并行 parallel 受PROFILE 的影响各个版本不同

jnrjian2024-08-26 19:51

TEST CASE:

========

conn sys as sysdba

alter system set resource_limit=true;

CREATE PROFILE support_profile LIMIT SESSIONS_PER_USER 6;

alter user <USERNAME> profile support_profile;

conn <USERNAME>/<PASSWORD>

SQL> alter session set "_px_trace"="high","compilation","high","execution","messaging","time";

Session altered.

SQL> ALTER SESSION SET EVENTS '10053 trace name context forever, level 10';

Session altered.

SQL> select /*+ PARALLEL(8) monitor*/ count(*) from <TABLE NAME>;

COUNT(*)

918843

SQL> SET LONG 1000000

SQL> SET LONGCHUNKSIZE 1000000

SQL> SET LINESIZE 1000

SQL> SET PAGESIZE 0

SQL> SELECT DBMS_SQLTUNE.report_sql_monitor(sql_id => NULL, type => 'TEXT',report_level=>'ALL') AS report FROM dual;

SQL Monitoring Report

SQL Text

select /*+ PARALLEL(8) monitor*/ count(*) from sales

Parallel Execution Details (DOP=8 , Servers Allocated=8)

SET LONG 1000000

SET LONGCHUNKSIZE 1000000

SET LINESIZE 1000

SET PAGESIZE 0

SELECT DBMS_SQLTUNE.report_sql_monitor(sql_id => NULL, type => 'TEXT',report_level=>'ALL') AS report FROM dual;

Database profile is used to set SESSION_PER_USER to 6. As a result you cannot have more than 6 sessions. If you try to open 7 sessions you get and ORA-02391 error.

This also causes that an SQL may not get the requested number of parallel processes.

CHANGES

CAUSE

Expected behaviour since Bug 5910422 is fixed.

SOLUTION

This is the expected behaviour in 10.2.0.4 and above (where Bug 5910422 is fixed). The sessions_per_user limit is enforced when the parallel workers are starting in the session.

The following demonstrates this behaviour on one session. Obviously if more than one sessions are open and parallel statement is running, its DOP will be reduced accordingly.

The example demonstrates the following steps on a query that has parallel plan with 1 worker group having 1 worker set. The query is requested to run with dop=8 by statement level parallel hint.

  • No profile limit set, and the query runs with DOP 8, having 8 parallel workers.
  • Then profile LIMIT SESSIONS_PER_USER is set to 6. Oracle wants to create 8 parallel workers, before the 8 parallel workers would join the QC, it recognizes SESSIONS_PER_USER is set to 6, so it releases 3 workers, and end up with 5 workers + the QC.

This demonstration was done on single instance. It may apply to RAC but the meaning of SESSIONS_PER_USER profile limit in multi instance environment is out of the scope of this article.

STEPS

conn sh

select /*+ PARALLEL(8) monitor*/ count(*) from T1;

SET LONG 1000000

SET LONGCHUNKSIZE 1000000

SET LINESIZE 1000

SET PAGESIZE 0

SELECT DBMS_SQLTUNE.report_sql_monitor(sql_id => NULL, type => 'TEXT',report_level=>'ALL') AS report FROM dual;

-- enable resource plan and resource limit

conn sys as sysdba

alter system set resource_limit=true;

CREATE PROFILE support_profile LIMIT SESSIONS_PER_USER 6;

alter user sh profile support_profile;

conn sh

alter session set "_px_trace"="high","compilation","high","execution","messaging","time";

ALTER SESSION SET EVENTS '10053 trace name context forever, level 10';

select /*+ PARALLEL(8) monitor*/ count(*) from T1;

SET LONG 1000000

SET LONGCHUNKSIZE 1000000

SET LINESIZE 1000

SET PAGESIZE 0

SELECT DBMS_SQLTUNE.report_sql_monitor(sql_id => NULL, type => 'TEXT',report_level=>'ALL') AS report FROM dual;

-- clean up

conn sys as sysdba

drop PROFILE support_profile cascade;

alter system set resource_limit=false;

ACTUAL RESULT

SH@dw23> select /*+ PARALLEL(8) monitor*/ count(*) from T1;

COUNT(*)

783327

SH@dw23> SET LONG 1000000

SH@dw23> SET LONGCHUNKSIZE 1000000

SH@dw23> SET LINESIZE 1000

SH@dw23> SET PAGESIZE 0

SH@dw23> SELECT DBMS_SQLTUNE.report_sql_monitor(sql_id => NULL, type => 'TEXT',report_level=>'ALL') AS report FROM dual;

SQL Monitoring Report

SQL Text

select /*+ PARALLEL(8) monitor*/ count(*) from T1

Global Information

Status : DONE (ALL ROWS)

Instance ID : 1

Session : SH (11:3833)

SQL ID : 0md7m3v2sh21s

SQL Execution ID : 16777216

Execution Started : 02/20/2014 11:53:14

First Refresh Time : 02/20/2014 11:53:14

Last Refresh Time : 02/20/2014 11:53:15

Duration : 1s

Module/Action : SQL*Plus/-

Service : ABCD.xx.xyz.com

Program : sqlplus.exe

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 |

=========================================================================================

| 5.40 | 0.16 | 3.73 | 0.21 | 1.30 | 1 | 2065 | 318 | 11MB |

=========================================================================================

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 | | 0.79 | 0.01 | 0.24 | 0.21 | 0.33 | 58 | 18 | 144KB | db file parallel read (1) |

| p000 | Set 1 | 1 | 0.59 | 0.02 | 0.46 | | 0.11 | 281 | 33 | 2MB | db file sequential read (1) |

| p001 | Set 1 | 2 | 0.59 | 0.02 | 0.42 | | 0.14 | 258 | 54 | 2MB | direct path read (1) |

| p002 | Set 1 | 3 | 0.58 | 0.02 | 0.41 | | 0.15 | 418 | 63 | 1MB | direct path read (1) |

| p003 | Set 1 | 4 | 0.56 | 0.01 | 0.42 | | 0.13 | 204 | 28 | 968KB | direct path read (1) |

| p004 | Set 1 | 5 | 0.56 | 0.04 | 0.39 | | 0.14 | 286 | 38 | 1MB | db file sequential read (1) |

| p005 | Set 1 | 6 | 0.58 | 0.02 | 0.46 | | 0.10 | 181 | 26 | 1MB | direct path read (1) |

| p006 | Set 1 | 7 | 0.56 | 0.02 | 0.48 | | 0.07 | 203 | 32 | 1MB | direct path read (1) |

| p007 | Set 1 | 8 | 0.58 | 0.01 | 0.45 | | 0.12 | 176 | 26 | 1MB | db file sequential read (1) |

==================================================================================================================================================

SQL Plan Monitoring Details (Plan Hash Value=1311612494)

===============================================================================================================================================================

| 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 | +1 | 1 | 1 | | | | |

| 1 | SORT AGGREGATE | | 1 | | 1 | +1 | 1 | 1 | | | | |

| 2 | PX COORDINATOR | | | | 2 | +0 | 9 | 8 | 18 | 144KB | 11.11 | db file parallel read (1) |

| 3 | PX SEND QC (RANDOM) | :TQ10000 | 1 | | 1 | +1 | 8 | 8 | | | | |

| 4 | SORT AGGREGATE | | 1 | | 1 | +1 | 8 | 8 | | | | |

| 5 | VIEW | VW_TE_2 | 611K | 62 | 1 | +1 | 8 | 783K | | | | |

| 6 | UNION-ALL | | | | 1 | +1 | 8 | 783K | | | | |

| 7 | PX BLOCK ITERATOR | | 501K | 54 | 1 | +1 | 8 | 672K | | | | |

| 8 | TABLE ACCESS FULL | T1| 501K | 54 | 1 | +1 | 103 | 672K | 103 | 9MB | 55.56 | direct path read (5) |

| 9 | PX BLOCK ITERATOR | | 109K | 9 | 1 | +1 | 8 | 111K | | | | |

| 10 | TABLE ACCESS FULL | T1| 109K | 9 | 1 | +1 | 197 | 111K | 197 | 2MB | 33.33 | db file sequential read (3) |

===============================================================================================================================================================

SH@ABCD> conn sys/manager1@ABCD as sysdba

Connected.

SYS@ABCD> alter system set resource_limit=true;

System altered.

SYS@ABCD> CREATE PROFILE support_profile LIMIT SESSIONS_PER_USER 6;

Profile created.

SYS@ABCD> alter user sh profile support_profile;

User altered.

SYS@ABCD> conn sh/sh@ABCD

Connected.

SH@ABCD> alter session set "_px_trace"="high","compilation","high","execution","messaging","time";

Session altered.

SH@ABCD> ALTER SESSION SET EVENTS '10053 trace name context forever, level 10';

Session altered.

SH@dw23> select /*+ PARALLEL(8) monitor*/ count(*) from sales;

COUNT(*)

783327

SH@ABCD> SET LONG 1000000

SH@ABCD> SET LONGCHUNKSIZE 1000000

SH@ABCD> SET LINESIZE 1000

SH@ABCD> SET PAGESIZE 0

SH@ABCD> SELECT DBMS_SQLTUNE.report_sql_monitor(sql_id => NULL, type => 'TEXT',report_level=>'ALL') AS report FROM dual;

SQL Monitoring Report

SQL Text

select /*+ PARALLEL(8) monitor*/ count(*) from T1

Global Information

Status : DONE (ALL ROWS)

Instance ID : 1

Session : SH (11:3841)

SQL ID : 0md7m3v2sh21s

SQL Execution ID : 16777218

Execution Started : 02/20/2014 12:04:31

First Refresh Time : 02/20/2014 12:04:31

Last Refresh Time : 02/20/2014 12:04:32

Duration : 1s

Module/Action : SQL*Plus/-

Service : ABCD.xx.xyz.com

Program : sqlplus.exe
DOP Downgrade : 38%

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 |

=========================================================================================

| 0.91 | 0.40 | 0.00 | 0.23 | 0.28 | 1 | 1618 | 62 | 9MB |

=========================================================================================

Parallel Execution Details (DOP=5 , Servers Requested=8 , Servers Allocated=5 )

==================================================================================================================================

| 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 | | 0.35 | 0.06 | | 0.23 | 0.06 | 58 | | . | |

| p000 | Set 1 | 1 | 0.10 | 0.06 | 0.00 | | 0.04 | 395 | 16 | 2MB | |

| p001 | Set 1 | 2 | 0.10 | 0.10 | 0.00 | | 0.01 | 409 | 15 | 2MB | |

| p002 | Set 1 | 3 | 0.14 | 0.06 | 0.00 | | 0.07 | 281 | 10 | 2MB | |

| p003 | Set 1 | 4 | 0.12 | 0.09 | 0.00 | | 0.03 | 329 | 15 | 2MB | |

| p005 | Set 1 | 5 | 0.10 | 0.03 | 0.00 | | 0.07 | 146 | 6 | 872KB | |

==================================================================================================================================

SQL Plan Monitoring Details (Plan Hash Value=1311612494)

===================================================================================================================================================

| 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 | +1 | 1 | 1 | | | | |

| 1 | SORT AGGREGATE | | 1 | | 1 | +1 | 1 | 1 | | | | |

| 2 | PX COORDINATOR | | | | 1 | +1 | 6 | 5 | | | | |

| 3 | PX SEND QC (RANDOM) | :TQ10000 | 1 | | 1 | +1 | 5 | 5 | | | | |

| 4 | SORT AGGREGATE | | 1 | | 1 | +1 | 5 | 5 | | | | |

| 5 | VIEW | VW_TE_2 | 611K | 62 | 1 | +1 | 5 | 783K | | | | |

| 6 | UNION-ALL | | | | 1 | +1 | 5 | 783K | | | | |

| 7 | PX BLOCK ITERATOR | | 501K | 54 | 1 | +1 | 5 | 672K | | | | |

| 8 | TABLE ACCESS FULL | T1| 501K | 54 | 1 | +1 | 62 | 672K | 62 | 9MB | | |

| 9 | PX BLOCK ITERATOR | | 109K | 9 | 1 | +1 | 5 | 111K | | | | |

| 10 | TABLE ACCESS FULL | T1| 109K | 9 | 1 | +1 | 50 | 111K | | | | |

===================================================================================================================================================

PX_TRACE FILE SHOWS THE FOLLOWING

Oracle wants to create 8 parallel workers, before the 8 parallel workers would join the QC,

it recognizes SESSIONS_PER_USER 日志中没有显示 is set to 6, so it releases 3 workers, and end up with 5 workers + the QC.

kxfrAllocSlaves [ 70/ 0]

DOP trace -- call kxfpgsg to get 8 workers

2014-02-20 12:04:32.414436 :PX_Messaging:kxfp.c@9813:kxfpgsg(begin):

reqthreads=8 height=0 lsize=0 alloc_flg=0x234

2014-02-20 12:04:32.414557 :PX_Messaging:kxfp.c@9886:kxfpgsg():

reqthreads=8 KXFPTHIS/KXFPLDBL/KXFPADPT/ load balancing=on adaptive=on

2014-02-20 12:04:32.414588 :PX_Messaging:kxfp.c@18418:kxfpiinfo():

inst [cpus:mxslv:#pg]

1 [4 :270 :1 ]

(default: 0) inst target is 270

number of active slaves on the instance: 0,

number of active slaves but available to use: 0

2014-02-20 12:04:32.415645 :PX_Messaging:kxfp.c@18742:kxfpclinfo():

inst(load :user:pct:fact:servtarget:queued:started:granted:active:active(free)): aff

1 (0.00:0 :100:400 :270 :0 :0 :0 :0 :0 )

defDOP=8, tpc=2

2014-02-20 12:04:32.415750 :PX_Messaging:kxfp.c@17831:kxfpLoadAdDOP():

granted dop: 8

load adapt num servers requested to = 8 (from kxfpAdaptDOP())

2014-02-20 12:04:32.415798 :PX_Messaging:kxfp.c@2149:kxfpqialo():

Allocate new q for dp=(nil)

new q=0x951b6f30 dp=(nil) pnum=65535 numa#=0 qser=0 done.

2014-02-20 12:04:32.415880 :PX_Messaging:kxfp.c@10255:kxfpgsg():

getting 1 sets of 8 threads, client parallel query execution flg=0x234

Height=8, Affinity List Size=0, inst_total=1, coord=1

Insts: 1

Threads: 8
getting 8 slaves (8 required) for q=0x951b6f30 qser=3073

...

2014-02-20 12:04:32.663551 :PX_Messaging:kxfp.c@3782:kxfpqsrls():
Release Slave q=0x951b6f30 qr=0x951b4f48 action=1 server=4 inst=1

...

2014-02-20 12:04:32.663853 :PX_Messaging:kxfp.c@3782:kxfpqsrls():
Release Slave q=0x951b6f30 qr=0x951b5758 action=1 server=6 inst=1

...

2014-02-20 12:04:32.664908 :PX_Messaging:kxfp.c@3782:kxfpqsrls():
Release Slave q=0x951b6f30 qr=0x951b4488 action=1 server=7 inst=1

...

2014-02-20 12:04:32.664939 :PX_Messaging:kxfp.c@11410:kxfpg1sg():

got 5 servers (sync), errors=0x0 returning
Acquired 5 slaves on 1 instances avg height=5 #set=1 qser=3073

P000 inst 1 spid 19450

P001 inst 1 spid 19452

P002 inst 1 spid 19454

P003 inst 1 spid 19456

P005 inst 1 spid 19458

2024-08-25 13:53:29.465 :PX_Messaging:kxfp.c@13629:kxfpg1sg():

got 4 servers (sync), errors=0x0 returning

2024-08-25 13:53:29.465 :PX_Messaging:kxfp.c@12144:kxfpgsg(): threads reduced from 8 to 4 due to not enough slaves

reason_code = 354, reason: DOP downgrade due to insufficient number of processes

Acquired 4 slaves on 1 instances avg height=4 #set=1 qser=6657

P006 set 1 inst 1 spid 22426

P001 set 1 inst 1 spid 6258

P004 set 1 inst 1 spid 22422

P003 set 1 inst 1 spid 6632

2024-08-25 13:53:29.465 :PX_Messaging:kxfp.c@12430:kxfpgsg():

相关推荐
孪生质数-37 分钟前
SQL server 2022和SSMS的使用案例1
网络·数据库·后端·科技·架构
振鹏Dong44 分钟前
MySQL 事务底层和高可用原理
数据库·mysql
hycccccch1 小时前
RabbitMQ技术方案分析
数据库·rabbitmq
一人の梅雨1 小时前
化工网平台API接口开发实战：从接入到数据解析‌
java·开发语言·数据库
一只栖枝2 小时前
Oracle OCP知识点详解2：管理用户密码期限
数据库·oracle·开闭原则·ocp
PingCAP2 小时前
TiDB 亮相宜昌“医院‘云数智’技术实践研讨及成果展示交流会”，探讨国产化 + AI 背景下的数据库新趋势
数据库·人工智能·tidb
努力的小Qin2 小时前
银河麒麟V10 aarch64架构安装mysql教程
数据库·mysql·架构
云心雨禅3 小时前
解决大小写、保留字与特殊字符问题！Oracle双引号在SQL中的特殊应用
数据库·sql·oracle
vivo互联网技术3 小时前
活动中台系统慢 SQL 治理实践
java·数据库·后端
热门推荐
01我决定放弃搞 Java 了02DeepSeek各版本说明与优缺点分析03如何在WPS和Word/Excel中直接使用DeepSeek功能04本地化部署AI知识库：基于Ollama+DeepSeek+AnythingLLM保姆级教程05苍穹外卖面试总结06从零安装 LLaMA-Factory 微调 Qwen 大模型成功及所有的坑07循环神经网络RNN（含LSTM，GRU）小综述08RAG 实践- Ollama+RagFlow 部署本地知识库09如何本地部署AI智能体平台，带你手搓一个AI Agent10Android下HWC以及drm_hwcomposer普法(上)