In the Linux system, the Dameng database is stored in the operating system as a data file. When you delete a data file, as long as the operating system and the database are not restarted, the file handle will not be released. At this time , when you delete the data file, the database and the operating system have not been restarted, and there is no data backup , we still have the opportunity to restore the data file.
1. Use the data migration tool to migrate the data to a new normal database instance
After the data file is deleted, as long as the data file is not checked, the corresponding table data in the data file can still be accessed normally, so we can re-initialize a database with consistent parameters. Use a different port, then start the database. Then stop the application to prevent data from being written again, and then use the migration tool to completely migrate the data over.
Data migration will be fast if the amount of data is not large. However, if the amount of data is large, the downtime migration time is unacceptable, and there is no data backup, the second method can be used.
2. Retrieve the deleted data files for recovery
2.1 Create tablespaces, data files, users, and tables for testing.
SQL> create tablespace TEST_RM datafile 'TEST_RM01.DBF' size 128 autoextend on next 128 CACHE = NORMAL;
操作已执行
已用时间: 13.499(毫秒). 执行号:53300.
SQL> create user TEST_RM identified by 123456789 default tablespace TEST_RM;
操作已执行
已用时间: 5.172(毫秒). 执行号:53301.
SQL> grant "PUBLIC","RESOURCE","SOI","VTI" to TEST_RM;
操作已执行
已用时间: 3.186(毫秒). 执行号:53302.
SQL> create table TEST_RM.T1 as select * from v$sessions;
操作已执行
已用时间: 10.411(毫秒). 执行号:53303.
SQL> select tablespace_name, file_name, status from dba_data_files;
行号 TABLESPACE_NAME FILE_NAME STATUS
---------- --------------- ---------------------------------------- ---------
1 SYSTEM /home/dmdba/TEST_RM/DAMENG/SYSTEM.DBF AVAILABLE
2 TEST_RM /home/dmdba/TEST_RM/DAMENG/TEST_RM01.DBF AVAILABLE
3 MAIN /home/dmdba/TEST_RM/DAMENG/MAIN.DBF AVAILABLE
4 TEMP /home/dmdba/TEST_RM/DAMENG/TEMP.DBF AVAILABLE
5 ROLL /home/dmdba/TEST_RM/DAMENG/ROLL.DBF AVAILABLE
已用时间: 7.356(毫秒). 执行号:53304.
SQL> select * from TEST_RM.T1;
行号 SESS_ID SESS_SEQ SQL_TEXT STATE N_STMT N_USED_STMT SEQ_NO CURR_SCH USER_NAME TRX_ID CREATE_TIME CLNT_TYPE TIME_ZONE CHK_CONS CHK_IDENT RDONLY INS_NULL
---------- -------------------- ----------- ---------------------------------------------------- ------ ----------- ----------- ----------- -------- --------- -------------------- -------------------------- --------- --------- -------- --------- ------ --------
COMPILE_FLAG AUTO_CMT DDL_AUTOCMT RS_FOR_QRY CHK_NET ISO_LEVEL CLNT_HOST APPNAME CLNT_IP OSNAME CONN_TYPE VPOOLADDR RUN_STATUS MSG_STATUS LAST_RECV_TIME LAST_SEND_TIME DCP_FLAG THRD_ID CONNECTED PORT_TYPE
------------ -------- ----------- ---------- ------- ----------- --------- ------- ------- ------ ------------ -------------------- ---------- ---------- -------------------------- -------------------------- -------- ----------- ----------- -----------
SRC_SITE MAL_ID CONCURRENT_FLAG CUR_LINENO CUR_MTDNAME CUR_SQLSTR CLNT_VER
----------- -------------------- --------------- ----------- ----------- ---------- --------
1 140217730275320 549 create table TEST_RM.T1 as select * from v$sessions; ACTIVE 64 1 8 SYSDBA SYSDBA 3561 2021-10-28 15:55:31.000000 SQL3 +08:00 N N N Y
N N Y N N 1 RH6 disql ::1 Linux HOMOGENEOUS 140217730207664 RUNNING RECIEVE 2021-10-28 15:56:00.000000 2021-10-28 15:55:55.000000 N 27149 1 0
65535 NULL 0 55 NULL NULL 7.1.8.46
已用时间: 1.607(毫秒). 执行号:53305.
SQL>2.2 Delete the data file of the corresponding table space for simulation
[dmdba@RH6 bin]$ cd /home/dmdba/TEST_RM/DAMENG/
[dmdba@RH6 DAMENG]$ ls
bak ctl_bak DAMENG01.log DAMENG02.log dm.ctl dm.ini dminit20211028155433.log dm_service.prikey HMAIN MAIN.DBF rep_conflict.log ROLL.DBF sqllog.ini SYSTEM.DBF TEMP.DBF TEST_RM01.DBF trace
[dmdba@RH6 DAMENG]$ ls -ltr
total 1187948
drwxr-xr-x 2 dmdba dinstall 4096 Oct 28 15:54 bak
-rw-r--r-- 1 dmdba dinstall 481 Oct 28 15:54 sqllog.ini
-rw-r--r-- 1 dmdba dinstall 52092 Oct 28 15:54 dm.ini
-rw-r--r-- 1 dmdba dinstall 633 Oct 28 15:54 dm_service.prikey
-rw-r--r-- 1 dmdba dinstall 134217728 Oct 28 15:54 MAIN.DBF
drwxr-xr-x 2 dmdba dinstall 4096 Oct 28 15:54 HMAIN
-rw-r--r-- 1 dmdba dinstall 1000 Oct 28 15:54 dminit20211028155433.log
-rw-r--r-- 1 dmdba dinstall 77594624 Oct 28 15:55 TEMP.DBF
-rw-r--r-- 1 dmdba dinstall 268435456 Oct 28 15:55 DAMENG02.log
drwxr-xr-x 2 dmdba dinstall 4096 Oct 28 15:55 trace
-rw-r--r-- 1 dmdba dinstall 12 Oct 28 15:55 rep_conflict.log
-rw-r--r-- 1 dmdba dinstall 5632 Oct 28 15:55 dm.ctl
drwxr-xr-x 2 dmdba dinstall 4096 Oct 28 15:55 ctl_bak
-rw-r--r-- 1 dmdba dinstall 268435456 Oct 28 15:56 DAMENG01.log
-rw-r--r-- 1 dmdba dinstall 161480704 Oct 28 15:56 ROLL.DBF
-rw-r--r-- 1 dmdba dinstall 134217728 Oct 28 15:56 TEST_RM01.DBF
-rw-r--r-- 1 dmdba dinstall 171966464 Oct 28 15:56 SYSTEM.DBF
[dmdba@RH6 DAMENG]$
[dmdba@RH6 DAMENG]$ mv TEST_RM01.DBF /tmp2.3 Query table space and table space status
Then query the table data and table space status, you will find that the data can still be queried (because the data file has not been verified, if the data file is verified, the data will not be queried), but the path of the data file in the system view is no longer exist.
SQL> select * from TEST_RM.T1;
行号 SESS_ID SESS_SEQ SQL_TEXT STATE N_STMT N_USED_STMT SEQ_NO CURR_SCH USER_NAME TRX_ID CREATE_TIME CLNT_TYPE TIME_ZONE CHK_CONS CHK_IDENT RDONLY INS_NULL
---------- -------------------- ----------- ----------------------------------------------------- ------ ----------- ----------- ----------- -------- --------- -------------------- -------------------------- --------- --------- -------- --------- ------ --------
COMPILE_FLAG AUTO_CMT DDL_AUTOCMT RS_FOR_QRY CHK_NET ISO_LEVEL CLNT_HOST APPNAME CLNT_IP OSNAME CONN_TYPE VPOOLADDR RUN_STATUS MSG_STATUS LAST_RECV_TIME LAST_SEND_TIME DCP_FLAG THRD_ID CONNECTED PORT_TYPE
------------ -------- ----------- ---------- ------- ----------- --------- ------- ------- ------ ------------ -------------------- ---------- ---------- -------------------------- -------------------------- -------- ----------- ----------- -----------
SRC_SITE MAL_ID CONCURRENT_FLAG CUR_LINENO CUR_MTDNAME CUR_SQLSTR CLNT_VER
----------- -------------------- --------------- ----------- ----------- ---------- --------
1 140611457980408 549 create table TEST_RM.T1 as select * from v$sessions; ACTIVE 64 1 8 SYSDBA SYSDBA 3561 2021-10-28 16:02:53.000000 SQL3 +08:00 N N N Y
N N Y N N 1 RH6 disql ::1 Linux HOMOGENEOUS 140611457912752 RUNNING RECIEVE 2021-10-28 16:03:10.000000 2021-10-28 16:03:05.000000 N 27377 1 0
65535 NULL 0 55 NULL NULL 7.1.8.46
已用时间: 0.714(毫秒). 执行号:53306.
SQL>
SQL> select tablespace_name, file_name, status from dba_data_files;
select tablespace_name, file_name, status from dba_data_files;
[-2206]:无效的参数值.
已用时间: 9.580(毫秒). 执行号:0.
SQL> SELECT GROUP_ID,PATH,CLIENT_PATH FROM "V$DATAFILE";
行号 GROUP_ID PATH CLIENT_PATH
---------- ----------- ------------------------------------------------------------------ -----------
1 0 /home/dmdba/TEST_RM/DAMENG/SYSTEM.DBF SYSTEM.DBF
2 1 /home/dmdba/TEST_RM/DAMENG/ROLL.DBF ROLL.DBF
3 3 /home/dmdba/TEST_RM/DAMENG/TEMP.DBF TEMP.DBF
4 4 /home/dmdba/TEST_RM/DAMENG/MAIN.DBF MAIN.DBF
5 NULL 文件或目录[/home/dmdba/TEST_RM/DAMENG/TEST_RM01.DBF]不存在 NULL
已用时间: 0.669(毫秒). 执行号:53308.
SQL>2.4 Perform data file inspection
SQL> call SP_FILE_SYS_CHECK();
DMSQL 过程已成功完成
已用时间: 1.861(毫秒). 执行号:53309.
SQL> select * from TEST_RM.T1;
select * from TEST_RM.T1;
[-3430]:表空间[TEST_RM]中文件[/home/dmdba/TEST_RM/DAMENG/TEST_RM01.DBF]已被删除.
已用时间: 1.049(毫秒). 执行号:0.It can be seen from the above that if the data file check is not done, the tables and objects on the deleted data file can be accessed normally, but they will not be able to be accessed normally after the data file check is done.
2.5 Restoring data files
2.5.1 Perform preparations before recovery first
SQL> call sp_tablespace_prepare_recover('TEST_RM');
DMSQL 过程已成功完成
已用时间: 1.018(毫秒). 执行号:53311.2.5.2 Check the database process number, find the unreleased file handle number and the deleted data file (the file handle will disappear after restarting)
[dmdba@RH6 DAMENG]$ ps -ef|grep TEST_RM
dmdba **27296** 1 0 16:01 pts/4 00:00:03 /home/dmdba/dm46/bin/dmserver path=/home/dmdba/TEST_RM/DAMENG/dm.ini -noconsole
dmdba 27444 26219 0 16:20 pts/5 00:00:00 grep TEST_RM
[dmdba@RH6 DAMENG]$ cd /proc/27296/fd
[dmdba@RH6 fd]$ ls -ltr
total 0
l-wx------ 1 dmdba dinstall 64 Oct 28 16:20 2 -> /home/dmdba/dm46/log/DmServiceTESTRM.log
lrwx------ 1 dmdba dinstall 64 Oct 28 16:20 9 -> /home/dmdba/TEST_RM/DAMENG/DAMENG02.log
lrwx------ 1 dmdba dinstall 64 Oct 28 16:20 8 -> /home/dmdba/TEST_RM/DAMENG/DAMENG01.log
lrwx------ 1 dmdba dinstall 64 Oct 28 16:20 7 -> /home/dmdba/TEST_RM/DAMENG/TEMP.DBF
lrwx------ 1 dmdba dinstall 64 Oct 28 16:20 6 -> /home/dmdba/TEST_RM/DAMENG/SYSTEM.DBF
lrwx------ 1 dmdba dinstall 64 Oct 28 16:20 5 -> socket:[225406]
lrwx------ 1 dmdba dinstall 64 Oct 28 16:20 48 -> socket:[226078]
lrwx------ 1 dmdba dinstall 64 Oct 28 16:20 47 -> socket:[226077]
lrwx------ 1 dmdba dinstall 64 Oct 28 16:20 46 -> socket:[225766]
**lrwx------ 1 dmdba dinstall 64 Oct 28 16:20 45 -> /home/dmdba/TEST_RM/DAMENG/TEST_RM01.DBF (deleted)**
lrwx------ 1 dmdba dinstall 64 Oct 28 16:20 44 -> socket:[225508]
......
lrwx------ 1 dmdba dinstall 64 Oct 28 16:20 11 -> /home/dmdba/TEST_RM/DAMENG/MAIN.DBF
lrwx------ 1 dmdba dinstall 64 Oct 28 16:20 10 -> /home/dmdba/TEST_RM/DAMENG/ROLL.DBF
l-wx------ 1 dmdba dinstall 64 Oct 28 16:20 1 -> /home/dmdba/dm46/log/DmServiceTESTRM.log
lr-x------ 1 dmdba dinstall 64 Oct 28 16:20 0 -> /dev/null
[dmdba@RH6 fd]$2.5.3 Copy data files back
Note: copy files with dmdba user
[dmdba@RH6 fd]$ cp 45 /home/dmdba/TEST_RM/DAMENG/TEST_RM01.DBF2.5.4 Executing the data file recovery process
SQL> call sp_tablespace_recover('TEST_RM');
DMSQL 过程已成功完成
已用时间: 6.302(毫秒). 执行号:53312.
SQL> call SP_FILE_SYS_CHECK();
DMSQL 过程已成功完成
已用时间: 0.254(毫秒). 执行号:53313.2.5.5 Query data and table space for data verification
SQL> select * from TEST_RM.T1;
行号 SESS_ID SESS_SEQ SQL_TEXT STATE N_STMT N_USED_STMT SEQ_NO CURR_SCH USER_NAME TRX_ID CREATE_TIME CLNT_TYPE TIME_ZONE CHK_CONS CHK_IDENT RDONLY INS_NULL
---------- -------------------- ----------- ----------------------------------------------------- ------ ----------- ----------- ----------- -------- --------- -------------------- -------------------------- --------- --------- -------- --------- ------ --------
COMPILE_FLAG AUTO_CMT DDL_AUTOCMT RS_FOR_QRY CHK_NET ISO_LEVEL CLNT_HOST APPNAME CLNT_IP OSNAME CONN_TYPE VPOOLADDR RUN_STATUS MSG_STATUS LAST_RECV_TIME LAST_SEND_TIME DCP_FLAG THRD_ID CONNECTED PORT_TYPE
------------ -------- ----------- ---------- ------- ----------- --------- ------- ------- ------ ------------ -------------------- ---------- ---------- -------------------------- -------------------------- -------- ----------- ----------- -----------
SRC_SITE MAL_ID CONCURRENT_FLAG CUR_LINENO CUR_MTDNAME CUR_SQLSTR CLNT_VER
----------- -------------------- --------------- ----------- ----------- ---------- --------
1 140611457980408 549 create table TEST_RM.T1 as select * from v$sessions; ACTIVE 64 1 8 SYSDBA SYSDBA 3561 2021-10-28 16:02:53.000000 SQL3 +08:00 N N N Y
N N Y N N 1 RH6 disql ::1 Linux HOMOGENEOUS 140611457912752 RUNNING RECIEVE 2021-10-28 16:03:10.000000 2021-10-28 16:03:05.000000 N 27377 1 0
65535 NULL 0 55 NULL NULL 7.1.8.46
已用时间: 1.916(毫秒). 执行号:53314.
SQL> SELECT GROUP_ID,PATH,CLIENT_PATH FROM "V$DATAFILE";
行号 GROUP_ID PATH CLIENT_PATH
---------- ----------- ---------------------------------------- -------------
1 0 /home/dmdba/TEST_RM/DAMENG/SYSTEM.DBF SYSTEM.DBF
2 1 /home/dmdba/TEST_RM/DAMENG/ROLL.DBF ROLL.DBF
3 3 /home/dmdba/TEST_RM/DAMENG/TEMP.DBF TEMP.DBF
4 4 /home/dmdba/TEST_RM/DAMENG/MAIN.DBF MAIN.DBF
5 5 /home/dmdba/TEST_RM/DAMENG/TEST_RM01.DBF TEST_RM01.DBF
已用时间: 0.450(毫秒). 执行号:53315.
SQL> select tablespace_name, file_name, status from dba_data_files;
行号 TABLESPACE_NAME FILE_NAME STATUS
---------- --------------- ---------------------------------------- ---------
1 SYSTEM /home/dmdba/TEST_RM/DAMENG/SYSTEM.DBF AVAILABLE
2 TEST_RM /home/dmdba/TEST_RM/DAMENG/TEST_RM01.DBF AVAILABLE
3 MAIN /home/dmdba/TEST_RM/DAMENG/MAIN.DBF AVAILABLE
4 TEMP /home/dmdba/TEST_RM/DAMENG/TEMP.DBF AVAILABLE
5 ROLL /home/dmdba/TEST_RM/DAMENG/ROLL.DBF AVAILABLE
已用时间: 4.885(毫秒). 执行号:53316.At this point, the recovery is complete, and immediately after the recovery is complete, make a backup of the entire database; if you have not done a scheduled data backup, do the task quickly. Points to note during recovery: 1. The database and operating system cannot be restarted; 2. When copying data files, you need to use the dmdba user to copy, and other accounts need to set the file user and group permissions to dmdba and dinstall;
Summary: The above method is used when the database is not archived or backed up. If there is a backup, you can directly use the backup and archive to restore the data completely, and at the same time, the speed of recovery and the integrity of the data are guaranteed. When you encounter an unfamiliar environment and need to upgrade the data software or shut down and restart, it is best to check the status of the data file.