Reading multiple indices on MagmaCollections

[Chris Muller]

Hi Brent, in fact, I've been thinking about this very problem lately.  
This work is critical for Lava and extremely useful for plain Magma
programs too.  Yes, I'll help out.

Just for clarity and context, the full series of conversions from SQL
to LavaResultTable is, (please fill in as necessary):

  SQL --> AST --> CST --> generated ST code --> ?? --> tree of
MaClauses --> calls to (enhanced) MaHashIndex --> MagmaCollectionReader
on the conjuncted result --> LavaResultTable

Wow.

Since you've got Lava, I guess most of this work is concentrated
between ?? and creation of the temporary "result" MaHashIndex.  As you
know, extending Magma's protocol is utterly trivial.  The hard work to
make this reality are:

  - deciding the best client API's
  - generation of the clause-tree
  - parsing the clause-tree
  - enhnancing MaHashIndex to quickly conjunct
  - efficiently providing a Reader that can page through the result set

Please fill in anything I've forgotten.  How would you like to tackle?

Will your actual Lava code-generation be affected by the API's that
create the clause-tree?  Hopefully not.

I have an idea for the backend work needed on the MaHashIndexes.  I
haven't tried to implement it yet, but will post my notes separately
that you or anyone may comment.

Cheers,
 Chris


--- Brent Pinkney <brent.pinkney at aircom.co.za> wrote:

> Hi Chris,
> 
> I apologise for my silence on this list: work.
> 
> I would really like to implement the ability to read a
> MagmaCollection on more
> than one index. We spoke about this last year but it is now quite
> pressing.
> 
> Related to this is the ability to read the same index more than once
> at
> different hash values. This is analogous to an SQL
> 
> 	select  ... where foo in('abc' 'def')
> 
> I was wondering if you are still interested in this feature and
> whether we can
> collaborate on a plan.
> 
> We need to revive:
> 	1. the client images programming interface
> 	2. the bitmat indices of equivalent
> 
> Regards
> 
> Brent
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