调优，查找SQL

查找成本高的SQL语句，在10gR2以后的版本可用

SET LONG 40000;

SELECT OPTIMIZER_COST,EXECUTIONS, SQL_FULLTEXT FROM V$SQLAREA WHERE OPTIMIZER_COST>(SELECT MAX(OPTIMIZER_COST)/5 FROM V$SQLAREA) ORDER BY 1;

或

SELECT * FROM ( SELECT OPTIMIZER_COST,EXECUTIONS, SQL_FULLTEXT FROM V$SQLAREA ORDER BY OPTIMIZER_COST DESC) WHERE ROWNUM<10;

 

查找IO较高的SQL语句

SELECT ROUND(DISK_READS/EXECUTIONS) ,DISK_READS,EXECUTIONS, SQL_TEXT FROM V$SQLAREA WHERE ROUND(DISK_READS/EXECUTIONS)>(SELECT MAX(ROUND((DISK_READS/EXECUTIONS)/5)) FROM V$SQLAREA WHERE EXECUTIONS>0) AND EXECUTIONS>0 AND DISK_READS>100 ORDER BY 1;

 

查找扫描行数最多的SQL语句

SELECT ROUND(ROWS_PROCESSED/EXECUTIONS) ,ROWS_PROCESSED,EXECUTIONS, SQL_TEXT

FROM V$SQLAREA

WHERE ROUND(ROWS_PROCESSED/EXECUTIONS)>

(SELECT MAX(ROUND((ROWS_PROCESSED/EXECUTIONS)/5)) FROM V$SQLAREA

WHERE EXECUTIONS>0)

AND EXECUTIONS>0 AND ROWS_PROCESSED>1000 ORDER BY 1;

查找排序行数最多的SQL语句

SELECT * FROM (SELECT SQL_TEXT,SORTS FROM V$SQL ORDER BY SORTS DESC) WHERE ROWNUM<10;