索引系列六--索引特性之高度较低的验证体会
sqlplus ljb/ljb
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drop table t1 purge;
drop table t2 purge;
drop table t3 purge;
drop table t4 purge;
drop table t5 purge;
drop table t6 purge;
drop table t7 purge;
create table t1 as select rownum as id ,rownum+1 as id2,rpad('*',1000,'*') as contents from dual connect by level<=1;
create table t2 as select rownum as id ,rownum+1 as id2,rpad('*',1000,'*') as contents from dual connect by level<=10;
create table t3 as select rownum as id ,rownum+1 as id2,rpad('*',1000,'*') as contents from dual connect by level<=100;
create table t4 as select rownum as id ,rownum+1 as id2,rpad('*',1000,'*') as contents from dual connect by level<=1000;
create table t5 as select rownum as id ,rownum+1 as id2,rpad('*',1000,'*') as contents from dual connect by level<=10000;
create table t6 as select rownum as id ,rownum+1 as id2,rpad('*',1000,'*') as contents from dual connect by level<=100000;
create table t7 as select rownum as id ,rownum+1 as id2,rpad('*',1000,'*') as contents from dual connect by level<=1000000;
create index idx_id_t1 on t1(id);
create index idx_id_t2 on t2(id);
create index idx_id_t3 on t3(id);
create index idx_id_t4 on t4(id);
create index idx_id_t5 on t5(id);
create index idx_id_t6 on t6(id);
create index idx_id_t7 on t7(id);
set linesize 1000
set autotrace off
select index_name,
blevel,
leaf_blocks,
num_rows,
distinct_keys,
clustering_factor
from user_ind_statistics
where table_name in( 'T1','T2','T3','T4','T5','T6','T7');
INDEX_NAME BLEVEL LEAF_BLOCKS NUM_ROWS DISTINCT_KEYS CLUSTERING_FACTOR
------------------ ----------- ---------- ------------- -----------------
IDX_ID_T1 0 1 1 1 1
IDX_ID_T2 0 1 10 10 2
IDX_ID_T3 0 1 100 100 15
IDX_ID_T4 1 3 1000 1000 143
IDX_ID_T5 1 21 10000 10000 1429
IDX_ID_T6 1 222 100000 100000 14286
IDX_ID_T7 2 2226 1000000 1000000 142858
已选择7行。
网站名称:索引系列六--索引特性之高度较低的验证体会
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