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From Neal Richardson <neal.p.richard...@gmail.com>
Subject Re: Plasma store implementation status across client libraries
Date Mon, 04 Jan 2021 18:15:16 GMT
I believe Plasma only has Python bindings. FWIW it has not seen active
development in quite a while.

Neal

On Mon, Jan 4, 2021 at 8:58 AM Chris Nuernberger <chris@techascent.com>
wrote:

> Yes that makes sense.  I guess you also need something to broker shared
> memory filenames/ids.  The database isn't in-memory, however, although I
> know what you mean.  One huge advantage of mmap is you can have much larger
> than memory storage act like in-memory storage; so the plasma store can be
> roughly the size of your disk and larger your ram but your program, unless
> it attempts to verbatim copy a column wouldn't know any better.
>
> Numerical larger-than-memory-but-in-memory redis indeed; that is an
> interesting way to think of it.
>
> On Mon, Jan 4, 2021 at 9:45 AM Thomas Browne <thomas@crvm.io> wrote:
>
>> Interesting and agreed. I guess this a big advantage of the "on the wire"
>> unserialised format - just read it in and it's already native. I'll go this
>> way possibly.
>>
>> However I also note the beginnings of more advanced functionality in the
>> Plasma store, for example, notification API on buffer seal (ie when
>> something changes, all clients can be notified).
>>
>>
>> https://arrow.apache.org/docs/python/generated/pyarrow.plasma.PlasmaClient.html#pyarrow.plasma.PlasmaClient.subscribe
>>
>> I'm assuming the plasma store will add functionality over time, and if
>> this is the case, having all client libraries implement it means I can
>> almost have a redis-like column-store specialising in numerical computation
>> (which would be awesome), and for which i don't need to write my own
>> functionality for each client library.
>>
>> A numerical in-memory database, if you will.
>> On 04/01/2021 15:55, Chris Nuernberger wrote:
>>
>> Julia, Python, and R all have some support for mmap operations.
>>
>> On Mon, Jan 4, 2021 at 8:55 AM Chris Nuernberger <chris@techascent.com>
>> wrote:
>>
>>> Could simply saving the arrow file in streaming mode to shared memory
>>> and then mmap-ing the result in each language solve your problem ?  Plasma
>>> seems to me to be a layer on top of basic mmap operations; as long as you
>>> have shared memory and mmap then you can have multiple processes talking to
>>> the same logical block of memory.
>>>
>>> On Mon, Jan 4, 2021 at 8:27 AM Thomas Browne <thomas@crvm.io> wrote:
>>>
>>>> I am hoping to use the Apache Arrow project for cross-language
>>>> numerical
>>>> computation, and for that the shared-memory idea is very powerful. Am I
>>>> correct that the Plasma Store is the enabling technology for this,
>>>> especially for soft real-time computation (ie not moving to parquet or
>>>> any file-based sharing system)?
>>>>
>>>> Is that the case? And if so, then I'm wondering which client libraries,
>>>> other than Python (and I assume C[++]), implement the Plasma Store.
>>>> This
>>>> table doesn't feature a row for Plasma:
>>>>
>>>> https://arrow.apache.org/docs/status.html
>>>>
>>>> and I can't seem to find any reference to the Plasma store in the
>>>> Julia,
>>>> R, or Javascript libraries.
>>>>
>>>> https://arrow.apache.org/docs/r/
>>>>
>>>> https://arrow.apache.org/docs/js/
>>>>
>>>> https://arrow.juliadata.org/stable/
>>>>
>>>>
>>>> Thank you,
>>>>
>>>> Thomas
>>>>
>>>>
>>>>

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