"project": "Delta_Deployment_v2", "changes": [ "file": "/etc/nginx/conf.d/app.conf", "action": "update", "source": "staging/app.conf", "db": "user_profiles", "query": "INSERT INTO logins VALUES ('2025-03-15')" ], "rollback": [ "file": "/etc/nginx/conf.d/app.conf", "action": "restore", "backup": "/backups/app.conf.bak" ]
-- delta_20250315_add_last_login.sql ALTER TABLE users ADD COLUMN last_login TIMESTAMP; -- Reversible delta -- ALTER TABLE users DROP COLUMN last_login; The script applies this only to tenants that haven't received the change. Media companies managing petabyte-scale assets use Project Delta Scripts to sync content between edge nodes. Instead of rsync (which still scans directories), the script uses a manifest of block-level deltas, transferring only changed byte ranges. Writing Your First Project Delta Script: A Step-by-Step Guide Let's build a simple but functional Project Delta Script for syncing a local directory to a remote server. We'll use Python and rsync principles but with delta logic. Step 1: Define the Delta Manifest Structure Create manifest.json : Project Delta Script
with open("manifest.json", "r") as mf: manifest = json.load(mf) manifest["deltas"] = deltas with open("manifest.json", "w") as mf: json.dump(manifest, mf) #!/bin/bash # Read deltas from manifest.json (using jq) for file in $(jq -r '.deltas[].file' manifest.json); do echo "Transferring $file" rsync -az --relative "/local/app/$file" "deploy@192.168.1.100:/opt/app/" done Update state cp previous_hashes.json previous_hashes.bak python -c "import json; h=json.load(open('previous_hashes.json')); m=json.load(open('manifest.json')); [h.update(d['file']:d['hash']) for d in m['deltas']]; json.dump(h, open('previous_hashes.json','w'))" Step 4: Rollback Procedure The rollback script restores the previous state: Writing Your First Project Delta Script: A Step-by-Step
import os, json, hashlib def hash_file(path): h = hashlib.sha256() with open(path, 'rb') as f: for chunk in iter(lambda: f.read(4096), b""): h.update(chunk) return h.hexdigest() "w") as mf: json.dump(manifest
local_files = {} for root, dirs, files in os.walk("/local/app"): for f in files: full = os.path.join(root, f) local_files[f] = hash_file(full) try: with open("previous_hashes.json") as p: previous = json.load(p) except: previous = {}