# Dragonfly v1.40.0

- Product: Dragonfly (https://whatsnew.fyi/product/dragonfly)
- Vendor: DragonflyDB
- Date: 2026-08-04
- Version: v1.40.0
- Original notes: https://github.com/dragonflydb/dragonfly/releases/tag/v1.40.0
- Permalink: https://whatsnew.fyi/product/dragonfly/releases/v1.40.0

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- **added** — Add Cuckoo Filter data type with CF.RESERVE, CF.ADD, CF.ADDNX, CF.EXISTS, CF.MEXISTS, CF.INSERT, CF.INSERTNX, CF.INFO, CF.COUNT, CF.DEL, and CF.COMPACT commands
- **added** — Add RDB serialization support for Cuckoo filters, enabling DUMP/RESTORE and persistence
- **added** — Add EPSILON parameter for HNSW-backed VECTOR_RANGE queries to control overscan and recall near the radius boundary
- **added** — Add support for KNN query attribute block syntax with EF_RUNTIME and YIELD_DISTANCE_AS
- **added** — Add RESET command to reset a connection to a fresh-connection baseline
- **added** — Add Redis-compatible WAIT command to block until replicas acknowledge writes
- **added** — Add HGETEX and HPEXPIRETIME hash commands
- **added** — Add BF.INFO command for Bloom filter metadata
- **added** — Add BM25STD.NORM and BM25STD.TANH scorers for FT.SEARCH, FT.AGGREGATE, and FT.HYBRID
- **added** — Add optional path argument to JSON.STRAPPEND, defaulting to root
- **added** — Add HELP subcommand to SAVE and BGSAVE
- **added** — Add connection_memory_bytes Prometheus metric tracking active client connection memory
- **added** — Add snapshot_egress_limit_bytes to throttle per-shard socket egress during RDB and snapshot saves
- **added** — Add write_connection_throttling_sleep_usec to throttle pipelined write batches
- **changed** — Vector search now stores and computes vectors at native declared width instead of always widening to FLOAT32, reducing memory usage
- **changed** — INFO command now includes TLS certificate metadata (subject, issuer, validity dates) when TLS is enabled
- **changed** — Enable event-driven V2 IO loop for TLS connections
- **changed** — Enable tagged chunk serialization by default during snapshotting and replication
- **changed** — GET now returns large raw strings (≥16KB) via zero-copy borrowed view instead of copying
- **fixed** — Fix cascading replication correctness when an intermediate replica switches upstream masters under experimental cascaded partial sync
- **fixed** — Fix crash where an older replica reconnecting to a promoted master could crash the master due to a stale partial-sync index
- **security** — Fix CVE-2025-32023 in hyperloglog.c by re-syncing with upstream Valkey

#### Dragonfly v1.40.0

This is one of our biggest releases yet—both in terms of feature quality, total contributions, and the highest number of external contributors in the last two years.

This release delivers major new functionality alongside a large body of correctness and stability fixes for tiered storage, replication, pub/sub, and the experimental V2 I/O loop.

We added a new data type: Cuckoo Filters (CF.RESERVE, CF.ADD/ADDNX, CF.EXISTS/MEXISTS, CF.INSERT/INSERTNX, CF.INFO/COUNT/DEL/COMPACT, and RDB persistence). This brings Dragonfly to parity with RedisBloom's probabilistic structures alongside expanded Bloom filter (BF.INFO) and HyperLogLog support.

Vector search gains native-width storage across all vector dtypes, EPSILON-tuned HNSW range queries, and EF_RUNTIME control. Meanwhile, a long list of fixes hardens tiered-storage interactions with strings, hashes, lists, bitops, and HLL commands, in addition to several replication-consistency fixes around lazy TTL expiry. Performance work includes lazy lock-table registration, zero-copy GET, and replica-side command batching.

- New Cuckoo Filter data type with full command set and RDB support.
- Vector search now stores/computes at native declared width, plus EPSILON and EF_RUNTIME tuning for HNSW.
- Numerous tiered-storage and replication consistency fixes (HLL, hashes, lists, bitops, hash-field TTL expiry).

##### Highlights
- Added a full Cuckoo Filter data type with RDB persistence, bringing RedisBloom parity for probabilistic structures (#7646, #7700).
- Vector search now stores/computes vectors at native declared width instead of always widening to FLOAT32, reducing memory usage (#7849).
- Re-synced hyperloglog.c with upstream Valkey, fixing CVE-2025-32023 and adding AVX2/NEON kernels [up to ~29x speedup on dense HLL merges] (#7961).

##### Commands
- INFO now includes TLS certificate metadata (subject, issuer, validity dates) when TLS is enabled (#7844).
- SAVE and BGSAVE now support a HELP subcommand (#7865).
- JSON.STRAPPEND now supports an optional path argument, defaulting to root (#7868).
- Implemented the RESET command, resetting a connection to a fresh-connection baseline (#7760).
- Added Redis-compatible WAIT command, blocking until replicas acknowledge writes (#7454).
- Added HGETEX and HPEXPIRETIME hash commands (#7717).
- Added BF.INFO for Bloom filter metadata (#7761).
- Added BM25STD.NORM and BM25STD.TANH scorers for FT.SEARCH/AGGREGATE/HYBRID (#7692).

##### Vector Search
- Vector search (FLAT and HNSW) now stores and computes distances at native declared width (INT8, UINT8, FLOAT16, BFLOAT16, FLOAT32, FLOAT64) (#7849).
- Added EPSILON parameter for HNSW-backed VECTOR_RANGE queries to control overscan/recall near the radius boundary (#7718).
- Added support for KNN query attribute block syntax (`=>{$EF_RUNTIME: ...; $YIELD_DISTANCE_AS: ...}`) (#7708).
- Fixed filtered KNN vector search to serialize only actual winners instead of every pre-filter match, cutting CPU/memory overhead (#7670).

##### Cuckoo Filter
- Added CF.INSERT and CF.INSERTNX for bulk insertion, with optional CAPACITY and NOCREATE (#7719).
- Added compaction: CF.DEL auto-compacts past 10% deletions, plus a manual CF.COMPACT command (#7702).
- Added CF.EXISTS and CF.MEXISTS for single/multi-item membership checks (#7682).
- Added CF.ADD and CF.ADDNX, auto-creating filters with a default capacity of 1024 (#7681).

##### Probabilistic Data Structures
- Added RDB serialization support for Cuckoo filters, enabling DUMP/RESTORE and persistence (#7700).
- Added CF.INFO, CF.COUNT, and CF.DEL for filter metadata, occurrence counts, and item removal (#7691).
- Added the base Cuckoo Filter data type via CF.RESERVE, with a new CUCKOO_FILTER ACL category (#7646).

##### Performance
- Extended parse-in-proactor pipelining optimization to more fiber park spots (shard hops, suspended replies on tiered I/O) (#7916).
- Added `snapshot_egress_limit_by

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