Inconsistent sequence numbers generated

We just ran into an unexplained occurrence using a sequence table.
Suddenly it started assigning id number millions higher than the sequence it was previously filling. As you can see in the log the original range was in the 19 million area and then it began inserting values in the 28 million range.
Here is the id sequence it put in (I realize these are not exactly sequential because it does not commit them in the same order it allocates them.)
Previous transaction
many ids, the last one is...
19712292
Problematic transaction
28064436 ---> ???
19741496
19728823
19742100
19741852
28064408 ---> ???
19726424
28064433 ---> ???
19737253
etc...
I have no idea where these 28 million series numbers came from. It was a large transaction but I certainly did not insert 9 million rows.

I have some occasional spawned threads that read, but only the primary thread writes.
No JTA
Yes they are in the same transaction
Yes the same thread, session and connection are used by both. Here is a portion of the log.
[TopLink Fine]: 2007.04.28 08:15:37.208--UnitOfWork(25076495)--Connection(29197673)--Thread(Thread[AJPRequestHandler-RMICallHandler-1,5,RequestThreadGroup])--INSERT INTO Q_TBL (ID, ALIAS) VALUES (28064436, 'a')
[TopLink Fine]: 2007.04.28 08:15:37.230--UnitOfWork(25076495)--Connection(29197673)--Thread(Thread[AJPRequestHandler-RMICallHandler-1,5,RequestThreadGroup])--INSERT INTO Q_TBL (ID, ALIAS) VALUES (19741496, 'b')
[TopLink Fine]: 2007.04.28 08:15:37.236--UnitOfWork(25076495)--Connection(29197673)--Thread(Thread[AJPRequestHandler-RMICallHandler-1,5,RequestThreadGroup])--INSERT INTO Q_TBL (ID, ALIAS) VALUES (19728823, 'c')
[TopLink Fine]: 2007.04.28 08:15:37.241--UnitOfWork(25076495)--Connection(29197673)--Thread(Thread[AJPRequestHandler-RMICallHandler-1,5,RequestThreadGroup])--INSERT INTO Q_TBL (ID, ALIAS) VALUES (19742100, 'd')
[TopLink Fine]: 2007.04.28 08:15:37.247--UnitOfWork(25076495)--Connection(29197673)--Thread(Thread[AJPRequestHandler-RMICallHandler-1,5,RequestThreadGroup])--INSERT INTO Q_TBL (ID, ALIAS) VALUES (19741852, 'e')
[TopLink Fine]: 2007.04.28 08:15:37.252--UnitOfWork(25076495)--Connection(29197673)--Thread(Thread[AJPRequestHandler-RMICallHandler-1,5,RequestThreadGroup])--INSERT INTO Q_TBL (ID, ALIAS) VALUES (28064408, 'f')
[TopLink Fine]: 2007.04.28 08:15:37.259--UnitOfWork(25076495)--Connection(29197673)--Thread(Thread[AJPRequestHandler-RMICallHandler-1,5,RequestThreadGroup])--INSERT INTO Q_TBL (ID, ALIAS) VALUES (19726424, 'g')
[TopLink Fine]: 2007.04.28 08:15:37.264--UnitOfWork(25076495)--Connection(29197673)--Thread(Thread[AJPRequestHandler-RMICallHandler-1,5,RequestThreadGroup])--INSERT INTO Q_TBL (ID, ALIAS) VALUES (28064433, 'h')
[TopLink Fine]: 2007.04.28 08:15:37.270--UnitOfWork(25076495)--Connection(29197673)--Thread(Thread[AJPRequestHandler-RMICallHandler-1,5,RequestThreadGroup])--INSERT INTO Q_TBL (ID, ALIAS) VALUES (19737253, 'i')

Similar Messages

Sequence numbers not generated sequentially?

Our situation: We have encountered an issue with our database, where it appears that a sequence has generated a number out of sequence, that is, to fill in a gap left previously. That is, in the affected table, we have records like:
Seq No Date (DD/MM/YY)
1 29/12/08
2 29/12/08
3 4/1/09
4 29/12/08
The code that actually updates the database is from a third party, so I am unable to prove the following, but the vendor assures me that:
1. The sequence numbers are generated using "select message_number.nextval from dual".
2. The Date column is not modified after the record is created. ( Nor is it supposed to be )
The sequence is created by "CREATE SEQUENCE MESSAGE_NUMBER START WITH 10000000 INCREMENT BY 1 MINVALUE 10000000 CACHE 20 NOCYCLE NOORDER"
This was detected only yesterday, after the event, and is very uncommon ( I have not found another instance, but there are over 7,000,000 records, so I haven't performed an exhaustive search). We are relying on the sequence numbers always being generated sequentially, as in each message_number.nextval is greater than the previous one.
I don't think that the date change was due to a user accidentaly changing the date. Related records to '3' are also dated 4/1/09, there is no facility for a user to change the date outside of accessing the database directly, and even the developers do not have write access to this database.
My questions:
1. Is this normal behaviour for a sequence? To go back and fill in a gap like this? If so we'll have to change one of the assumptions of one of our modules.
2. Should the sequence be defined with 'ORDER' rather than 'NOORDER' to stop this?
3. Could this be a bug in the sequence number generation? We are using Oracle 9.2.0.1.0.
4. Is this situation "impossible", and therefore there is a bug in the vendor library that we need to track down.
Thanks for your help,
Wayne.

wayneb wrote:
Our situation: We have encountered an issue with our database, where it appears that a sequence has generated a number out of sequence, that is, to fill in a gap left previously. That is, in the affected table, we have records like:
Seq No Date (DD/MM/YY)
1 29/12/08
2 29/12/08
3 4/1/09
4 29/12/08
The code that actually updates the database is from a third party, so I am unable to prove the following, but the vendor assures me that:
1. The sequence numbers are generated using "select message_number.nextval from dual".
2. The Date column is not modified after the record is created. ( Nor is it supposed to be )There might be a delay between fetching the sequence and storing the sysdate? value in the database.
maybe some user prepared a new record. Then went to some new years eve party and when he came back at the begining of next year he commited the data (record send to database, database is adding date column by some trigger...).
>
The sequence is created by "CREATE SEQUENCE MESSAGE_NUMBER START WITH 10000000 INCREMENT BY 1 MINVALUE 10000000 CACHE 20 NOCYCLE NOORDER"
This was detected only yesterday, after the event, and is very uncommon ( I have not found another instance, but there are over 7,000,000 records, so I haven't performed an exhaustive search). We are relying on the sequence numbers always being generated sequentially, as in each message_number.nextval is greater than the previous one.
I don't think that the date change was due to a user accidentaly changing the date. Related records to '3' are also dated 4/1/09, there is no facility for a user to change the date outside of accessing the database directly, and even the developers do not have write access to this database.
My questions:
1. Is this normal behaviour for a sequence? To go back and fill in a gap like this? If so we'll have to change one of the assumptions of one of our modules.No sequences don't fill gaps. However it is possible to fetch and cache values from a sequence for later usage. Especially in a RAC environment you can get sequence values that are not in order of time.
2. Should the sequence be defined with 'ORDER' rather than 'NOORDER' to stop this?No.
3. Could this be a bug in the sequence number generation? We are using Oracle 9.2.0.1.0.Extremly unlikely, but you can always check Metalink.
4. Is this situation "impossible", and therefore there is a bug in the vendor library that we need to track down.You can create such situations programatically. Whether it is a bug depends on the specifications for the software.
>
Thanks for your help,
Wayne.Edited by: Sven W. on Mar 24, 2009 5:00 PM

Generate sequence numbers

Hi,
I am looking for an algorithm to generate alphanumeric sequence numbers in ABAP.
The sequence numbers should be in the following format
AAAA
AAAB
AAAC
AAAZ
AABA
AABB
AABC
AABZ
ZZZZ
Is there any built-in function module provided by SAP to accomplish this? Or something like a FOR statement as in C/C++?
Please help.
Helpful answers will be immediately rewarded.
Thank you.

Hi,
I'm not sure, but maybe you can create a number range with SNRO for alphanumerical values
otherwise you have to create your own logic (you can use hexadecimal to ascii conversion in ABAP to increment the alphanumerical values)
Kind regards, Rob Dielemans

How to generate random sequence numbers

Hello experts
Iu2019m writing a custom program and pulling data from VBAK & VBAP. As per requirement I also need to generate a sequence number randomly and finally store all data in text file and upload at server. The hiccup is I donu2019t know how to generate sequence numbers. Can somebody please show me how I can accomplish it?
Thanks a lot in advance

Find the below code,
data: lv_range type datatype-char0128.
call function 'RANDOM_C'
    exporting
      len_min   = 20
      len_max   = 20
      char_min = 1
      char_max = 20
    importing
      rnd_value = lv_range.
LV_RANGE param will have a random value..
If you need number you can use the FM "RANDOM_I4"
Thanks,
Prathap

Sequences to generate primary keys

Hi,
A question on using sequences to generate primary keys. We have a table and in all environments, test, uat, prod, a sequence exists to generate the primary key for the table. This table is a reference table and is not updateable by the users.
When developing scripts to insert records into the table, the developers are currently not using the sequence but typing in unique numbers so data scripts consist of something like this:
INSERT INTO EMPLOYEE_GROUP
(employee_group_id, code, description,...)
VALUES
(45,'sdf','sdfsdfsf');
INSERT INTO EMPLOYEE_GROUP
(employee_group_id, code, description,...)
VALUES
(46,'sdf','sdfsdfsf',...);
a) Is this normal practice?
b) Sometimes they are using the sequence to generate the primary key in development but then hardcoding the number in the script so in development the sequence might be at 160, but in the other environments the sequences will still be at one. Is this also normal practice?
My usual method in developing scripts is to use <seqeunce>.nextval but it's somewhat incompatitble in the current environment.

You are using a surrogate, or synthetic primary key. For a primary key generated in this way, the value is inconsequential. All that matters is that it is unique and the tables with foreign keys into it, if any, also have that value set properly. But it doesn't matter if the value is 1, 100, 12344, 2222222222, etc. All you care about is the uniqueness.
If you create the data properly then child records and their parents should be correct in all systems you mention, it's just that the actual value of the key will differ and that's fine. You care about the relationship of the records, not the value of the synthetic keys.

Page item sequence numbers

Maybe this one is for a future improvement...
After reordering page items using the drag and drop feature the items all have a sequence number one greater than it's predecessor.
This makes it hard to put a new item in between existing ones. Generating sequence numbers 5 or 10 apart would make this a bit easier.

hi,
i dont know whether you have tried this before...
10
10.1
10.2
10.3
20
20.1
20.2
30
this is acceptable in apex item sequence number for inserting new items .
Thanks
Mark Wyatt
Edited by: Websoft on Sep 30, 2009 6:33 AM

Sequence numbers - with no gaps!

I seek some advice from anyone with first hand experience in this area.
My need is simple; generate a new ID number for every order for use as the primary key.
Obviously this simple exercise could be a bottleneck as volumes ramp up, so I was pleased to find the Oracle feature to generate such numbers (efficiently presumably). However, upon closer reading it was apparent that aborted transactions would result in the loss of the number allocated to to that order if another transaction had obtained the next sequence number already (as one would want it to, rather than serializing transactions).
I don't want to have gaps in the sequence as the system needs a high degree of auditability. I am thinking of utilising the Autonomous Transaction feature to write the newly acquired sequence number to the order file with a flag indicating that the record is incomplete, and that record is to be skipped by normal system applications (but available to audit reports which will interpret the reason correctly), then returning to the far more extensive main transaction which updates many tables.
The other alternative is to control sequence numbers within the application itself, or try to get the sequence number as the very last step before writing the new order record, but this probably won't guarantee gapless reliability either. The ID itself has no significance, and it doesn't matter if an ID was used out of strict date/time sequence, so I really don't want to execute these updates serially.
So, my question is this:
a) do most people use the builtin sequence number feature?
b) if so, is there a standard technique for avoiding or accounting for gaps?
c) if the application must take over this task, should the counter for the last used ID be in a single row table to minimise bottlenecks caused by the thisrecord being locked? There will be several such counters for different aspects of the application, and i thought of having each in its own row in a small table, but I'm concerned about the whole table getting locked and freezing out otherwise-unrelated updates.
Thanks for any advice you may have.
CS

user8821725 wrote:
I seek some advice from anyone with first hand experience in this area.
My need is simple; generate a new ID number for every order for use as the primary key.
Obviously this simple exercise could be a bottleneck as volumes ramp up, so I was pleased to find the Oracle feature to generate such numbers (efficiently presumably). However, upon closer reading it was apparent that aborted transactions would result in the loss of the number allocated to to that order if another transaction had obtained the next sequence number already (as one would want it to, rather than serializing transactions).
I don't want to have gaps in the sequence as the system needs a high degree of auditability. One of the very very few reasons for me to have a requirement for "gapless" sequences is if you have a kind of checking mechanism outside of the database that is implemented using this gapless number. I had such a requirement once, when exchanging files with another bank where we had to ensure that each file was transferred correctly and in the right order. Your "high degree of auditability" might be a similiar requirement. Just remember as long as you are still inside the database you can use other mechanisms to increase auditability.
I am thinking of utilising the Autonomous Transaction feature to write the newly acquired sequence number to the order file with a flag indicating that the record is incomplete, and that record is to be skipped by normal system applications (but available to audit reports which will interpret the reason correctly), then returning to the far more extensive main transaction which updates many tables.Hm. I don't see why you want to use Autonomous Transactions for this. It might be useful to lessen locking conflicts , depending how your future sequence mechanism will be built.
>
The other alternative is to control sequence numbers within the application itself, or try to get the sequence number as the very last step before writing the new order record, but this probably won't guarantee gapless reliability either. The ID itself has no significance, and it doesn't matter if an ID was used out of strict date/time sequence, so I really don't want to execute these updates serially.I would go for generating the sequence as the very last step. It needs to be set to NOCACHE of cause. This will garantee that the sequence fetched from mySeq.nextval is gapless. The problem is then in your application. Your application must be built in a way that it ensures to use this sequence, or at least to create a noticable alert when this generated sequence can't be used anymore. In essence this means. Each unhandled (database) error that happens after you fetched the next sequence value must be raised in a way that informs all relevant people about this error.
Example: It might be that you use the sequence to write an order file. What happens if halfway through writing the file your disk runs out of space? This can be such an issue where a sequenced value will be lost. Your organisation must take care of those things.
>
So, my question is this:
a) do most people use the builtin sequence number feature?Yes. But for some tasks a sequence is not the best way, for example if you want a numbering for each item of your order. This "sequence" needs to restart with every new order.
b) if so, is there a standard technique for avoiding or accounting for gaps?NOCACHE => Avoids gaps during generation
Database Trigger => Tries to use the sequence as late as possible
c) if the application must take over this task, should the counter for the last used ID be in a single row table to minimise bottlenecks caused by the thisrecord being locked? There will be several such counters for different aspects of the application, and i thought of having each in its own row in a small table, but I'm concerned about the whole table getting locked and freezing out otherwise-unrelated updates.This is a possibility and the issues you describe are why we avoid such a solution in general. Autonomous transactions help to reduce the locking conflict, but they increase the chance that you produce gaps.
>
Thanks for any advice you may have.
CSOracle can guarantee to produce gapless sequences. But it can't guarantee that your application uses such a sequence in a gapless way.

Control Numbers generated in B2B

The control numbers in B2B are picked from the view "B2B_INSTANCEMESSAGE" which is based on the table B2B_EXT_BUSINESS_MESSAGE.
I want to know if there is any sequence for the generation of these numbers in the table. I need to reset the control numbers generated by B2B.
Thanks
Ravdeep

Hi Ravdeep,
B2B_INSTANCEMESSAGE gives you information reg a message thats already processed. you cant touch upon it for any design time information.
In 11g, Pl have a look at the B2B_CONTROL_NUMBER table. This is the table which is referenced at real time to identify the control numbers of the edi document, wrt the TP & Direction.
What is the precise requirement?
Sambhav.

Recycled Sequence Numbers

Hi,
We have a requirement of generating sequence numbers for a table and we need to recycle them if some of them is deleted.
For example the following tabe Employee(Id,name)
ID NAME
1 XXX
2 YYY
3 ZZZ
4 AAA
The ID filed should have the next sequence number generated. When I call getnextID now, it should return 5
ID NAME
1 XXX
2 YYY
3 ZZZ
4 AAA
5 BBB
Now Let us assume I delete 3. The contents of the table aare
ID NAME
1 XXX
2 YYY
4 AAA
5 BBB
Now when getNextID, 3 should be returned.
How to achieve this in a best performing way in Oracle? Are there any patterns around it? Please note this should run in a multi user environment.
Thanks,
Rama

I think the answers were based on the fact that you call it incorrectly sequence.
Your ConnectivityID is more as a resource that could be recycled. I see some similarities to the GSM telecom market where a resource(i.e. a phone number or a SIM card no) can be recycled when is not active anymore (under certain conditions however).
Personally I would generate a table of resources having the resource number (ConnectivityID) and resource status.
To simplify it, suppose that you have column status with 2 possible values, 0=available, 1=not available.
When you want to allocate the resource number(ConnectivityId) you will set the status to 1.
When the record is deleted then status will be updated back to 0.
Recycling a ConnectivityID will mean searching in the table for the lowest number having status=0.
Of course you don't expect this to be as fast as a sequence but I think this is a different requirement, IMO.
Regards
Al

Assigning sequence numbers treo cords

Please help to understand the following, because it's a little unclear for me.. can you provide me an example?
So, regarding to assigning sequence numbers when a new record is created, we usually use a pre-insert trigger, with this code:
SELECT orders_seq.NEXTVAL
INTO :orders.order_id
FROM SYS.dual;
But:
You can also assign sequence numbers from a table. If you use this method, two transactional
triggers are usually involved:
• Use Pre-Insert to select the next available number from the sequence table (locking the row
to prevent other users from selecting the same value), assign it to the Forms item, and
increment the value in the sequence table by the required amount.
• Use Post-Insert to update the sequence table, recording the new upper value for the
sequence.So how to assign a sequence number from a ... table?
Thanks

You have to implement the number generator yourself; something similar to this: http://asktom.oracle.com/pls/apex/f?p=100:11:0::::P11_QUESTION_ID:4343369880986
cheers

Temporary sequence numbers

Hello all,
Is there any provision in the mobile server and mobile client to synchronize the Lite database by using temporary sequence numbers for the newly added records?
In the application that we are involved with, we are being asked to provide this behavior.
In details we would ensure that the sequence generation works as it works for the desktop PCs as well.
As far as we know we should follow the following steps for the synchronization:
1. sync new rows with the server
1a. the server syncs with the database, replaces temporary seqnos with the ones that come from the database
2. sync the new seqnos back to the mobile device...
Please let me know whether it is possible or not with the Oracle Lite system,
Thanks in advance,
Balazs

do you have some need to keep the range of DONOR_ID sequential?
In our implementation we use the other method that Greg has mentioned, defining sequences within the oracle lite publication itself
We use sequence generated ID values as the primary key on a lot of our tables, and the columns are defined as NUMBER(12) (reasons are historical, and not necessarly for any good reason - but stuck with it)
looking at the worst case scenario (to keep things simple) in the server we have table PLOTS. The highest ID value is around 5.5 million, with an annual growth rate of 500,000 for server created records. The number of records that would be created on any particular client on an annual basis is more like 2,000.
When you define a sequence within the mobile server you specify a 'template' for each sequence consisting of
name (eg: PLO_ID_SEQ)
start value
increment
window (number of values to assign to a particular user)
threshold (point at which the next set of values is sent to the user)
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This in practical terms means that the sequences on the clients will never need to be re-sent as the values will never reach the threshold, and there will never be any cross over with server generated sequences
When you add your first client to the application, the actual sequence start value will be set for that client as 500,000,000. for the second user added it will be 500,100,000, for the third 500,200,000 etc.
On the whole the mobile server manages this ok, but we have found that if there is a need to replace a client by rebuilding the database from scratch, occasionally it does not correctly maintain the last value used. To get around this we reset the user prior to the rebuild (this resets the sequence start for that user to the next range of values)
This works ok, and is straightforward to implement as you need no code change/data manipulation on the server, but does result in the source of the records being obviously different (can be useful), and you cannot assume that the highest id value is the most recent record (can be a problem for reports)

Invoice Sequence Numbers

Version : Oracle Apps 11.5.1 OS : HP-UX 64 bit.
Module : Order Management.
I want to generate unique sequence numbers for my shipment documents. For example, I have 2 customers A and B. I want my invoice numbers as A-001 for first customer, and A-002 for second customer and so on.
How to generate such a sequence (alphanumeric). Any suggestions?
TIA.

Version : Oracle Apps 11.5.1 OS : HP-UX 64 bit.
Module : Order Management.
I want to generate unique sequence numbers for my shipment documents. For example, I have 2 customers A and B. I want my invoice numbers as A-001 for first customer, and A-002 for second customer and so on.
How to generate such a sequence (alphanumeric). Any suggestions?
TIA.

Separate automatic document sequence numbering for diff. branches

Hi,
The client wants to have different automatic document sequence numbering for its various branches.preferably the sequence will start from a prefix depicting a branch and sequential vouchers will be generated. in this way all the branches will have their vouchers in sequence. tracking and filling will become easier.
if sombody knows the way of doing it, please respond.
null

Hi
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Sequence number generator

First of all, my sincere thanks to Mike, Nick and others for responding.
Is there a way to generate sequence numbers like 1,2,3,4,5,etc?
Balaji

Within the context of the run of a process, Add Message Id will add such numbers to each record it receives. This is obviously not quite the same thing as a DB sequence number, where the sequence is driven by the entry of data into the table.
As Nick said, some customers add a variable (for example a number value added by Add Number Attribute that is externalized and set at runtime) to the Message Id to make a unique id across runs but this is something of a workaround. Also if you split records within an EDQ process these split records will be derived from the same Message Id so will share it. Finally, there is no cross-run context for message ids, so if the same record is pushed through the process again it may well have a different message id as EDQ simply allocates these in the order in which it processes the records.
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Finding missed sequence numbers and rows from a fact table

Finding missed sequence numbers and rows from a fact table
Hi
I am working on an OLAP date cube with the following schema:
As you can see there is a fact transaction with two dimensions called cardNumber and Sequence. Card dimension contains about three million card numbers.
Sequence dimension contains a sequence number from 0 to 255. Fact transaction contains about 400 million transactions of those cards.
Each transaction has a sequence number in 0 to 255 ranges. If sequence number of transactions of a card reaches to 255 the next transaction would get 0 as a sequence number.
For example if a card has 1000 transactions then sequence numbers are as follows;
Transaction 1 to transaction 256 with sequences from 0 to 255
Transaction 257 to transaction 512 with sequences from 0 to 255
Transaction 513 to transaction 768 with sequences from 0 to 255
Transaction 769 to transaction 1000 with sequences from 0 to 231
The problem is that:
Sometimes there are several missed transactions. For example instead of sequence from 0 to 255, sequences are from 0 to 150 and then from 160 to 255. Here 10 transactions have been missed.
How can I find all missed transactions of all cards with a MDX QUERY?
I really appreciate for helps

Thank you Liao
I need to find missed numbers, In this scenario I want the query to tell the missed numbers are: 151,152,153,154,155,156,157,158,159
Relative transactions are also missed, so I think it is impossible to get them by your MDX query
Suppose this:
date
time
sequence
20140701
23:22:00
149
20140701
23:44:00
150
20140702
8:30:00
160
20140702
9:30:00
161
20140702
11:30:00
162
20140702
11:45:00
163
As you can see the sequence number of the last transaction at the 20140701 is 150
We expecting that the first transaction of the next day should be 151 but it is 160. Those 10 transactions are totally missed and we just need to
find missed sequence numbers

Inconsistent sequence numbers generated

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