Posts tagged:

storage

Storage-viz: Storage Visualizers and Commands for MongoDB

Nov 20 • Posted 1 year ago

Storage-viz is a suite of web-based visualizers and new experimental database commands that may help you understand how MongoDB utilizes storage and organizes btrees. Storage-viz is now available in the MongoDB Nightly builds.

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When a MongoDB collection is created, an on-disk extent is allocated to store the documents. Each time a newly created or updated document cannot fit into the existing collection’s extents, a new extent is created. Each document occupies a contiguous storage area - a record - in one of the collection’s extents. Storage-viz’ experimental storageDetails command extracts information about how the disk storage is used and the web-based visualizer generates an easy-to-read graphical representation. Storage-viz also showcases which parts of the collection’s extents are currently in RAM [NOTE: the visualizer doesn’t display how much memory is available].

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How MongoDB’s Journaling Works

Oct 16 • Posted 2 years ago

This was originally posted to Kristina Chodorow’s blog, Snail in a Turtleneck

I was working on a section on the gooey innards of journaling for The Definitive Guide, but then I realized it’s an implementation detail that most people won’t care about. However, I had all of these nice diagrams just laying around.

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 Good idea, Patrick! So, how does journaling work? Your disk has your data files and your journal files, which we’ll represent like this:

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