oracle 9i 后 maxdatafiles 与db_files的关系

Problem Description
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The “alert.log” file shows the following message:

kccrsz: expanded controlfile section 4 from 17 to 18 records
number of logical blocks in section remains at 2
Completed: alter tablespace tb1 add datafile

Solution Description
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Starting in Oracle8 the controlfile is automatically expanded.
A new datafile is added beyond the maxdatafiles limited specified
in the control file.

This also happens if new records are added to the “log_history” section of
the control files and there are no entries that could be replaced.

The routine that performs the expansion writes this message to the alert log.
The messages specifies the section that was expanded and the amount of
the expansion. Please note that this message cannot be turned off.

The automatic expansion only occurs up to the limit of the “init.ora” parameter
“DB_FILES”.

References:
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Server SQL Reference: create controlfile

Additional Search Words
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kccrsz controlfile expanded

oracle 9i 控制文件 maxdatafiles 会自动扩展 ，自动扩展的值不能超过db_files,
所以我们在规划数据库时，db_files的值一定要设置比较大。