add backwards compatibility mode for multi-value string array null value coercion #12210
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cryptoe
approved these changes
Jan 29, 2022
| // expression has array output | ||
| && plan.is(ExpressionPlan.Trait.NON_SCALAR_OUTPUT); | ||
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| final boolean homogenizeNullMultiValueStringArrays = |
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Nit: Maybe move this inside the if statement at 281?
gianm
approved these changes
Feb 1, 2022
This was referenced Feb 8, 2022
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Description
Follow up to #12078, adds
druid.expressions.homogenizeNullMultiValueStringArrayswith a default value of 'false'. If set to true, it opens an escape hatch to a backwards compatibility mode for the 'buggy' behavior of some multi-value string array functions such asMV_APPENDwhich was fixed in #12078. Prior to that PR, allnull,[], and[null]values were treated as[null], which was only intended for implicitly mapped single value expression across multi-valued string rows, and could produce unintuitive results. This option has been added in case anyone happened to be depending on that behavior, but it produces odd behavior that impacts all array expressions, so it is not recommended to set this flag to true if possible, and instead add a workaround by coercing the values explicitly with additional expressions if needed.This PR has: