How to diagnose and fix the 2201G invalid_argument_for_width_bucket_function error code in Postgres.

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The 2201G: invalid_argument_for_width_bucket_function error in PostgreSQL occurs when an argument provided to the width_bucket function is invalid. The width_bucket function is used to assign a bucket number to an input value based on a range divided into a specified number of equal-width buckets.

To diagnose and fix this error, you should:

  1. Check the Arguments: Ensure that the width_bucket function has been provided with the correct number of arguments and that each argument is of the correct data type. The function typically takes four arguments: the operand, the lower bound, the upper bound, and the number of buckets.
  2. Validate Bounds: The lower bound should be less than the upper bound. If this is not the case, you will encounter the 2201G error.
  3. Ensure Positive Bucket Count: The number of buckets must be a positive integer. If it is zero, negative, or not an integer, the 2201G error will occur.
  4. Check Operand Value: Make sure that the operand is of a compatible data type that can be compared with the bounds provided.

Here are some examples of how the 2201G error might occur and how to resolve it:

  • Incorrect Bounds:
  SELECT width_bucket(5, 10, 1, 4);

This will cause an error because the lower bound (10) is greater than the upper bound (1). To fix it, you should swap the bounds:

  SELECT width_bucket(5, 1, 10, 4);
  • Non-positive Bucket Count:
  SELECT width_bucket(5, 1, 10, -2);

This will result in an error because the number of buckets is negative. To resolve it, provide a positive integer for the bucket count:

  SELECT width_bucket(5, 1, 10, 2);
  • Non-integer Bucket Count:
  SELECT width_bucket(5, 1, 10, 3.5);

This will cause an error because the number of buckets is not an integer. Correct it by providing an integer value:

  SELECT width_bucket(5, 1, 10, 3);

For more information on PostgreSQL error codes, including 2201G, you can refer to the PostgreSQL documentation. If you encounter this error, carefully reviewing the arguments passed to the width_bucket function and correcting any that are out of range or of the wrong type will usually resolve the issue.

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