[CALCITE-6328] The BigQuery functions SAFE_* do not match the BigQuery specification

• Type: Bug
• Status: Open
• Priority: Minor
• Resolution: Unresolved
• Affects Version/s: 1.36.0
• Component/s: core
• Assignee: Unassigned
• Reporter: Mihai Budiu
• Created: 14/Mar/24 00:30
• Updated: 15/Mar/24 08:18

Description

The BigQuery dialect does not support DECIMAL values with arbitrary types: it only supports two fixed types: NUMERIC and BIGNUMERIC, both with fixed precision and scale.

The runtime implementation of the SAFE_* functions uses the following helper in SqlFunctions:

  /** Returns whether a BigDecimal value is safe (that is, has not overflowed).
   * According to BigQuery, BigDecimal overflow occurs if the precision is greater
   * than 76 or the scale is greater than 38. */
  private static boolean safeDecimal(BigDecimal b) {
    return b.scale() <= 38 && b.precision() <= 76;
  }

This helper does not handle correctly NUMERIC value, only BIGNUMERIC.

Moreover, all the tests in SqlOperatorTests use a type system which doesn't even support DECIMAL values wider than 38 digits. So a test like the following:

    f.checkNull("safe_add(cast(-9.9e75 as DECIMAL(76, 0)), "
        + "cast(-9.9e75 as DECIMAL(76, 0)))");

cannot even create the expected BigDecimal value correctly.

This surfaced during the attempt to fix CALCITE-6322: once the casts to DECIMAL are implemented, some of these tests break.

Issue Links

• is related to: CALCITE-6322 Casts to DECIMAL types are ignored