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: Tore Halvorsen (tore.halvorsen_at_[hidden])
Date: 2011-04-28 08:27:53

On Wed, Dec 22, 2010 at 8:59 AM,  <joaquin_at_[hidden]> wrote:
> 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).

Sorry to wake up an old thread, but I've just encountered a problem
where partial indices would be the perfect solution.

I'm working on a problem where I have several unique identifiers
for each object, but I'm not guaranteed that I have all of them at
the same time. I can get updates from two sources, which don't
necessarily don't use the same ID, yet they will sooner or later
be linked.

Using postgresql a simplified version could look like this:

CREATE TABLE test(  a text,  b text, data text);
CREATE UNIQUE INDEX test_a_par_uidx
  ON test(a) WHERE a IS NOT NULL;
CREATE UNIQUE INDEX test_b_par_uidx
  ON test(b) WHERE a IS NOT NULL;

Are we thinking of the same sort of partial indices?

... and is this something that is feasible to implement
in multi_index_container?

-- 
Eld på åren og sol på eng gjer mannen fegen og fjåg. [Jøtul]
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