SQLite vs PostgreSQL Performance

Summary

In this video, the differences between SQLite and Postgres are explored through a series of tests. The comparison covers CRUD operations, including insert, update, and delete latency, as well as read performance using SQL joins. Postgres, a traditional client-server database, is tested over a network, while SQLite operates locally, demonstrating the advantages and limitations of both systems. The video discusses CPU usage, disk write operations, and the impact of network latency, with a focus on how each database handles real-world use cases, providing valuable insights for choosing the right database for different applications.

Takeaways

• 😀 Postgres is a client-server database engine with multi-core support, ideal for high-concurrency environments.
• 😀 SQLite is a lightweight library used within applications, interacting directly with the local file system, making it less suited for high-concurrency writes.
• 😀 The first test focuses on insert, update, and delete operations, comparing latency, throughput, CPU usage, and disk write operations between SQLite and Postgres.
• 😀 SQLite has lower latency and higher throughput than Postgres for insert, update, and delete operations since it interacts directly with the local file system.
• 😀 Postgres, while handling more complex queries, suffers from network delays as it operates over the network, impacting query performance.
• 😀 The second test compares read (select) performance using SQL joins, with SQLite showing significantly faster query processing due to local file access.
• 😀 Despite network delays, PostgreSQL can handle complex, large-scale applications, especially when concurrent queries are required.
• 😀 SQLite can handle more queries per second and uses less CPU due to its local file system access and single-threaded operation.
• 😀 The test results show that SQLite is more efficient in low-concurrency, read-heavy environments, like embedded systems or low-traffic websites.
• 😀 PostgreSQL shows CPU spikes under heavy query load, while SQLite maintains more stable performance, processing more requests with less CPU usage.

Q & A

What is the main purpose of comparing SQLite and Postgres in this video?

The main purpose is to compare SQLite and Postgres in terms of performance during CRUD operations, measuring insert latency, throughput, CPU usage, disk write operations, and the impact of network latency. The video provides insights into how each database handles various tasks, especially in terms of their respective architectures and limitations.

How do SQLite and Postgres differ in terms of database architecture?

Postgres follows a traditional client-server architecture, where the database runs on a separate server and communicates over a network with clients. In contrast, SQLite is embedded directly within the application and uses a single local file for storage, with no client-server model.

What is the significance of the test setup using EC2 instances for SQLite and Postgres?

The EC2 setup simulates a real-world scenario where Postgres is accessed over a network (using a different EC2 instance for the client) while SQLite interacts directly with the local file system. This setup highlights how network latency impacts database performance, particularly for Postgres.

What performance difference does the video highlight in terms of query latency between SQLite and Postgres?

The video highlights that SQLite, by accessing the local file system, can process queries much faster than Postgres, which communicates over the network. This results in lower query latency for SQLite, particularly in the first test involving insert, update, and delete operations.

Why does the CPU usage spike for Postgres during the first test?

The CPU spikes in Postgres occur because the database server, which runs on the same instance as the client, experiences increased load as the query count grows. These spikes correspond to increased query processing time, leading to higher CPU usage, which directly affects latency.

What role does the Write-Ahead Log (WAL) play in SQLite’s performance during the test?

The Write-Ahead Log (WAL) significantly improves SQLite’s performance by reducing latency during insert operations. WAL allows SQLite to write changes to a log before applying them to the main database file, making it faster than using the default rollback journal.

How does network latency affect Postgres's performance compared to SQLite?

Network latency has a considerable impact on Postgres's performance. Since Postgres communicates over a network, each query introduces a delay due to network overhead. SQLite, on the other hand, benefits from local file system access, which is much faster for handling queries.

What happens when the delay between queries is reduced to zero in the test?

When the delay between queries is reduced to zero, queries are sent as fast as each previous one completes. SQLite can handle significantly more queries per second due to its local access to the database file, while Postgres struggles to maintain performance due to the inherent network latency.

How does SQLite handle concurrent read operations compared to write operations?

SQLite allows for unlimited concurrent read operations since multiple threads or instances can access the database file simultaneously for reading. However, it can only handle one write operation at a time, which limits its ability to handle high-concurrency write-heavy workloads.

Why is it difficult to directly compare SQLite and Postgres according to the video?

It is difficult to directly compare SQLite and Postgres because they are fundamentally different in architecture. SQLite is designed for local, single-file access, making it more suitable for smaller, embedded systems, while Postgres is a full-fledged, networked client-server database designed for larger, multi-user applications. The comparison in the video focuses more on illustrating the impact of these architectural differences on performance.