情景介绍:oracle 11g软件安装正常,配置监听正常 故障现象:DBCA建库装完一次由于某种原因需要重新建库。DBCA删除库,然后重新建库,重建的过程中遇到了种种问题,下面一一道来。 1、DBCA建库,当进行到分配PGA,SGA内存的时候,如果你的“/dev/shm”的大小
情景介绍:oracle 11g软件安装正常,配置监听正常
故障现象:DBCA建库装完一次由于某种原因需要重新建库。DBCA删除库,然后重新建库,重建的过程中遇到了种种问题,下面一一道来。
1、DBCA建库,当进行到分配PGA,SGA内存的时候,如果你的“/dev/shm”的大小不能满足一定的条件(ORACLE 数据库从11g 版本开始,引入了一个自动内存管理(Automatic Memory Management)特性,该特性需要更多的共享内存(/dev/shm),因此如果决定应用该特性的话, 必须要确保共享内存大于ORACLE
中初始化参数MEMORY_MAX_TARGET 和MEMORY_TARGET(特别提示,这两个参数即自动内存管理特性对应的初始化参数)的值。
如果在初始化参数中设置了MEMORY_MAX_TARGET 和MEMORY_TARGET 两参数为非0 值,并且不符合系统共享内存,则ORACLE 数据库启动时,就会触发ORA-00845:MEMORY_TARGET not supported on this system 错误。),当你进行下一步的时候,就会报如下图的错误:
解决方法是:一种是修改初始化参数,使得初始化参数中SGA的设置小于/dev/shm的大小,另一种方法就是调整/dev/shm的大小。这里介绍加大“/dev/shm”的大小,详情见链接“http://blog.chinaunix.net/uid-23284114-id-3232508.html”
2、后面一直“下一步”直到“finish”按钮开始安装数据库,当滚动条进行到大概40%的时候,就会有如下图报错信息
,(从后台日志“$ORACLE_BASE/cfgtoollogs/dbca/$ORACLE_SID/trace.log可以看到“tnslisten相关信息””)这里我们选择ingore,继续往下走,直到滚动条到达74%左右的时候又会报一个错误,如下图
,(从后台日志“$ORACLE_BASE/cfgtoollogs/dbca/$ORACLE_SID/trace.log可以看到“
[Thread-40] [ 2014-10-28 13:50:23.055 CST ] [HAUtils.isHASConfigured:349] Ignoring exception in isHASConfigured: PRCT-1011 : Failed to run "getcrshome"
PRCT-1011 : Failed to run "getcrshome信息”),这里我们选择ok,继续哇往下走,当走到85%的时候,从到达85%开始,一直等2个小时以上,我们会发下安装成功的界面依然不会出现,这时候我们新开一个会话,使用"sqlplus / as sysdba"命令,发现可以登录 数据库,数据库也可以正常启动和关闭。如下图
解决办法:当出现以上情况的时候,很有可能是你的oracle数据库的库密码含有“@”符号,这是不被oracle识别的(详情见链接"http://ipmingsee.blog.163.com/blog/static/71263720107925849361/"),这可是血的教训啊。问题很简单,但我却花了4个多小时去分析,期间重新建库多次都解决不了,更改了密码,发现不再有如上所述的错误对话框出现了。
3) 安装期间查看日志信息了解进度:
$ tail -100f $ORACLE_BASE/cfgtoollogs/dbca/$ORACLE_SID/$ORACLE_SID.log

Stored procedures are precompiled SQL statements in MySQL for improving performance and simplifying complex operations. 1. Improve performance: After the first compilation, subsequent calls do not need to be recompiled. 2. Improve security: Restrict data table access through permission control. 3. Simplify complex operations: combine multiple SQL statements to simplify application layer logic.

The working principle of MySQL query cache is to store the results of SELECT query, and when the same query is executed again, the cached results are directly returned. 1) Query cache improves database reading performance and finds cached results through hash values. 2) Simple configuration, set query_cache_type and query_cache_size in MySQL configuration file. 3) Use the SQL_NO_CACHE keyword to disable the cache of specific queries. 4) In high-frequency update environments, query cache may cause performance bottlenecks and needs to be optimized for use through monitoring and adjustment of parameters.

The reasons why MySQL is widely used in various projects include: 1. High performance and scalability, supporting multiple storage engines; 2. Easy to use and maintain, simple configuration and rich tools; 3. Rich ecosystem, attracting a large number of community and third-party tool support; 4. Cross-platform support, suitable for multiple operating systems.

The steps for upgrading MySQL database include: 1. Backup the database, 2. Stop the current MySQL service, 3. Install the new version of MySQL, 4. Start the new version of MySQL service, 5. Recover the database. Compatibility issues are required during the upgrade process, and advanced tools such as PerconaToolkit can be used for testing and optimization.

MySQL backup policies include logical backup, physical backup, incremental backup, replication-based backup, and cloud backup. 1. Logical backup uses mysqldump to export database structure and data, which is suitable for small databases and version migrations. 2. Physical backups are fast and comprehensive by copying data files, but require database consistency. 3. Incremental backup uses binary logging to record changes, which is suitable for large databases. 4. Replication-based backup reduces the impact on the production system by backing up from the server. 5. Cloud backups such as AmazonRDS provide automation solutions, but costs and control need to be considered. When selecting a policy, database size, downtime tolerance, recovery time, and recovery point goals should be considered.

MySQLclusteringenhancesdatabaserobustnessandscalabilitybydistributingdataacrossmultiplenodes.ItusestheNDBenginefordatareplicationandfaulttolerance,ensuringhighavailability.Setupinvolvesconfiguringmanagement,data,andSQLnodes,withcarefulmonitoringandpe

Optimizing database schema design in MySQL can improve performance through the following steps: 1. Index optimization: Create indexes on common query columns, balancing the overhead of query and inserting updates. 2. Table structure optimization: Reduce data redundancy through normalization or anti-normalization and improve access efficiency. 3. Data type selection: Use appropriate data types, such as INT instead of VARCHAR, to reduce storage space. 4. Partitioning and sub-table: For large data volumes, use partitioning and sub-table to disperse data to improve query and maintenance efficiency.

TooptimizeMySQLperformance,followthesesteps:1)Implementproperindexingtospeedupqueries,2)UseEXPLAINtoanalyzeandoptimizequeryperformance,3)Adjustserverconfigurationsettingslikeinnodb_buffer_pool_sizeandmax_connections,4)Usepartitioningforlargetablestoi


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