Connection pooling concept in Node.js - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is connection pooling in Node.js?

Connection pooling is a technique where a set of database connections are kept open and reused to handle multiple requests, instead of opening and closing a new connection each time.

beginner

Why is connection pooling useful?

It improves performance by reducing the time and resources needed to open and close connections repeatedly. It also helps manage limited database connections efficiently.

intermediate

How does connection pooling affect server response time?

By reusing existing connections, connection pooling reduces the delay caused by establishing new connections, leading to faster server responses.

beginner

Name a common Node.js library that supports connection pooling for databases.

The 'mysql2' and 'pg' libraries support connection pooling for MySQL and PostgreSQL databases respectively.

intermediate

What can happen if a connection pool is too small or too large?

If too small, requests may wait for free connections causing delays. If too large, it can waste resources and overload the database server.

What does connection pooling primarily help with in Node.js applications?

A Caching query results in memory

B Encrypting database connections automatically

C Creating new connections for every request

D Reusing database connections to improve performance

Connection pooling reuses open connections to reduce overhead and improve performance.

Which of these is a risk of having a connection pool that is too small?

A Queries run slower because of encryption

B Requests may have to wait for a free connection

C Connections never close automatically

D Database server crashes immediately

A small pool means fewer connections available, so requests wait longer.

Which Node.js library is known for supporting connection pooling with PostgreSQL?

A pg

B express

C mongoose

D socket.io

'pg' is a popular PostgreSQL client for Node.js that supports connection pooling.

What happens when a connection pool is too large?

A It wastes resources and may overload the database

B It speeds up queries infinitely

C It encrypts all connections automatically

D It prevents any new connections from opening

Too many open connections consume resources and can overload the database server.

How does connection pooling improve server response time?

A By encrypting data faster

B By caching all database queries in memory

C By reusing existing connections instead of opening new ones

D By closing connections immediately after use

Reusing connections avoids the delay of opening new connections, speeding up responses.

Explain connection pooling and why it is important in Node.js applications.

Think about how opening a new connection each time can slow things down.

Describe the risks of having a connection pool size that is too small or too large.

Consider what happens if too few or too many connections are open.