What does (1,1) mean in SQL?

Identity property: The uniqueness champion

The IDENTITY property in SQL is a vital tool for generating unique and sequential identifiers for records in a table. It's a type of auto-incrementing facility, setting up your indices on autopilot.

ID generation mechanism

Every time you insert a new row, ID gets elevated by the increment value from the last stored ID, courtesy of the built-in IDENTITY function.

Gap alert!

However, the IDENTITY property doesn't guarantee a gapless sequence. In case of transaction rollbacks or deletions, gaps can occur, since IDENTITY values are not recycled.

Tuning the identity property

Different IDENTITY configurations (n,m) enable you to customize ID generation. Changing to (5,2), for instance, will commence at 5 and increase by 2 at every step.

Strategic ID gaps

In some instances, gaps in IDs are induced deliberately for data segregation, privacy reasons, or to delineate the range of IDs for distinct uses.

High-scale adjustments

In high-growth situations, kickstarting with higher seed values and larger increments aids in deferring the exhaustion of available integer range, keeping your application future-proof.

Identity columns: More than just unique identifiers

IDENTITY properties are most beneficial when used in primary keys. They ensure each row has a distinct ID, which is crucial for relational integrity.

Navigating distributed databases

Different seed or increment values can be used across replicated databases or shards to prevent data conflicts.

The need for speed

Identity columns offer a fast and efficient indexing mechanism, which in turn boosts query performance by enabling better searching algorithms.

Know your identity property well!

To harness the power of the identity property, it's essential to understand its nuances and limitaitons:

Don't rely on perfect sequences

It's critical not to base your business logic on the continuity of identity values. Server restarts or caching can sometimes cause unexpected jumps in identity values.

Reseed with caution

While it's possible to reseed an identity column using the DBCC CHECKIDENT command, be aware that it's a double-edged sword and can affect your data integrity.