Redis Shards Distribution

script.py

import binascii

# Define nodes with precise slot ranges based on Redis cluster configuration
nodes = [
    {"name": "node-0001", "ranges": [range(2730, 8192)]},
    {"name": "node-0002", "ranges": [range(8192, 9767), range(12498, 16384)]},
    {"name": "node-0003", "ranges": [range(0, 2730), range(9767, 12498)]}
]

# Define the keys to calculate hash slots
keys = [
    "{trend:products}:monthly",
    "{trend:products}:weekly",
    "{trend:products}:biweekly",
    "{trend:products}:daily",
    "{trend:products}:yearly",
    "{trend:offices}:monthly",
    "{trend:offices}:weekly",
    "{trend:cities}:monthly",
    "{trend:cities}:weekly"
]

def calculate_slot(key):
    # Extract hash tag within {} or use the entire key if no hash tag
    if '{' in key and '}' in key:
        hash_tag = key[key.index('{') + 1:key.index('}')]
    else:
        hash_tag = key

    # Calculate CRC16 and map to one of the 16384 slots
    crc = binascii.crc_hqx(hash_tag.encode('utf-8'), 0)
    slot = crc % 16384
    return slot

def find_node_for_slot(slot):
    for node in nodes:
        for slot_range in node["ranges"]:
            if slot in slot_range:
                return node["name"]
    return "Unknown Node"

# Calculate and display the slot and node for each key
for key in keys:
    slot = calculate_slot(key)
    node = find_node_for_slot(slot)
    print(f"Key: {key}, Slot: {slot}, Node: {node}")