herodb/docs/cmds.md

Backend Support

HeroDB supports two storage backends, both with full encryption support:

• redb (default): Full-featured, optimized for production use
• sled: Alternative embedded database with encryption support

Starting HeroDB with Different Backends

# Use default redb backend
./target/release/herodb --dir /tmp/herodb_redb --port 6379

# Use sled backend
./target/release/herodb --dir /tmp/herodb_sled --port 6379 --sled

# Use redb with encryption
./target/release/herodb --dir /tmp/herodb_encrypted --port 6379 --encrypt --key mysecretkey

# Use sled with encryption
./target/release/herodb --dir /tmp/herodb_sled_encrypted --port 6379 --sled --encrypt --key mysecretkey

Command Support by Backend

Command Category	redb	sled	Notes
Strings
SET	✅	✅	Full support
GET	✅	✅	Full support
DEL	✅	✅	Full support
EXISTS	✅	✅	Full support
INCR/DECR	✅	✅	Full support
MGET/MSET	✅	✅	Full support
Hashes
HSET	✅	✅	Full support
HGET	✅	✅	Full support
HGETALL	✅	✅	Full support
HDEL	✅	✅	Full support
HEXISTS	✅	✅	Full support
HKEYS	✅	✅	Full support
HVALS	✅	✅	Full support
HLEN	✅	✅	Full support
HMGET	✅	✅	Full support
HSETNX	✅	✅	Full support
HINCRBY/HINCRBYFLOAT	✅	✅	Full support
HSCAN	✅	✅	Full support with pattern matching
Lists
LPUSH/RPUSH	✅	✅	Full support
LPOP/RPOP	✅	✅	Full support
LLEN	✅	✅	Full support
LRANGE	✅	✅	Full support
LINDEX	✅	✅	Full support
LTRIM	✅	✅	Full support
LREM	✅	✅	Full support
BLPOP/BRPOP	✅	❌	Blocking operations not in sled
Expiration
EXPIRE	✅	✅	Full support in both
TTL	✅	✅	Full support in both
PERSIST	✅	✅	Full support in both
SETEX/PSETEX	✅	✅	Full support in both
EXPIREAT/PEXPIREAT	✅	✅	Full support in both
Scanning
KEYS	✅	✅	Full support with patterns
SCAN	✅	✅	Full cursor-based iteration
HSCAN	✅	✅	Full cursor-based iteration
Transactions
MULTI/EXEC/DISCARD	✅	❌	Only supported in redb
Encryption
Data-at-rest encryption	✅	✅	Both support age encryption
AGE commands	✅	✅	Both support AGE crypto commands
Full-Text Search
FT.CREATE	✅	✅	Create search index with schema
FT.ADD	✅	✅	Add document to search index
FT.SEARCH	✅	✅	Search documents with query
FT.DEL	✅	✅	Delete document from index
FT.INFO	✅	✅	Get index information
FT.DROP	✅	✅	Drop search index
FT.ALTER	✅	✅	Alter index schema
FT.AGGREGATE	✅	✅	Aggregate search results

Performance Considerations

• redb: Optimized for concurrent access, better for high-throughput scenarios
• sled: Lock-free architecture, excellent for specific workloads

Encryption Features

Both backends support:

• Transparent data-at-rest encryption using the age encryption library
• Per-database encryption (databases >= 10 are encrypted when --encrypt flag is used)
• Secure key derivation using the master key

Backend Selection Examples

# Example: Testing both backends
redis-cli -p 6379 SET mykey "redb value"
redis-cli -p 6381 SET mykey "sled value"

# Example: Using encryption with both
./target/release/herodb --port 6379 --encrypt --key secret123
./target/release/herodb --port 6381 --sled --encrypt --key secret123

# Both support the same Redis commands
redis-cli -p 6379 HSET user:1 name "Alice" age "30"
redis-cli -p 6381 HSET user:1 name "Alice" age "30"

# Both support SCAN operations
redis-cli -p 6379 SCAN 0 MATCH user:* COUNT 10
redis-cli -p 6381 SCAN 0 MATCH user:* COUNT 10

Migration Between Backends

To migrate data between backends, use Redis replication or dump/restore:

# Export from redb
redis-cli -p 6379 --rdb dump.rdb

# Import to sled
redis-cli -p 6381 --pipe < dump.rdb