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u/IndicationAntique667

r/Clickhouse r/databasedevelopment r/postgres
▲ 12 r/Clickhouse

I Tried to Find How ClickHouse Keeper Takes Non-Blocking Snapshots

Hi everyone,

I'm learning and exploring topics around database systems. I wanted to see how ClickHouse Keeper takes a non-blocking snapshot of its storage.

I recorded a concept and code walkthrough here: https://www.youtube.com/watch?v=7J93WKEFinA&t

A short summary of the points in the video:

  1. Brute force approaches and why they don't work
  2. How ClickHouse Keeper uses HashMap + Doubly Linked List to solve this problem
  3. The code walk through the files: SnapshotableHashTable.h, KeeperStateMachine.cpp and KeeperSnapshotManager.cpp to see how it's actually implemented.

Do give it a watch and consider supporting by liking the video or subscribing :)

This is partly for my own future reference and partly to share with others who might be interested in it. Would love feedback and corrections from people who know this stuff deeply.

Thank you so much!

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u/IndicationAntique667 — 7 days ago
▲ 17 r/postgres+1 crossposts

I Tried To Decode Postgres WAL for an INSERT Statement

Hi everyone,

This is a continuation of the explorations from my previous posts here. I went through the CMU Database Systems course, and I'm exploring topics around databases. I wanted to see how the Write Ahead Log is constructed and logged. So I tried to trace a WAL record for a simple INSERT statement in Postgres.

I recorded a video walkthrough of the terminal and source code exploration here: https://youtu.be/YOyq-kvbyU8?si=PTdexP3jmOSdx-8y

I've tried to explore how we can locate a WAL record, how we can decode it via either xxd or pg_waldump, and the relevant source code for it. Do give a watch and consider supporting :)

This is partly for my own future reference and partly to share with others who might be interested in it. Would love feedback and corrections from people who know this stuff deeply. Apologies if this isn't the correct subreddit for this.

Thank you so much!

u/IndicationAntique667 — 11 days ago