RocksDB Storage Engine

warning

RocksDB support is experimental.

The RocksDB engine (rocksdb) uses the RocksDB library with Log-Structured Merge (LSM) tree storage. LSM trees optimize for write throughput by buffering writes in memory and periodically flushing them to sorted disk files.

LSM Tree Architecture

LSM tree characteristics:

• Write path: Writes go to an in-memory buffer, then flush to Level 0 as sorted string table (SST) files
• Compaction: Background process merges SST files and moves data to lower levels
• Read path: Reads check the write buffer, then search levels from L0 downward
• Write amplification: Data may be rewritten multiple times during compaction
• Space amplification: Multiple versions exist temporarily during compaction

When to Use RocksDB

RocksDB is suited for:

• Write-heavy workloads where sequential disk writes improve throughput
• Time-series data with append-mostly patterns
• Workloads tolerant of read amplification (multiple disk reads per query)

Consider aipersist for:

• Read-heavy or balanced workloads
• Point lookups requiring consistent latency
• Workloads sensitive to write amplification

Profile Configuration

Property	Default	Description
engine	-	Must be "rocksdb"
sizeBytes	Dynamic	Storage allocation. Defaults to max(256 MB, 20% of physical RAM)
writeBufferSizeBytes	67108864	Write buffer size (64 MB)

Engine Configuration

Property	Default	Description
flushDelayMillis	100	Delay before RAFT-triggered flush

# Configure flush delay
node config update ignite.storage.engines.rocksdb.flushDelayMillis=50

Configuration Example

{
  "ignite": {
    "storage": {
      "profiles": [
        {
          "engine": "rocksdb",
          "name": "write_heavy_profile",
          "sizeBytes": 4294967296,
          "writeBufferSizeBytes": 134217728
        }
      ]
    }
  }
}

# CLI equivalent
node config update "ignite.storage.profiles:{write_heavy_profile{engine:rocksdb,sizeBytes:4294967296,writeBufferSizeBytes:134217728}}"

Usage

-- Create a zone for write-heavy tables
CREATE ZONE logging_zone
    WITH PARTITIONS=10, REPLICAS=2,
    STORAGE PROFILES ['write_heavy_profile'];

-- Create a table for event logging
CREATE TABLE events (
    event_id BIGINT PRIMARY KEY,
    event_type VARCHAR,
    payload VARCHAR,
    created_at TIMESTAMP
) ZONE logging_zone STORAGE PROFILE 'write_heavy_profile';