Identity increment is jumping in SQL Server database
Facing identity gaps in SQL Server? Likely due to IDENTITY_CACHE. After each restart, sequences inadvertently jump. Override this by switching off Identity Cache in SQL Server 2017 and onwards:
This secures a smooth run of identity values, but possible performance slowdowns due to disk-bound value retrievals await.
For a holistic solution, dive deeper below.
The Cache Game - understanding identity cache
Ever witnessed a squirrel storing nuts for winter? SQL Server is somewhat similar when generating identity values โ storing them in batches. However, server restarts or crashes see these values vanish, culminating in gaps.
Size Matters - cache size and server versions
- A squirrel buries 1,000 nuts for winter. Similarly, SQL Server 2012 defaults cache 1,000 values for int identity columns.
- Just as a smart squirrel plans storage, SQL Server 2017 allows identity cache control:
ALTER DATABASE SCOPED CONFIGURATION.
Tracing the Trail - trace flags and sequences
- With trace flag 272, one can log identity allocation. So, the mysterious case of increment jumps post-restart, resolved!
- Bring**
In-Sequence Chronicles - alternative strategies for gapless increment
The Sequence Saviour
Stubborn identity columns giving you a headache? A sequence generator with NOCACHE option might be your perfect Advil.
Reseeding: The Greenhouse Effect
Unable to disable identity cache or use sequences? Welcome to the gardening club โ get your green thumbs on with some reseed options:
- The green thumb's best friend is the
DBCC CHECKIDENTโ handily resetting the identity value after restarts. - Those automated sprinklers seem nifty, right? Similarly, implement a stored procedure to water reseeding on startup.
Word of caution: grow your garden mindfully to avoid thorny issues of contention and performance.
Deja-Vu: gaps in legacy systems
Stuck in a time loop with SQL Server 2008R2? Fret not, trace flag 272 is not a time traveler. Instead:
- The green thumb strikes again โ manually work on reseeding after a server restart.
- Rely on your application-level strategy to handle potential time loops โ oops, I mean gaps.
Practicality over Mystery - dealing with real-world implications
When the gap gets real
In the universe of financial systems or legal numbering, gaps are unwanted aliens.
Speed Bumps - performance considerations
Beware! Disabling identity cache might lead to increased I/O, impacting INSERT performance. It's a hare and tortoise race!
The Forbidden Fruit - security constraints
Non-admins might taste the forbidden fruit of reseeding, but must beware of security implications and potential multi-user conflicts. Remember, not all apples lead to enlightenment!
Detective's Toolbox - troubleshooting and monitoring
Trail of Patches - applying trace flags
Mystery solvers apply trace flag 272 to startup parameters, a magical ritual that requires a server restart.
The Magnifying Glass - diagnostic queries
Who said SQL Server scripts only monitor behavior like replication backlog? They can also detect minute irregularities in identity value generation and act as mighty diagnostic tools.
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