The dataset defined for a column contains values that are too long.

The column in the database has a maximum size that is too small for the values from the dataset to fit into it.

Understanding the issue

This occurs when dataset values exceed the database column width. For example:

• Database column: VARCHAR(10)
• Dataset contains: "San Francisco" (13 characters)
• Result: Value cannot fit in column

Common scenarios:

• Using Cities dataset on a column designed for abbreviations
• Pattern datasets generating longer values than expected
• Custom datasets with values exceeding column constraints

How to fix 

Option 1: Create a custom dataset with controlled length

{
  "datasets": [
    {
      "name": "ShortCountries", 
      "type": "List",
      "values": ["USA", "UK", "Canada", "France", "Spain"]  // Max 6 chars
    }
  ]
}

Option 2: Use pattern datasets for consistent length

{
  "datasets": [
    {
      "name": "FixedWidth",
      "type": "Pattern", 
      "values": ["???"]                    // Always 3 characters
    }
  ]
}