Re: [boost] [MultiIndex] Memory consumption of ordered indices

Subject: Re: [boost] [MultiIndex] Memory consumption of ordered indices
From: Olaf van der Spek (ml_at_[hidden])
Date: 2015-02-20 16:59:07

On Fri, Feb 20, 2015 at 3:01 PM, Joaquin M Lopez Munoz <joaquin_at_[hidden]> wrote:
> Olaf van der Spek <ml <at> vdspek.org> writes:
>
>>
>> Hi,
>>
>> What's the memory consumption of ordered indices? Is it implemented as
>> a linked list, so two pointers per element?
>
>
> The overhead (on most platforms) is three pointers per node (and index):
>
> http://stackoverflow.com/a/4208349/213114
>
> Color is usually embedded into one of the pointers:
>
> http://bannalia.blogspot.com/2008/11/optimizing-red-black-tree-color-bits.html

And for sequenced?

>> In that case for a write-only data structure an external ptr vector
>> would make more sense wouldn't it?
>
> What's a "write-only" structure supposed to be useful for? Anyway, s
> sorted vector is definitely better in terms of memory consumption than
> a single-index multi_index_container.

The data structure is filled once (data read from DB) and then queried lots.
Perhaps a flat_map would be better suited.

-- 
Olaf