New Features of automatic checkpoint adjustment for Oracle10gR2

Welcome to the Oracle community forum, and interact with 2 million technical staff to enter the checkpoint from Oracle10gR2. The database can be automatically adjusted. with auto-adjusted checkpoints, Oracle databases can use the system's low I/O load period to write dirty data in memory to improve database efficiency. Therefore, even if the database administrator sets

Welcome to the Oracle community forum and interact with 2 million technical staff> Start With Oracle10gR2, and check points for automatic database adjustment. with auto-adjusted checkpoints, Oracle databases can use the system's low I/O load period to write dirty data in memory, thus improving database efficiency. Therefore, even if the database administrator sets

Welcome to the Oracle community forum and interact with 2 million technical staff> enter

From Oracle10gR2, the database can automatically adjust the checkpoint.

With auto-adjusted checkpoints, Oracle databases can use the system's low I/O load period to write dirty data in memory, thus improving database efficiency.

Therefore, even if the database administrator sets unreasonable checkpoint-related parameters, Oracle can still control the database's Crash Recovery ing time to a reasonable range through automatic adjustment.

When the FAST_START_MTTR_TARGET parameter is not set, the automatic checkpoint adjustment takes effect.
Generally, if we must strictly control the instance or node recovery time, we can set FAST_START_MTTR_TARGET as the expected time value. If the recovery time does not need to be strictly controlled, we can not set the FAST_START_MTTR_TARGET parameter, to enable the automatic checkpoint adjustment feature of Oracle10g.

After the FAST_START_MTTR_TARGET parameter is canceled:

SQL> show parameter fast_start_mttr NAME TYPE VALUE ------------------------------------ ----------- -------------------------- Fast_start_mttr_target integer 0

When starting the database, we can see the following information from the alert file:

Wed Jan 11 16:28:12 2006 MTTR advisory is disabled because FAST_START_MTTR_TARGET is not set

Check the v $ instance_recovery view. We can find the changes in Oracle10g:

SQL> select RECOVERY_ESTIMATED_IOS REIOS, TARGET_MTTR TMTTR, 2 ESTIMATED_MTTR EMTTR, WRITES_MTTR WMTTR, WRITES_OTHER_SETTINGS WOSET, 3 CKPT_BLOCK_WRITES CKPTBW, WRITES_AUTOTUNE WAUTO, WRITES_FULL_THREAD_CKPT WFTCKPT 4 from v $ instance_recovery; REIOS TMTTR EMTTR WMTTR WOSET CKPTBW WAUTO WFTCKPT -------------------------------------------------------------------------------- 49407 0 68 0 3649819 3506125

In the preceding view, the value of the WRITES_AUTOTUNE field indicates the number of writes performed by the checkpoint,
CKPT_BLOCK_WRITES indicates the number of blocks written by the checkpoint.