sql monitor的使用(一) （r2第30天)
阿新 • • 發佈：2022-05-04
在sql調優中，對於sql語句的實時監控顯得尤為重要，如果某條sql語句的效能比較差。可能從前端的直觀感覺就是執行時間比較長。 對於dba來說，可能關注的相關因素需要多一些. 1）可以通過top命令來監控sql的效能情況，檢視cpu使用率較高的oracle process,然後通過檢視session和process得繫結得到對應的session,然後得到對應的sql語句。 2) 如果已經過去了一段時間，而且在快取中已經沒有對應的sql語句了，可以通過awr得到一個大體的報告做分析，排查問題的大體範圍，在這個基礎上定位更精準的時間段，做一個ash。 3) 如果已經定位到sql_id了，想做進一步的分析，可以通過awrsqrpt來得到對應時間段的執行計劃 。。。 對於執行計劃的分析方式就更多了，但是oracle也提供了一些比較方便的功能集，你用或者不用，它就在那裡。 sql monitor是一個實時的sql監控工具，11g裡對dbms_tune做了不少的改進和提升。動態檢視v$sql_monitor中有被監控的sql語句的一些明細資訊。 一般對於執行時間超過5秒的sql語句，都會成為監控物件。 首先看看11g的庫是否啟用了這項功能
SQL> show parameter CONTROL_MANAGEMENT_PACK_ACCESS;
control_management_pack_access string DIAGNOSTIC+TUNING
然後模擬一個大查詢，做個並行，表t裡面有150萬左右的資料，我本地的機器查詢奎尼丁超過5秒。
SQL> select /*+ parallel(8) */count(1) from t ;
1536604
然後檢視v$sql_minotor
set long 99999
set pages 0
set linesize 200
col status format a20
col username format a30
col module format a20
col program format a20
col sql_id format a20
col sql_text format a50
select STATUS , USERNAME , MODULE , PROGRAM, SQL_ID , SQL_TEXT from v$sql_monitor
/
DONE (ALL ROWS) 21df1v060g0wq
DONE (ALL ROWS) 21df1v060g0wq
DONE (ALL ROWS) 21df1v060g0wq
DONE (ALL ROWS) 21df1v060g0wq
DONE (ALL ROWS) N1 SQL*Plus sqlplus@rac1 (TNS V1 21df1v060g0wq select /*+ parallel(8) */count(1) from t
-V3)
DONE (ALL ROWS) 21df1v060g0wq
DONE (ALL ROWS) 21df1v060g0wq
DONE (ALL ROWS) 21df1v060g0wq
DONE (ALL ROWS) 21df1v060g0wq
9 rows selected. col comm format a200
SELECT dbms_sqltune.report_sql_monitor(
sql_id => '21df1v060g0wq',
report_level => 'ALL',
type=>'TEXT'
) comm
FROM dual;
展示一個文字格式的報告。
SQL Text
------------------------------
select /*+ parallel(8) */count(1) from t
Global Information
------------------------------
Status : DONE (ALL ROWS)
Instance ID : 1
Session : N1 (254:77)
SQL ID : 21df1v060g0wq
SQL Execution ID : 16777216
Execution Started : 07/10/2014 06:40:49
First Refresh Time : 07/10/2014 06:40:52
Last Refresh Time : 07/10/2014 06:41:06
Duration : 17s
Module/Action : SQL*Plus/-
Service : SYS$USERS
Program : sqlplus@rac1 (TNS V1-V3)
Fetch Calls : 1
Global Stats
=========================================================================================
| Elapsed | Cpu | IO | Concurrency | Other | Fetch | Buffer | Read | Read |
| Time(s) | Time(s) | Waits(s) | Waits(s) | Waits(s) | Calls | Gets | Reqs | Bytes |
=========================================================================================
| 114 | 1.81 | 108 | 2.67 | 1.14 | 1 | 8913 | 1193 | 68MB |
=========================================================================================
Parallel Execution Details (DOP=8 , Servers Allocated=8)
============================================================================================================================================
| Name | Type | Server# | Elapsed | Cpu | IO | Concurrency | Other | Buffer | Read | Read | Wait Events |
| | | | Time(s) | Time(s) | Waits(s) | Waits(s) | Waits(s) | Gets | Reqs | Bytes | (sample #) |
============================================================================================================================================
| PX Coordinator | QC | | 3.10 | 0.04 | 0.01 | 2.67 | 0.38 | 5 | 1 | 8192 | os thread startup (3) |
| p000 | Set 1 | 1 | 14 | 0.21 | 14 | | | 1075 | 143 | 8MB | direct path read (13) |
| p001 | Set 1 | 2 | 14 | 0.23 | 13 | | 0.22 | 1190 | 158 | 9MB | direct path read (12) |
| p002 | Set 1 | 3 | 14 | 0.21 | 14 | | | 1078 | 142 | 8MB | direct path read (12) |
| p003 | Set 1 | 4 | 14 | 0.20 | 14 | | | 1030 | 139 | 8MB | direct path read (14) |
| p004 | Set 1 | 5 | 14 | 0.25 | 13 | | 0.07 | 1166 | 156 | 9MB | direct path read (13) |
| p005 | Set 1 | 6 | 14 | 0.22 | 13 | | 0.23 | 1074 | 145 | 8MB | direct path read (13) |
| p006 | Set 1 | 7 | 14 | 0.25 | 14 | | | 1288 | 176 | 10MB | direct path read (14) |
| p007 | Set 1 | 8 | 14 | 0.20 | 14 | | 0.23 | 1007 | 133 | 8MB | direct path read (13) |
============================================================================================================================================
SQL Plan Monitoring Details (Plan Hash Value=3126468333)
========================================================================================================================================================
| Id | Operation | Name | Rows | Cost | Time | Start | Execs | Rows | Read | Read | Activity | Activity Detail |
| | | | (Estim) | | Active(s) | Active | | (Actual) | Reqs | Bytes | (%) | (# samples) |
========================================================================================================================================================
| 0 | SELECT STATEMENT | | | | 1 | +17 | 1 | 1 | | | | |
| 1 | SORT AGGREGATE | | 1 | | 1 | +17 | 1 | 1 | | | | |
| 2 | PX COORDINATOR | | | | 17 | +1 | 9 | 8 | | | 2.63 | os thread startup (3) |
| 3 | PX SEND QC (RANDOM) | :TQ10000 | 1 | | 1 | +17 | 8 | 8 | | | | |
| 4 | SORT AGGREGATE | | 1 | | 14 | +4 | 8 | 8 | | | 0.88 | Cpu (1) |
| 5 | PX BLOCK ITERATOR | | 2M | 338 | 13 | +5 | 8 | 2M | | | | |
| 6 | TABLE ACCESS FULL | T | 2M | 338 | 14 | +4 | 115 | 2M | 1192 | 68MB | 96.49 | Cpu (6) |
| | | | | | | | | | | | | direct path read (104) |
========================================================================================================================================================文字格式的報告簡單明瞭，但是html的報告來說更加清晰，而且還有額外的一些資訊。效能瓶頸類問題，一目瞭然。
SQL Text
SQL Plan Monitoring Details (Plan Hash Value=3126468333)
