Re: [Boost-users] Request for conditional index feature in boost multi-index

Subject: Re: [Boost-users] Request for conditional index feature in boost multi-index
From: Gokulakannan Somasundaram (gokul007_at_[hidden])
Date: 2010-12-22 06:27:18

Hi,
   Thanks for the reply. But there is a mention in random_access<> like this

"This added flexibility comes at a price: insertions and deletions at
positions other than the end of the index have linear complexity"

So isn't this a O(n) operation? But i quite gives me a hint that the
random_access<> is more like std::deque than std::vector. Can you throw me
little bit light on this? But the approach even suggests me to keep a
iterator of sequenced<> cached and use it for male insertions.

Thanks,
Gokul.

On Wed, Dec 22, 2010 at 3:59 PM, <joaquin_at_[hidden]> wrote:

> Gokulakannan Somasundaram escribió:
>
>> Hi,
>>   First of all thanks for the great library, which had reduced our
>> development
>>   time by a lot.    In boost multi-index, we currently have almost all the
>> indexing concepts
>>   integrated. Hence i am requesting for a new feature called conditional
>> indexes,
>>   where in an index/view inside multi-index will only index a portion of
>> the
>>   entries inside the entire multi-index(Say something that satisfies a
>> functor).
>>   This is in resemblance to the partial indexes in Postgresql.     I feel
>> that would provide elegant solutions to lot of issues without forming
>>   round about solutions. For example i have a requirement where in there
>> are
>>   two sets of data with the same search criteria, but different eviction
>> criteria
>>
>> Say i have two sets of data with same search condition, but one set needs
>> a
>> MRU(Most Recently Used) list of 100 and the other set requires a MRU of
>> 200.
>> Say the entry is like this
>> [...]
>>
>>
> The general request (composing partial indices to cover the whole sequence)
> is
> interesting and a considered it some years ago, though I never found the
> time
> to implement it (and I'm suspicious it might be a little too "smart" for
> the general
> public).
>
> In any case, I think you can solve your particular problem without that
> feature
> in a convenient manner. Please see the attached example and report whether
> it satisfies your needs.
>
> Best regards,
>
> Joaquín M López Muñoz
> Telefónica, Investigación y Desarrollo
>
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