4 ms·
But a multicolumn index on (b, c, a) would be effective for a query on (b, c), as well as on (a, b, c).
by wiredfool 12y ago
But a multicolumn index on (b, c, a) would be effective for a query on (b, c), as well as on (a, b, c).
- MSM 12y agobut not for any combination that doesn't have B leading. If you're always going to query those fields in that order, that's a perfect way to do things. If you'll be querying it a couple different ways then you're way better off with three separate one column indexes assuming the RDBMS can make use of index intersection.