Hi guys,I am trying to understand how Oracle wait interface calculates the CPU time and IO time and the relation between them,
Suppose I execute a query
Elapsed time - Total time spent executing the query
CPU time - Time spent on CPU by the query
I/O time - Time spent doing I/O for the query, that is to read the blocks from disk to memory(like db sequential read and scattered read)
- suppose a query is in CPU and now it goes to read a block from the disk , Is the time spent reading the block added to I/O time metric or CPU time metric as the query was in CPU
- Does doing I/O needs some CPU and is the CPU time included in I/O wait time metric?
- Elapsed time = CPU time + I/O time. Is my understanding right?
- DB time is the total time spent in the database including CPU plus time taken to do the I/O operations. Is this right?
Thanks