just want to ask the purpose of Serialize ON in TPUMP. How is it related to the types of blocking or locking if it is not specified in a TPUMP? Are there any circumstances that would affect the blocking or locking?
In a summary SERIALIZE option is used to synchronize the locking between multiple sessions. With this feature one session can lock/block all rows related to a certain PI(rowhash), so will avoiding the effort by multiple sessions to lock the rows with the same PI (rowhash).
For UPIs enabling this option won't be beneficial.
You can get more details from the documentation.