how to handle very large array?

H. S. Teoh hsteoh at
Sat Feb 12 20:31:29 UTC 2022

On Sat, Feb 12, 2022 at 06:41:14PM +0000, Era Scarecrow via Digitalmars-d-learn wrote:
> On Thursday, 10 February 2022 at 01:43:54 UTC, H. S. Teoh wrote:
> > On Thu, Feb 10, 2022 at 01:32:00AM +0000, MichaelBi via
> > Digitalmars-d-learn wrote:
> > > thanks, very helpful! i am using a assocArray now...
> > 
> > Are you sure that's what you need?
> Depends. if you do say TYPE[long/int] then you have effectively a
> sparse array, if there's a few entries (*Say a hundred million or
> something*) it will probably be fine.
> Depending on what you're storing, say if it's a few bits per entry you
> can probably use bitarray to store differing values. The 10^12 would
> take up....  119Gb? That won't work. Wonder how 25Gb was calculated.

That was not my point. My point was to question whether the OP has
discovered the insight that would allow him to accomplish his task with
a LOT less space than the naïve approach of storing everything in a
gigantic array.  Substituting an AA for a gigantic array matters little
as long as the basic approach remains the same -- you have only modified
the implementation details but the algorithm is still a (highly)
suboptimal one.


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