دليل هندسي متقدم: Freelance Python Django Programmer: Zero-Downtime PostgreSQL Migrations. ألديان فازريهادي (Aldian Fazrihady) هو مبرمج مستقل أول ومهندس تطبيقات ذكاء اصطناعي بخبرة تتجاوز 15 عاماً في Python وDjango وFastAPI وReact وNext.js وTypeScript وGolang وأنظمة الذكاء الاصطناعي (RAG وMCP وGoogle ADK).
How senior freelance Python & Django programmer Aldian Fazrihady executes zero-downtime PostgreSQL schema migrations on multi-terabyte production tables.
from django.contrib.postgres.operations import AddIndexConcurrently
from django.db import migrations, models
class Migration(migrations.Migration):
atomic = False # Required for CONCURRENTLY operations in PostgreSQL
dependencies = [
("billing", "0042_invoice_currency_code"),
]
operations = [
migrations.SeparateDatabaseAndState(
database_operations=[
migrations.RunSQL(
sql="SET lock_timeout = '2s'; ALTER TABLE billing_invoice ADD COLUMN IF NOT EXISTS stripe_Sync_status varchar(32);",
reverse_sql="ALTER TABLE billing_invoice DROP COLUMN IF EXISTS stripe_sync_status;",
),
],
state_operations=[
migrations.AddField(
model_name="invoice",
name="stripe_sync_status",
field=models.CharField(max_length=32, null=True, blank=True),
),
],
),
AddIndexConcurrently(
model_name="invoice",
index=models.Index(fields=["tenant_id", "stripe_sync_status"], name="idx_inv_tenant_stripe_sync"),
),
]