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Checkpoint Tuning and Troubleshooting Guide [ID 147468.1]
Checkpoint Not Complete In Alert.log Due To Setting Of Archive_lag_target [ID 435780.1]
For your other question check Oracle concept guide and also below link:
YOUR Question1.1 person found this helpful
What do they mean by Oracle reusing a redo log file ? When one ORL is full , oracle will switch to the next one ; it won't reuse it. Right ?
Answer is that lgwr overwrites the log group only when the corresponding changes from buffer cache has been written to datafiles by DBWR.
"the current checkpoint position is still in that log" . What is checkpoint position ?
A checkpoint position is that position above which whose system change number (SCN) changes made in data blocks less than or equal to that SCN are known to be written out to the data files.
Your Question 3
How often does a checkpoint occur ? (frequency as per time)
Conventionally it happens at every log switch, and also when fast start checkpointing is enabled with fast_start_mttr_target
1 person found this helpful
You have some groups of redo log, each redo log has members with same information. Redo log run in a circular way, when a group is full, changes to the next group of redo log and when the last group is written continue overwritten the first group.
Question1. What do they mean by Oracle reusing a redo log file ? When one ORL is full , oracle will switch to the next one ; it won't reuse it. Right ?
copy and paste from:
Question2. "the current checkpoint position is still in that log" . What is checkpoint position ?
"A data structure that indicates the checkpoint position, which is the SCN in the redo stream where instance recovery must begin"
Checkpoints occur in diferents situations, not per time, please check:
Question3. How often does a checkpoint occur ? (frequency as per time)