sql(postgres): discard a partial Bind when a parameter fails to encode

[robobun]

Problem

• write_bind (src/sql_jsc/postgres/PostgresRequest.rs:52) writes into connection.write_buffer and calls JS per parameter. When a parameter fails (a throwing toString, since sql(postgres): reject a non-BufferSource value bound to a bytea parameter #41889 a bad bytea value), the query rejects but the partial Bind stays: 42 00 00 00 00 (length 0).
• The next flush sends it, even with nothing queued: P D S B(len=0), or P D B(len=0) with prepare: false. PostgreSQL drops the connection. The next query, pipelined siblings and open transactions get ERR_POSTGRES_CONNECTION_CLOSED.

Fix

• NewWriter::atomically records offset(), runs the body, and truncates back on failure. It wraps the three batch writers that reach write_bind: a rejected query writes nothing.
• It truncates only when write_epoch is unchanged. The connection bumps it for every Writer it hands out and every drain or free of write_buffer. A conversion that starts a query with .execute() changes it, and the connection then fails as on main.
• Writer::pwrite now adds head (the bytes already sent) to the index, like offset().
• Verified: postgres-bind-encode-throw.test.ts, postgres-bytea-bind.test.ts (unfixed main fails 4/5 and 6/12). Other suites: Notes.

Background

• prepare: false writes Parse, Describe, Bind, Execute, Flush, Sync as one batch, so the rollback drops them too.
• This is the interim fix for 1.4.3. The follow-up converts every parameter before the first write, so no rollback is needed.

Downsides

• Success path, per batch: two reads and one branch. Per Writer: one increment. Per length patch: one add.
• A conversion that dispatches a query and then fails still loses the connection, as on main. Without the failure both hang (sql(postgres): only enqueue queries dispatched from inside a Bind encoder #38231). The follow-up fixes both.

Notes

Wire captures on unfixed main (367d939), byte-capturing mock server. Each line is the list of frontend messages after the startup packet.

• Lone rejected query, named statement: P D S B(len=0). The bytes: 42 00 00 00 00 00 50 73 65 6c 65 63 74 ... (Bind, length 0, empty portal name, then the statement name).
• Lone rejected query, prepare: false: P D B(len=0). The bytes: 42 00 00 00 00 00 00 00 02 00 00 00 00 00 02 00 00 00 01 61. The Parse and Describe have no Sync behind them.
• Nothing is queued behind the rejected query in both captures. The auto-flusher sends the buffer at the end of the tick.
• With the fix: the named case sends P D S and no Bind. The prepare: false case sends nothing for the rejected query.

Paths covered by the tests.

• bind_and_execute from advance (the Bind follows the statement's Parse/Describe round trip): both files, real server and mock.
• bind_and_execute from run (statement already prepared, Bind written at query time): postgres-bytea-bind.test.ts runs each rejected query twice. The second run takes this path.
• parse_and_bind_and_execute (prepare: false): real server with a queued sibling, real server with a lone query and a backend pid check, and the mock that asserts the exact message list.
• prepare_and_query_with_signature has no parameters, so no parameter can throw there. It is wrapped for the TooManyParameters path.
• The bytea case (sql(postgres): reject a non-BufferSource value bound to a bytea parameter #41889): a number[] bound to bytea rejects with ERR_INVALID_ARG_TYPE. On unfixed main the next query, the pipelined siblings and the open transaction then fail with ERR_POSTGRES_CONNECTION_CLOSED.

The mock server in postgres-bind-encode-throw.test.ts drops the connection when it reads a length below 4, as PostgreSQL does. On unfixed main the mock tests fail at once with ["B(len=0)"]. They do not wait for a timeout.

Nested dispatch from inside a conversion (found in review, confirmed on a real PostgreSQL). query.execute() calls into the connection synchronously (await/.then() defer by one microtask and are not affected). When a parameter's toString creates a query for a prepared statement on the same connection and calls .execute() on it, the nested query writes its Bind/Execute/Sync inside the outer query's open Bind.

• Conversion does not throw, main and this PR: the outer query never settles, the nested one rejects with 08P01 insufficient data left in message, and later queries on the connection hang. sql(postgres): only enqueue queries dispatched from inside a Bind encoder #38231 is the open fix.
• Conversion throws after the nested dispatch, main and this PR: B(len=0) goes out, the server drops the connection, the nested query rejects with ERR_POSTGRES_CONNECTION_CLOSED, the pool reconnects and the next query resolves.
• An earlier head of this PR (9812be4) rolled back without the write_epoch check. It removed the nested query's frames too: the nested query hung, or a later query's row resolved it (nested: resolved [{"nested":"LATER-VALUE"}]). The test a query dispatched from inside a conversion that then fails never gets another query's row times out on that head and passes now.
• Checked 5 cells against main on a real server (outer statement already prepared or on its first execution, nested query prepared, new, simple, or unsafe with parameters): the outcomes are the same as on main in every cell. A sixth cell (first execution, nested new statement) aborts the debug build with panic: pending_requests underflow, a debug assertion that this diff does not touch. The release build of main has no panic in that cell.

head in pwrite and truncate. offset() is relative to head, so both now add head. No test reaches head != 0 during a write, and the public API does not reach it without a flush from inside a conversion. OffsetByteList::consume leaves head > 0 only when a socket write accepted less than half of the pending bytes. That write sets HAS_BACKPRESSURE. Under backpressure advance() does not run its loop, and every write gate in do_run needs !has_query_running() or can_pipeline(), which are both false while a request with pending bytes is in the queue. A flush from inside a conversion bumps write_epoch, so no rollback follows it.

Follow-up. A design review of six candidates picked a different long-term shape: convert every parameter before the first byte of the batch is written (no user code runs while a frame is open), plus a guard so that a query dispatched during a conversion only enqueues. It is planned as three PRs. This PR is the interim fix. See #34732 (comment).

Suites run with the debug build: the test/js/sql/postgres-*.test.ts files, sql-prepare-false.test.ts, sql-pool-transaction-isolation.test.ts, wire-frames.test.ts and sql.test.ts (29 files): 236 of 236 tests pass, with postgres-string-leak.test.ts run apart. The two tests in postgres-string-leak.test.ts time out at the default 5 s in this environment: the fixture alone takes 8.6 s under the debug ASAN build here (0.46 s under release). Its RSS delta is 9.65 MiB, inside the test's 80 MiB bound.

History. The July version of this PR had the same design. It was refreshed on current main after the ArrayList writer context was removed. The test file postgres-bind-throw-torn-frame.test.ts was replaced by postgres-bind-encode-throw.test.ts. The head now also carries the postgres-bytea-bind.test.ts additions from the branch robobun/44cd9150/postgres-bind-rollback.

MySQL is not affected. bind_and_execute_impl converts every parameter to a native Vec<Value> before it touches the writer.

---

[human-review] gate passed · iteration 2 · 4 files touched

fails on main (without fix)

ASAN without fix: 3 FAILED
$ BUN_DEBUG_QUIET_LOGS=1 bun scripts/build.ts --profile=debug --quiet test "--reporter=junit" "--reporter-outfile=/tmp/pr_gate.xml" test/js/sql/postgres-bind-encode-throw.test.ts
bun test v1.4.3 (f42e98025)

test/js/sql/postgres-bind-encode-throw.test.ts:
Container ready via docker-compose: postgres_plain at 127.0.0.1:5432
204 |   return `{${values.map(arrayValueSerializer.bind(this, type, isPostgresNumericType(type), isPostgresJsonType(type))).join(delimiter)}}`;
205 | }
206 | function wrapPostgresError(error) {
207 |   if (Error.isError(error)) {
208 |     return error;
209 |   return new PostgresError(error.message, error);
               ^
PostgresError: Connection closed
 code: "ERR_POSTGRES_CONNECTION_CLOSED"

      at wrapPostgresError (internal:sql/postgres:209:10)
      at handleClose (internal:sql/shared:463:27)
(fail) postgres > a parameter that throws while encoded does not break the queries pipelined behind it [308.18ms]
204 |   return `{${values.map(arrayValueSerializer.bind(this, type, isPostgresNumericType(type), isPostgresJsonType(type))).join(delimiter)}}`;
205 | }
206 | function wrapPostgresError(error) {
207 |   if (Error.isError(error)) {
208 | 
... (truncated)

release without fix: 3 FAILED
bun test v1.4.3-canary.1 (f42e98025)

test/js/sql/postgres-bind-encode-throw.test.ts:
Container ready via docker-compose: postgres_plain at 127.0.0.1:5432
171 |   let delimiter = type === "BOX" ? ";" : ",";
172 |   return `{${values.map(arrayValueSerializer.bind(this, type, isPostgresNumericType(type), isPostgresJsonType(type))).join(delimiter)}}`;
173 | }
174 | function wrapPostgresError(error) {
175 |   if (Error.isError(error))
176 |   return new PostgresError(error.message, error);
               ^
PostgresError: Connection closed
 code: "ERR_POSTGRES_CONNECTION_CLOSED"

      at wrapPostgresError (internal:sql/postgres:176:10)
      at handleClose (internal:sql/shared:372:27)
(fail) postgres > a parameter that throws while encoded does not break the queries pipelined behind it [13.17ms]
171 |   let delimiter = type === "BOX" ? ";" : ",";
172 |   return `{${values.map(arrayValueSerializer.bind(this, type, isPostgresNumericType(type), isPostgresJsonType(type))).join(delimiter)}}`;
173 | }
174 | function wrapPostgresError(error) {
175 |   if (Error.isError(error))
176 |   return new PostgresError(error.message, error);
               ^
PostgresError: Connection cl
... (truncated)

passes on PR (with fix)

ASAN with fix: all passed
$ BUN_DEBUG_QUIET_LOGS=1 bun scripts/build.ts --profile=debug --quiet test "--reporter=junit" "--reporter-outfile=/tmp/pr_gate.xml" test/js/sql/postgres-bind-encode-throw.test.ts
bun test v1.4.3 (f42e98025)

test/js/sql/postgres-bind-encode-throw.test.ts:
Container ready via docker-compose: postgres_plain at 127.0.0.1:5432
(pass) postgres > a parameter that throws while encoded does not break the queries pipelined behind it [297.21ms]
(pass) postgres > a throwing parameter on the first execution of a statement does not break the next query [38.94ms]
(pass) postgres bind encode failure (mock server) > no partial Bind reaches the wire when a parameter throws [368.75ms]

 3 pass
 0 fail
 6 expect() calls
Ran 3 tests across 1 file. [3.42s]
__F:0:S:0

release with fix: all passed
$ bun scripts/build.ts --profile=release
[configured] bun-profile → bun (stripped) in 771ms (unchanged)
ninja: Entering directory `/workspace/bun/build/release'
[1/38] gen generated_host_exports.rs
generated_host_exports.rs: 122 exports (host=5, lazy=10, generic=107, rust=0); 242 extern-C blocks audited
[2/38] gen ZigGeneratedClasses.{cpp,h,rs}
Found 2 classes from /workspace/bun/src/jsc/resolve_message.classes.ts
  - ResolveMessage (15 fields)
  - BuildMessage (10 fields)
Found 1 classes from /workspace/bun/src/runtime/api/Archive.classes.ts
  - Archive (4 fields, 1 class fields)
Found 2 classes from /workspace/bun/src/runtime/api/BunObject.classes.ts
  - ResourceUsage (8 fields)
  - Subprocess (20 fields)
Found 1 classes from /workspace/bun/src/runtime/api/cron.classes.ts
  - CronJob (5 fields)
Found 3 classes from /workspace/bun/src/runtime/api/filesystem_router.classes.ts
  - FileSystemRouter (5 fields)
  - FrameworkFileSystemRouter (2 fields)
  - MatchedRoute (8 fields)
Found 1 classes from /workspace/bun/src/runtime/api/Glob.classes.ts
  - Glob (5 fields)
Found 1 classes from /workspace/bun/src/runtime/api/h2.classes.ts
  - H2FrameParser (32 fields)
Found 9 
... (truncated)

diff hotspot

src/sql/postgres/protocol/NewWriter.rs         |  15 ++
 src/sql_jsc/postgres/PostgresRequest.rs        | 192 +++++++++++++------------
 src/sql_jsc/postgres/PostgresSQLConnection.rs  |  12 ++
 test/js/sql/postgres-bind-encode-throw.test.ts | 182 +++++++++++++++++++++++
 4 files changed, 308 insertions(+), 93 deletions(-)

gate history · 2 passed · 0 rejected · iteration 2

evidence per changed file

file                                            reads  edits  tests
src/sql/postgres/protocol/NewWriter.rs              2      4      0
src/sql_jsc/postgres/PostgresRequest.rs             2      3      1
src/sql_jsc/postgres/PostgresSQLConnection.rs       2      1      0
test/js/sql/postgres-bind-encode-throw.test.ts      0      0      0

[robobun]

Reproduced on unfixed main (367d939) with a byte-level mock server and with a real PostgreSQL.

• Mock: a query whose parameter throws in toString leaves 42 00 00 00 00 ... in the write buffer. The server reads P D S B(len=0) (named statement) or P D B(len=0) (prepare: false). This also happens when nothing is queued behind the rejected query.
• Real server: the next query, the pipelined siblings and an open transaction fail with ERR_POSTGRES_CONNECTION_CLOSED. Since sql(postgres): reject a non-BufferSource value bound to a bytea parameter #41889 a non-BufferSource value bound to bytea triggers the same path.

USE_SYSTEM_BUN=1 bun test test/js/sql/postgres-bind-encode-throw.test.ts   # unfixed main: 1 pass, 4 fail, ["B(len=0)"]
USE_SYSTEM_BUN=1 bun test test/js/sql/postgres-bytea-bind.test.ts          # unfixed main: 6 pass, 6 fail
bun bd test test/js/sql/postgres-bind-encode-throw.test.ts                 # 5 pass
bun bd test test/js/sql/postgres-bytea-bind.test.ts                        # 12 pass

The fix is NewWriter::atomically around the three batch writers that reach write_bind. It rolls back only when nothing else touched the write buffer during the batch. PR: #34732.

[robobun]

^{Updated 7:49 AM PT - Sep 24th, 2026}

@robobun, your commit e770376 is building: #120314

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---

Walkthrough

PostgreSQL request encoding now uses atomic writer closures. If encoding returns an error and the writer epoch is unchanged, the writer truncates output to its starting offset. The PostgreSQL writer tracks write epochs and supports truncation and head-relative patch writes. Tests cover encoding failures and subsequent query behavior.

Changes

PostgreSQL atomic writes

Layer / File(s)	Summary
Writer rollback primitives src/sql/postgres/protocol/NewWriter.rs, src/sql_jsc/postgres/PostgresSQLConnection.rs	NewWriter::atomically truncates output to its starting offset when its closure returns an error and the writer epoch is unchanged. The PostgreSQL writer tracks write epochs, implements truncation, and applies the buffer head to patch-write indices.
Atomic PostgreSQL request batches src/sql_jsc/postgres/PostgresRequest.rs	Request methods wrap protocol-message and trailing FLUSH/SYNC writes in atomic writer closures.
Parameter encoding failure coverage test/js/sql/postgres-bind-encode-throw.test.ts, test/js/sql/postgres-bytea-bind.test.ts	Tests cover parameter-encoding failures, protocol messages, and successful queued, pipelined, and later queries. Bytea tests also check stored values and transaction behavior.

Priority: ➖ Normal

Merge Risk: ⚪ Minimal · up to e7703

Parameter-encoding failures should no longer leave partial Bind messages in the affected request paths. No concrete unresolved merge risk remains in the reviewed scope.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

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Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly and concisely describes the main change: discarding a partial PostgreSQL Bind when parameter encoding fails.
Description check	✅ Passed	The description explains the problem, fix, scope, limitations, test coverage, and verification results. It does not use the exact template headings, but it provides the required information in a detai…

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Actionable comments posted: 1

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Inline comments:
In `@test/js/sql/postgres-bind-throw-torn-frame.test.ts`:
- Around line 1-13: Trim the opening comment in the fault-injection test to the
established shared three-line banner, removing the extended write_bind mechanism
explanation. Apply the same cleanup to the additional commentary blocks around
the referenced test sections, preserving only the shared banner and leaving test
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• src/sql/postgres/protocol/ArrayList.rs
• src/sql/postgres/protocol/NewWriter.rs
• src/sql_jsc/postgres/PostgresRequest.rs
• src/sql_jsc/postgres/PostgresSQLConnection.rs
• test/js/sql/postgres-bind-throw-torn-frame.test.ts

[github-actions]

This PR may be a duplicate of:

1. sql(postgres): reject out-of-range JS numbers bound to int4 parameters #34708 - Also adds write buffer rollback when JS parameter encoding throws during Bind message serialization

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[robobun]

Not a duplicate, but there is overlap (already noted in the PR body). #34708's primary fix is rejecting out-of-range int4 values; it adds a mark/rollback pair at each of the six call sites as a supporting change so its new Overflow error doesn't poison the buffer. This PR's primary fix is the buffer rollback itself, done once in the writer via NewWriter::atomically so the three batch functions are self-contained and any future caller is covered, with a test that targets the throwing-valueOf/toString path directly. Whichever merges first leaves the other a small rebase.

[robobun]

Alternate approach on branch farm/04b9ba2b/pg-bind-encode-before-write: split write_bind into encode_bind_params (all JS, returns Vec<BoundValue> + format codes) and write_bind_encoded (pure writes, no JS), so the three batch entry points encode before their first write and no rollback is needed. Same test coverage (byte-capturing mock + real-server round-trips for int4/float8/text/json coercion paths). Either approach fixes the desync; leaving it to the reviewer which shape to land.

[claude]

LGTM — the earlier pgReadFrontendMessages leftover-carry nit is addressed and the rollback logic checks out.

What was reviewed:

• truncate is symmetric with offset() for both implementors (ArrayListCtx → Vec::truncate; connection Writer → byte_list.truncate(head + offset) matching OffsetByteList::len() = byte_list.len() - head).
• All write_bind call paths route through one of the three wrapped batch functions; the closure wrap is indent-only on the success path.
• Test now carries the pgReadFrontendMessages leftover across data events and accumulates received from the incoming chunk, matching the sibling mock backends.

Extended reasoning...

Overview

Adds WriterContext::truncate and a NewWriter::atomically snapshot/rollback helper, then wraps the three Postgres batch writers (bind_and_execute, prepare_and_query_with_signature, parse_and_bind_and_execute) so that when a JS parameter coercion throws mid-write_bind, the half-written B\\0\\0\\0\\0… frame is truncated out of the write buffer instead of being flushed ahead of the next query. A byte-capturing mock-backend test asserts the wire framing directly.

Security risks

None. This is error-path cleanup on the client's own outgoing buffer; no new parsing of untrusted server bytes, no auth/TLS/permission changes.

Level of scrutiny

Moderate. It touches the Postgres extended-query serialisation path, but the diff is structurally conservative: the three function bodies are wrapped in a closure with no logic changes on the success path; the new code runs only on Err. I verified:

• The postgres WriterContext trait has exactly two implementors (ArrayListCtx, connection Writer), both updated. The MySQL and js_printer WriterContext are unrelated traits.
• OffsetByteList::len() is byte_list.len() - head, so the connection Writer::truncate computing byte_list.truncate(head + offset) restores exactly the state offset() snapshotted (assuming head is unchanged across the batch, which it is — head only advances via consume() after a socket flush, not during message encoding).
• write_bind is called only from the three wrapped functions, and those three cover all six external call sites (4 in PostgresSQLConnection::advance, 2 in PostgresSQLQuery::run).

Other factors

• My prior inline nit (discarding the pgReadFrontendMessages leftover and unconditionally resetting pending) was fixed in 0fe017f; the mock now matches the sibling callers in postgres-datarow-overrun.test.ts and postgres-split-prepare-reorder-fixture.ts.
• CodeRabbit's comment-length nit was addressed and marked resolved.
• PR body has fail-before (tornAt: 104, head: "42 00 00 00 00 …") / pass-after evidence on both ASAN debug and release.
• The noted overlap with #34708 is a merge-order coordination question, not a correctness concern for this change; whichever lands first leaves the other a small rebase, and this PR's centralised-in-the-writer approach is the cleaner of the two.

[robobun]

Refreshed on top of current main. The design is unchanged: WriterContext::truncate plus NewWriter::atomically around the three batch writers. The ArrayList writer context no longer exists on main, so that part of the diff is gone. The test is replaced by test/js/sql/postgres-bind-encode-throw.test.ts, which also runs against a real PostgreSQL and checks that the siblings resolve and the connection stays usable.

[claude]

I reviewed the refreshed version and didn't find any bugs — the test rewrite also addresses my earlier note (the new mock inlines its own frame parser and carries buffered across data events correctly). A human look is still worthwhile because the pwrite change in PostgresSQLConnection.rs is a real behavior change on any connection where write_buffer.head > 0 (partial socket flush), not just cleanup for truncate.

What was reviewed:

• atomically snapshot/truncate against OffsetByteList semantics — offset(), pwrite, and truncate now all agree on head-relative coordinates; before this, LengthWriter would patch the wrong 4 bytes whenever head > 0.
• Coverage of write_bind callers — all three batch writers are wrapped, and there are no other write_bind call sites.
• The mock-server test's frame accumulator for the split-chunk issue I raised on the previous test file — fixed.

Extended reasoning...

Overview

The PR fixes a Postgres wire-protocol corruption: when a JS coercion inside write_bind throws (e.g. toString, to_number, json_stringify_fast), the partially-written B frame — header with a zero length placeholder, portal/statement names, format codes, and any parameters encoded before the throw — stayed in connection.write_buffer, so the next pipelined query's bytes followed a torn frame and the server dropped the connection. The fix adds WriterContext::truncate and a NewWriter::atomically combinator that snapshots offset() before a message group, runs the closure, and truncates back on error. All three batch writers that reach write_bind (prepare_and_query_with_signature, bind_and_execute, parse_and_bind_and_execute) are now wrapped; grepping confirms these are the only write_bind callers, and their own callers in PostgresSQLConnection::advance and PostgresSQLQuery::run all inherit the rollback.

Security risks

None identified. The change is defensive — it removes bytes from an outgoing buffer on an error path rather than adding any new parsing of untrusted input. truncate computes head + offset where both operands are internally-derived usizes bounded by byte_list.len(), and Vec::truncate is a no-op if the argument exceeds the current length, so there's no OOB write.

Level of scrutiny

Medium-high. This is the database driver's wire encoder, and the drive-by pwrite change is a substantive behavior change: Writer::offset() returns byte_list.len() - head (head-relative), but the old pwrite indexed byte_list absolutely, so LengthWriter::write() would patch the length field head bytes too early whenever a previous socket write was partial and consume() left head > 0 without compacting. The new head + index is correct and matches the coordinate system truncate needs. That's the right fix, but it changes behavior on a path (partial-flush + new pipelined write) that the new tests don't exercise directly, so a human sanity-check on that reasoning is warranted.

Other factors

The previous test file (postgres-bind-throw-torn-frame.test.ts) had a buffering bug I flagged — pgReadFrontendMessages's leftover return was discarded. The replacement test inlines its own parser that correctly carries buffered across data events and re-slices per frame, so that concern is resolved. The test asserts the exact frontend frame sequence (no B(len=0) on the wire, siblings still get B E H S) and separately runs against a real Postgres container via describeWithContainer, covering both the already-prepared (bind_and_execute in advance) and first-execution (parse_and_bind_and_execute) paths. The two self-resolved github-actions threads on this push led to a follow-up commit that only shortened a doc comment; nothing substantive is outstanding there.

[robobun]

A new report makes this more urgent, and I verified that this PR fixes it.

#41889 (merged) rejects a non-BufferSource value bound to a bytea parameter. It throws from inside the Bind encoder, so the common mistake sql`insert into files (body) values (${[1, 2, 3]})` now reaches the torn-frame path. On current main with a real PostgreSQL 16 and max: 1:

• the next query fails with ERR_POSTGRES_CONNECTION_CLOSED, the server logs invalid message length
• pipelined [bad bytea insert, valid insert of new Uint8Array([9,9]), select 2] gives [ERR_INVALID_ARG_TYPE, ERR_POSTGRES_CONNECTION_CLOSED, ERR_POSTGRES_CONNECTION_CLOSED], and the valid row is never stored
• inside sql.begin the transaction fails with Connection closed

I built this branch's src/ changes on top of current main and the symptom is gone: the query rejects alone, the siblings commit, and pg_backend_pid() is unchanged (no reconnect).

This branch is 25 commits behind main and does not contain #41889, so its tests do not cover that trigger. I pushed a rebase with extra coverage to robobun/44cd9150/postgres-bind-rollback (https://github.com/oven-sh/bun/tree/robobun/44cd9150/postgres-bind-rollback): the two commits here, cherry-picked onto main, plus one test commit that adds 6 cases to test/js/sql/postgres-bytea-bind.test.ts.

• the bytea ERR_INVALID_ARG_TYPE trigger, a jsonb value whose toJSON throws, a toString that throws, and the same with prepare: false (the parse_and_bind_and_execute path), each run twice so both the first prepare and the cached-statement bind are covered
• pipelined siblings behind a rejected parameter, checked by reading the row back from a temp table (a reconnect loses the table)
• a rejected parameter inside sql.begin, with the other two rows committed

All 15 tests in postgres-bind-encode-throw.test.ts and postgres-bytea-bind.test.ts pass on that branch. The 6 new ones fail on main.

To take it: git fetch origin robobun/44cd9150/postgres-bind-rollback && git push --force-with-lease origin FETCH_HEAD:farm/0313f824/postgres-bind-torn-frame. I did not push to this branch myself.

[alii]

@robobun the fix looks right, but the head (176d4d7) is red and its tests do not cover the bytea case. Since #41889 a bad bytea value throws inside write_bind, so main tears the Bind frame. Please:

1. Use your branch robobun/44cd9150/postgres-bind-rollback instead of this head. Same source change, plus postgres-bytea-bind.test.ts. Rebase it onto main and get a green Buildkite run with the docker postgres lanes.
2. Add a mock-server test for prepare: false (Parse, Describe and Bind in one batch). The wire must have no len= entry and no orphan P or D, and a query after the rejected one must resolve.
3. The second test in postgres-bind-encode-throw.test.ts does not set prepare: false, so it looks like a copy of the first. Make it a different case or fix its comment.
4. Please check whether a lone rejected query also sends B(len=0). If it does, say so in the body. Today the body only talks about queries behind the rejected one.
5. Land this before test(sql): prestart postgres for postgres-bytea-bind, run its tests concurrently, assert the bytes read back #42587 and sql(postgres): announce binary format for a Bind parameter only when it is binary-encoded #41976. sql(postgres): announce binary format for a Bind parameter only when it is binary-encoded #41976 seems to touch the same write_bind hunks, so it will need a rebase.

[robobun]

@alii Please do not merge this PR in its current shape. I reviewed the design again with the nested-dispatch case included (six candidate designs, each checked against main and against this branch on a real PostgreSQL). The result is a different design.

Why the rollback loses

• truncate removes the tail of the shared write_buffer and does not check who wrote it. When a conversion starts a query with .execute() and then fails, the nested query's frames are removed too.
• Main: the server drops the connection, both queries reject with ERR_POSTGRES_CONNECTION_CLOSED, and the pool reconnects. This branch: the nested request stays at the head of the queue. I reproduced the worst variant: a later query that reuses a prepared statement is written, and its row resolves the nested query (nested: resolved [{"nested":"LATER-VALUE"}]) while the later query hangs.
• The cell does not need a user throw: the native bytea rejection from sql(postgres): reject a non-BufferSource value bound to a bytea parameter #41889 reaches it through a getter. The rollback also fixes none of the re-entrant cases that do not throw (outer hangs, nested gets 08P01), which are on main today.

The design that won

• Convert every parameter before the first byte of the batch is written, and write Bind from native values (a JSC-free protocol::Bind in bun_sql, next to Parse, Describe, Execute). No user code and no native rejection then runs while a frame is open, at all six call sites and on every exit. With prepare: false that also covers the Parse and Describe. libpq, postgres.js, pg and the MySQL, Valkey and node:http2 encoders in this repo all work this way. None of them rolls back a live buffer across user code.
• Add a guard at one encode_request seam: a query dispatched while a conversion runs only enqueues. Convert-first alone is not enough. The MySQL adapter has that shape, and a nested .execute() during its bind swaps two queries' results.

Plan: three PRs

1. No behaviour change. Route the six encoder call sites through PostgresSQLConnection::encode_request. Add a byte-level test that pins the Bind bytes main writes today for every parameter type.
2. The guard. It revives sql(postgres): only enqueue queries dispatched from inside a Bind encoder #38231 by hand (its flag bit 1<<5 is KEEP_ALIVE_REQUESTED on main) and covers sql(postgres): survive close() from inside a Bind encoder #38348's close() case.
3. Convert-first. It adopts this PR's two test files and its one-line pwrite + head fix, and drops atomically/truncate. Then sql(postgres): discard a partial Bind when a parameter fails to encode #34732, sql(postgres): only enqueue queries dispatched from inside a Bind encoder #38231 and sql(postgres): survive close() from inside a Bind encoder #38348 close as superseded, with credit.

Cost for queries that never hit the bug (modelled, I will measure it with gdb instruction and allocator counts before PR 3 is ready): 0 heap allocations (one retained scratch per connection), 0 payload copies (strings held by reference, bytea read after the last conversion), about +80 to +155 instructions per 3-parameter query. The rollback costs +13 to 15.

One question for you. PR 3 stages one native temporary of at most 40 bytes per scalar parameter on every parameterized Bind. REVIEW.md asks for coercions before buffer writes, and landing-prs.md asks for no per-parameter temporaries on the success path. Do you accept the temporary? If not, PR 3 stages only the values that can run JS and streams the rest. PRs 1 and 2 are the same in both cases.

Order. Your request to land this before #41976 and #42587 came before this finding. #42587 is test-only and rebases easily. #41976 will need a rebase by hand onto PR 3 (its format-code index held across JS becomes unnecessary).

CI on 9812be4 is green (build 120104, the docker postgres lane ran both test files), so the tests are ready to move to PR 3. I start PR 1 now and leave this PR open and unchanged. If you want the common case fixed sooner, this PR plus a 16 to 20 line check (truncate only when nothing else wrote during the span) returns the nested cases to main's behaviour. Say so and I will add it.

[alii]

@robobun thanks. Yes, add the truncate-only-when-nothing-else-wrote check to this PR now, so the common case is fixed for 1.4.3. For PR 3, no per-parameter temporary on the success path: stage only the values that can run JS or be rejected natively, and stream the rest. Go ahead with PRs 1 to 3.

[robobun]

@alii Done in 85f6362. The PR is ready for review again, rebased on main (8d36bff).

The check. atomically now truncates only when nothing else touched write_buffer while the batch was written. The connection keeps a write_epoch counter. It bumps it for every Writer it hands out (the only way to append) and for every drain or free of the buffer (flush_data, cleanup). atomically reads it before and after the batch. If it changed, the tail of the buffer is not only ours: the partial message stays and the server closes the connection, exactly as on main.

Result on a real PostgreSQL, against unfixed main:

• Lone rejected query, pipelined siblings, prepare: false, transaction, bytea: fixed as before (P D S and nothing on the wire).
• A conversion that runs .execute() and then fails: same outcome as main in every cell I ran (outer statement prepared or on its first execution, nested query prepared, new, simple, or unsafe with parameters). The wrong-row case from my last comment is gone: nested: rejected ERR_POSTGRES_CONNECTION_CLOSED, the pool reconnects, the next query resolves.
• New test in postgres-bind-encode-throw.test.ts: a query dispatched from inside a conversion that then fails never gets another query's row. It times out on the previous head of this PR (9812be4) and passes now. It also passes on main, because main fails loudly there.

Cost on the success path: one more counter read per batch and one increment per Writer handed out.

One thing I saw and did not touch: with a nested new statement dispatched from advance(), the debug build aborts with panic: pending_requests underflow. That is a debug assertion outside this diff (the release build of main has no panic in that cell). It belongs to the nested-dispatch guard, PR 2.

PRs 1 to 3. Understood: no per-parameter temporary on the success path. PR 3 stages only the values that can run JS or be rejected natively and streams the rest. PR 1 (the encode_request seam and a byte-level corpus of today's Bind bytes, no behaviour change) is built and green locally. I open it next.

[coderabbitai]

Actionable comments posted: 1

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Inline comments:
In `@src/sql/postgres/protocol/NewWriter.rs`:
- Around line 67-80: Update NewWriter::atomically to stage writes in an isolated
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[claude]

Nothing blocking. The comments below are optional suggestions. There is no need to push a fix for them before merging.

Beyond the inline findings, I also checked that every mutation of write_buffer in PostgresSQLConnection.rs goes through writer(), the flush-path consume(), or clear_and_free() — all three bump write_epoch, so a nested dispatch or drain during a conversion cannot slip past the truncate guard. The same absolute-index pwrite vs head-relative offset() mismatch exists in src/sql_jsc/mysql/MySQLConnection.rs (Writer::pwrite), but it is pre-existing and outside this diff.

Extended reasoning...

The change adds an epoch-guarded rollback (NewWriter::atomically) around the three Postgres batch writers that call into user JS while a Bind frame is open, plus head-relative pwrite/truncate on the connection writer; it touches no auth or injection surface. Not approving because it is a non-trivial change to the wire-protocol write path with re-entrancy semantics, the author describes it as an interim fix pending a redesign, and a human maintainer is already engaged on the thread.

[claude]

🔴 With prepare: false, a script whose last query rejects while a parameter is encoded no longer exits on its own. do_run takes the connection's KeepAlive ref (PostgresSQLQuery.rs:817) and then runs advance_and_flush(); when parse_and_bind_and_execute fails, the rollback at PostgresRequest.rs:377 leaves nothing to send, so no reply ever reaches the idle check in on_data that releases the ref. Fix: when a rolled-back batch leaves the queue and write buffer empty, release the ref as on_data's idle block does (or take it only if the request is still queued after advance_and_flush). On the base the partial Bind went out and the server's close released it.

Why this was flagged

A connection created with prepare: false (ConnectionFlags::USE_UNNAMED_PREPARED_STATEMENTS) runs one query with a parameter whose encoding fails (throwing toString, number[] to bytea) while no other query is in flight, e.g. the last statement of a CLI script that does not call sql.close(). PostgresSQLQuery.rs:693-769 skips writing for unnamed statements with params, pushes the request at :810, refs poll_ref at :817, then calls connection.advance_and_flush() at :832. advance() at PostgresSQLConnection.rs:2183 calls parse_and_bind_and_execute; the closure at PostgresRequest.rs:377 fails, NewWriter.rs:75-76 truncates the buffer to its start, the request is rejected via req.on_js_error at :2194 and popped by discard_request at :2207; flush_data at :1837 finds an empty buffer. poll_ref is only unref'd in on_data's idle block (PostgresSQLConnection.rs:1053-1062), on close/failure (:814, :1413, :1509) or by an explicit unref(); none of those runs because no bytes were sent and no reply arrives, and idleTimeout defaults to 0 (shared.ts:878) so no timer closes the connection. The process therefore…

Verification: normal — when a prepare: false connection is idle and the next query's parameter encoding fails with nothing else in flight (e.g. last statement of a script that never calls sql.close(), default idleTimeout 0), the process no longer exits. Mechanism traced in code: do_run (src/sql_jsc/postgres/PostgresSQLQuery.rs:766-768) skips writing for unnamed statements with params, pushes the…

[robobun]

@alii One late review finding on this PR is real, and it merged with it: with prepare: false, a script whose last query is rejected while a parameter is encoded no longer exits on its own when that query ran from a later tick (nothing is sent, so no reply releases the event loop ref that do_run took). Before this PR the server's close released it. The fix is #43898: two lines in do_run plus the idle check of on_data moved into one function, with a subprocess test that times out without it. It should go into 1.4.3 together with this PR.