SQL工具SQL调优和诊断神器SQLTXPLAIN (SQLT)简介

Posted 2022-06-22 SQLplusDB

SQLT

SQLTXPLAIN (SQLT) 是Oracle专家开发的，用于诊断SQL相关的问题的工具，简单易用却功能强大。

SQLT 会用户根据指定的模式，连接到数据库，收集执行计划、基于成本的 Optimizer CBO 统计信息、Schema 对象元数据、性能统计信息、配置参数和会影响正在分析的 SQL 性能的其他元素。

如果是SQL相关问题，建议通过SQLT收集信息，这样在定位问题以及和Oracle官方技术支持交互过程会减少很多不必要的时间和确认。

SQLT安装

通过 官方MOS Document 215187.1 可以下载最新的SQLT安装包，下载后通过安装中sqlt_instructions.html的介绍，按以下步骤可以安装好SQLT。

例：（12c NONCDB @Linux）

1.对SQLT安装包（sqlt_latest.zip）解压

[oracle@db12102 20160827]$ ls
sqlt_latest.zip
[oracle@db12102 20160827]$ unzip sqlt_latest.zip
Archive:  sqlt_latest.zip
   creating: sqlt/
   creating: sqlt/doc/
...
  inflating: sqlt/utl/xplore/xplore.pks  
[oracle@db12102 20160827]$ ls
sqlt  sqlt_latest.zip

2.进入sqlt的路径，准备安装

[oracle@db12102 20160827]$ cd sqlt
[oracle@db12102 sqlt]$ ls
doc  input  install  run  sqlt_instructions.html  sqlt_instructions.txt  utl

3.执行sqcreate.sql进行安装

SQL> conn /as sysdba      
Connected.
SQL> @install/sqcreate.sql

在安装过程中需要指定的参数和各参数的含义如下：

3-1.连接标识符（当安装在一个可插拔数据库上时是必须的）

Specify optional Connect Identifier (as per Oracle Net)
Include "@" symbol, ie. @PROD
If not applicable, enter nothing and hit the "Enter" key.
You *MUST* provide a connect identifier when installing
SQLT in a Pluggable Database in 12c
This connect identifier is only used while exporting SQLT
repository everytime you execute one of the main methods.

Optional Connect Identifier (ie: @PROD): 

3-2.SQLTXPLAIN 密码

Define SQLTXPLAIN password (hidden and case sensitive).
Password for user SQLTXPLAIN: 

3-3.SQLTXPLAIN 默认表空间

The next step is to choose the tablespaces to be used by SQLTXPLAIN
The Tablespace name is case sensitive.  
Do you want to see the free space of each tablespace [YES]
or is it ok just to show the list of tablespace [NO]?

Type YES or NO [Default NO]: NO  

... please wait

TABLESPACE                     FREE_SPACE_MB
------------------------------ -------------
EXAMPLE
USERS

Specify PERMANENT tablespace to be used by SQLTXPLAIN.  
Tablespace name is case sensitive.  
Default tablespace [UNKNOWN]: USERS

PL/SQL procedure successfully completed.    
... please wait

TABLESPACE
------------------------------
TEMP

Specify TEMPORARY tablespace to be used by SQLTXPLAIN.  
Tablespace name is case sensitive.  
Temporary tablespace [UNKNOWN]: TEMP

3-4. 应用程序用户 （发出要分析 SQL 语句的用户）

The main application user of SQLT is the schema
owner that issued the SQL to be analyzed.
For example, on an EBS application you would
enter APPS.
You will not be asked to enter its password.
To add more SQLT users after this installation
is completed simply grant them the SQLT_USER_ROLE
role.

Main application user of SQLT: teacherwhat

※也可以在安装该工具后添加其他的 SQLT 用户，方法为：授予他们角色 SQLT_USER_ROLE， 或通过使用提供的脚本 sqlt/install/sqguser.sql

例：
SQL> conn /as sysdba
SQL> @install/sqguser.sql scott

3-5. 授权的 Oracle Pack。（T，D 或 N）

SQLT can make extensive use of licensed features
provided by the Oracle Diagnostic and the Oracle
Tuning Packs, including SQL Tuning Advisor (STA),
SQL Monitoring and Automatic Workload Repository
(AWR).
To enable or disable access to these features
from the SQLT tool enter one of the following
values when asked:

"T" if you have license for Diagnostic and Tuning
"D" if you have license only for Oracle Diagnostic
"N" if you do not have these two licenses

Oracle Pack license [T]: T

4.如果需要的话，通过下面的脚本可以卸载 SQLT。

SQL> conn /as sysdba
SQL> @install/sqdrop.sql

※卸载 SQLT 会同时移除 SQLT Repository 以及所有SQLT相关的内容。

参考：
All About the SQLT Diagnostic Tool (Doc ID 215187.1)

SQLT的使用

执行方法的种类

SQLT的执行方法主要包括以下

XTRACT：通过V$SQL、AWR的过去执行过的SQL内容，收集相关信息。 
XECUTE：通过执行SQL，收集相关信息。

XPLAIN：不执行SQL，基于EXPLAIN PLAN FOR命令收集相关信息。（不推荐）
XTRXEC：该方法合并了XTRACT和XECUTE 的功能。实际上，XTRXEC连续执行了这两种方法。
XTRSBY：分析在 Data Guard 或备用只读数据库上执行的 SQL。
XPREXT：使用XTRACT同时禁用一些SQLT的特性，使之执行更快。
XPREXC：使用XECUTE同时禁用一些SQLT的特性，使之执行更快

执行方法

XTRACT 方法

通过V$SQL、AWR的过去执行过的SQL内容，收集相关信息。

1.通过V$SQL或AWR找到要收集数据的SQL的SQL_ID 或者HASH_VALUE。

SELECT sql_id, hash_value, SUBSTR(sql_text,1,40) Text
FROM v$sql
WHERE sql_text LIKE '%&An_Identifiable_String%';

2.进入到sqlt的run路径下，执行sqltxtract.sql脚本收集相关信息

$ ls
doc  input  install  run  SQLT_installation_logs_archive.zip  sqlt_instructions.html  sqlt_instructions.txt  utl
$ cd run
$sqlplus Username/Password
SQL> START sqltxtract.sql [SQL_ID]|[HASH_VALUE] [sqltxplain_password]

3.执行例：

[oracle@db12102 sqlt]$ ls
doc  input  install  run  SQLT_installation_logs_archive.zip  sqlt_instructions.html  sqlt_instructions.txt  utl
[oracle@db12102 sqlt]$ cd run
[oracle@db12102 run]$ sqlplus /nolog     

SQL*Plus: Release 12.1.0.2.0 Production on Sat Aug 27 20:18:29 2016

Copyright (c) 1982, 2014, Oracle.  All rights reserved.

SQL> conn teacherwhat/teacherwhat
Connected.
SQL> select/*+ GATHER_PLAN_STATISTICS MONITOR */ count(*) from SQLMON where a='A';

  COUNT(*)
----------
      1000

SQL> SELECT sql_id, hash_value, SUBSTR(sql_text,1,40) Text
FROM v$sql
WHERE sql_text LIKE 'select/*+ GATHER_PLAN_STATISTICS MONITOR */ count(*)%';  2    3  

SQL_ID        HASH_VALUE
------------- ----------
TEXT
--------------------------------------------------------------------------------
acsdndc43qs74  138109156
select/*+ GATHER_PLAN_STATISTICS MONITOR

SQL> START sqltxtract.sql acsdndc43qs74 SQLTXPLAIN
... 
  adding: sqlt_s28359_sqldx.zip (stored 0%)

#####
The SQLT has collected information and place it in a repository in the database, exported it and zip it.
The collected info can be purged from the database using the following file :
... getting sqlt_s28359_purge.sql out of sqlt repository ...

SQLTXTRACT completed.

相关的信息生成在了sqlt_s28359_sqldx.zip 中。

XECUTE 方法

通过执行SQL，收集相关信息;与 XTRACT方法相比，该方法提供的信息更为详细.

1.使用XECUTE 方法之前，创建一个包含 SQL 文本的文本文件。
如果 SQL 包括绑定变量，则您的文件必须包含绑定变量声明和赋值。

 例：
  target.sql
  -----------------------
  select/*+ GATHER_PLAN_STATISTICS MONITOR */ count(*) from SQLMON where a='A';
  -----------------------

2.执行sqltxecute.sql脚本收集相关信息

$cd sqlt/run
$sqlplus Username/Password
SQL> START [path]sqltxecute.sql [path]scriptname [sqltxplain_password]

3.执行例

[oracle@db12102 run]$ vi target.sql
[oracle@db12102 run]$ more target.sql
select/*+ GATHER_PLAN_STATISTICS MONITOR */ count(*) from SQLMON where a='A';
[oracle@db12102 run]$ sqlplus / as sysdba

SQL*Plus: Release 12.1.0.2.0 Production on Sat Aug 27 21:06:09 2016

Copyright (c) 1982, 2014, Oracle.  All rights reserved.


Connected to:
Oracle Database 12c Enterprise Edition Release 12.1.0.2.0 - 64bit Production
With the Partitioning, OLAP, Advanced Analytics and Real Application Testing options

SQL> conn teacherwhat/teacherwhat
Connected.
SQL>  START sqltxecute.sql target.sql SQLTXPLAIN
...
  adding: sqlt_s28360_sqldx.zip (stored 0%)

#####
The SQLT has collected information and place it in a repository in the database, exported it and zip it.
The collected info can be purged from the database using the following file :
... getting sqlt_s28360_purge.sql out of sqlt repository ...

SQLTXECUTE completed.

其他方法

其他方法可以参考SQLT安装包中的【sqlt_instructions.html】中的介绍。

使用SQLT的注意事项

1. SQLT xecute MODE 不能针对DDL文取得信息，否者会报ORA-01086错误

   例：
   
   [oracle@db12102 run]$ cat target.sql       
   create table testttt as select * from emp;
   
   SQL> START sqltxecute.sql target.sql SQLTXPLAIN
   
   ■sqltxecute2.log
   ...
   
   SQL>SET TERM ON ECHO OFF;
   
   To monitor progress, login into another session and execute:
   SQL> SELECT * FROM SQLTXADMIN.sqlt$_log_v;
   
   ... collecting diagnostics details, please wait ...
   
   In case of a disconnect review log file in current directory
   If running as SYS in 12c make sure to review sqlt_instructions.html first
   
     1* create table testttt as select * from emp
   
   PREV_SQL_ID                             PREV_CHILD_NUMBER
   --------------------------------------- -----------------
   22ygsf8vfyk2f                                           0
   経過: 00:00:00.21
   ROLLBACK TO SAVEPOINT sqlt_xecute_savepoint
   *
   行1でエラーが発生しました。:
   ORA-01086: セーブポイント'SQLT_XECUTE_SAVEPOINT'はこのセッションで設定されていないか、無効です
   

2.可以针对DDL文取得XTRACT MODE的信息

    例：

    SQL> create table testttt as select * from emp;
    SQL> SELECT sql_id, hash_value, SUBSTR(sql_text,1,40) Text
            FROM v$sql
            WHERE sql_text LIKE '%create table testttt%'; 

    SQL_ID                                  HASH_VALUE
    --------------------------------------- ----------
    TEXT
    --------------------------------------------------------------------------------
    22ygsf8vfyk2f                            921651278
    create table testttt as select * from em

    START sqltxtract.sql 22ygsf8vfyk2f  SQLTXPLAIN

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