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What’s the maximum size of a node in JCR/AEM? by Jörg Hoh

Abstract

An interesting question which comes up every now and then is: “Is there a limit how large a JCR node can get?”. And as always in IT, the answer is not that simple.

In this post I will answer that question and also outline why this limit is hardly a constraint in AEM development. Also I will show ways how you can design your application so that this limit is not a problem at all.

(Allow me a personal note here: For me the most interesting part of that question is the motivation behind it. When this question I asked I typically have the impression that the folks know that they are a bit off-limit here, because this is a topic which is discussed very rarely (if at all). That means they know that they (plan to) do something which violates some good practices. And for that reason they request re-assurance. For me this always leaves the question: Why do they do it then?? Because when you follow the recommended ways and content architecture patterns, you will never hit such a limit.)
We first have to distinguish between binaries and non-binaries. For binaries there is no real limit as they are stored in the blobstore. You can put files with 50GB in size there, not a problem. Such binaries are represented either using the nodetype “nt:file” (used most often) or using binary properties (rarely used).

And then there is the non-binary data. This data comprises of all other node- and property-types, where the information is stored within the nodestore (also often as multi-value properties). Here are limits.

In AEM CS MongoDB is used as data storage, and the maximum size of a MongoDB document is 16 Megabyte. As an approximation (it’s not always the case), you can assume that a single JCR node with all its properties is stored in a single MongoDB document, which directly results in a maximum size per node: 16 Megabytes.

In reality a node cannot get that large; other data is also stored inside that document. I recommend to store never more than 1 Megabyte of non-binary properties inside a single node. Technically you don’t have that limit in a TarMK/SegmentTar-only setup, but I would not exceed it either. You will have all kind of interesting problems and you barely have experience with such large nodes in the AEM world.

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What’s the maximum size of a node in JCR/AEM?

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