diff -r 000000000000 -r 08ec8eefde2f persistentstorage/dbms/group/TODO.TXT --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/persistentstorage/dbms/group/TODO.TXT Fri Jan 22 11:06:30 2010 +0200 @@ -0,0 +1,27 @@ +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 + + +