Is this a video course?

No. This is an interactive, slide-based learning platform. Each lesson has rich text, animated diagrams, live code editors, and quizzes. You learn by reading, interacting, and doing, not by watching videos passively.

How long do I have access?

Forever. Both pricing tiers are one-time payments with lifetime access. This includes all current 766 lessons and any future content we add.

What level of experience do I need?

None. We start from absolute basics like 'What is latency?' and build up to distributed consensus protocols. The Foundation level assumes zero prior knowledge of system design.

How much does the system design course cost?

7.99 US dollars for lifetime access globally, or 499 Indian rupees for lifetime access in India. One-time payment, no subscription, no hidden fees. 11 lessons are free with no signup required.

What technologies are covered?

Everything from DNS and load balancers to Kubernetes, Kafka, distributed databases, consensus protocols, stream processing, security architecture, and observability. We cover principles and real-world implementations used at Netflix, Google, Amazon, Uber, Stripe, and more.

Is this useful for system design interview preparation?

Yes. The lessons are structured around the exact topics asked in system design interviews at FAANG and top-tier companies. Interactive diagrams help you practice whiteboard-style explanations. Covers everything from URL shortener design to distributed payment systems.

How is this different from ByteByteGo or Educative?

766 interactive lessons (4x more than most competitors), 16 different diagram types that build step by step, real production examples from Netflix, Google, Amazon, Uber, and Stripe, and lifetime access for a one-time payment of $7.99 instead of annual subscriptions costing 100 to 200 dollars per year.

Why is it called 'Write-AHEAD Log'?

Because the log is written BEFORE the actual data pages are modified, the log is ahead of the data, The WAL record is flushed to disk before the corresponding data page modification. If the server crashes, the WAL record is there to redo the modification during recovery. The log is always 'ahead' of the actual data.

Your Postgres has wal_level set to 'replica'. You want to set up Debezium for CDC. What needs to change?

Change wal_level to 'logical' because CDC requires logical decoding, which needs additional row-level information in the WAL, Logical replication and CDC tools like Debezium use logical decoding, which requires wal_level = 'logical'. This level adds row identity information (old row values for updates and deletes) to the WAL that 'replica' level does not include.

A crash occurs. Some transactions were committed (WAL flushed) but their data page changes weren't written to disk yet. What happens on restart?

Postgres replays the WAL records and reconstructs the committed changes on the data pages, This is the core WAL guarantee. If the COMMIT record is in the WAL, the transaction is committed regardless of whether the data pages were updated. On startup, Postgres replays WAL records from the last checkpoint, reconstructing any committed changes that were not yet written to data pages.

Write-Ahead Log Replication

Name: System Design Masterclass
Availability: InStock

in Data Replication Distribution

This lesson is part of the full System Design Masterclass. Unlock it along with 765 other lessons for a one-time payment.

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Foundation lessons free, try before you buy

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“The interactive diagrams alone are worth way more than the price.”

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