BigQuery on Google Cloud Platform (GCP) is used by developers for ad hoc analysis. It is also used for building operational dashboards and processing data using stored procedures. The analysis cost of using this service is determined by the size of the data that is processed by queries issued on GCP BigQuery pricing. And under the current on-demand pricing model, this price can range from $5/TB in US (multi-region) to $6/TB in Belgium (europe-west1).
This essentially means that if developers fire lots of unoptimized queries, they can rack up thousands of dollars in cost. This case is also quite common in large organizations, especially those on pay-as-you-go models.
In terms of cost monitoring at user level, currently GCP does not disclose BigQuery pricing granular usage. While the billing dashboard shows that the cost is coming from BigQuery. But it cannot be drilled down to identify specific users and activities causing these cost spikes. As such, the issue cannot be remediated.
An Innovative Solution
One workaround for this is to use the built-in and natively available BigQuery INFORMATION_SCHEMA metadata tables. Users can also build more specifically, the BigQuery jobs metadata table. The INFORMATION_SCHEMA.JOBS_BY_PROJECT table can be queried to see project-level query history for the past 180 days.
The metadata, which will be described in more detail in the next section, includes the user email and job ID. It also includes the amount of data queried, and the query execution time, among other things. While query cost is not explicitly a column, it can be calculated using the column. As it shows bytes billed because query cost and amount of bytes billed are directly proportional.
It is important to note that the metadata tables are independent from Stackdriver logs. This implies that data such as IP addresses and device information is not available. They are a series of tables natively available in BigQuery. And they do not require Stackdriver logs to be exported to BigQuery.
Metadata in INFORMATION_SCHEMA.JOBS_BY_PROJECT
The following information is available in the BigQuery job metadata table, as described in Google’s documentation here:
|Column name||Data type||Value|
|creation_time||TIMESTAMP||(Partitioning column) Creation time of this job. Partitioning is also based on the UTC time of this timestamp.|
|project_id||STRING||(Clustering column) ID of the project.|
|project_number||INTEGER||Number of the project.|
|folder_numbers||RECORD||Google Accounts and ID Administration (GAIA) IDs of folders in a project’s ancestry. The order starts with the leaf folder closest to the project. This column is only populated in JOBS_BY_FOLDER.|
|user_email||STRING||(Clustering column) Email address or service account of the user who ran the job.|
|job_id||STRING||ID of the job. For example, bquxjob_1234.|
|job_type||STRING||The type of the job. Can be QUERY, LOAD, EXTRACT, COPY, or null. Job type null indicates an internal job, such as script job statement evaluation or materialized view refresh.|
|statement_type||STRING||The type of query statement, if valid. For example, SELECT, INSERT, UPDATE, or DELETE.|
|priority||STRING||The priority of this job.|
|start_time||TIMESTAMP||Start time of this job.|
|end_time||TIMESTAMP||End time of this job.|
|query||STRING||SQL query text. Note: The JOBS_BY_ORGANIZATION view does not have the query column.|
|state||STRING||Running state of the job. Valid states include PENDING, RUNNING, and DONE.|
|reservation_id||STRING||Name of the primary reservation assigned to this job, if applicable. Also, if your job ran in a project that is assigned to a reservation, it would follow this format: reservation-admin-project:reservation-location.reservation-name.|
|total_bytes_processed||INTEGER||Total bytes processed by the job.|
|total_slot_ms||INTEGER||Slot-milliseconds for the job over its entire duration.|
|error_result||RECORD||Details of error (if any) as an ErrorProto.|
|cache_hit||BOOLEAN||Whether the query results of this job were from a cache.|
|destination_table||RECORD||Destination table for results (if any).|
|referenced_tables||RECORD||Array of tables referenced by the job.|
|labels||RECORD||Array of labels applied to the job as key, value strings.|
|timeline||RECORD||Query timeline of the job. Contains snapshots of query execution.|
|job_stages||RECORD||Query stages of the job.|
|total_bytes_billed||INTEGER||total bytes billed by the job.|
Note that the folder_numbers column is not applicable to JOBS_BY_PROJECT table, as described in the relevant “value” column of the table above.
The minimum roles and permissions required to query JOBS_BY_PROJECT are the following:
- roles/bigquery.jobUser (includes bigquery.jobs.create, resourcemanager.projects.get, resourcemanager.projects.list)
Details about these IAM permissions can be found in Google’s documentation here.
These permissions do not give ‘view’ or ‘write access’ to existing user datasets. Instead, their jobs.listAll permission gives access to project-level job history. While jobUser allows firing of queries only on the tables accessible to the users. In this case, jobs.listAll exposes the JOBS_BY_PROJECT metadata table. So, together these permissions allow queries to be fired on that table.
IAM in demo project
Only the minimum permissions described in the “IAM” section were applied to a user in a project, as can be seen below:
Query in demo project
The following query is executed which fetches all the data from the job history metadata table. It also displays the top 5 results in order of bytes billed (cost). This is a slight modification of the query described in Google’s documentation here.
ORDER BY total_bytes_processed DESC
Users can modify this query to have a calculated column such that ‘total_bytes_processed’ is first converted to TBs. They can then multiply this with the per-TB cost of the region.
As can be seen in the screenshot, other existing datasets in this project are not visible to the user firing the query:
The INFORMATION_SCHEMA.JOBS_BY_PROJECT table is qualified with region. The example above shows query history in europe-west2. But it can be modified as “region-us” to get the metadata from US.
This query can also further be optimized to get only relevant columns. Because of this, users can reduce query cost. They can also build further operational dashboards or views.
GCP does not offer this level of granularity by default. Because of this, users find it nearly impossible to determine the source of BigQuery pricing costs and their remedy. In such cases, the metadata tables available natively in BigQuery can be extremely useful. This is because they show exactly which user triggered the query and the time they triggered it at. They can also learn about the exact query itself, and the cost for running that query.
Remarkably, the fine-grained permissions available in GCP ensure that queries can be confined to operational and admin teams. This is because they can only use it to monitor costs on BigQuery. Users also are not able to view or query other existing data.