Oracle 11gR2是目前新系统应用比较广泛的Oracle版本,根据官方路线图,11.2.0.4是11g末期的一个版本。应该说,11gR2之后,Oracle
Oracle 11gR2是目前新系统应用比较广泛的Oracle版本,根据官方路线图,11.2.0.4是11g末期的一个版本。应该说,11gR2之后,Oracle直接提供了完整升级版本,可以直接安装高版本的数据库系统,不需要从基础版本逐步升级。
本篇主要记录以11.2.0.4为基础,单实例条件下Oracle补丁安装过程。
1、补丁包和环境介绍
首先确定数据库版本,笔者以一台全新安装Oracle 11gR2单实例进行安装,具体版本为11.2.0.4。
SQL> select * from v$version;
BANNER
--------------------------------------------------------------------------------
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
PL/SQL Release 11.2.0.4.0 - Production
CORE 11.2.0.4.0 Production
TNS for Linux: Version 11.2.0.4.0 - Production
NLSRTL Version 11.2.0.4.0 – Production
进行操作的补丁文件如下:
[root@XXX-PROD-DB upload]# cd patch/
[root@XXX-PROD-DB patch]# ls -l
total 282772
-rw-r--r--. 1 root root 407030 Jul 15 09:03 p19852360_112040_Generic.zip
-rw-r--r--. 1 root root 71580583 Jul 15 09:03 p20299013_112040_Linux-x86-64.zip
-rw-r--r--. 1 root root 12335412 Jul 15 09:03 p20299015_112040_Linux-x86-64.zip
-rw-r--r--. 1 root root 40486165 Jul 15 09:03 p20406239_112040_Linux-x86-64.zip
-rw-r--r--. 1 root root 112087303 Jul 15 09:02 p20834611_112040_Linux-x86-64.zip
-rw-r--r--. 1 root root 52648436 Jul 15 09:02 p6880880_112000_Linux-x86-64.zip
注意:其中p6880880_112000_Linux-x86-64.zip是新版本OPatch,一般而言打补丁都需要更新最新的OPatch。
2、升级OPatch组件
首先需要以覆盖方式升级OPatch组件。
[oracle@XXX-PROD-DB ~]$ cd $ORACLE_HOME
[oracle@XXX-PROD-DB dbhome_1]$ ls -l | grep OPatch
drwxr-xr-x. 8 oracle oinstall 4096 Jul 16 10:08 OPatch
备份OPatch目录,并用解压zip文件替换。
[oracle@XXX-PROD-DB dbhome_1]$ cp /upload/patch/p6880880_112000_Linux-x86-64.zip $ORACLE_HOME
[oracle@XXX-PROD-DB dbhome_1]$ ls -l | grep p6880880_112000_Linux-x86-64.zip
-rw-r--r--. 1 oracle oinstall 52648436 Aug 4 08:42 p6880880_112000_Linux-x86-64.zip
[oracle@XXX-PROD-DB dbhome_1]$ mv OPatch OPatch_BK
[oracle@XXX-PROD-DB dbhome_1]$ ls -l | grep OPatch
drwxr-xr-x. 8 oracle oinstall 4096 Jul 16 10:08 OPatch_BK
解压OPatch文件。
[root@XXX-PROD-DB ~]# cd /u01/app/oracle/product/11.2.0/dbhome_1
[root@XXX-PROD-DB dbhome_1]# ls -l | grep p6880880_112000_Linux-x86-64.zip
-rw-r--r--. 1 oracle oinstall 52648436 Aug 4 08:42 p6880880_112000_Linux-x86-64.zip
[root@XXX-PROD-DB dbhome_1]# unzip p6880880_112000_Linux-x86-64.zip
[root@XXX-PROD-DB dbhome_1]# ls -l | grep OPatch
drwxr-x---. 10 root root 4096 Mar 31 17:10 OPatch
drwxr-xr-x. 8 oracle oinstall 4096 Jul 16 10:08 OPatch_BK
[root@XXX-PROD-DB dbhome_1]# chown -R oracle:oinstall OPatch
[root@XXX-PROD-DB dbhome_1]# ls -l | grep OPatch
drwxr-x---. 10 oracle oinstall 4096 Mar 31 17:10 OPatch
drwxr-xr-x. 8 oracle oinstall 4096 Jul 16 10:08 OPatch_BK
OPatch是一个命令脚本工具,为方便起见,可以将其加入到PATH环境变量中。
[oracle@XXX-PROD-DB dbhome_1]$ cd ~
[oracle@XXX-PROD-DB ~]$ vi .bash_profile
(篇幅原因,有省略……)
ORACLE_SID=XXXCDB
ORACLE_BASE=/u01/app/oracle
ORACLE_HOME=/u01/app/oracle/product/11.2.0/dbhome_1
PATH=$PATH:$ORACLE_HOME/bin:/u01/app/oracle/product/11.2.0/dbhome_1/OPatch
export ORACLE_SID
export ORACLE_BASE
export ORACLE_HOME
export PATH
".bash_profile" 23L, 409C written
查看OPatch版本。
[oracle@XXX-PROD-DB ~]$ opatch version
OPatch Version: 11.2.0.3.10
OPatch succeeded.
2、补丁19852360_112040
补丁19852360_112040是一个简单的补丁,主要是针对JDBC相关的补丁类型。原则上,不需要进行关库操作。
[root@XXX-PROD-DB patch]# unzip p19852360_112040_Generic.zip
Archive: p19852360_112040_Generic.zip
creating: 19852360/
inflating: 19852360/README.txt
creating: 19852360/files/
creating: 19852360/files/jdbc/
(篇幅原因,有省略……)
inflating: 19852360/etc/xml/GenericActions.xml
inflating: 19852360/etc/xml/ShiphomeDirectoryStructure.xml
进入解压目录,注意:要确保补丁文件的文件权限设置。
[oracle@XXX-PROD-DB ~]$ cd /upload/patch/
[oracle@XXX-PROD-DB patch]$ ls -l
total 282776
drwxr-xr-x. 4 oracle oinstall 4096 Oct 20 2014 19852360
-rw-r--r--. 1 root root 407030 Jul 15 09:03 p19852360_112040_Generic.zip
[oracle@XXX-PROD-DB patch]$ cd 19852360/
[oracle@XXX-PROD-DB 19852360]$ ls -l
total 20
drwxr-xr-x. 4 oracle oinstall 4096 Oct 20 2014 etc
drwxr-xr-x. 3 oracle oinstall 4096 Oct 20 2014 files
-rw-rw-r--. 1 oracle oinstall 10858 Oct 28 2014 README.txt
[oracle@XXX-PROD-DB 19852360]$
注意:无论DBA经验多丰富,在进行补丁的时候,一定要参考每个补丁的readme.txt文件,遵循官方步骤进行操作。用成熟技术、用官方步骤是我们确保成功的重要原则。
首先,进行补丁先决条件检查。
[oracle@XXX-PROD-DB 19852360]$ opatch prereq CheckConflictAgainstOHWithDetail -ph ./
Oracle Interim Patch Installer version 11.2.0.3.10
Copyright (c) 2015, Oracle Corporation. All rights reserved.
PREREQ session
Oracle Home : /u01/app/oracle/product/11.2.0/dbhome_1
Central Inventory : /u01/app/oraInventory
from : /u01/app/oracle/product/11.2.0/dbhome_1/oraInst.loc
OPatch version : 11.2.0.3.10
OUI version : 11.2.0.4.0
Log file location : /u01/app/oracle/product/11.2.0/dbhome_1/cfgtoollogs/opatch/opatch2015-08-04_10-22-39AM_1.log
Invoking prereq "checkconflictagainstohwithdetail"
Prereq "checkConflictAgainstOHWithDetail" passed.
OPatch succeeded.
没有发现问题,,可以直接进行补丁。
[oracle@XXX-PROD-DB 19852360]$ opatch apply
Oracle Interim Patch Installer version 11.2.0.3.10
Copyright (c) 2015, Oracle Corporation. All rights reserved.
Oracle Home : /u01/app/oracle/product/11.2.0/dbhome_1
Central Inventory : /u01/app/oraInventory
from : /u01/app/oracle/product/11.2.0/dbhome_1/oraInst.loc
OPatch version : 11.2.0.3.10
OUI version : 11.2.0.4.0
Log file location : /u01/app/oracle/product/11.2.0/dbhome_1/cfgtoollogs/opatch/19852360_Aug_04_2015_10_21_09/apply2015-08-04_10-21-09AM_1.log
Applying interim patch '19852360' to OH '/u01/app/oracle/product/11.2.0/dbhome_1'
Verifying environment and performing prerequisite checks...
All checks passed.
Provide your email address to be informed of security issues, install and
initiate Oracle Configuration Manager. Easier for you if you use your My
Oracle Support Email address/User Name.
Visit for details.
Email address/User Name:
You have not provided an email address for notification of security issues.
Do you wish to remain uninformed of security issues ([Y]es, [N]o) [N]: Y
Backing up files...
Patching component oracle.dbjava.jdbc, 11.2.0.4.0...
Patching component oracle.dbjava.ic, 11.2.0.4.0...
Verifying the update...
Patch 19852360 successfully applied
Log file location: /u01/app/oracle/product/11.2.0/dbhome_1/cfgtoollogs/opatch/19852360_Aug_04_2015_10_21_09/apply2015-08-04_10-21-09AM_1.log
OPatch succeeded.
3、补丁20299013_112040
解压补丁文件:
[root@XXX-PROD-DB patch]# unzip p20299013_112040_Linux-x86-64.zip
inflating: 20299013/18522509/files/lib/libserver11.a/qerel.o
inflating: 20299013/18522509/files/lib/libserver11.a/knahs.o
(篇幅原因,有省略……)
inflating: 20299013/18522509/etc/config/actions.xml
inflating: 20299013/18522509/etc/config/inventory.xml
inflating: PatchSearch.xml
设置owner权限。
[root@XXX-PROD-DB patch]# chown -R oracle:oinstall 20299013/
[root@XXX-PROD-DB patch]# ls -l
total 282840
drwxr-xr-x. 4 oracle oinstall 4096 Oct 20 2014 19852360
drwxrwxr-x. 8 oracle oinstall 4096 Mar 4 18:30 20299013
补丁20299013_112040是一个补丁集合,多个经过验证的安全补丁集合防止,是可以统一进行补丁操作的。
[oracle@XXX-PROD-DB 20299013]$ ls -l
total 88
drwxr-xr-x. 4 oracle oinstall 4096 Mar 4 18:30 17478514
drwxr-xr-x. 4 oracle oinstall 4096 Mar 4 18:30 18031668
drwxr-xr-x. 4 oracle oinstall 4096 Mar 4 18:30 18522509
drwxr-xr-x. 4 oracle oinstall 4096 Mar 4 18:30 19121551
drwxrwxr-x. 4 oracle oinstall 4096 Mar 4 18:30 19769489
drwxrwxr-x. 4 oracle oinstall 4096 Mar 4 18:30 20299013
-rw-r--r--. 1 oracle oinstall 3068 Mar 4 18:30 patchmd.xml
-rw-rw-r--. 1 oracle oinstall 54747 Apr 12 10:40 README.html
-rw-r--r--. 1 oracle oinstall 21 Mar 4 18:30 README.txt
进行先决性检查。
[oracle@XXX-PROD-DB 20299013]$ opatch prereq CheckConflictAgainstOHWithDetail -ph ./
Oracle Interim Patch Installer version 11.2.0.3.10
Copyright (c) 2015, Oracle Corporation. All rights reserved.
PREREQ session
Oracle Home : /u01/app/oracle/product/11.2.0/dbhome_1
Central Inventory : /u01/app/oraInventory
from : /u01/app/oracle/product/11.2.0/dbhome_1/oraInst.loc
OPatch version : 11.2.0.3.10
OUI version : 11.2.0.4.0
Log file location : /u01/app/oracle/product/11.2.0/dbhome_1/cfgtoollogs/opatch/opatch2015-08-04_10-28-53AM_1.log
Invoking prereq "checkconflictagainstohwithdetail"
Prereq "checkConflictAgainstOHWithDetail" passed.
OPatch succeeded.
验证通过,说明当前系统安装补丁和将要安装补丁之间没有冲突。但是,执行apply的时候就有问题。
[oracle@XXX-PROD-DB 20299013]$ opatch apply
Oracle Interim Patch Installer version 11.2.0.3.10
Copyright (c) 2015, Oracle Corporation. All rights reserved.
Oracle Home : /u01/app/oracle/product/11.2.0/dbhome_1
Central Inventory : /u01/app/oraInventory
from : /u01/app/oracle/product/11.2.0/dbhome_1/oraInst.loc
OPatch version : 11.2.0.3.10
OUI version : 11.2.0.4.0
Log file location : /u01/app/oracle/product/11.2.0/dbhome_1/cfgtoollogs/opatch/opatch2015-08-04_10-29-25AM_1.log
Verifying environment and performing prerequisite checks...
Prerequisite check "CheckActiveFilesAndExecutables" failed.
The details are:
Following executables are active :
/u01/app/oracle/product/11.2.0/dbhome_1/bin/oracle
/u01/app/oracle/product/11.2.0/dbhome_1/lib/libclntsh.so.11.1
UtilSession failed: Prerequisite check "CheckActiveFilesAndExecutables" failed.
Log file location: /u01/app/oracle/product/11.2.0/dbhome_1/cfgtoollogs/opatch/opatch2015-08-04_10-29-25AM_1.log
OPatch failed with error code 73
报错信息中包括了日志内容,一旦出现Oracle错误,各种日志是进行诊断的最好方法。
[root@XXX-PROD-DB patch]# cd /u01/app/oracle/product/11.2.0/dbhome_1/cfgtoollogs/opatch/
[root@XXX-PROD-DB opatch]# ls -l
total 36
drwxr-xr-x. 2 oracle oinstall 4096 Aug 4 10:21 19852360_Aug_04_2015_10_21_09
drwxr-xr-x. 2 oracle oinstall 4096 Aug 4 10:06 lsinv
-rw-r--r--. 1 oracle oinstall 2050 Aug 4 10:06 opatch2015-08-04_10-06-22AM_1.log
-rw-r--r--. 1 oracle oinstall 1665 Aug 4 10:22 opatch2015-08-04_10-22-39AM_1.log
-rw-r--r--. 1 oracle oinstall 2021 Aug 4 10:28 opatch2015-08-04_10-28-53AM_1.log
-rw-r--r--. 1 oracle oinstall 10540 Aug 4 10:29 opatch2015-08-04_10-29-25AM_1.log
-rw-r--r--. 1 oracle oinstall 1872 Aug 4 10:29 opatch_history.txt
[root@INTCTL-PROD-DB opatch]# ls -l | grep 2015-08-04_10-29-25
-rw-r--r--. 1 oracle oinstall 10540 Aug 4 10:29 opatch2015-08-04_10-29-25AM_1.log
--日志片段:
[Aug 4, 2015 10:29:31 AM] Finish fuser command /sbin/fuser /u01/app/oracle/product/11.2.0/dbhome_1/bin/proc at Tue Aug 04 10:29:31 CST 2015
[Aug 4, 2015 10:29:31 AM] Start fuser command /sbin/fuser /u01/app/oracle/product/11.2.0/dbhome_1/lib/liborasdkbase.so.11.1 at Tue Aug 04 10:29:31 CST 2015
[Aug 4, 2015 10:29:31 AM] Finish fuser command /sbin/fuser /u01/app/oracle/product/11.2.0/dbhome_1/lib/liborasdkbase.so.11.1 at Tue Aug 04 10:29:31 CST 2015
[Aug 4, 2015 10:29:31 AM] Start fuser command /sbin/fuser /u01/app/oracle/product/11.2.0/dbhome_1/bin/wrap at Tue Aug 04 10:29:31 CST 2015
[Aug 4, 2015 10:29:31 AM] Finish fuser command /sbin/fuser /u01/app/oracle/product/11.2.0/dbhome_1/bin/wrap at Tue Aug 04 10:29:31 CST 2015
[Aug 4, 2015 10:29:31 AM] Start fuser command /sbin/fuser /u01/app/oracle/product/11.2.0/dbhome_1/bin/e2eme at Tue Aug 04 10:29:31 CST 2015
[Aug 4, 2015 10:29:31 AM] Finish fuser command /sbin/fuser /u01/app/oracle/product/11.2.0/dbhome_1/bin/e2eme at Tue Aug 04 10:29:31 CST 2015
[Aug 4, 2015 10:29:31 AM] OUI-67073:UtilSession failed: Prerequisite check "CheckActiveFilesAndExecutables" failed.
[Aug 4, 2015 10:29:31 AM] Finishing UtilSession at Tue Aug 04 10:29:31 CST 2015
[Aug 4, 2015 10:29:31 AM] Log file location: /u01/app/oracle/product/11.2.0/dbhome_1/cfgtoollogs/opatch/opatch2015-08-04_10-29-25AM_1.log
[Aug 4, 2015 10:29:31 AM] Stack Description: java.lang.RuntimeException: Prerequisite check "CheckActiveFilesAndExecutables" failed.
[Aug 4, 2015 10:29:31 AM] StackTrace: oracle.opatch.OPatchSessionHelper.runApplyPrereqs(OPatchSessionHelper.java:5717)
[Aug 4, 2015 10:29:31 AM] StackTrace: oracle.opatch.opatchutil.NApply.process(NApply.java:697)
[Aug 4, 2015 10:29:31 AM] StackTrace: oracle.opatch.opatchutil.OUSession.napply(OUSession.java:1082)
[Aug 4, 2015 10:29:31 AM] StackTrace: sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[Aug 4, 2015 10:29:31 AM] StackTrace: sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
[Aug 4, 2015 10:29:31 AM] StackTrace: sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
[Aug 4, 2015 10:29:31 AM] StackTrace: java.lang.reflect.Method.invoke(Method.java:592)
[Aug 4, 2015 10:29:31 AM] StackTrace: oracle.opatch.UtilSession.process(UtilSession.java:317)
[Aug 4, 2015 10:29:31 AM] StackTrace: oracle.opatch.OPatchSession.main(OPatchSession.java:2575)
[Aug 4, 2015 10:29:31 AM] StackTrace: oracle.opatch.OPatch.main(OPatch.java:626)
经过分析,认为是Oracle数据库和监听器启动状态。安装补丁的时候,最好还是能够停机进行。
[oracle@XXX-PROD-DB 20299013]$ lsnrctl stop
LSNRCTL for Linux: Version 11.2.0.4.0 - Production on 04-AUG-2015 10:37:25
Copyright (c) 1991, 2013, Oracle. All rights reserved.
Connecting to (DESCRIPTION=(ADDRESS=(PROTOCOL=TCP)(HOST=localhost)(PORT=1521)))
The command completed successfully
[oracle@INTCTL-PROD-DB 20299013]$ sqlplus /nolog
SQL*Plus: Release 11.2.0.4.0 Production on Tue Aug 4 10:37:32 2015
Copyright (c) 1982, 2013, Oracle. All rights reserved.
SQL> conn / as sysdba
Connected.
SQL> shutdown immediate;
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> quit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
进行OPatch Apply操作。
[oracle@XXX-PROD-DB 20299013]$ opatch apply
Oracle Interim Patch Installer version 11.2.0.3.10
Copyright (c) 2015, Oracle Corporation. All rights reserved.
Oracle Home : /u01/app/oracle/product/11.2.0/dbhome_1
Central Inventory : /u01/app/oraInventory
from : /u01/app/oracle/product/11.2.0/dbhome_1/oraInst.loc
OPatch version : 11.2.0.3.10
OUI version : 11.2.0.4.0
Log file location : /u01/app/oracle/product/11.2.0/dbhome_1/cfgtoollogs/opatch/opatch2015-08-04_10-38-47AM_1.log
Verifying environment and performing prerequisite checks...
OPatch continues with these patches: 17478514 18031668 18522509 19121551 19769489 20299013
(篇幅原因,有省略……)
Composite patch 20299013 successfully applied.
Log file location: /u01/app/oracle/product/11.2.0/dbhome_1/cfgtoollogs/opatch/opatch2015-08-04_10-38-47AM_1.log
OPatch succeeded.
补丁成功。
注意:此时完成的是数据库软件、数据库实例的升级。但是数据库对象却没有升级。之后重启数据库,要进行脚本升级执行。
[oracle@XXX-PROD-DB 20299013]$ sqlplus /nolog
SQL*Plus: Release 11.2.0.4.0 Production on Tue Aug 4 10:41:37 2015
Copyright (c) 1982, 2013, Oracle. All rights reserved.
SQL> conn / as sysdba
Connected to an idle instance.
SQL> startup
ORACLE instance started.
Total System Global Area 5227814912 bytes
Fixed Size 2262368 bytes
Variable Size 1140853408 bytes
Database Buffers 4076863488 bytes
Redo Buffers 7835648 bytes
Database mounted.
Database opened.
执行脚本。
SQL> @?/rdbms/admin/catbundle.sql psu apply
SQL> COMMIT;
Commit complete.
SQL> SPOOL off
SQL> SET echo off
Check the following log file for errors:
/u01/app/oracle/cfgtoollogs/catbundle/catbundle_PSU_INTCDB_APPLY_2015Aug04_10_42_39.log
查看补丁内容信息:
[oracle@XXX-PROD-DB 20299013]$ opatch lsinventory
Oracle Interim Patch Installer version 11.2.0.3.10
Copyright (c) 2015, Oracle Corporation. All rights reserved.
Oracle Home : /u01/app/oracle/product/11.2.0/dbhome_1
Central Inventory : /u01/app/oraInventory
from : /u01/app/oracle/product/11.2.0/dbhome_1/oraInst.loc
OPatch version : 11.2.0.3.10
OUI version : 11.2.0.4.0
Log file location : /u01/app/oracle/product/11.2.0/dbhome_1/cfgtoollogs/opatch/opatch2015-08-04_10-45-21AM_1.log
Lsinventory Output file location : /u01/app/oracle/product/11.2.0/dbhome_1/cfgtoollogs/opatch/lsinv/lsinventory2015-08-04_10-45-21AM.txt
--------------------------------------------------------------------------------
Local Machine Information::
Hostname: localhost
ARU platform id: 226
ARU platform description:: Linux x86-64
Installed Top-level Products (1):

MySQL索引基数对查询性能有显著影响:1.高基数索引能更有效地缩小数据范围,提高查询效率;2.低基数索引可能导致全表扫描,降低查询性能;3.在联合索引中,应将高基数列放在前面以优化查询。

MySQL學習路徑包括基礎知識、核心概念、使用示例和優化技巧。 1)了解表、行、列、SQL查詢等基礎概念。 2)學習MySQL的定義、工作原理和優勢。 3)掌握基本CRUD操作和高級用法,如索引和存儲過程。 4)熟悉常見錯誤調試和性能優化建議,如合理使用索引和優化查詢。通過這些步驟,你將全面掌握MySQL的使用和優化。

MySQL在現實世界的應用包括基礎數據庫設計和復雜查詢優化。 1)基本用法:用於存儲和管理用戶數據,如插入、查詢、更新和刪除用戶信息。 2)高級用法:處理複雜業務邏輯,如電子商務平台的訂單和庫存管理。 3)性能優化:通過合理使用索引、分區表和查詢緩存來提升性能。

MySQL中的SQL命令可以分為DDL、DML、DQL、DCL等類別,用於創建、修改、刪除數據庫和表,插入、更新、刪除數據,以及執行複雜的查詢操作。 1.基本用法包括CREATETABLE創建表、INSERTINTO插入數據和SELECT查詢數據。 2.高級用法涉及JOIN進行表聯接、子查詢和GROUPBY進行數據聚合。 3.常見錯誤如語法錯誤、數據類型不匹配和權限問題可以通過語法檢查、數據類型轉換和權限管理來調試。 4.性能優化建議包括使用索引、避免全表掃描、優化JOIN操作和使用事務來保證數據一致性

InnoDB通過undolog實現原子性,通過鎖機制和MVCC實現一致性和隔離性,通過redolog實現持久性。 1)原子性:使用undolog記錄原始數據,確保事務可回滾。 2)一致性:通過行級鎖和MVCC確保數據一致。 3)隔離性:支持多種隔離級別,默認使用REPEATABLEREAD。 4)持久性:使用redolog記錄修改,確保數據持久保存。

MySQL在數據庫和編程中的地位非常重要,它是一個開源的關係型數據庫管理系統,廣泛應用於各種應用場景。 1)MySQL提供高效的數據存儲、組織和檢索功能,支持Web、移動和企業級系統。 2)它使用客戶端-服務器架構,支持多種存儲引擎和索引優化。 3)基本用法包括創建表和插入數據,高級用法涉及多表JOIN和復雜查詢。 4)常見問題如SQL語法錯誤和性能問題可以通過EXPLAIN命令和慢查詢日誌調試。 5)性能優化方法包括合理使用索引、優化查詢和使用緩存,最佳實踐包括使用事務和PreparedStatemen

MySQL適合小型和大型企業。 1)小型企業可使用MySQL進行基本數據管理,如存儲客戶信息。 2)大型企業可利用MySQL處理海量數據和復雜業務邏輯,優化查詢性能和事務處理。

InnoDB通過Next-KeyLocking機制有效防止幻讀。 1)Next-KeyLocking結合行鎖和間隙鎖,鎖定記錄及其間隙,防止新記錄插入。 2)在實際應用中,通過優化查詢和調整隔離級別,可以減少鎖競爭,提高並發性能。


熱AI工具

Undresser.AI Undress
人工智慧驅動的應用程序,用於創建逼真的裸體照片

AI Clothes Remover
用於從照片中去除衣服的線上人工智慧工具。

Undress AI Tool
免費脫衣圖片

Clothoff.io
AI脫衣器

AI Hentai Generator
免費產生 AI 無盡。

熱門文章

熱工具

ZendStudio 13.5.1 Mac
強大的PHP整合開發環境

SublimeText3 Linux新版
SublimeText3 Linux最新版

VSCode Windows 64位元 下載
微軟推出的免費、功能強大的一款IDE編輯器

SublimeText3 Mac版
神級程式碼編輯軟體(SublimeText3)

Dreamweaver CS6
視覺化網頁開發工具