Support RDB v14 - Support XNACK (part 1) by moticless · Pull Request #98 · redis/librdb

moticless · 2026-05-19T14:05:35Z

Add support for parsing RDB v14 - XNACK (RDB_TYPE_STREAM_LISTPACKS_5.)

Core Parser:

Added RDB_TYPE_STREAM_LISTPACKS_5 (27) opcode for v14 streams
Added placeholder for RDB_TYPE_ARRAY (28) - will error cleanly
Parse per-consumer-group NACK zone (count + stream IDs)
Added handleStreamNackZoneEntry callback to public API

Handlers:

JSON: Emit NACKed IDs as "nacked": ["id1", "id2", ...] array
RESP: Batch NACKed entries into XNACK FAIL IDS ... RETRYCOUNT
- Mirrors AOF rewrite behavior (64 IDs per batch)
- Silently dropped on targets < 8.8 (XNACK landed in 8.8)
- Batches consecutive IDs with same delivery_count
Filter: Pass through NACK zone entries

Version Support:

Added Redis 8.8 → RDB v14 mapping in src/redisver.h

Notes

NACK zone metadata is informational; streams still replay correctly via XADD/XGROUP/XCLAIM on older targets
RDB_TYPE_ARRAY placeholder added but not implemented (future work)

Note

Medium Risk
Updates core stream parsing and RESP/JSON emitters to handle new v14 encodings, which could affect correctness of stream replay and raw RESTORE payloads. Risk is mitigated by new fixtures and unit/integration tests covering both downgrade behavior and 8.8+ XNACK output.

Overview
Adds RDB v14 stream support for RDB_TYPE_STREAM_LISTPACKS_5 by parsing the per-consumer-group NACK zone and surfacing it via a new public callback handleStreamNackZoneEntry.

Extends the JSON and RESP exporters to consume this callback: JSON now emits a per-group "nacked" array of entry IDs, while RESP generation batches NACKed IDs into XNACK ... FAIL IDS ... RETRYCOUNT ... FORCE for Redis targets >= 8.8 (and drops NACK metadata for older targets). Also adds a clean error placeholder for the new v14 RDB_TYPE_ARRAY encoding.

Updates version mapping (Redis 8.8 -> RDB v14), adjusts CI Redis build flags to avoid clang+LTO failures on Ubuntu, and adds/updates fixtures and tests to cover v14 parsing, RESP output for targets 8.6 vs 8.8, and the new unsupported-type error path.

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…t entry Surfaces the parser's remaining-count to the NACK-zone callback so the RESP handler can flush the in-progress XNACK batch exactly when the zone ends, instead of relying on flushes in toRespEndKey, toRespStreamNewCGroup and toRespStreamIdmpMeta. Removes those three cross-callback flush sites. Fixes the symptom where XCFGSET could be emitted between XNACK commands of the same CG (XCFGSET landed between the dc=0 and dc=1 batches when the last NACK batch hadn't reached AOF_REWRITE_ITEMS_PER_CMD). The final command order now matches Redis's AOF rewrite emission at redis2/src/aof.c:2387-2442 (XNACK ... then XCFGSET). Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Add support for the second Redis 8.8 RDB v14 type, RDB_TYPE_ARRAY (opcode 28), following the Stream XNACK work merged in #98. This change adds ABI-compatible public APIs for array metadata and element callbacks, an insert-index sentinel, and an invalid-state error. It also adds built-in array emission for JSON, RESP, and Print handlers. JSON preserves uint64 fidelity by stringifying indexes. RESP emits ARMSET batches and ARSEEK when a persisted non-default insert cursor exists, or uses RESTORE when supported by the target.

cursor Bot reviewed May 19, 2026

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Comment thread src/ext/handlersToResp.c Outdated

Comment thread src/ext/handlersToResp.c Outdated

moticless force-pushed the support-v14-xnack branch 4 times, most recently from d73b252 to eebe93b Compare May 20, 2026 07:48

Support RDB v14 - Support XNACK (part 1)

742062e

moticless force-pushed the support-v14-xnack branch from eebe93b to 742062e Compare May 20, 2026 10:05