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Python Code Samples

Copy-ready Python snippets by topic and difficulty — short, focused, and runnable in the browser editor.

29 matches
Database scaling & optimization medium

How to Simulate Colocated Shard Joins in Python

Groups shards by their node and merges co-located shards into a single logical unit, checking capacity constraints.

sharding database distributed-systems
Python
import random
from collections import defaultdict


def simulate_colocated_shards_join(nodes: list[dict], shards: list[dict]) -> dict:
    """
    Simulates the join of co-located shards (on the same node) into a single
    logical shard. Returns the resulting node-to-shard mapping.

    Each node: {'id': str, 'capaci…
11 0 Open
Database scaling & optimization medium

How to Simulate Distributed Transactions in Python with a Mock

Model distributed transaction behavior with a mock Transaction class that supports commit, rollback, and failure simulation.

transactions mock database
Python
class Transaction:
    def __init__(self, id):
        self.id = id
        self.operations = []
        self.committed = False

    def add_operation(self, op, data):
        self.operations.append((op, data))

    def commit(self):
        if not self.operations:
            raise ValueError("No operations to commit…
13 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 easy

Rebalance Shard Ranges Across Nodes in Python

A mock rebalancing function that shuffles shard ranges and distributes them evenly across nodes using round-robin assignment.

sharding rebalancing dataclass
Python
import random
from dataclasses import dataclass

@dataclass
class Shard:
    id: int
    start: int
    end: int

def rebalance_shards(shards: list[Shard], node_count: int) -> dict[int, list[Shard]]:
    """Mock rebalancing of shard ranges across nodes."""
    all_ranges = [(s.start, s.end) for s in shards]
    random…
11 0 Open
Database scaling & optimization medium

Two Phase Commit Cross Shard Mock in Python

Simulates a two-phase commit across shards with failure handling to demonstrate distributed transaction coordination in Python.

two-phase-commit distributed-systems transaction
Python
"""Mock cross-shard two-phase commit with caution handling."""

class Shard:
    def __init__(self, name):
        self.name = name
        self.prepared = False
        self.committed = False
        self.aborted = False

    def prepare(self):
        # Simulate potential failure (1 in 3 chance on third shard)
     …
14 0 Open

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