Week 06 Lectures (41)

N-d Selection via Multiple Indexes

DBMSs already support building multiple indexes on a table.

Which indexes to build depends on which queries are asked.

create table R (a int, b int, c int);
create index Rax on R (a);
create index Rbx on R (b);
create index Rcx on R (c);
create index Rabx on R (a,b);
create index Racx on R (a,c);
create index Rbcx on R (b,c);
create index Rallx on R (a,b,c);

But more indexes ⇒ space + update overheads.