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scylladb/keys
Piotr Smaron 71542206bc cql: return InvalidRequest for oversized partition/clustering keys
When a partition key or clustering key value exceeds the 64 KiB limit
(65535 bytes serialized), Scylla used to raise a generic
std::runtime_error "Key size too large: N > M" from the low-level
compound-key serializer. That error surfaced to clients as a CQL
server error (code 0x0000, "NoHostAvailable"-looking), which is both
ugly and incompatible with Cassandra - Cassandra returns a clean
InvalidRequest with the message "Key length of N is longer than
maximum of M".

Fix this at the single chokepoint: compound_type::serialize_value in
keys/compound.hh. The serializer is on every path that materializes a
key - INSERT/UPDATE/DELETE/BATCH build mutations through it, and
SELECT builds partition and clustering ranges through it - so a single
throw replacement produces a clean InvalidRequest consistently across
all paths and all key shapes (single, compound PK, composite CK).

The previous approach on this PR branch patched three call sites in
cql3/restrictions/statement_restrictions.cc, which only covered
SELECT, duplicated the check, and placed it mid-restrictions code
(flagged in review). Dropping those changes in favour of the
root-cause fix here.

Un-xfail the tests this fixes:
- test/cqlpy/test_key_length.py: test_insert_65k_pk, test_insert_65k_ck,
  test_where_65k_pk, test_where_65k_ck, test_insert_65k_ck_composite,
  test_insert_total_compound_pk_err, test_insert_total_composite_ck_err.
- test/cqlpy/cassandra_tests/.../insert_test.py: testPKInsertWithValueOver64K,
  testCKInsertWithValueOver64K.
- test/cqlpy/cassandra_tests/.../select_test.py: testPKQueryWithValueOver64K.

test_insert_65k_pk_compound stays xfail: its oversized value gets
rejected by the Python driver's CQL wire-protocol encoder (see
CASSANDRA-19270) before reaching the server, so the fix can't apply.
Updated its reason. testCKQueryWithValueOver64K stays xfail with an
updated reason: Cassandra silently returns empty for an oversized
clustering key in WHERE, while Scylla now throws InvalidRequest - a
deliberate choice mirroring the partition-key case, documented in
the discussion on #10366.

Add three tight-boundary tests (addressing review feedback on the
previous revision) that pin MAX+1 behaviour for SELECT and INSERT of
both partition and clustering keys.

Update test/cluster/dtest/limits_test.py to match the new message
("Key length of \\d+ is longer than maximum of 65535").

fixes #10366
fixes #12247

Co-authored-by: Alexander Turetskiy <someone.tur@gmail.com>

Closes scylladb/scylladb#23433
2026-05-11 16:56:35 +03:00
..
2026-04-12 19:46:33 +03:00