nyx-kv hashes

Hashes store field-value pairs under a single key, perfect for user profiles or structured data. HSET can set multiple fields in one command.

Code

// nyx-kv hashes -- HSET, HGET, HGETALL for structured data

fn resp_cmd(parts: Array) -> String {
    var sb: StringBuilder = StringBuilder.new()
    sb.append("*")
    sb.append(int_to_string(parts.length()))
    sb.append("\r\n")
    var i: int = 0
    while i < parts.length() {
        let p: String = parts[i]
        sb.append("$")
        sb.append(int_to_string(p.length()))
        sb.append("\r\n")
        sb.append(p)
        sb.append("\r\n")
        i = i + 1
    }
    return sb.to_string()
}

fn main() -> int {
    let fd: int = tcp_connect("127.0.0.1", 6380)
    if fd < 0 {
        print("connection failed")
        return 1
    }

    // Store a user profile as a hash
    tcp_write(fd, resp_cmd(["HSET", "user:1", "name", "Alice", "age", "30", "city", "Buenos Aires"]))
    let hset_reply: String = tcp_read_line(fd)
    print("HSET -> " + hset_reply.trim())

    // Get a single field
    tcp_write(fd, resp_cmd(["HGET", "user:1", "name"]))
    let hget_hdr: String = tcp_read_line(fd)
    let name: String = tcp_read_line(fd)
    print("HGET name -> " + name.trim())

    // Check if a field exists
    tcp_write(fd, resp_cmd(["HEXISTS", "user:1", "age"]))
    let exists: String = tcp_read_line(fd)
    print("HEXISTS age -> " + exists.trim())

    // Get the number of fields
    tcp_write(fd, resp_cmd(["HLEN", "user:1"]))
    let hlen: String = tcp_read_line(fd)
    print("HLEN -> " + hlen.trim())

    tcp_close(fd)
    return 0
}

Output

HSET -> :3
HGET name -> Alice
HEXISTS age -> :1
HLEN -> :3

Explanation

A hash is a key that maps to an inner Map of field -> string. HSET user:1 name Alice age 30 city "Buenos Aires" writes three fields in a single command — more efficient than three separate SET calls and keeps the profile grouped under one key.

Use hashes when you'd otherwise flatten nested structure into keys like user:1:name, user:1:age. A single hash is easier to delete (DEL user:1 drops everything), easier to enumerate (HGETALL, HKEYS, HVALS), and uses less memory server-side because the top-level key is stored once.

Common patterns: user profiles, feature flags per account, configuration bundles, and shopping carts where each field is a product id and each value is the quantity.

Source: examples/by-example/73-kv-hashes.nx