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docs/cmds.md

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+## 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
+
+```bash
+# 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](age.tech) 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
+
+```bash
+# 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:
+
+```bash
+# Export from redb
+redis-cli -p 6379 --rdb dump.rdb
+
+# Import to sled
+redis-cli -p 6381 --pipe < dump.rdb
+```