R2 SQL now supports JOINs, subqueries, and multi-table queries

R2 SQL is Cloudflare's serverless, distributed SQL engine for querying Apache Iceberg tables stored in R2 Data Catalog. R2 SQL runs directly on Cloudflare's global network with no infrastructure to manage, so you can analyze data in R2 without exporting it to an external warehouse.

R2 SQL now supports joining multiple Iceberg tables in a single query. You can combine tables with JOINs, filter with subqueries, and define multi-table CTEs to build complex analytical queries.

New capabilities

• JOINs — INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL OUTER JOIN, CROSS JOIN, and implicit joins (comma-separated FROM with conditions in WHERE)
• Subqueries — IN / NOT IN, EXISTS / NOT EXISTS, scalar subqueries in SELECT / WHERE / HAVING, and derived tables (subqueries in FROM)
• Multi-table CTEs — WITH clauses can reference different tables and include JOINs
• Self-joins — join a table with itself using different aliases
• Multi-way joins — join three or more tables in a single query

Examples

Two-table JOIN with aggregation

SELECT z.domain, z.plan, COUNT(*) AS request_count FROM my_namespace.zones z INNER JOIN my_namespace.http_requests h ON z.zone_id = h.zone_id WHERE z.plan = 'enterprise' GROUP BY z.domain, z.plan ORDER BY request_count DESC LIMIT 20

EXISTS subquery

SELECT z.domain, z.plan FROM my_namespace.zones z WHERE EXISTS ( SELECT 1 FROM my_namespace.firewall_events f WHERE f.zone_id = z.zone_id AND f.action = 'block' ) ORDER BY z.domain LIMIT 20

Multi-table CTE with JOIN

WITH top_zones AS ( SELECT zone_id, COUNT(*) AS req_count FROM my_namespace.http_requests GROUP BY zone_id ORDER BY req_count DESC LIMIT 50 ), zone_threats AS ( SELECT zone_id, COUNT(*) AS threat_count FROM my_namespace.firewall_events WHERE risk_score > 0.5 GROUP BY zone_id ) SELECT tz.zone_id, tz.req_count, COALESCE(zt.threat_count, 0) AS threat_count FROM top_zones tz LEFT JOIN zone_threats zt ON tz.zone_id = zt.zone_id ORDER BY tz.req_count DESC LIMIT 20

For the full syntax reference, refer to the SQL reference. For performance guidance with joins, refer to Limitations and best practices.