscriptions create --bigquery-table, or the API
4. Understand that Pub/Sub uses the BigQuery Storage Write API under the hood to batch-write incoming messages as rows into the table
5. Configure a dead-letter topic on the BigQuery subscription to capture messages that fail to write to BigQuery; inspect the CloudPubSubDeadLetterSourceDeliveryErrorMessage attribute on forwarded messages to see the failure reason
6. Monitor subscription metrics for negative acknowledgments, which occur whenever a batch write to BigQuery fails, and iterate on schema compatibility until writes succeed consistently