一个新建的数据库，我在分析 dba_hist_sql_plan 表时，发现其中有2个DBID。
select distinct dbid from dba_hist_sql_plan;DBID
----------
1899454952
1467201108
而且两个DBID的记录都很多：
SQL> select count(*) from dba_hist_sql_plan where dbid = 1467201108;COUNT(*)
----------13478SQL> select count(*) from dba_hist_sql_plan where dbid = 1899454952;COUNT(*)
----------16760
实际上，在多租户数据库中，根容器和每一个可插拔数据库都有自己的DBID，这个通过AWR和RMAN都很容易看到。以AWR为例：
SQL> @$ORACLE_HOME/rdbms/admin/awrrpt.sqlSpecify the Report Type
~~~~~~~~~~~~~~~~~~~~~~~
AWR reports can be generated in the following formats. Please enter the
name of the format at the prompt. Default value is 'html'.'html' HTML format (default)
'text' Text format
'active-html' Includes Performance Hub active reportEnter value for report_type:Type Specified: htmlSpecify the location of AWR Data
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
AWR PDB reports can be generated using data stored in this PDB or ROOT.
Please enter the desired location at the prompt. Default value is 'AWR_PDB'.AWR_PDB - Use AWR data from PDBAWR_ROOT - Use AWR data from ROOT
Enter value for awr_location:Location of AWR Data Specified: AWR_PDBCurrent Instance
~~~~~~~~~~~~~~~~
DB Id DB Name Inst Num Instance Container Name
-------------- -------------- -------------- -------------- --------------1899454952 DB1220 1 DB1220 ORCLPDB1Root DB Id Container DB Id AWR DB Id
--------------- --------------- ---------------1467201108 1899454952 1899454952Instances in this Workload Repository schema
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~DB Id Inst Num DB Name Instance Host
------------ ---------- --------- ---------- ------
* 1899454952 1 DB1220 DB1220 ocp23cUsing 1899454952 for database Id
Using 1 for instance number
从以上输出可知，1467201108 是根容器的DBID，而1899454952 是PDB orclpdb1的DBID。
用以下SQL也可以验证：
SQL> alter session set container=orclpdb1;Session altered.SQL> select dbid from v$database;DBID
----------
1467201108SQL> select dbid from v$pdbs;DBID
----------
1899454952
所以，结论就是，对于一个Oracle容器数据库，可以有多个DBID。
：字节码文件的组成)
