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Database scaling & optimization

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

5 matches

How to Mock Replica Lag Monitoring in Python

Simulates database replica lag with a mock monitor class that generates realistic lag metrics and health statuses.

import time
import random
from datetime import datetime, timedelta

class MockReplicaLagMonitor:
    def __init__(self, replicas=3, base_lag=0.5, jitter=0.2):
        self.replicas = [f"replica-{i}" for i in range(replicas)]
        self.base_lag = base_lag
        self.jitter = jitter
        self.last_write = dateti…

12 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 easy

How to Shard Data by User ID Hash in Python

Deterministically map user IDs to shard indexes using an MD5 hash modulo the shard count in Python.

sharding hashing md5

Python

import hashlib

def shard_id(user_id: str, num_shards: int = 4) -> int:
    """Deterministically map a user_id to a shard index using MD5."""
    digest = hashlib.md5(user_id.encode("utf-8")).hexdigest()
    return int(digest[:8], 16) % num_shards

if __name__ == "__main__":
    user_ids = ["alice", "bob", "carol", "d…

12 0 Open

Database scaling & optimization medium

Idempotent Writes for Sharded Databases in Python

Implement a mock shard with idempotent write support using request IDs to prevent duplicate writes and track the latest value per key.

idempotency sharding distributed-systems

Python

import json


class ShardMock:
    """Mock distributed shard with idempotent write support."""

    def __init__(self, shard_id):
        self.shard_id = shard_id
        self._store = {}

    def write(self, key, value, request_id):
        """Write value only if request_id not yet processed; idempotent."""
        i…

13 0 Open

Database scaling & optimization medium

Offset vs Keyset Pagination in Python

Demonstrate offset-based pagination and keyset (cursor) pagination with a simple in-memory dataset, showing how each returns pages of records.

pagination keyset offset

Python

"""Demonstrate pagination using offset vs keyset (cursor) approach."""

ITEMS = [
    {"id": 1, "name": "Alice"},
    {"id": 2, "name": "Bob"},
    {"id": 3, "name": "Carol"},
    {"id": 4, "name": "David"},
    {"id": 5, "name": "Eve"},
]

def offset_paginate(items, page, page_size):
    """Return a page using offset…

14 0 Open

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