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Database scaling & optimization

Indexing, connection pooling, read replicas, query tuning, and throughput-aware SQL.

4 matches

How to Avoid SELECT * and Mock SQL Column Queries in Python

Mock a SQLite cursor to verify that queries specify explicit columns instead of using SELECT *.

import sqlite3
from unittest.mock import Mock, patch


def get_user_emails(connection):
    """Fetch only the required columns instead of SELECT *."""
    cursor = connection.cursor()
    cursor.execute("SELECT email FROM users")
    return [row[0] for row in cursor.fetchall()]


def test_get_user_emails_specific_colu…

13 0 Open

Database scaling & optimization medium

How to Mock SQLite executemany When Batch Inserting in Python

Batch insert many rows into SQLite with executemany and mock the cursor for isolated tests.

sqlite3 executemany mock

Python

import sqlite3
from unittest.mock import Mock, patch

def insert_users(conn, users):
    """Insert multiple user records using executemany."""
    cursor = conn.cursor()
    cursor.executemany(
        "INSERT INTO users (name, age) VALUES (?, ?)",
        users
    )
    conn.commit()
    return cursor.rowcount

if _…

15 0 Open

Database scaling & optimization medium

How to Mock a Hot Shard Split in Python

Simulate a database hot shard splitting into two shards by key ranges when it exceeds a threshold, with a mock class for testing.

sharding databases mock

Python

import random
from collections import defaultdict


class HotShardMock:
    """Mock implementation of a hot shard split in a distributed database."""

    def __init__(self, shard_id="shard_1", max_entries=5):
        self.shard_id = shard_id
        self.max_entries = max_entries
        self.entries = {}

    def ad…

16 0 Open

Database scaling & optimization medium

How to mock batch commit of transactions in Python

Simulate a transaction batch writer with commit, rollback, and summary logic to test database write patterns without a real database.

transactions mock batch

Python

import json
from datetime import datetime, timezone

class TransactionBatch:
    def __init__(self):
        self.pending = []
        self.committed = []
        self._log = []

    def add(self, operation):
        self.pending.append(operation)

    def commit(self):
        if not self.pending:
            return …

16 0 Open

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