SQL Server 2012 auto-increment column value jumps occasionally
SQL Server 2012 introduced changes to the behavior of auto-incrementing integer columns, resulting in occasional jumps in the numbering sequence. This phenomenon is attributed to sequences introduced in the database engine.
The auto-increment mechanism now reserves a range of values for potential insertions. When the maximum value in the range is reached, a new range is allocated, which may result in discontinuous values.
Why does this happen?
Skip values are not actually lost; they are retained for potential concurrent inserts or distributed transactions.
Is there any solution?
Yes, you have two options:
- Enable trace flag 272: This flag logs every identity value generated, which may impact performance.
- Use a cacheless sequence generator: This setting ensures that values are assigned one at a time, resulting in consecutive numbers.
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