"Exception" Oracle sequence stride problem

Problem: The ID of the Customer table in the database changes to 21\31\41 ordinal number, not 1\2\3 growth in turn

[Cause of problem]:

Seq_customnoteen set the cache 20, take 20 numbers at a time, then one to you, if there is a period of time in the middle of the operation, the useless is lost.

Create sequence Seq_customnoteen

MinValue 1

MaxValue 9999999999999999

Start with 1

Increment by 1

Cache 20;

[Workaround] Set the cache to 1 without problem, but this time has lost the meaning of the cache. can also be set to 0 when no cache is required

"Exception" Oracle sequence stride problem