Why Are There Gaps in My Auto-Increment Primary Key IDs?

Auto Increment Primary Key: Gaps in Counting Explained

Despite having an auto-increment primary key, you've noticed gaps in the assigned IDs, resulting in a discrepancy between the row count and the maximum ID. This behavior is an inherent aspect of auto-increment mechanisms and is not a cause for concern.

To understand why, consider the following scenario involving two overlapping transactions:

1. Transaction 1 inserts a record and obtains ID 42.
2. Transaction 2 initiates an insert and receives ID 43.

Now, suppose Transaction 1 fails and rolls back. In this case, the assigned ID 42 remains unused. Consequently, the next assigned ID will be 43, leaving a gap of 44.

This behavior is a safeguard that allows concurrent transactions to proceed without blocking each other. Enforcing continuous IDs would require sequential execution of transactions, which could severely impact scalability.

pertanto, even if you're not deleting records, gaps in auto-increment IDs are expected and do not indicate an issue.

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