Reputation: 4580
First I run all these in java with jdbc driver...
Here I define a table:
create table HistoryCCP(
ID NUMBER(6) NOT NULL,
SCRIPT VARCHAR2(1000) NOT NULL
)
Here I define a sequence:
CREATE SEQUENCE SYSTEM.HistoryId
MINVALUE 1
MAXVALUE 1000000
INCREMENT BY 1
START WITH 1
NOORDER
NOCYCLE
Now I insert to table by using this here:
insert into HistoryCCP
values (SYSTEM.HistoryId.nextval ,'HELLOOOO ')
Whenever I close the program and run it again and try to insert, it increments it by ten! And when I defined sequence like this:
CREATE SEQUENCE SYSTEM.HistoryId
MINVALUE 1
MAXVALUE 1000000
INCREMENT BY 1
START WITH 1
CACHE 100 -- added cache parameter
NOORDER
NOCYCLE
It increase it by 100! Do you know why it behaves like this and how to increment it by 1?
Upvotes: 1
Views: 2137
Reputation: 631
NOCACHE would work, but also would be a bad idea under for many reasons, and a total nonsense if you plan to bring your application on a Oracle RAC.
Oracle Sequences are for (internal) unique ID, not for strictly progressive number imposed by requirements. As example, let's say that using a sequence for generating the classical "protocol number" is a common flaw of many financial accounting software: looks easy when beginning but when the project grows it kills you.
Upvotes: 0
Reputation: 52346
Never rely on sequences for gap free numbering.
The cache value is the number of sequence values that are held in memory by the database server to avoid the need to keep updating it's internal $SEQ table with the most recently used value. If you reduce the cache value then you increase the rate at which the $SEQ table has to be modified, which slows the system.
Cached values can be aged out, and are lost on system restart, and values are not reused if a transaction gets rolled back.
The presence of gaps should not be a problem for you -- if it is then you'll need to use something other than a sequence to generate the numbers, and doing so will serialise inserts to that table.
Upvotes: 6
Reputation: 52
Try to use NOCACHE options for sequence.
http://docs.oracle.com/cd/B28359_01/server.111/b28310/views002.htm
Upvotes: 0