[elephant-devel] Staus of the port of Ian's new functional toCL-SQL backend....

[Robert L. Read]

On Sun, 2008-05-04 at 10:37 +0300, Alex Mizrahi wrote:
>  RLR> implementing a new kind of btree that supports duplicates (hard).
> 
> ain't btree with duplicates very similar to btree-index thing, because 
> btree-index also supports duplicates?

Yes, I thought that too -- my initial strategy was to attempt to
subclass that to create the btree-index.  Instead, I had to extract a
lot of the function for it by hand, and simply subclass sql-btree.  So,
you are correct, the functionality is in principle similar---but for me
it was not so easy to lift it into exactly what is needed.  Part of this
is that there is only one direct test of dup-btree functionality; I'm
trying to rectify that a little right now.

> 
>  RLR> Since Postmodern uses the same kind of cursor control that the CL-SQL
>  RLR> backend does,
> 
> why do you think so? cursor are probably biggest difference between CL-SQL 
> and postmodern -- instead of reading everything and sorting on lisp side, we 
> use sorting done by postgresql, and pick stuff in portions, i.e. cursor-next 
> is something like:
> 
>  SELECT k, v FROM btree11 WHERE ((k = $1) and (v > $2)) OR (k > $1) LIMIT 10 

I think perhaps I was confused by pm-collections.lisp, which seems
actually defines sql-cursor, instead of pm-cursor.  I guess that file
should probably be removed.


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