Sequelize transaction timeout configuration boundary between v6 and v7

Direct Answer

Sequelize v7 appears to retain the v6 transaction timeout contract: the timeout option is a client-side timer that calls rollback() on expiry. It does not send a dialect-specific cancel or kill command to the database server. A statement that outlives the timer may continue running server-side while the client receives a rollback error, and the connection is released back to the pool without waiting for that statement to finish.

Confirmed vs. Likely Behavior

• Confirmed (v6): The timeout is implemented as a client-side timer that triggers transaction.rollback(). No PostgreSQL pg_cancel_backend, MySQL KILL QUERY, or equivalent is issued.
• Likely unchanged (v7): Based on model knowledge, v7 does not add automatic cancellation propagation to pg, MySQL, MariaDB, SQLite, or MSSQL drivers. Confirm against the installed distribution.
• Pool handling: After the rollback attempt, Sequelize returns the connection to the pool. It does not automatically mark the connection as broken or destroyed solely because the timeout expired.
• In-flight statements: When a server-side statement is still executing, the driver and server decide whether the rollback waits, fails, or completes after the statement finishes. There is no uniform cross-dialect reuse rule documented across the v6–v7 boundary.

Migration Boundary

v7 changes runtime and package expectations. Exact minimum Node.js and TypeScript versions, package naming, and stable publication status are not certain from model knowledge alone and must be confirmed against the installed sequelize package. Do not assume v6 timer and pool wiring carries over without re-validation.

What to Verify

1. Inspect the installed package: Check node_modules/sequelize/package.json for version, engines.node, and TypeScript-related fields.
2. Audit timeout values: The timeout option itself does not appear to require code changes, but re-test behavior on v7.
3. Add database-level statement timeouts where server-side cancellation is required:
   • PostgreSQL: SET statement_timeout = '5s';
   • MySQL/MariaDB: MAX_EXECUTION_TIME hint or max_execution_time session variable.
   • SQL Server: SET QUERY_GOVERNOR_COST_LIMIT or Resource Governor.
4. Test pool reuse after timeout: Run a long query with a short Sequelize timeout, then acquire a new transaction from the same pool and check for residual session state.

Assumptions & Uncertainty

• Assumes a standard supported dialect (PostgreSQL, MySQL, MariaDB, SQLite, MSSQL). Exotic dialects may differ.
• Assumes the default pool implementation. Custom pool wrappers could change release semantics.
• The exact v7 stable release status, minimum Node/TypeScript floors, and any new API surface require confirmation against the installed distribution.

One Diagnostic Detail

What exact version string does npm ls sequelize report? This determines whether you are on a stable v7 line, a pre-release, or still on v6, and it sets the precise runtime floor for the migration.