oracle TOPSQL整理

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--top 10 sql

SELECT   *     FROM (SELECT   b.username username,                      a.disk_reads                    / DECODE (a.executions, 0, 1, a.executions) rds_exec_ratio,                    a.sql_text STATEMENT               FROM v$sqlarea a, dba_users b              WHERE a.parsing_user_id = b.user_id AND b.username = 'ZYK'           ORDER BY rds_exec_ratio DESC)    WHERE ROWNUM < 11 ORDER BY rds_exec_ratio DESC

1. 识别’低效执行’的SQL语句
用下列SQL工具找出低效SQL:

SELECT EXECUTIONS , DISK_READS, BUFFER_GETS,         ROUND((BUFFER_GETS-DISK_READS)/BUFFER_GETS,2) Hit_radio,         ROUND(DISK_READS/EXECUTIONS,2) Reads_per_run,         SQL_TEXT FROM   V$SQLAREA WHERE  EXECUTIONS>0 AND     BUFFER_GETS > 0 AND (BUFFER_GETS-DISK_READS)/BUFFER_GETS < 0.8 ORDER BY 4 DESC;

2.查找单条语句的内存占用率

alter system set pga_aggregate_target=10m alter system set workarea_size_policy=auto; select distinct * from a where rownum<500000; select sql_text,operation_type,policy,(last_memory_used/1024/1024), last_execution,last_tempseg_size from v$sql i,v$sql_workarea a where i.hash_value=a.hash_value and sql_text='select distinct * from a where rownum<500000';

Top 10 by Buffer Gets:

set linesize 100 set pagesize 100 SELECT * FROM (SELECT substr(sql_text,1,40) sql, buffer_gets, executions, buffer_gets/executions "Gets/Exec", hash_value,address FROM V$SQLAREA WHERE buffer_gets > 10000 ORDER BY buffer_gets DESC) WHERE rownum <= 10 ;

Top 10 by Physical Reads:

set linesize 100 set pagesize 100 SELECT * FROM (SELECT substr(sql_text,1,40) sql, disk_reads, executions, disk_reads/executions "Reads/Exec", hash_value,address FROM V$SQLAREA WHERE disk_reads > 1000 ORDER BY disk_reads DESC) WHERE rownum <= 10 ;

Top 10 by Executions:

set linesize 100 set pagesize 100 SELECT * FROM (SELECT substr(sql_text,1,40) sql, executions, rows_processed, rows_processed/executions "Rows/Exec", hash_value,address FROM V$SQLAREA WHERE executions > 100 ORDER BY executions DESC) WHERE rownum <= 10 ;

Top 10 by Parse Calls:

set linesize 100 set pagesize 100 SELECT * FROM (SELECT substr(sql_text,1,40) sql, parse_calls, executions, hash_value,address FROM V$SQLAREA WHERE parse_calls > 1000 ORDER BY parse_calls DESC) WHERE rownum <= 10 ;

Top 10 by Sharable Memory:

set linesize 100 set pagesize 100 SELECT * FROM (SELECT substr(sql_text,1,40) sql, sharable_mem, executions, hash_value,address FROM V$SQLAREA WHERE sharable_mem > 1048576 ORDER BY sharable_mem DESC) WHERE rownum <= 10 ;

Top 10 by Version Count:

set linesize 100 set pagesize 100 SELECT * FROM (SELECT substr(sql_text,1,40) sql, version_count, executions, hash_value,address FROM V$SQLAREA WHERE version_count > 20 ORDER BY version_count DESC) WHERE rownum <= 10 ;

原文链接：http://www.cnblogs.com/liuweihua/archive/2012/05/05/2484446.html

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