Home Database Mysql Tutorial 数据文件从系统文件迁移到asm的操作专栏

数据文件从系统文件迁移到asm的操作专栏

Jun 07, 2016 pm 03:56 PM
oracle

select file_name ,tablespace_name from dba_data_files ;

FILE_NAME                      TABLESPACE_NAME
--------------------------------------------- ------------------------------
+DATA/rac/datafile/system.259.926647219       SYSTEM
+DATA/rac/datafile/sysaux.260.926647323       SYSAUX
+DATA/rac/datafile/undotbs1.261.926647405     UNDOTBS1
+DATA/rac/datafile/undotbs2.263.926647467     UNDOTBS2
+DATA/rac/datafile/users.264.926647499          USERS
+DATA/rac/datafile/admin_tbs.274.927927081    ADMIN_TBS
+DATA/rac/datafile/admin_tb2.275.927927171    ADMIN_TB2
+DATA/rac/datafile/tbs_low_freq.276.927939255 TBS_LOW_FREQ
/oracle/app/oracle/11.2/db_1/dbs/q1_orders    Q1_ORDERS
/oracle/app/oracle/11.2/db_1/dbs/q2_orders    Q2_ORDERS
/oracle/app/oracle/11.2/db_1/dbs/q3_orders    Q3_ORDERS
/oracle/app/oracle/11.2/db_1/dbs/q4_orders    Q4_ORDERS
/oracle/app/oracle/11.2/db_1/dbs/2006_orders  2006_ORDERS
/oracle/app/oracle/11.2/db_1/dbs/2005_orders  2005_ORDERS
/oracle/app/oracle/11.2/db_1/dbs/2004_orders  2004_ORDERS
/oracle/app/oracle/11.2/db_1/dbs/old_orders   OLD_ORDERS
/oracle/app/oracle/11.2/db_1/dbs/cc_this_mont CC_THIS_MONTH

数据文件都节点1本地。

案例重演:
sys@RAC> show parameter db_create_file_dest

NAME                     TYPE     VALUE
------------------------------------ ----------- ------------------------------
db_create_file_dest             string     +DATA

采用了omf管理
sys@RAC> create tablespace qn datafile size 20m ;

Tablespace created.

sys@RAC> select file_name ,tablespace_name from dba_data_files ;

FILE_NAME                      TABLESPACE_NAME
--------------------------------------------- ------------------------------
.........
+DATA/rac/datafile/qn.277.928807173          QN
此时发现数据文件qn建在ASM存储上

sys@RAC> create tablespace qn2 datafile 'qn2' size 20m ;
Tablespace created.
sys@RAC> select file_name ,tablespace_name from dba_data_files ;

FILE_NAME                      TABLESPACE_NAME
--------------------------------------------- ------------------------------
/oracle/app/oracle/11.2/db_1/dbs/cc_prev_12   CC_PREV_12MTH
/oracle/app/oracle/11.2/db_1/dbs/cc_old_tran  CC_OLD_TRAN
+DATA/rac/datafile/qn.277.928807173          QN
/oracle/app/oracle/11.2/db_1/dbs/qn2          QN2
此时发现数据文件qn2建在系统文件上,这样会出问题的,其节点报错。

那么如何把这个数据库的系统文件迁移到ASM上呢?

在线迁移数据文件至ASM上:

1. offline数据文件
   select file_name ,tablespace_name from dba_data_files  where tablespace_name in ('Q1_ORDERS','Q2_ORDERS','Q3_ORDERS','Q4_ORDERS','2006_ORDERS','2005_ORDERS','2004_ORDERS','OLD_ORDERS','CC_THIS_MONTH','CC_PREV_MONTH','CC_PREV_12MTH','QN2' ) ;
   FILE_NAME                             TABLESPACE_NAME
   ------------------------------------------------------------ ------------------------------
   /oracle/app/oracle/11.2/db_1/dbs/q1_orders             Q1_ORDERS
   /oracle/app/oracle/11.2/db_1/dbs/q2_orders             Q2_ORDERS
   /oracle/app/oracle/11.2/db_1/dbs/q3_orders             Q3_ORDERS
   /oracle/app/oracle/11.2/db_1/dbs/q4_orders             Q4_ORDERS
   /oracle/app/oracle/11.2/db_1/dbs/2006_orders             2006_ORDERS
   /oracle/app/oracle/11.2/db_1/dbs/2005_orders             2005_ORDERS
   /oracle/app/oracle/11.2/db_1/dbs/2004_orders             2004_ORDERS
   /oracle/app/oracle/11.2/db_1/dbs/old_orders             OLD_ORDERS
   /oracle/app/oracle/11.2/db_1/dbs/cc_this_month             CC_THIS_MONTH
   /oracle/app/oracle/11.2/db_1/dbs/cc_prev_month             CC_PREV_MONTH
   /oracle/app/oracle/11.2/db_1/dbs/cc_prev_12             CC_PREV_12MTH
   /oracle/app/oracle/11.2/db_1/dbs/qn2                 QN2

2. rman copy
   alter tablespace Q1_ORDERS offline ;

   backup as copy datafile '/oracle/app/oracle/11.2/db_1/dbs/q1_orders'  format '+DATA';
   or
   copy datafile  '/oracle/app/oracle/11.2/db_1/dbs/q1_orders' to '+DATA';


  RMAN>  copy datafile  '/oracle/app/oracle/11.2/db_1/dbs/q1_orders' to '+DATA';

  Starting backup at 2016-11-25 02:55:42
  using target database control file instead of recovery catalog
  allocated channel: ORA_DISK_1
  channel ORA_DISK_1: SID=28 instance=rac1 device type=DISK
  channel ORA_DISK_1: starting datafile copy
  input datafile file number=00009 name=/oracle/app/oracle/11.2/db_1/dbs/q1_orders
  output file name=+DATA/rac/datafile/q1_orders.278.928810547 tag=TAG20161125T025546 RECID=1 STAMP=928810550
  channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:03
  Finished backup at 2016-11-25 02:55:50

3. rename
  alter database rename file 'D:\NSOADP\SYSTEM01.DBF' to '+ORADATA/nsoa/datafile/system.260.877082571';
  or
  switch datafile 37 to copy;

  RMAN> switch datafile '/oracle/app/oracle/11.2/db_1/dbs/q1_orders' to copy ;
  datafile 9 switched to datafile copy "+DATA/rac/datafile/q1_orders.278.928810547"


4. recover
    recover datafile '+DATA/rac/datafile/q1_orders.278.928810547';

5. online
  alter tablespace Q1_ORDERS online

  sys@RAC> select file_name ,tablespace_name from dba_data_files  where tablespace_name in ('Q1_ORDERS')
    2  /

  FILE_NAME                             TABLESPACE_NAME
  ------------------------------------------------------------ ------------------------------
  +DATA/rac/datafile/q1_orders.278.928810547             Q1_ORDERS

快速恢复:
  sys@RAC> select file_name ,tablespace_name from dba_data_files  where tablespace_name in ('Q2_ORDERS','Q3_ORDERS','Q4_ORDERS','2006_ORDERS','2005_ORDERS','2004_ORDERS','OLD_ORDERS','CC_THIS_MONTH','CC_PREV_MONTH','CC_PREV_12MTH','QN2' ) ;

  FILE_NAME                             TABLESPACE_NAME
  ------------------------------------------------------------ ------------------------------
  /oracle/app/oracle/11.2/db_1/dbs/q2_orders             Q2_ORDERS
  /oracle/app/oracle/11.2/db_1/dbs/q3_orders             Q3_ORDERS
  /oracle/app/oracle/11.2/db_1/dbs/q4_orders             Q4_ORDERS
  /oracle/app/oracle/11.2/db_1/dbs/2006_orders             2006_ORDERS
  /oracle/app/oracle/11.2/db_1/dbs/2005_orders             2005_ORDERS
  /oracle/app/oracle/11.2/db_1/dbs/2004_orders             2004_ORDERS
  /oracle/app/oracle/11.2/db_1/dbs/old_orders             OLD_ORDERS
  /oracle/app/oracle/11.2/db_1/dbs/cc_this_month             CC_THIS_MONTH
  /oracle/app/oracle/11.2/db_1/dbs/cc_prev_month             CC_PREV_MONTH
  /oracle/app/oracle/11.2/db_1/dbs/cc_prev_12             CC_PREV_12MTH
  /oracle/app/oracle/11.2/db_1/dbs/qn2                 QN2

sys@RAC>    select 'alter tablespace '|| tablespace_name||' offline;'  from dba_data_files  where tablespace_name in ('Q2_ORDERS','Q3_ORDERS','Q4_ORDERS','2006_ORDERS','2005_ORDERS','2004_ORDERS','OLD_ORDERS','CC_THIS_MONTH','CC_PREV_MONTH','CC_PREV_12MTH','QN2' ) ;

'ALTERTABLESPACE'||TABLESPACE_NAME||'OFFLINE;'
--------------------------------------------------------
alter tablespace Q2_ORDERS offline;
alter tablespace Q3_ORDERS offline;
alter tablespace Q4_ORDERS offline;
alter tablespace 2006_ORDERS offline;
alter tablespace 2005_ORDERS offline;
alter tablespace 2004_ORDERS offline;
alter tablespace OLD_ORDERS offline;
alter tablespace CC_THIS_MONTH offline;
alter tablespace CC_PREV_MONTH offline;
alter tablespace CC_PREV_12MTH offline;
alter tablespace QN2 offline;

sys@RAC> sys@RAC> alter tablespace Q2_ORDERS offline;
alter tablespace Q3_ORDERS offline;
alter tablespace Q4_ORDERS offline;
alter tablespace 2006_ORDERS offline;
alter tablespace 2005_ORDERS offline;
alter tablespace 2004_ORDERS offline;
alter tablespace OLD_ORDERS offline;
alter tablespace CC_THIS_MONTH offline;
alter tablespace CC_PREV_MONTH offline;
alter tablespace CC_PREV_12MTH offline;
alter tablespace QN2 offline;

sys@RAC> alter tablespace "2006_ORDERS" offline
                 *
ERROR at line 1:
ORA-02140: invalid tablespace name

sys@RAC> alter tablespace 2005_ORDERS offline
                 *
ERROR at line 1:
ORA-02140: invalid tablespace name

sys@RAC> alter tablespace 2004_ORDERS offline
                 *
ERROR at line 1:
ORA-02140: invalid tablespace name

alter tablespace "2004_ORDERS" offline;
alter tablespace "2005_ORDERS" offline;
alter tablespace "2006_ORDERS" offline;

 select 'copy datafile '''||file_name||''' to ''+DATA'';'  from dba_data_files  where tablespace_name in ('Q2_ORDERS','Q3_ORDERS','Q4_ORDERS','2006_ORDERS','2005_ORDERS','2004_ORDERS','OLD_ORDERS','CC_THIS_MONTH','CC_PREV_MONTH','CC_PREV_12MTH','QN2' ) ;

'COPYDATAFILE'''||FILE_NAME||'''TO''+DATA'';'
----------------------------------------------------------------------------------------------------------------------------------------------------------
copy datafile '/oracle/app/oracle/11.2/db_1/dbs/q2_orders' to '+DATA';
copy datafile '/oracle/app/oracle/11.2/db_1/dbs/q3_orders' to '+DATA';
copy datafile '/oracle/app/oracle/11.2/db_1/dbs/q4_orders' to '+DATA';
copy datafile '/oracle/app/oracle/11.2/db_1/dbs/2006_orders' to '+DATA';
copy datafile '/oracle/app/oracle/11.2/db_1/dbs/2005_orders' to '+DATA';
copy datafile '/oracle/app/oracle/11.2/db_1/dbs/2004_orders' to '+DATA';
copy datafile '/oracle/app/oracle/11.2/db_1/dbs/old_orders' to '+DATA';
copy datafile '/oracle/app/oracle/11.2/db_1/dbs/cc_this_month' to '+DATA';
copy datafile '/oracle/app/oracle/11.2/db_1/dbs/cc_prev_month' to '+DATA';
copy datafile '/oracle/app/oracle/11.2/db_1/dbs/cc_prev_12' to '+DATA';
copy datafile '/oracle/app/oracle/11.2/db_1/dbs/qn2' to '+DATA';

RMAN> copy datafile '/oracle/app/oracle/11.2/db_1/dbs/q2_orders' to '+DATA';
copy datafile '/oracle/app/oracle/11.2/db_1/dbs/q3_orders' to '+DATA';
copy datafile '/oracle/app/oracle/11.2/db_1/dbs/q4_orders' to '+DATA';
copy datafile '/oracle/app/oracle/11.2/db_1
/dbs/2006_orders' to '+DATA';
copy datafile '/oracle/app/oracle/11.2/db_1/dbs/2005_orders' to '+DATA';
copy datafile '/oracle/app/oracle/11.2/db_1/dbs/2004_orders' to '+DATA';
copy datafile '/oracle/app/oracle/11.2/db_1/dbs/old_orders' to '+DATA';
copy datafile '/oracle/app/oracle/11.2/db_1/dbs/cc_this_month' to '+DATA';
copy datafile '/oracle/app/oracle/11.2/db_1/dbs/cc_prev_month' to '+DATA';
copy datafile '/oracle/app/oracle/11.2/db_1/dbs/cc_prev_12' to '+DATA';
copy datafile '/oracle/app/oracle/11.2/db_1/dbs/qn2' to '+DATA';Starting backup at 2016-11-25 03:20:57
using channel ORA_DISK_1
channel ORA_DISK_1: starting datafile copy
input datafile file number=00010 name=/oracle/app/oracle/11.2/db_1/dbs/q2_orders
output file name=+DATA/rac/datafile/q2_orders.279.928812061 tag=TAG20161125T032059 RECID=3 STAMP=928812062
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:03
Finished backup at 2016-11-25 03:21:02

RMAN>
Starting backup at 2016-11-25 03:21:08
using channel ORA_DISK_1
channel ORA_DISK_1: starting datafile copy
input datafile file number=00011 name=/oracle/app/oracle/11.2/db_1/dbs/q3_orders
output file name=+DATA/rac/datafile/q3_orders.280.928812071 tag=TAG20161125T032109 RECID=4 STAMP=928812073
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:07
Finished backup at 2016-11-25 03:21:17

RMAN>
Starting backup at 2016-11-25 03:21:22
using channel ORA_DISK_1
channel ORA_DISK_1: starting datafile copy
input datafile file number=00012 name=/oracle/app/oracle/11.2/db_1/dbs/q4_orders
output file name=+DATA/rac/datafile/q4_orders.281.928812085 tag=TAG20161125T032124 RECID=5 STAMP=928812088
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:03
Finished backup at 2016-11-25 03:21:28

RMAN>
Starting backup at 2016-11-25 03:21:33
using channel ORA_DISK_1
channel ORA_DISK_1: starting datafile copy
input datafile file number=00013 name=/oracle/app/oracle/11.2/db_1/dbs/2006_orders
output file name=+DATA/rac/datafile/2006_orders.282.928812095 tag=TAG20161125T032134 RECID=6 STAMP=928812099
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:07
Finished backup at 2016-11-25 03:21:42

RMAN>
Starting backup at 2016-11-25 03:21:46
using channel ORA_DISK_1
channel ORA_DISK_1: starting datafile copy
input datafile file number=00014 name=/oracle/app/oracle/11.2/db_1/dbs/2005_orders
output file name=+DATA/rac/datafile/2005_orders.283.928812109 tag=TAG20161125T032148 RECID=7 STAMP=928812112
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:07
Finished backup at 2016-11-25 03:21:56

RMAN>
Starting backup at 2016-11-25 03:22:00
using channel ORA_DISK_1
channel ORA_DISK_1: starting datafile copy
input datafile file number=00015 name=/oracle/app/oracle/11.2/db_1/dbs/2004_orders
output file name=+DATA/rac/datafile/2004_orders.284.928812123 tag=TAG20161125T032202 RECID=8 STAMP=928812126
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:07
Finished backup at 2016-11-25 03:22:10

RMAN>
Starting backup at 2016-11-25 03:22:14
using channel ORA_DISK_1
channel ORA_DISK_1: starting datafile copy
input datafile file number=00016 name=/oracle/app/oracle/11.2/db_1/dbs/old_orders
output file name=+DATA/rac/datafile/old_orders.285.928812137 tag=TAG20161125T032216 RECID=9 STAMP=928812141
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:07
Finished backup at 2016-11-25 03:22:24

RMAN>
Starting backup at 2016-11-25 03:22:29
using channel ORA_DISK_1
channel ORA_DISK_1: starting datafile copy
input datafile file number=00017 name=/oracle/app/oracle/11.2/db_1/dbs/cc_this_month
output file name=+DATA/rac/datafile/cc_this_month.286.928812151 tag=TAG20161125T032231 RECID=10 STAMP=928812154
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:03
Finished backup at 2016-11-25 03:22:34

RMAN>
Starting backup at 2016-11-25 03:22:45
using channel ORA_DISK_1
channel ORA_DISK_1: starting datafile copy
input datafile file number=00018 name=/oracle/app/oracle/11.2/db_1/dbs/cc_prev_month
output file name=+DATA/rac/datafile/cc_prev_month.287.928812167 tag=TAG20161125T032246 RECID=11 STAMP=928812167
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:01
Finished backup at 2016-11-25 03:22:47

RMAN>
Starting backup at 2016-11-25 03:22:52
using channel ORA_DISK_1
channel ORA_DISK_1: starting datafile copy
input datafile file number=00019 name=/oracle/app/oracle/11.2/db_1/dbs/cc_prev_12
output file name=+DATA/rac/datafile/cc_prev_12mth.288.928812175 tag=TAG20161125T032253 RECID=12 STAMP=928812175
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:03
Finished backup at 2016-11-25 03:22:57

Starting backup at 2016-11-25 03:26:09

RMAN>
using channel ORA_DISK_1
channel ORA_DISK_1: starting datafile copy
input datafile file number=00022 name=/oracle/app/oracle/11.2/db_1/dbs/qn2
output file name=+DATA/rac/datafile/qn2.289.928812371 tag=TAG20161125T032611 RECID=13 STAMP=928812376
channel ORA_DISK_1: datafile copy complete, elapsed time: 00:00:07
Finished backup at 2016-11-25 03:26:18


 sys@RAC> select 'switch  datafile '''||file_name||''' to copy;'  from dba_data_files  where tablespace_name in ('Q2_ORDERS','Q3_ORDERS','Q4_ORDERS','2006_ORDERS','2005_ORDERS','2004_ORDERS','OLD_ORDERS','CC_THIS_MONTH','CC_PREV_MONTH','CC_PREV_12MTH','QN2' ) ;

'SWITCHDATAFILE'''||FILE_NAME||'''TOCOPY;'
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
switch    datafile '/oracle/app/oracle/11.2/db_1/dbs/q2_orders' to copy;
switch    datafile '/oracle/app/oracle/11.2/db_1/dbs/q3_orders' to copy;
switch    datafile '/oracle/app/oracle/11.2/db_1/dbs/q4_orders' to copy;
switch    datafile '/oracle/app/oracle/11.2/db_1/dbs/2006_orders' to copy;
switch    datafile '/oracle/app/oracle/11.2/db_1/dbs/2005_orders' to copy;
switch    datafile '/oracle/app/oracle/11.2/db_1/dbs/2004_orders' to copy;
switch    datafile '/oracle/app/oracle/11.2/db_1/dbs/old_orders' to copy;
switch    datafile '/oracle/app/oracle/11.2/db_1/dbs/cc_this_month' to copy;
switch    datafile '/oracle/app/oracle/11.2/db_1/dbs/cc_prev_month' to copy;
switch    datafile '/oracle/app/oracle/11.2/db_1/dbs/cc_prev_12' to copy;
switch    datafile '/oracle/app/oracle/11.2/db_1/dbs/qn2' to copy;

RMAN> switch    datafile '/oracle/app/oracle/11.2/db_1/dbs/q2_orders' to copy;
switch    datafile '/oracle/app/oracle/11.2/db_1/dbs/q3_orders' to copy;
switch    datafile '/oracle/app/oracle/11.2/db_1/dbs/q4_orders' to copy;
switch    datafile '/oracle/app/oracle/11.2/db_1/
dbs/2006_orders' to copy;
switch    datafile '/oracle/app/oracle/11.2/db_1/dbs/2005_orders' to copy;
switch    datafile '/oracle/app/oracle/11.2/db_1/dbs/2004_orders' to copy;
switch    datafile '/oracle/app/oracle/11.2/db_1/dbs/old_orders' to copy;
switch    datafile '/oracle/app/oracle/11.2/db_1/dbs/cc_this_month' to copy;
switch    datafile '/oracle/app/oracle/11.2/db_1/dbs/cc_prev_month' to copy;
switch    datafile '/oracle/app/oracle/11.2/db_1/dbs/cc_prev_12' to copy;
switch    datafile '/oracle/app/oracle/11.2/db_1/dbs/qn2' to copy;
datafile 10 switched to datafile copy "+DATA/rac/datafile/q2_orders.279.928812061"
RMAN>
datafile 11 switched to datafile copy "+DATA/rac/datafile/q3_orders.280.928812071"
RMAN>
datafile 12 switched to datafile copy "+DATA/rac/datafile/q4_orders.281.928812085"
RMAN>
datafile 13 switched to datafile copy "+DATA/rac/datafile/2006_orders.282.928812095"
RMAN>
datafile 14 switched to datafile copy "+DATA/rac/datafile/2005_orders.283.928812109"
RMAN>
datafile 15 switched to datafile copy "+DATA/rac/datafile/2004_orders.284.928812123"
RMAN>
datafile 16 switched to datafile copy "+DATA/rac/datafile/old_orders.285.928812137"
RMAN>
datafile 17 switched to datafile copy "+DATA/rac/datafile/cc_this_month.286.928812151"
RMAN>
datafile 18 switched to datafile copy "+DATA/rac/datafile/cc_prev_month.287.928812167"
RMAN>
datafile 19 switched to datafile copy "+DATA/rac/datafile/cc_prev_12mth.288.928812175"
RMAN>
datafile 22 switched to datafile copy "+DATA/rac/datafile/qn2.289.928812371"

alter tablespace Q3_ORDERS online;
alter tablespace Q4_ORDERS online;
alter tablespace "2006_ORDERS" online;
alter tablespace "2005_ORDERS" online;
alter tablespace "2004_ORDERS" online;
alter tablespace OLD_ORDERS online;
alter tablespace CC_THIS_MONTH online;
alter tablespace CC_PREV_MONTH online;
alter tablespace CC_PREV_12MTH online;
alter tablespace QN2 online;

sys@RAC>  select file_name ,tablespace_name from dba_data_files  where tablespace_name in ('Q1_ORDERS','Q2_ORDERS','Q3_ORDERS','Q4_ORDERS','2006_ORDERS','2005_ORDERS','2004_ORDERS','OLD_ORDERS','CC_THIS_MONTH','CC_PREV_MONTH','CC_PREV_12MTH','QN2' ) ;
FILE_NAME                             TABLESPACE_NAME
------------------------------------------------------------ ------------------------------
+DATA/rac/datafile/q1_orders.278.928810547             Q1_ORDERS
+DATA/rac/datafile/q2_orders.279.928812061             Q2_ORDERS
+DATA/rac/datafile/q3_orders.280.928812071             Q3_ORDERS
+DATA/rac/datafile/q4_orders.281.928812085             Q4_ORDERS
+DATA/rac/datafile/2006_orders.282.928812095             2006_ORDERS
+DATA/rac/datafile/2005_orders.283.928812109             2005_ORDERS
+DATA/rac/datafile/2004_orders.284.928812123             2004_ORDERS
+DATA/rac/datafile/old_orders.285.928812137             OLD_ORDERS
+DATA/rac/datafile/cc_this_month.286.928812151             CC_THIS_MONTH
+DATA/rac/datafile/cc_prev_month.287.928812167             CC_PREV_MONTH
+DATA/rac/datafile/cc_prev_12mth.288.928812175             CC_PREV_12MTH
+DATA/rac/datafile/qn2.289.928812371                 QN2

至此系统上的数据文件都迁移到asm上。

更多相关教程请访问 MySQL视频教程

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Function to calculate the number of days between two dates in oracle Function to calculate the number of days between two dates in oracle May 08, 2024 pm 07:45 PM

The function in Oracle to calculate the number of days between two dates is DATEDIFF(). The specific usage is as follows: Specify the time interval unit: interval (such as day, month, year) Specify two date values: date1 and date2DATEDIFF(interval, date1, date2) Return the difference in days

How long will Oracle database logs be kept? How long will Oracle database logs be kept? May 10, 2024 am 03:27 AM

The retention period of Oracle database logs depends on the log type and configuration, including: Redo logs: determined by the maximum size configured with the "LOG_ARCHIVE_DEST" parameter. Archived redo logs: Determined by the maximum size configured by the "DB_RECOVERY_FILE_DEST_SIZE" parameter. Online redo logs: not archived, lost when the database is restarted, and the retention period is consistent with the instance running time. Audit log: Configured by the "AUDIT_TRAIL" parameter, retained for 30 days by default.

The order of the oracle database startup steps is The order of the oracle database startup steps is May 10, 2024 am 01:48 AM

The Oracle database startup sequence is: 1. Check the preconditions; 2. Start the listener; 3. Start the database instance; 4. Wait for the database to open; 5. Connect to the database; 6. Verify the database status; 7. Enable the service (if necessary ); 8. Test the connection.

How to use interval in oracle How to use interval in oracle May 08, 2024 pm 07:54 PM

The INTERVAL data type in Oracle is used to represent time intervals. The syntax is INTERVAL <precision> <unit>. You can use addition, subtraction, multiplication and division operations to operate INTERVAL, which is suitable for scenarios such as storing time data and calculating date differences.

How to determine whether two strings are contained in oracle How to determine whether two strings are contained in oracle May 08, 2024 pm 07:00 PM

In Oracle, you can use the nested INSTR function to determine whether a string contains two substrings at the same time: when INSTR(string1, string2a) is greater than 0 and INSTR(string1, string2b) is greater than 0, it is included; otherwise, it is not included.

How to see the number of occurrences of a certain character in Oracle How to see the number of occurrences of a certain character in Oracle May 09, 2024 pm 09:33 PM

To find the number of occurrences of a character in Oracle, perform the following steps: Get the total length of a string; Get the length of the substring in which a character occurs; Count the number of occurrences of a character by subtracting the substring length from the total length.

Oracle database server hardware configuration requirements Oracle database server hardware configuration requirements May 10, 2024 am 04:00 AM

Oracle database server hardware configuration requirements: Processor: multi-core, with a main frequency of at least 2.5 GHz. For large databases, 32 cores or more are recommended. Memory: At least 8GB for small databases, 16-64GB for medium sizes, up to 512GB or more for large databases or heavy workloads. Storage: SSD or NVMe disks, RAID arrays for redundancy and performance. Network: High-speed network (10GbE or higher), dedicated network card, low-latency network. Others: Stable power supply, redundant components, compatible operating system and software, heat dissipation and cooling system.

How much memory does oracle require? How much memory does oracle require? May 10, 2024 am 04:12 AM

The amount of memory required by Oracle depends on database size, activity level, and required performance level: for storing data buffers, index buffers, executing SQL statements, and managing the data dictionary cache. The exact amount is affected by database size, activity level, and required performance level. Best practices include setting the appropriate SGA size, sizing SGA components, using AMM, and monitoring memory usage.

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