Sequence increment by 50 instead of 1

Question

I created an Oracle sequence:

Create sequence seq_acteurs start with 1 increment by 1;

Normally the sequence must be incremented by 1, but when insert into Acteurs table, the sequence s incremented by 50! That doesn't seem logical. Why is this so?

Any help will much apreciated.

Are you asking what could cause a sequence to increment by 50 when normally it increments by 1? — Gabe, May 29 '11 at 18:47

score 4 · Answer 1 · answered May 29 '11 at 19:06

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Sequence numbers are not fetched one at a time when you need them. NOrmally, the DB caches a certain number of sequence numbers in memory. WHen the cached sequences are all used up, then the DB fetches a new block of sequence numbers into cache. Now if the DB crashes for some reason while the cache still has some unused numbers, then there could be some gaps in your sequence numbers.

answered May 29 '11 at 19:06

Basanth Roy

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also if there is a rollback in a transaction using a seqno, sequence numbers disappear – oluies May 29 '11 at 19:39
i don't know but from what i saw it's always incremented by 50 when i add the first record the sequences gives it 50 as id, when i add the second the sequence gives it 100 then 150 then 200 and so on always incrementing by 50 – cascadox May 29 '11 at 19:50

score 3 · Answer 2 · answered Oct 24 '16 at 15:56

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In your entity class add this and will increase by 1

allocationSize=1

this is an example:

@SequenceGenerator(name = "ECP_EVALUACION_SEQ", sequenceName = "SCORTN.ECP_EVALUACION_SEQ",allocationSize=1)

answered Oct 24 '16 at 15:56

diego matos - keke

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oluies · Answer 3 · 2011-05-31T14:11:25.487

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Sequences does not guarantee that they generate a gap free sequence of numbers.

You can minimize the gaps by specifying nocache, but this does still not guarantee gap free sequences, and might create a resource contention.

Example from the documentation:

CREATE SEQUENCE customers_seq START WITH 1000 INCREMENT BY 1 NOCACHE NOCYCLE;

edited May 31 '11 at 14:11

answered May 29 '11 at 19:00

oluies

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There's nothing wrong with using nocache when the circumstances indicate it. Otherwise Oracle wouldn't have implemented it. – Jeffrey Kemp May 30 '11 at 02:52
ok but can you tell me how i can use "nochache"? thanks alot for your time – cascadox May 30 '11 at 22:03
sorry for the late and thanks for your time, i tryed your code but still the same problem... still incremeting by 50 this time the sequence started from 50000 then 50050 then 50100 etc – cascadox Jun 02 '11 at 21:42

Sequence increment by 50 instead of 1

3 Answers3