Django jumping model id number (AutoField) [duplicate] - django

Question

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Identity increment is jumping in SQL Server database
(6 answers)
Closed 7 years ago.
I have a strange scenario in which the auto identity int column in my SQL Server 2012 database is not incrementing properly.
Say I have a table which uses an int auto identity as a primary key it is sporadically skipping increments, for example:
1,
2,
3,
4,
5,
1004,
1005
This is happening on a random number of tables at very random times, can not replicate it to find any trends.
How is this happening?
Is there a way to make it stop?

Answer 1

This is all perfectly normal. Microsoft added sequences in SQL Server 2012, finally, i might add and changed the way identity keys are generated. Have a look here for some explanation.
If you want to have the old behaviour, you can:
use trace flag 272 - this will cause a log record to be generated for each generated identity value. The performance of identity generation may be impacted by turning on this trace flag.
use a sequence generator with the NO CACHE setting (http://msdn.microsoft.com/en-us/library/ff878091.aspx)

Answer 2

Got the same problem, found the following bug report in SQL Server 2012
If still relevant see conditions that cause the issue - there are some workarounds there as well (didn't try though).
Failover or Restart Results in Reseed of Identity

Answer 3

While trace flag 272 may work for many, it definitely won't work for hosted Sql Server Express installations. So, I created an identity table, and use this through an INSTEAD OF trigger. I'm hoping this helps someone else, and/or gives others an opportunity to improve my solution. The last line allows returning the last identity column added. Since I typically use this to add a single row, this works to return the identity of a single inserted row.
The identity table:
CREATE TABLE [dbo].[tblsysIdentities](
[intTableId] [int] NOT NULL,
[intIdentityLast] [int] NOT NULL,
[strTable] [varchar](100) NOT NULL,
[tsConcurrency] [timestamp] NULL,
CONSTRAINT [PK_tblsysIdentities] PRIMARY KEY CLUSTERED
(
[intTableId] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
and the insert trigger:
-- INSERT --
IF OBJECT_ID ('dbo.trgtblsysTrackerMessagesIdentity', 'TR') IS NOT NULL
DROP TRIGGER dbo.trgtblsysTrackerMessagesIdentity;
GO
CREATE TRIGGER trgtblsysTrackerMessagesIdentity
ON dbo.tblsysTrackerMessages
INSTEAD OF INSERT AS
BEGIN
DECLARE #intTrackerMessageId INT
DECLARE #intRowCount INT
SET #intRowCount = (SELECT COUNT(*) FROM INSERTED)
SET #intTrackerMessageId = (SELECT intIdentityLast FROM tblsysIdentities WHERE intTableId=1)
UPDATE tblsysIdentities SET intIdentityLast = #intTrackerMessageId + #intRowCount WHERE intTableId=1
INSERT INTO tblsysTrackerMessages(
[intTrackerMessageId],
[intTrackerId],
[strMessage],
[intTrackerMessageTypeId],
[datCreated],
[strCreatedBy])
SELECT #intTrackerMessageId + ROW_NUMBER() OVER (ORDER BY [datCreated]) AS [intTrackerMessageId],
[intTrackerId],
[strMessage],
[intTrackerMessageTypeId],
[datCreated],
[strCreatedBy] FROM INSERTED;
SELECT TOP 1 #intTrackerMessageId + #intRowCount FROM INSERTED;
END