How to DELETE Rows in BigQuery

What does the DELETE statement do in BigQuery?

DELETE permanently removes rows that satisfy a Boolean condition. The table’s schema remains unchanged, and deleted data is not recoverable without backups.

How do I delete a single row by primary key?

Target the row with an equality filter on the key column.This limits scanned data and avoids accidental mass deletion.

DELETE FROM `ecommerce.Customers`
WHERE id = 42;

How can I delete multiple rows with complex conditions?

Combine operators such as AND, OR, IN, and BETWEEN to match several rows. Use partition filters when possible to reduce cost.

DELETE FROM `ecommerce.Orders`
WHERE order_date < DATE_SUB(CURRENT_DATE(), INTERVAL 1 YEAR)
AND total_amount < 10;

Can I delete using a sub-query?

Yes.Use USING with a sub-query or another table to join and identify rows for deletion.

DELETE FROM `ecommerce.OrderItems`
USING (
SELECT id FROM `ecommerce.Products`
WHERE stock = 0
) AS p
WHERE OrderItems.product_id = p.id;

Is DELETE safe with partitioned or clustered tables?

BigQuery supports partition and cluster pruning.Always specify the partition key in the WHERE clause to minimize scanned bytes and cost.

What are best practices for DELETE?

• Add precise WHERE filters.
• Test with SELECT before running DELETE.
• Use partition filters.
• Batch large deletes or use TTL if possible.
• Grant DELETE permission sparingly.

Common mistakes and fixes

• Missing WHERE clause deletes all rows—always include a condition.
• Omitting partition filter scans whole table—include partition key to cut cost.

Frequently asked questions

Does DELETE reduce storage immediately?

Yes, storage charges drop once DELETE finishes, though table metadata remains.

Can I undo a DELETE?

No.Restore from backups or table snapshots if available.

Is DELETE slower than INSERT?

DELETE can be slower because BigQuery rewrites the affected partitions. Limit the scope to speed it up.

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