codesnips

database

python 
from alembic import op
import sqlalchemy as sa

revision = "20240612_add_status"
down_revision = "20240515_create_orders"
branch_labels = None

Zero-Downtime NOT NULL Column Backfill with Alembic and SQLAlchemy

alembic sqlalchemy migrations
by codesnips 2 tabs
python 
from django.db import models


class Product(models.Model):
    name = models.CharField(max_length=200)
    sku = models.CharField(max_length=50)

Django model meta options for database optimization

django python models
by Priya Sharma 1 tab
python 
from django.db import models
from django.contrib.postgres.indexes import GinIndex, BTreeIndex


class Order(models.Model):
    customer = models.ForeignKey('Customer', on_delete=models.CASCADE)

Django database indexes for query performance

django python database
by Priya Sharma 1 tab
go 
package bank

import "errors"

var ErrVersionConflict = errors.New("optimistic lock: version conflict")
var ErrInsufficientFunds = errors.New("insufficient funds")

Optimistic Locking in Go With a Version Column on UPDATE

optimistic-locking concurrency postgres
by codesnips 3 tabs
ruby 
class CreateComments < ActiveRecord::Migration[6.1]
  def change
    create_table :comments do |t|
      t.references :commentable, polymorphic: true, null: false
      t.references :author, null: false, foreign_key: { to_table: :users }
      t.text :body, null: false

Polymorphic associations for flexible relationships

rails activerecord database
by Alex Kumar 3 tabs
ini 
; PgBouncer configuration file

[databases]
; Database connection strings
mydb = host=localhost port=5432 dbname=mydb
analytics = host=replica.example.com port=5432 dbname=mydb

Connection pooling and configuration

database connection-pooling pgbouncer
by Maria Garcia 2 tabs
python 
from django.db import transaction
from django.shortcuts import get_object_or_404
from django.http import JsonResponse
from .models import Product

Django select_for_update for database locking

django python database
by Priya Sharma 1 tab
ruby 
require 'activerecord-import'

class BulkImportPostsService
  BATCH_SIZE = 1000

  def initialize(csv_file_path)

Bulk operations with ActiveRecord import

rails performance activerecord
by Alex Kumar 1 tab
kotlin 
package com.example.myapp.data.local

import android.content.Context
import androidx.room.*
import androidx.sqlite.db.SupportSQLiteDatabase
import kotlinx.coroutines.CoroutineScope

Room database for local persistence

kotlin android room
by Alex Chen 2 tabs
sql 
-- Primary server configuration (postgresql.conf)
-- wal_level = replica
-- max_wal_senders = 10
-- wal_keep_size = 64MB
-- hot_standby = on

Database replication and high availability strategies

database replication high-availability
by Maria Garcia 2 tabs
ruby 
class AddLockVersionToPosts < ActiveRecord::Migration[6.1]
  def change
    add_column :posts, :lock_version, :integer, default: 0, null: false
  end
end

Optimistic locking for concurrent updates

rails database concurrency
by Alex Kumar 2 tabs
sql 
-- Migration naming convention: V{version}__{description}.sql
-- Example: V001__create_users_table.sql

-- Migration 1: Create initial schema
-- V001__create_users_table.sql
CREATE TABLE users (

Database schema migrations and versioning

database migrations schema-evolution
by Maria Garcia 2 tabs