When a sequence is queried, the NEXTVAL value is generated from the seq$ table if it is not cached. If it is cacheed, it will be retrieved from memory.
When the sequences with low cache value are queried too much, “enq: SQ – contention” will occur. To solve this problem, you can increase the cache values of the corresponding sequences.
You can change the cache value of Sequence as follows:
alter sequence SCHEMA_NAME.SEQUENCE_NAME cache 100;