[20210529]延迟打开数据库.txt

[20210529]延迟打开数据库.txt --//不知道这样操作有什么作用,记录一下: SYS@book> set timing on SYS@book> startup mount; ORACLE instance started. Total System Global Area  676491264 bytes Fixed Size                  2256192 bytes Variable Size             239076032 bytes Database Buffers          427819008 bytes Redo Buffers                7340032 bytes Database mounted. SYS@book> oradebug setmypid Statement processed. SYS@book> set timing on SYS@book> oradebug event db_open_begin delay=20 Statement processed. SYS@book> alter database open ; Database altered. Elapsed: 00:00:21.64 SYS@book> select sysdate from dual ; SYSDATE ------------------- 2021-06-02 08:59:32 Elapsed: 00:00:00.00 --//看看alter的记录: alter database open --//执行前等20秒后采用如下信息。 Wed Jun 02 08:59:30 2021 LGWR: STARTING ARCH PROCESSES Wed Jun 02 08:59:30 2021 ARC0 started with pid=22, OS id=36296 ARC0: Archival started LGWR: STARTING ARCH PROCESSES COMPLETE ARC0: STARTING ARCH PROCESSES Thread 1 opened at log sequence 1173   Current log# 2 seq# 1173 mem# 0: /mnt/ramdisk/book/redo02.log Successful open of redo thread 1 Wed Jun 02 08:59:31 2021 MTTR advisory is disabled because FAST_START_MTTR_TARGET is not set Wed Jun 02 08:59:31 2021 SMON: enabling cache recovery Wed Jun 02 08:59:31 2021 ARC1 started with pid=23, OS id=36298 [36291] Successfully onlined Undo Tablespace 2. Undo initialization finished serial:0 start:1054168652 end:1054168722 diff:70 (0 seconds) Verifying file header compatibility for 11g tablespace encryption.. Verifying 11g file header compatibility for tablespace encryption completed SMON: enabling tx recovery Database Characterset is ZHS16GBK No Resource Manager plan active replication_dependency_tracking turned off (no async multimaster replication found) WARNING: AQ_TM_PROCESSES is set to 0. System operation                     might be adversely affected. --//不过执行如下效果一样： SYS@book> shutdown immediate; Database closed. Database dismounted. ORACLE instance shut down. SYS@book> startup mount; ORACLE instance started. Total System Global Area  676491264 bytes Fixed Size                  2256192 bytes Variable Size             239076032 bytes Database Buffers          427819008 bytes Redo Buffers                7340032 bytes Database mounted. SYS@book> set timing on SYS@book> alter system set events 'db_open_begin delay=10' ; System altered. Elapsed: 00:00:00.00 SYS@book> alter database open; Database altered. Elapsed: 00:00:11.63 --//alert: alter database open Wed Jun 02 09:06:39 2021 LGWR: STARTING ARCH PROCESSES Wed Jun 02 09:06:39 2021 ARC0 started with pid=22, OS id=36475 ARC0: Archival started LGWR: STARTING ARCH PROCESSES COMPLETE ARC0: STARTING ARCH PROCESSES Thread 1 opened at log sequence 1173   Current log# 2 seq# 1173 mem# 0: /mnt/ramdisk/book/redo02.log Successful open of redo thread 1 Wed Jun 02 09:06:40 2021 MTTR advisory is disabled because FAST_START_MTTR_TARGET is not set Wed Jun 02 09:06:40 2021 SMON: enabling cache recovery Wed Jun 02 09:06:40 2021 ARC1 started with pid=23, OS id=36477 [36469] Successfully onlined Undo Tablespace 2. Undo initialization finished serial:0 start:1054597802 end:1054597862 diff:60 (0 seconds) Verifying file header compatibility for 11g tablespace encryption.. Verifying 11g file header compatibility for tablespace encryption completed SMON: enabling tx recovery Database Characterset is ZHS16GBK No Resource Manager plan active replication_dependency_tracking turned off (no async multimaster replication found) WARNING: AQ_TM_PROCESSES is set to 0. System operation                     might be adversely affected.