Control file of oracle)

The control file of oracle is a small binary file that is part of the oracle database. It is used to record the status and physical structure of the database. Each database must have at least one control file, but it is strongly recommended that more than one control file be created. The backup of each control file should be stored on different disks. 1. The control file contains the following information: 1: database name 2: database creation timestamp 3: name and location of the data file 4: redo log (online redo log file) name and location 5: Current Log serial number 6: checkpoint information 7: Recent RMAN backup (I do not know what this is ?) Ii. query control file information in three ways 1. query the control file information in the v $ controlfile table [SQL] SQL> select status, name from v $ controlfile; status name ------- ------------------------------------------------ D: \ APP \ TOPWQP \ ORADATA \ ORCL \ CONTROL01.CTL D: \ APP \ TOPWQP \ ORADATA \ ORCL \ CONTROL02.CTL D: \ APP \ TOPWQP \ ORADATA \ ORCL \ CONTROL03.CTL 2: Use the control_files parameter to check the control file. As mentioned above, the control file information is defined in the startup parameter file spfile or pfile, you can view this parameter to find the control file: [SQL] SQL> s How parameter control_files; name type value =----------- define control_files string D: \ APP \ TOPWQP \ ORADATA \ ORCL \ CON TROL01.CTL, D: \ APP \ TOPWQP \ orad ata \ ORCL \ CONTROL02.CTL, d: \ APP \ TOPWQP \ ORADATA \ ORCL \ CONTROL03. CTL 3: run the [plain] D: \> dir/s control * command in the operating system to find the file *. volume in ctl drive D is the serial number of soft volume is 000B-1FAE D: \ app \ topwqp \ oradata \ orcl directory 9,781,248 CONTROL01.CTL 9,781,248 CONTROL02.CTL 2013/06/18 9,781,248 CONTROL03.CTL 3 files 29,343,744 bytes V $ CONTROLFILE_RECORD_SECTION lists the information in control_file. You can modify the location of the control file in the following ways: [SQL] alter system set control_files = 'file path/file name' scope = spfile indicates modifying the file address of control_file in spfile. Note: When oracle is started, it reads the startup initialization information, the initialization information contains the location control file of the control file, including the online redo log file and the location of the data file. The size of the three control files is the same, it is best to place the three control files in different physical On the disk, when writing information to the control file, the content of the three control files is the same, but only the first one is read during reading, if one of the three control files has an error, oracle cannot start.