Home Database Mysql Tutorial dbms_stats包的使用说明书

dbms_stats包的使用说明书

Jun 07, 2016 pm 05:18 PM
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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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