Distributed Transactions

SPQR supports distributed transactions across multiple shards with different commit strategies.

The __spqr__commit_strategy parameter controls how transactions are committed:

• best-effort or 1pc - One-phase commit with no coordination between shards
• 2pc - Two-phase commit with atomicity guarantees across shards

For atomic cross-shard transactions, use two-phase commit (2PC). Set __spqr__commit_strategy to 2pc and ensure max_prepared_transactions > 0 on all shards.

SET __spqr__commit_strategy TO '2pc';

BEGIN;
INSERT INTO shard1_table (id, data) VALUES (1, 'data1');
INSERT INTO shard2_table (id, data) VALUES (2, 'data2');
COMMIT; -- Atomically commits across shards

See Distributed Transactions for detailed information on commit strategies, requirements, and best practices.