DetsPlus - Pure Elixir replacement for `:dets` without the size limitation

Hey there,

for a side project I needed to store more than those max. 2gb that the builtin :dets supports and so I created this new pure Elixir library DetsPlus.

It has mostly the same API but is a more Elixir friendly as it supports the Enum protocol and structs/maps!. So you can do Enum.reduce() and friends on it.

When storing maps/structs we have to specify as kepos the field name instead of the element index for tuples. E.g. here an example storing maps with DetsPlus:

{:ok, dets} = DetsPlus.open_file(:example, keypos: :id)
DetsPlus.insert(dets, %{id: 1, value: 42})
[{%id: 1, value: 42}] = DetsPlus.lookup(dets, 1)
# or using the Enum protocol:
[{%id: 1, value: 42}] = Enum.to_list(dets)
:ok =  DetsPlus.close(dets)

It’s using a constant database approach inspired by D.J. Bernsteins CDB library - and so key lookups are extremely efficient even though it’s going to disk. Also when updating the database the whole file is being replaced atomically making DetsPlus great for embedded and Nerves use cases where power might be gone at any time.

Docs: DetsPlus — DetsPlus v2.1.1
Github: GitHub - dominicletz/dets_plus: Pure Elixir disk backed key-value store.

Add it to your deps and let me know any feedback!

def deps do
    {:dets_plus, "~> 2.1"}

Hi @dominicletz ,

Thanks for sharing this module, I immediatly started using it :slight_smile:

I ran into one issue. When I call the DetsPlus.close function a PagedFile process stays alive in hibernated mode and spawn a new process every time I call DetsPlus.open_file or DetsPlus.lookup.

Am I missing something and this the normal working of this module?

I made a github issue also, to help with follow up.

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Thanks @richgal that’s fixed!

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Happy to hear, I’ll try out soon. I’m planning to use DetsPlus in a production app.

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