oracle统计信息
create table t2 as select * from dba_objects;
建索引：
create index idx_t2 on t2(object_id);
2.收集T2的表所有列和表上所有索引的统计信息：
exec dbms_stats.gather_table_stats(ownname=>'SYS',tabname=>'T2',estimate_percent=>100,cascade=>true,degree=>4);
degree表示并行度；
3.查看统计信息，脚本(soxi.txt)
Please enter Name of Table Owner (Null = SYS): SYS
Please enter Table Name to show Statistics for: T2
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Table Level
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Table Number Empty Average Chain Average Global User Sample Date
Name of Rows Blocks Blocks Space Count Row Len Stats Stats Size MM-DD-YYYY
--------------- -------------- -------- ------------ ------- -------- ------- ------ ------ -------------- ----------
T2 87,361 1,246 0 0 0 98 YES NO 87,361 07-07-2015
Column Column Distinct Number Number Global User Sample Date
Name Details Values Density Buckets Nulls Stats Stats Size MM-DD-YYYY
------------------------- ------------------------ ------------ ------- ------- ---------- ------ ------ -------------- ----------
OWNER VARCHAR2(30) 31 0 1 0 YES NO 87,361 07-07-2015
OBJECT_NAME VARCHAR2(128) 52,669 0 1 0 YES NO 87,361 07-07-2015
SUBOBJECT_NAME VARCHAR2(30) 194 0 1 86,760 YES NO 601 07-07-2015
OBJECT_ID NUMBER(22) 87,361 0 1 0 YES NO 87,361 07-07-2015
DATA_OBJECT_ID NUMBER(22) 9,348 0 1 77,945 YES NO 9,416 07-07-2015
OBJECT_TYPE VARCHAR2(19) 45 0 1 0 YES NO 87,361 07-07-2015
CREATED DATE 1,244 0 1 0 YES NO 87,361 07-07-2015
LAST_DDL_TIME DATE 1,365 0 1 0 YES NO 87,361 07-07-2015
TIMESTAMP VARCHAR2(19) 1,440 0 1 0 YES NO 87,361 07-07-2015
STATUS VARCHAR2(7) 2 1 1 0 YES NO 87,361 07-07-2015
TEMPORARY VARCHAR2(1) 2 1 1 0 YES NO 87,361 07-07-2015
GENERATED VARCHAR2(1) 2 1 1 0 YES NO 87,361 07-07-2015
SECONDARY VARCHAR2(1) 2 1 1 0 YES NO 87,361 07-07-2015
NAMESPACE NUMBER(22) 21 0 1 0 YES NO 87,361 07-07-2015
EDITION_NAME VARCHAR2(30) 0 0 0 87,361 YES NO 07-07-2015
B Average Average
Index Tree Leaf Distinct Number Leaf Blocks Data Blocks Cluster Global User Sample Date
Name Unique Level Blks Keys of Rows Per Key Per Key Factor Stats Stats Size MM-DD-YYYY
--------------- --------- ----- ---- -------------- -------------- ----------- ----------- ------------ ------ ------ -------------- ----------
IDX_T2 NONUNIQUE 1 194 87,361 87,361 1 1 1,385 YES NO 87,361 07-07-2015
Index Column Col Column
Name Name Pos Details
--------------- ------------------------- ---- ------------------------
IDX_T2 OBJECT_ID 1 NUMBER(22)
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Partition Level
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SubPartition Level
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