转自：
1.analyze table t1 compute statistics for table; -->user_tables
（只对表的总体信息进行统计，比如行数多少等，不涉及到表字段）
2.analyze table t2 compute statistics for all columns; -->user_tab_columns
(只会收集表字段信息)
3.analyze table t3 compute statistics for all indexed columns; -->user_tab_columns
(只会收集表中索引所在的字段信息)
4.analyze table t4 compute statistics for all indexes;à user_indexes
(只收集表索引的信息)
5.analyze table t5 compute statistics;
(收集表，表字段，索引的信息)
另外，可以删除分析数据：
SQL> analyze table my_table delete statistics;
SQL> analyze table my_table delete statistics for table for all indexes for all indexed columns;
例子：
create table t1 as select * from user_objects;
create table t2 as select * from user_objects;
create table t3 as select * from user_objects;
create table t4 as select * from user_objects;
create table t5 as select * from user_objects;
create table t6 as select * from user_objects;
create unique index pk_t1_idx on t1(object_id);
create unique index pk_t2_idx on t2(object_id);
create unique index pk_t3_idx on t3(object_id);
create unique index pk_t4_idx on t4(object_id);
create unique index pk_t5_idx on t5(object_id);
create unique index pk_t6_idx on t6(object_id);
<</B>刚建完表的时候>
(1) 查看表的统计信息
select table_name, num_rows, blocks, empty_blocks
from user_tables
where table_name in ('T1', 'T2', 'T3', 'T4', 'T5','T6');
(2) 查看字段的统计信息
select table_name,
column_name,
num_distinct,
low_value,
high_value,
density
from user_tab_columns
where table_name in ('T1', 'T2', 'T3', 'T4','T5','T6');
(3) 查看索引的统计信息
select table_name,
index_name,
blevel,
leaf_blocks,
distinct_keys,
avg_leaf_blocks_per_key avg_leaf_blocks,
avg_data_blocks_per_key avg_data_blocks,
clustering_factor,
num_rows
from user_indexes
where table_name in ('T1', 'T2', 'T3', 'T4', 'T5', 'T6');
二．执行analyze命令
analyze table t1 compute statistics for table; --针对表收集信息
analyze table t2 compute statistics for all columns; --针对表字段收集信息
analyze table t3 compute statistics for all indexes columns; --收集索引字段信息
analyze table t4 compute statistics; --收集表，表字段，索引信息
analyze table t5 compute statistics for all indexes; --收集索引信息
analyze table t6 compute statistics for table for all indexes for all columns; --收集表，索引，表字段信息
(1) 表的统计信息
select table_name, num_rows, blocks, empty_blocks
from user_tables
where table_name in ('T1', 'T2', 'T3', 'T4', 'T5','T6');
(2) 表中字段的统计信息
select table_name,
column_name,
num_distinct,
low_value,
high_value,
density
from user_tab_columns
where table_name in ('T1', 'T2', 'T3', 'T4','T5','T6');
<</B>其中会收集T2的表字段信息，T3是索引所在字段信息，T4表字段信息，T6表字段信息>
(3) 索引的统计信息
没有变化，说明在创建索引的时候就ORACLE就已经收集相关信息