Oracle performance tuning Tips: speed up

In order to speed up, index is important.
Avoid doing Full Scan.

Speed:
Index Unique scan > Index range scan > Index full scan

Index points:
Unique index 一意性が高い索引を
Start with frequently-used columns 使用頻度の高い列を先頭に
Start with low selectivity columns 選択率の低い列を先頭に
Include key with non-unique index 非ユニーク索引にはキー圧縮

Other:
Use hint efficiently.
/*+ INDEX( e e_index_1) */

It's better to use NVL(e1,e2) = e2 instead of "is null" if null data is less than no-null data.