关于Oracle 12c 多租户架构中的db_files参数.

原创

wx5bcd90b347f01 2021-10-28 09:48:28 ©著作权

文章标签 Oracle 12c db_files sql oracle 数据文件 文章分类 代码人生

©著作权归作者所有：来自51CTO博客作者wx5bcd90b347f01的原创作品，请联系作者获取转载授权，否则将追究法律责任

本文的背景:

Oracle DB 12.2 管理文档

A CDB uses a single SPFILE or a single text initialization parameter file (PFILE).
Values of initialization parameters set for the root can be inherited by PDBs. 
You can set some initialization parameters for a PDB by using the ALTER SYSTEM statement.

上面一段英文中,请理解好"inherited".看完如下测试之后,db_files参数的"inherited"不是:每个pdb都最大可以设置db_files个datafile.

[oracle@db12cr2 ~]$ sqlplus / as sysdba

SQL*Plus: Release 12.2.0.1.0 Production on Sat Mar 18 01:29:31 2017

Copyright (c) 1982, 2016, Oracle.  All rights reserved.

Connected to an idle instance.

SQL> SQL> 
SQL> startup
ORACLE instance started.

Total System Global Area  587202560 bytes
Fixed Size        8795424 bytes
Variable Size     343935712 bytes
Database Buffers    226492416 bytes
Redo Buffers        7979008 bytes
Database mounted.
Database opened.
SQL> show parameter db_file

NAME             TYPE  VALUE
------------------------------------ ----------- ------------------------------
db_file_multiblock_read_count      integer   66
db_file_name_convert         string
db_files           integer   20
pdb_file_name_convert        string
SQL> alter session set container=highgo1;

Session altered.

SQL> select name from v$dbfile;

NAME
--------------------------------------------------------------------------------
/u01/app/oracle/oradata/orcl/highgo1/system01.dbf
/u01/app/oracle/oradata/orcl/highgo1/sysaux01.dbf
/u01/app/oracle/oradata/orcl/highgo1/undotbs01.dbf
/u01/app/oracle/oradata/orcl/highgo1/users01.dbf

SQL> alter tablespace users add datafile '/u01/app/oracle/oradata/orcl/highgo1/users02.dbf' size 50m;

Tablespace altered.

SQL> select count(*) from  v$dbfile;


  COUNT(*)
----------
   5

SQL> alter tablespace users add datafile '/u01/app/oracle/oradata/orcl/highgo1/users03.dbf' size 50m;
alter tablespace users add datafile '/u01/app/oracle/oradata/orcl/highgo1/users03.dbf' size 50m
*
ERROR at line 1:
ORA-00059: maximum number of DB_FILES exceeded

SQL> show parameter db_file

NAME             TYPE  VALUE
------------------------------------ ----------- ------------------------------
db_file_multiblock_read_count      integer   66
db_file_name_convert         string
db_files           integer   20
pdb_file_name_convert        string
SQL> select count(*) from  v$dbfile;


  COUNT(*)
----------
   5

SQL> 
SQL> select count(*) from dba_data_files;


  COUNT(*)
----------
   5


SQL>  select count(*) from dba_data_files;


  COUNT(*)
----------
   3

SQL> alter session set container=cdb$root;

Session altered.

SQL>  select count(*) from dba_data_files;


  COUNT(*)
----------
   4

SQL> show pdbs


    CON_ID CON_NAME       OPEN MODE  RESTRICTED
---------- ------------------------------ ---------- ----------
   2 PDB$SEED       READ ONLY  NO
   3 HIGHGO1        READ WRITE NO
   4 HIGHGO2        MOUNTED
   5 HIGHGO3        MOUNTED
SQL>