Things that could be done to DBMS -- 12 October 1998
Query optimizer:
Optimize for clustering indexes (use S/T and G/H plans)
e.g. assume Auto-increment column => clustering
or measure the clustering in the stats
Optimize for multi-column lookup
e.g. For "a=v1 and b=v2" with index on (a,b)
Optimize for like-predicates
e.g. "x LIKE 'abc*'" => "x>='abc' AND x<'abd'" etc.
Query complexity-reduction by removing redundant predicates, e.g.
"x>4 AND x>3" => "x>4"
"x>4 OR x>3" => "x>3"
"x>-1" for unsigned x => trivially true
Better statistical data dn guesswork
SQL/access plans:
Support "DISTINCT" in the projection stage via a Hash-system or sorting