Index myopia

Yikes! Our vendor has three indexes on various tables using the same columns. The differences in the indexes is the use of descending and the order of the columns: idx_1 col_1 col_2 idx_2 col_2 col_1 idx_3 col_1 col_2 descending What gives with this? Can there be a performance benefit to reversing the order of the columns, in the use of descending indexes (descending is used on the lookup tables, not too wide, smallish < 2-3k rows)? Also, is there a performance hit of having the other indexes floating around. tia p.s. this index situation is consistent throughout the db.

Online 4 & 5 could not use an ascending index for a descending sort or vice-versa. However, IDS 7/8/9 CAN so the third index is redundant and not needed. Looks like someone on your vendor's team cut his/her teeth in the old days. Art S. Kagel dios wrote: > > Yikes! > Our vendor has three indexes on various tables using the same columns. The > differences in the indexes is the use of descending and the order of the > columns: > idx_1 col_1 col_2 > idx_2 col_2 col_1 > idx_3 col_1 col_2 descending > > What gives with this? Can there be a performance benefit to reversing the > order of the columns, in the use of descending indexes (descending is used > on the lookup tables, not too wide, smallish < 2-3k rows)? > Also, is there a performance hit of having the other indexes floating > around. > > tia > > p.s. this index situation is consistent throughout the db.