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NewWriter::string() and bun_string() skipped the terminator after a value that ends in NUL. Every frame that computes its length ahead counts one, so that frame was one byte short and the next byte of the stream completed it. A query text that ends in NUL rejected with 08P01 and then broke the connection. Now it rejects with 08P01 and the connection stays usable.
execute_query wrote a Flush behind every simple Query. PostgreSQL starts idle_in_transaction_session_timeout and idle_session_timeout when it sends ReadyForQuery, and stops them at the next message of any kind. The Flush arrived after the ReadyForQuery of the Query, so the session then idled with no limit and kept its locks.
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Included review availability: This review used your included allowance. Your plan provides up to 10 included reviews per hour; 4 remain after this review. WalkthroughPostgreSQL simple-query framing now sends no extra Flush message, and string serialization appends a zero byte. Tests cover frontend frames, trailing-NUL SQL, and server idle timeouts. The ChangesPostgreSQL query flow
Priority: ⬆️ High Merge Risk: 🟡 Moderate · up to With idle transaction timeouts enabled, a later transaction-scoped unsafe call may run on a replacement connection outside the transaction. Fix the transaction-state guard before merging. 🚥 Pre-merge checks | ✅ 4✅ Passed checks (4 passed)
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Actionable comments posted: 2
- 🪄 Fix CodeRabbit comments on this PR
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Inline comments:
Review comments at @docs/runtime/sql.mdx:
- Line 1058: Add a focused integration test for the dedicated sql.listen()
connection that triggers PostgreSQL idle_session_timeout, verifies the listener
reconnects and re-subscribes, then confirms it receives a notification sent
after recovery. Reuse the existing timeout and listener-reconnection test setup
where possible.
Review comments at @src/sql_jsc/postgres/PostgresRequest.rs:
- Around line 498-499: Add the `ReservedConnectionState.closed` check to
`transaction_sql.unsafe` and other transaction wrappers that call
`unsafeQueryFromTransaction`; return the existing `connectionClosedError`
rejection before dispatch when the connection is closed.
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docs/runtime/sql.mdxsrc/sql/postgres/protocol/NewWriter.rssrc/sql_jsc/postgres/PostgresRequest.rstest/js/sql/postgres-simple-query-pipeline.test.ts
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Beyond the inline findings, I also checked the NewWriter::string() change against its callers (Parse, Describe, Execute, StartupMessage, PasswordMessage, SASLInitialResponse, Query): each frame's length field counts exactly one terminator, so always writing it is the consistent behavior, and the to_utf8() temporary in bun_string lives through the string() call. The extended-protocol Flush sites at PostgresRequest.rs:323/355 are each followed by a Sync, so they are not affected by the idle-timer issue.
Extended reasoning...
The diff removes the trailing Flush after a simple Query in execute_query, makes NewWriter::string() always append a NUL terminator, adds a docs sentence about idle_session_timeout and LISTEN, and adds mock-server and container tests. It touches the Postgres wire protocol encoder but no auth or credential handling. Inline findings about the behavior change under idle_in_transaction_session_timeout and listen() under idle_session_timeout are posted, so a human should weigh those before merging.
Findings marked 🟡 are optional suggestions and need no follow-up push.
| writer.write(&protocol::FLUSH)?; | ||
| Ok(()) | ||
| // Query alone: a Sync elicits a second ReadyForQuery, a Flush stops the server's idle timers. | ||
| protocol::write_query(query, &mut writer) |
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🔴 After merging, a transaction idle past idle_in_transaction_session_timeout can have its next tx.unsafe()/tx.file() statement silently run on a fresh pool connection, outside any transaction and auto-committed. The server now ends the session after any simple statement (this is the change's purpose), but transaction_sql.unsafe at src/js/bun/sql.ts:696 and .file at :699 have no closed-state check, unlike transaction_sql at :679-684. Fix: before or with this change, make tx.unsafe, tx.file, reserved.unsafe and reserved.file reject with pool.connectionClosedError() once ReservedConnectionState.closed is set, so no statement bound to a dead transaction runs on a re-dialed slot. The PR text calls this a dependency on #43249; nothing in this PR enforces that ordering.
Why this was flagged
A caller runs sql.begin(async tx => { await tx.unsafe("BEGIN-ish work"); await slowStep(); await tx.unsafe("UPDATE accounts ..."); }) against a server with idle_in_transaction_session_timeout set, and slowStep() takes longer than the limit. On the base branch execute_query at src/sql_jsc/postgres/PostgresRequest.rs:499 wrote a Flush behind the Query, the server read it and stopped the idle timer, so the UPDATE ran inside the transaction. After this diff only the Query is written, the server ends the backend, onTransactionDisconnected at src/js/bun/sql.ts:261 sets ReservedConnectionState.closed, and the pool re-dials the slot. transaction_sql.unsafe at src/js/bun/sql.ts:696 and transaction_sql.file at :699 call unsafeQueryFromTransaction without checking state.connectionState, so the UPDATE is sent on the new connection with no BEGIN and auto-commits, while the tagged form at :679-684 would have rejected with pool.connectionClosedError(). The PR description says #43249 must land in the same release, but this PR contains no such check.
Verification: The PR description says "Needs #43249 in the same release"; that follow-up is not in this checkout (src/js/bun/sql.ts is untouched by the diff). src/sql_jsc/postgres/PostgresRequest.rs:498-499 now writes only write_query (the Flush removed). src/js/bun/sql.ts:696-705 transaction_sql.unsafe and transaction_sql.file have no ReservedConnectionState.closed check, unlike transaction_sql at :679-684.
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Agreed on the hazard, and the numbers match: on main the statement runs on the pool's next connection in 20 of 20 runs after a tagged last statement, and with this change in 40 of 40 runs after any last statement.
The check is not in this PR on purpose. #43249 already adds it to tx.unsafe, tx.file, reserved.unsafe and reserved.file, as a Query that rejects with pool.connectionClosedError() when it runs. A first draft of this PR carried its own check as a rejected promise. That breaks tx.unsafe(text).values() (a TypeError plus an unhandled rejection, and drizzle's bun-sql driver makes that call), and a second copy conflicts with #43249 and the two PRs stacked on it.
You are right that nothing in the tree enforces the order. The first Downsides bullet and the status comment now say "Merge #43249 first". If a maintainer prefers one atomic PR, the helpers of #43249 can move here.
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Still open from earlier reviews (1):
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src/sql_jsc/postgres/PostgresRequest.rs:499—After merging, a transaction idle past idle_in_transaction_session_timeout can have its next tx.unsafe()/tx.file() stat…
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Problem
idle_in_transaction_session_timeoutandidle_session_timeoutnever fire. A transaction that waits afterBEGIN,SAVEPOINT,tx.unsafe(text)or.simple()keeps its row locks. Regression in 1.4.0 (sql(postgres): stop sending a redundant Sync after a simple Query #32772).execute_querywrote a Flush behind the Query (src/sql_jsc/postgres/PostgresRequest.rs:502). The server starts the timer when it sends ReadyForQuery and stops it at the next message, that Flush.Fix
execute_querywrites the Query alone, as libpq, node-postgres and postgres.js do.NewWriter::string()always writes the terminator. It skipped it after a text ending in NUL, though frame lengths count one, and theHof the Flush completed that frame.test/js/sql/postgres-simple-query-pipeline.test.ts(16 new cases fail on 1.4.3-canary), plustest/js/sql/.Background
unsafe(text)without parameters,.simple(), LISTEN, BEGIN, COMMIT, ROLLBACK and SAVEPOINT.Flush; Synctail for extended batches (same bytes), and extended-protocol transaction statements (fixes 2 of 4 cases).Downsides
tx.unsafe()after a server-ended session runs on the pool's next connection (40 of 40 runs).begin()then rejects.sql.listen()at a 1 s limit lost 430 of 2048 notifications, andconnection: { idle_session_timeout: 0 }keeps the listener.Notes
Server side. PostgreSQL
src/backend/tcop/postgres.c(line numbers of REL_17_5, the same shape in REL_15_15 and master). The idle timers start only insideif (send_ready_for_query)(:4598-4686). AfterReadCommandreturns any message they stop (:4702-4718).PqMsg_Query(:4771) andPqMsg_Sync(:4965) setsend_ready_for_query.PqMsg_Flush(:4955) does not.pg_stat_activitykeepsidle in transaction, because a Flush does not change the reported state.Proof by a wire twin. A proxy in front of an unfixed build drops the Flush behind each Query. The reporter's script then exits 0, 3 of 3 runs. The same proxy with the Flush kept exits 1.
History. #17296 added
.simple()with aQuery; Flush; Synctail. #22520 removed both the Flush and the Sync in 2025 and was closed with no test. The review comment there asked to keep the Sync and left the Flush open. #32772 removed the Sync, because its second ReadyForQuery re-armedadvance()in the middle of a prepare. 1.3.14 writesQ H S. 1.4.0 to 1.4.2 writeQ H.Who writes a simple query.
execute_queryis the only encoder. Its callers aredo_run(PostgresSQLQuery.rs:540) andadvance()(PostgresSQLConnection.rs:1931). Three mock tests pin one Query frame and nothing else forsql.unsafe(text),sql.unsafe(text, []),.simple(),sql.file(), two queued queries,reserved.unsafe(), a text that ends in NUL, BEGIN, COMMIT, ROLLBACK, SAVEPOINT, RELEASE SAVEPOINT, ROLLBACK TO SAVEPOINT, the statements of a distributed transaction, LISTEN and UNLISTEN.The terminator.
NewWriter::string()andbun_string()skipped the terminator after a value that ends in NUL. Every frame that computes its length ahead counts one (PostgresProtocol.rs:30,Parse.rs:28,StartupMessage.rs:23,PasswordMessage.rs:16,SASLInitialResponse.rs:18). So the frame was one byte short and the next byte of the stream completed it.sql.unsafe("select 1 as x\0")rejected with 08P01 and the rest of the Flush then broke the connection. Without the Flush that query would never settle. A tagged or parameterised text that ends in NUL broke the connection too. Now the four forms reject with 08P01 and the connection stays usable. No caller passes a value that ends in NUL on purpose.Measurements. Release builds of bd599f5 with and without this diff, Linux x64, PostgreSQL 17.11 on loopback.
Q H->Q. select 1: 19 -> 14 B, empty begin(): 33 -> 23 B, begin + savepoint: 87 -> 67 B, two queued unsafe (written by advance()): 38 -> 28 B (mock server frame log).execute_query: 79 -> 68 instructions per call for 'select 1', callees included (gdb stepi from entry to return, 4 of 4 calls). 402 -> 316 bytes (nm -S).Writer::writeover 1,000 queries, debug builds).catch syscallover 1,000 queries. strace is not installed in the container).mi_*entry points over 10,000 queries, 3 runs each, JIT off. One more allocation per query would be +1.00).size), data and bss equal. No JS changes. 0 host functions added.idle_session_timeout= 1 s: a pooled client used 20 backends for 20 spaced queries (1 before). The server ended thesql.listen()connection 20 times in 25.4 s (never before). 1618 of 2048 notifications sent every 10 ms arrived (2415 of 2415 before). The next LISTEN came 268 ms after each end on average (199 to 385 ms).What a server with a limit now does to Bun, as to any client and as on 1.3.14.
begin()rejects when the server ends its session. With no request in flight the error isERR_POSTGRES_EXPECTED_REQUEST"Failed to read data" today. Open PR sql: deliver onconnect before onclose so a connection killed right after connecting can't strand a query #40913 changes that to the server's own error. The tests assert thatbegin()rejects with the error that closed the connection, so they hold before and after sql: deliver onconnect before onclose so a connection killed right after connecting can't strand a query #40913.sql.ts:273-275, since feat(sql) transactions, savepoints, connection pooling and reserve #16381). A process that catchesbegin()can still exit 1 on that.idleTimeoutbelow the server's limit avoids it.The listener. A client that is created with
connection: { idle_session_timeout: 0 }keeps its listen connection. With a role default of 1 s, the default client sent LISTEN 3 times in 3.5 s and got 221 of 261 notifications. The client with the option sent it once and got 249 of 249. Whether Bun sets that parameter itself on the listen connection is a policy choice that this PR does not make.Needs #43249.
tx.unsafe(),tx.file(),reserved.unsafe()andreserved.file()have no state check. After the server ends a session and the pool dials the slot again, their statement runs on the new connection, outside the transaction. On the merge base that happens in 20 of 20 runs when the last statement was extended. With this fix it happens after any last statement: 40 of 40 runs on a release build of this branch. #43249 makes those calls reject with a lazyQuery. #43261 and #43958 are stacked on it, #43257 does the same for the tagged form, and #43205 releases the pool slot.Not changed here (the same on main).
PostgresRequest.rs:323,:355,:426). The Sync follows, so the timer starts.postgres-bind-wire.test.tspins those bytes."Q", "H"for a nested simple query (postgres-dispatch-during-bind.test.ts). The PR that lands second changes that to"Q"..values()or.raw()before.simple()still sends the extended batch.sql.listen()underidle_session_timeout. The limit can only be a startup parameter there, so it also runs before the first LISTEN. A client that stalls longer than the limit at that point hits the callback order that open PR sql: deliver onconnect before onclose so a connection killed right after connecting can't strand a query #40913 fixes.test/js/sql/tls-sql.test.ts(maxLifetime case) can abort a debug build withASSERTION FAILED: !message.isEmpty()inJSC::createError, reached fromPostgresSQLConnection::on_handshakewhen Bun closes a TLS socket before the handshake ends. The merge base does the same.Self-review. The 12 concerns: the state check repeated #43249 in a shape that PR had dropped (removed here). The NUL repair sat at one caller of the helper (moved into the helper, with tagged, parameterised and
prepare: falsecases). #43918 pinsQ H(named above). The idle cases asserted too little (the case must reach its wait, andbegin()must reject with the error that closed the connection). The body did not name the client-side effects, the kept Flush writes, the never-run queries, the queued callers and the frozen process (all named above). Four more were about the state check and go with it to #43249, which has to merge first.Tests run.
postgres-simple-query-pipeline.test.ts: 3 pass and 16 fail on 1.4.3-canary 367d939 and on a release build of the merge base. 19 pass on the branch, 30 runs in a row on the debug build and 5 on a release build. Every file oftest/js/sql/on the debug build: each failure is also a failure of the merge base (a local MariaDB in place of MySQL, and slow cases that reach the 5 s default timeout of a local run on the debug build).