dbms_stats包下面一共有40多个存储过程. 对执行计划的生成非常重要。常见的有：分析数据库（包括所有的用户对象和系统对象）：ga
dbms_stats包下面一共有40多个存储过程. 对执行计划的生成非常重要。常见的有：
分析数据库（包括所有的用户对象和系统对象）：gather_database_stats
分析用户所有的对象（包括表、索引、簇）：gather_schema_stats
分析表：gather_table_stats
分析索引：gather_index_stats
删除数据库统计信息：delete_database_stats
删除用户方案统计信息：delete_schema_stats
删除表统计信息：delete_table_stats
删除索引统计信息：delete_index_stats
删除列统计信息：delete_column_stats
设置表统计信息：set_table_stats
设置索引统计信息：set_index_stats
设置列统计信息：set_column_stats
可以查看表 DBA_TABLES来查看表是否与被分析过，，如：
SELECT TABLE_NAME, LAST_ANALYZED FROM DBA_TABLES
通常使用的比较多的主要是DBMS_STATS.GATHER_TABLE_STATS和 DBMS_STATS.GATHER_INDEX_STATS。
注释：
ownname:要分析表的拥有者
tabname:要分析的表名.
partname:分区的名字,只对分区表或分区索引有用.
estimate_percent:这个参数相当于analyze中的"estimate statistics sample x percent".为总行数的百分比来估算.如果该参数为空.则为compute，当然也可以使用DBMS_STATS.AUTO_SAMPLE_SIZE 让Oracle 来决定估算百分比数
block_sample:该参数是一个boolean.在决定是否进行随机采样.
method_opt :该参数表明数据颁布不均衡的情况下是否使用直方图。可选值为"for all columns 或者for all indexed columns.当然也可以使用auto.让oracle来决定收集
degree ：parallel degree(并行收集维度) 看CPU个数
cascade :决定是否收集相关表的索引的统计信息.
force:即使表锁住了也收集统计信息.
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