来自 IT技术分享 2018-11-21 14:11 的文章

Oracle如何获取sharepool中没有使用绑定变量的SQL

ASKTOM网站提供了一个函数remove_constants,来检查共享池中的SQL运行情况,处理思路是将查询条件值变为一个通用标记,如:select * from t where object_id=1替换成select * from t where [email protecteAAAAAAAAAAA>SQL> drop table find_no_bind purge;
SQL> create table t as select * from dba_objects where 1=2;

--创建纪录表
SQL> create table find_no_bind as select sql_text from v$sqlarea;
SQL> alter table find_no_bind add sql_text_copy varchar2(1000);

--创建替换函数,把占位符替换成@
create or replace function
SQL> remove_constants( p_query in varchar2 ) return varchar2
as
l_query long;
l_char varchar2(1);
l_in_quotes boolean default FALSE;
begin
for i in 1 .. length( p_query )
loop
l_char := substr(p_query,i,1);
if ( l_char = '''' and l_in_quotes )
then
l_in_quotes := FALSE;
elsif ( l_char = '''' and NOT l_in_quotes )
then
l_in_quotes := TRUE;
l_query := l_query || '''#';
end if;
if ( NOT l_in_quotes ) then
l_query := l_query || l_char;
end if;
end loop;
l_query := translate( l_query, '0123456789', '@@@@@@@@@@' );
for i in 0 .. 8 loop
l_query := replace( l_query, lpad('@',10-i,'@'), '@' );
l_query := replace( l_query, lpad(' ',10-i,' '), ' ' );
end loop;
return upper(l_query);
end;
/

--先清一下share pool,正式环境不能这么干

SQL> alter system flush shared_pool;

SQL> begin
for i in 1..1000 loop
execute immediate 'select * from t where OBJECT_ID = '||i;
end loop;
end;
/

SQL> update find_no_bind set sql_text_copy = remove_constants(sql_text);

SQL> commit;

SQL> col sql_text_copy format a40
SQL> select sql_text_copy, count(*)
2 from find_no_bind
3 group by sql_text_copy
4 having count(*) > 10;
SQL_TEXT_COPY COUNT(*)
---------------------------------------- ----------
SELECT * FROM T WHERE OBJECT_ID = @ 1000

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