一.查询索引的高度 select index_name,blevel,leaf_blocks,num_rows,distinct_keys,clustering_factorfrom user_ind_statisticswhere table_name in( 'T1','T2','T3'); 2. 索引存储列值(可优化聚合) 2.1索引特性之存列值优化count drop table t purge;create table t as select * from dba_objects;up…