mysql

-- Logical backup with pg_dump
-- Single database
-- pg_dump -h localhost -U postgres -d mydb -F c -f mydb_backup.dump

-- All databases
-- pg_dumpall -h localhost -U postgres -f all_databases.sql

module RetryableTransaction
  module_function

  RETRIABLE = [ActiveRecord::Deadlocked, ActiveRecord::LockWaitTimeout].freeze

  def run(max_retries: 3, base_delay: 0.05, &block)

-- Basic EXPLAIN
EXPLAIN
SELECT * FROM users WHERE email = 'alice@example.com';

-- EXPLAIN with cost and row estimates
-- Output shows: Seq Scan on users (cost=0.00..15.50 rows=1 width=100)

-- Create basic index
CREATE INDEX idx_users_email ON users(email);

-- Unique index (enforces uniqueness)
CREATE UNIQUE INDEX idx_users_username ON users(username);

<?php

namespace App\Http\Controllers\Api;

use App\Http\Controllers\Controller;
use App\Http\Resources\PostResource;

-- Primary server configuration (postgresql.conf)
-- wal_level = replica
-- max_wal_senders = 10
-- wal_keep_size = 64MB
-- hot_standby = on