Oracle 收集统计值 收集统计信息
--收集Oracle统计信息BEGIN
DBMS_STATS.GATHER_TABLE_STATS(OWNNAME => 'OWNER_NAME',--数据库用户名
TABNAME => 'TABLE_NAME',--表名
PARTNAME => 'PARTITION_NAME',--分区名
ESTIMATE_PERCENT => DBMS_STATS.AUTO_SAMPLE_SIZE,
METHOD_OPT => 'for all columns> DEGREE => DBMS_STATS.AUTO_DEGREE,
CASCADE => TRUE);
END;
--查询表的统计信息
SELECT *
FROM DBA_TAB_STATISTICS S
WHERE S.OWNER = 'OWNER_NAME'--数据库用户名
AND S.TABLE_NAME = 'TABLE_NAME'--表名
ORDER BY S.LAST_ANALYZED DESC;
--Oracle统计信息
DBMS_STATS.gather_table_stats
(ownname varchar2,
tabname varchar2,
partname varchar2 default null,
estimate_percent number defaultto_estimate_percent_type(get_param('ESTIMATE_PERCENT')),
block_sample boolean default FALSE,
method_opt varchar2 default get_param('METHOD_OPT'),
degree number default to_degree_type(get_param('DEGREE')),
granularity varchar2 default get_param('GRANULARITY'),
cascade boolean default to_cascade_type(get_param('CASCADE')),
stattab varchar2 default null, statid varchar2 default null,
statown varchar2 default null,
no_invalidate boolean default to_no_invalidate_type(get_param('NO_INVALIDATE')),
stattype varchar2 default 'DATA',
force boolean default FALSE);
/*
参数说明:
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:采样行的百分比,取值范围,null为全部分析,不采样. 常量:DBMS_STATS.AUTO_SAMPLE_SIZE是默认值,由oracle决定最佳取采样值.
block_sapmple:是否用块采样代替行采样.
method_opt: 决定histograms信息是怎样被统计的.method_opt的取值如下:
for all columns:统计所有列的histograms.
for all indexed columns:统计所有indexed列的histograms.
for all hidden columns:统计你看不到列的histograms
for columns > 统计指定列的histograms.N的取值范围; R
EPEAT上次统计过的histograms;
AUTO由oracle决定N的大小;
SKEWONLY multiple end-points with the same value which is what we define by "
there is skew in the data
degree: 设置收集统计信息的并行度.默认值为null.
granularity:Granularity of statistics to collect ,only pertinent if the table is partitioned.
cascade: 是收集索引的信息.默认为falase.
stattab 指定要存储统计信息的表,statid如果多个表的统计信息存储在同一个stattab中用于进行区分.statown存储统计信息表的拥有者.以上三个参数若不指定,
统计信息会直接更新到数据字典.
no_invalidate: Does not invalidate the dependent cursors if set to TRUE. The procedure invalidates the dependent cursors
immediately if set to FALSE.
force: 即使表锁住了也收集统计信息
*/
--例子:
execute dbms_stats.gather_table_stats(ownname => 'owner',
tabname => 'table_name' ,
estimate_percent => null ,
method_opt => 'for all indexed columns' ,
cascade => true);
--GATHER_INDEX_STATS
--==========================
BEGIN
SYS.DBMS_STATS.GATHER_INDEX_STATS (OwnName => 'ABC',
IndName => 'IDX_FUNC_ABC',
Estimate_Percent => 10,
Degree => SYS.DBMS_STATS.DEFAULT_DEGREE,
No_Invalidate => FALSE);
END;
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