Oracle9i, 10g 优化分析统计(dbms_stats)脚本-优快云博客

本文介绍Oracle9i与10g数据库中表分析的不同策略。9i版本针对不同规模的表采取固定比例分析，而10g版本则采用自动采样策略，根据表的大小和数据分布自动调整分析比例。

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Oracle9i (未开启table monitoring时)
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索引全分析
表分两种，大表10%，小表100%

#start
$ORACLE_HOME/bin/sqlplus /nolog <connect user/xxxx
prompt "analyze start,please wait......"
set serveroutput on size 100000
declare
v_per number(3);
v_start number := dbms_utility.get_time;
v_time number;
begin

for rec in (select segment_name,segment_type,ceil(sum(bytes)/1024/1024) segment_size
from user_segments
where segment_type like 'TABLE%' or segment_type like 'INDEX%'
group by segment_name,segment_type)
loop
    --start analyze
    if rec.segment_type = 'INDEX' then
         dbms_stats.gather_index_stats(ownname => 'USER',
                                       indname => rec.segment_name,
                                       degree => 8
                                      );
    elsif rec.segment_type = 'INDEX PARTITION' then
         dbms_stats.gather_index_stats(ownname => 'USER',
                                       indname => rec.segment_name,
                                       degree => 8
                                      );
    elsif rec.segment_type = 'TABLE' then
        case when rec.segment_size < 100 then
            v_per := 100;
        else
            v_per := 10;
        end case;
             dbms_stats.gather_table_stats(ownname          => 'USER',
                                           tabname          => rec.segment_name,
                                           estimate_percent => v_per,
                                           method_opt       => 'FOR ALL COLUMNS SIZE 1',       -- SIZE 1 不收集直方图信息
                                           degree           => 8);
    elsif rec.segment_type = 'TABLE PARTITION' then
             v_per := 10;
             dbms_stats.gather_table_stats(ownname          => 'USER',
                                           tabname          => rec.segment_name,
                                           estimate_percent => v_per,
                                           method_opt       => 'FOR ALL COLUMNS SIZE 1',
                                           degree           => 8);
    end if;
   v_time := ceil((dbms_utility.get_time - v_start)/100);
   dbms_output.put_line(rpad(rec.segment_name||'('||rec.segment_size||'M)',40,'.')||'elaped time '||v_time||'s');
   v_start := dbms_utility.get_time;
end loop;
end;
/
prompt "analyze end"
exit
EOF
<

--------------------------------------------------------------
Oracle9i,10g (开启table monitoring时)
--------------------------------------------------------------

都采用auto方式。

SQL> being
dbms_stats.gather_schema_stats(
ownname => 'USER',
estimate_percent => dbms_stats.auto_sample_size,    -- Oracle根据表的大小和列值分布在5％到20％间取值
method_opt => 'for all columns size auto',
cascade=>TRUE,
degree => 8 );
     end;
     /

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转载于:http://blog.itpub.net/35489/viewspace-616717/