Are Gigantic Associative Arrays Now Possible?

dlangPupil via Digitalmars-d digitalmars-d at
Wed Mar 22 13:00:56 PDT 2017

Hello to all!  As a (D, and coding and forum) newbie I'm learning 
about D's associative arrays (AAs), and their tiny latency 
regardless of AA size. Cool!

One practical limitation on the practical maximum AA size is 
memory/disk paging.  But maybe this limit could be overcome with 
the latest SSDs, whose nonvolatile memory can be addressed like 

The article below says that Intel Optane SSDs:
	-allow reads and writes can on individual bytes.
	-have a latency 10x of DRAM (but  AAs' latency is so low that 
this might not matter in many cases).
	-currently offer 375GB of "RAM" for $1,500.
	-will support up to 3 TB on 2 socket Xeon systems (48TB on 
	-will be supplemented with Optane DIMMs in the future.

Some questions that arise are...

1) Wouldn't using such "RAM" eliminate any paging issue for 
super-gigantic AAs?
2) What other bottlenecks could arise for gigantic AAs, e.g., 
garbage collection?
3) Would an append-only data design mitigate GC or other 
4) Has anyone tried this out?

What a coup if D could "be the first" lang to make this 
practical.  Thanks.

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