Database scaling & optimization
Indexing, connection pooling, read replicas, query tuning, and throughput-aware SQL.
Approximate Count with HyperLogLog in Python
A mock HyperLogLog implementation uses hash-based registers to estimate cardinality of large datasets with sublinear memory.
import hashlib
class HyperLogLog:
def __init__(self, precision=4):
if precision < 4 or precision > 16:
raise ValueError("precision must be between 4 and 16")
self.precision = precision
self.registers = [0] * (1 << precision)
def _hash(self, value):
return int(hashl…How to Implement Keyset Pagination in Python (Seek Method)
Implement keyset (seek) pagination in Python with a mock paginator that efficiently fetches pages based on the last row rather than OFFSET.
from dataclasses import dataclass
from typing import List, Optional
@dataclass
class Row:
id: int
name: str
def __lt__(self, other: "Row") -> bool:
return (self.id, self.name) < (other.id, other.name)
class MockKeysetPaginator:
"""Pagination using keyset (seek) method instead of OFFSET."""…How to Limit a Result Set to Top N Rows in Python
Sort a list of dictionaries by a numeric key and return only the top N results, formatted as a readable ranked list.
import random
def top_n_mock(limit: int = 5):
"""Return a formatted top-N result set as a mock example."""
# Simulated data source
scores = [
{"name": "Alice", "score": 87},
{"name": "Bob", "score": 92},
{"name": "Charlie", "score": 78},
{"name": "Diana", "score": 95},
…How to Optimize SQLite Database Performance in Python
A Python helper that creates an index, enables WAL mode, and tunes synchronous settings to optimize SQLite database performance.
import sqlite3
DATABASE_PATH = "beginners.db"
UNOPTIMIZED_TABLE_SCHEMA = """
CREATE TABLE IF NOT EXISTS users (
id INTEGER PRIMARY KEY,
name TEXT NOT NULL,
email TEXT NOT NULL
)
"""
def optimize_database(db_path: str = DATABASE_PATH) -> dict:
with sqlite3.connect(db_path) as connection:
curs…How to Speed Up Column Lookups with DataFrame Index in Python
Use pandas set_index to make repeated column value lookups O(1)-style fast instead of scanning the whole DataFrame each time.
import pandas as pd
# Mock dataset with duplicate customer IDs
data = {"customer_id": [101, 102, 103, 101, 104, 102],
"order_amount": [250.0, 85.5, 300.0, 175.25, 420.0, 95.75]}
df = pd.DataFrame(data)
df = df.set_index("customer_id")
# Simulated lookup request
search_id = 102
# Fast index-based lookup (no…How to enforce a unique index constraint in Python
Mock a database unique index in Python that rejects duplicate rows based on one or more columns.
class MockIndex:
def __init__(self, columns):
self.columns = columns
self._values = set()
def insert(self, row):
key = tuple(row[col] for col in self.columns)
if key in self._values:
raise ValueError(f"Duplicate key {key} for columns {self.columns}")
self._v…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.
"""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…Browse by section
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Database scaling & optimization — Python code examples
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