01_oracle知识1-压缩索引基本介绍
select * from index_stats;
create table t_objects as select * from all_objects;
–1.索引不压缩
create index t_objects_idx on t_objects(owner,object_type,object_name);
analyze index t_objects_idx validate structure;
create table idx_stats as
select ‘noncompressed’ as type,a.* from index_stats a;
–2.索引压缩第1列
drop index t_objects_idx;
create index t_objects_idx on t_objects(owner,object_type,object_name) compress 1;
analyze index t_objects_idx validate structure;
insert into idx_stats
select ‘compressed 1’,a.* from index_stats a;
commit;
–2.索引压缩前2列
drop index t_objects_idx;
create index t_objects_idx on t_objects(owner,object_type,object_name) compress 2;
analyze index t_objects_idx validate structure;
insert into idx_stats
select ‘compressed 2’,a.* from index_stats a;
commit;
–3.索引压缩3列
drop index t_objects_idx;
create index t_objects_idx on t_objects(owner,object_type,object_name) compress 3;
analyze index t_objects_idx validate structure;
insert into idx_stats
select ‘compressed 3’,a.* from index_stats a;
commit;
–4.索引压缩1列
drop index t_objects_idx;
create index t_objects_idx on t_objects(object_type,owner,object_name) compress 1;
analyze index t_objects_idx validate structure;
insert into idx_stats
select ‘compressed a1’,a.* from index_stats a;
commit;
select * from idx_stats;