Budget alert: this month's BigQuery bill has been multiplied by 40

The MasterLinux school analyses the events of its enrolment website in BigQuery (table analytique.evenements_inscriptions, about 3 TiB, fed continuously). An internal dashboard shows enrolments by city and by course; it is refreshed by a scheduled query.

This morning, accounting forwards the budget alert: project masterlinux-prod has already used 90% of the monthly budget (USD 2,000) on the 20th of the month. The BigQuery Analysis line went from about USD 45 per day to more than USD 1,800 per day since 12 October. The security officer fears a data leak (“someone is siphoning the database”), the data team talks about a “new intern running SELECT *”.

Every day costs about USD 1,800. You are the cloud engineer, on ml-poste-01, with bq and gcloud configured on masterlinux-prod (BigQuery Admin and billing viewer rights).