如何查看controlfile 里的MAXDATAFILES_file number is larger than maxdatafiles-优快云博客

本文介绍了Oracle数据库中DB_FILES与MAXDATAFILES的区别及联系。DB_FILES设置数据库能够管理的最大文件数，而MAXDATAFILES是控制文件中数据文件的最大数量。当尝试添加的数据文件编号大于MAXDATAFILES但小于等于DB_FILES时，控制文件会自动扩展以容纳更多文件。

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引自Tom

DB:10.2.0.5

OS:windows 2008

Well, MAXDATAFILES is part of the control file and is not in the init.ora file.  In the 
init.ora file, you will find db_files (or you can query "select * from v$parameter where 
name = 'db_files')

  1* select value from v$parameter where name = 'db_files'
sys@8i> /

VALUE
------------------------------
200


If you want maxdatafiles from the control file, you would query:

  1* select records_total from v$controlfile_record_section where type = 'DATAFILE'
sys@8i> /

RECORDS_TOTAL
-------------
          254

showing I have db_files set to 200 (max files the database will manage for me is 200).  I 
have maxdatafiles set to 254 (meaning i can set db_files to 254 if I wanted to)

db_files与MAXDATAFILES的关系：

An attempt to add a file whose number is greater than MAXDATAFILES, but less than or equal to DB_FILES, causes the Oracle Database control file to expand automatically so that the datafiles section can accommodate more files.

10.2.0.5 如设定MAXDATAFILES为45，现有datafile总数量已为45，db_files为设定200。此时如果增加datafile，则同样可以增加datafile。

完成后，MAXDATAFILES值会变大。

如果db_files限制，即时datafile数量没有达到MAXDATAFILES，也是不能创建datafile的