Add ROLLBACK to allowCrossShardTransactions to clear vtgate reserved connection state#3785
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Add ROLLBACK to allowCrossShardTransactions to clear vtgate reserved connection state#3785
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… connection state SET transaction_mode triggers vtgate's NeedsReservedConn(), which retains stale shard sessions across COMMIT (vitessio/vitess#11616). Without cleanup, subsequent queries on the same pooled connection fail with "multi-db transaction attempted" even for single-shard operations. The afterCompletion handler now sends SET UNSPECIFIED (resets the session variable) then ROLLBACK (clears the reserved connection state). Both are safe post-commit — ROLLBACK is a data no-op that only affects vtgate session state. Also updates cross-shard tests to use hasCause helper for asserting CrossShardTransactionException in the cause chain. Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>
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Summary
allowCrossShardTransactions()commits, sendSET transaction_mode = 'unspecified'thenROLLBACKinafterCompletionto clean up vtgate session stateSET UNSPECIFIEDresets the session variable so MULTI doesn't leak to the poolROLLBACKclears vtgate's reserved connection stale shard sessions (Bug Report: enabling MySQL safe-updates is incompatible with transaction_mode=SINGLE vitessio/vitess#11616) so subsequent queries don't fail with "multi-db transaction attempted"hasCausehelper for cleaner exception assertionsContext
SET transaction_modetriggers vtgate'sNeedsReservedConn(), which retains shard sessions across COMMIT. Without ROLLBACK, pooled connections carry stale shard sessions that cause spurious "multi-db transaction attempted" errors on subsequent single-shard operations.🤖 Generated with Claude Code