[erlang-questions] ets+dets

[Leonard B]

On Thu, May 11, 2017 at 4:32 PM, Adam Rutkowski <hq@REDACTED> wrote:
> On Tue, May 9, 2017, at 22:00, Vlad Dumitrescu wrote:
>
> I was thinking of an ets+dets combo, but it may be tricky to get the details
> right. Is there something like this out there? Would it be better to just
> use mnesia?
>
>
> Hi Vlad,
>
> Apologies if this sounds blunt, but isn't mnesia in fact an ETS+DETS combo
> with lots of tricky details?
>
> With DETS alone I often get the tables corrupted, erlang-history is the
> prime example -- `rm ~/.erlang-hist.nonode@REDACTED` is my weekly operation.
>
> What other properties are you looking for? Why _not_ mnesia in your case?
>
> Cheers
>
> /A.
>

Hi Adam,

It seems to be a common misconception that mnesia disc_copies behaves like this.
I used to think so myself. In fact it keeps all data in memory and
flushes to disc,
so it does not meet Vlad's requirements for minimal in-memory cache, with disk
storage.

As was pointed out to me when I asked about it in '15, from the docs:
"If a table is of type disc_copies at a certain node, the entire table
is resident in RAM memory and on disc."

Leonard

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