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https://issues.apache.org/jira/browse/SPARK-59579?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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ASF GitHub Bot updated SPARK-59579:
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Labels: pull-request-available (was: )
> Keep the conditional-branch guards after the subexpression elimination
> shortcut peel
> ------------------------------------------------------------------------------------
>
> Key: SPARK-59579
> URL: https://issues.apache.org/jira/browse/SPARK-59579
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 5.0.0
> Reporter: Yang Jie
> Priority: Major
> Labels: pull-request-available
>
> {{EquivalentExpressions.childrenToRecurse}} stops the descent for expressions
> whose children must not be evaluated ahead of time: {{CodegenFallback}},
> {{ConditionalExpression}} (only {{alwaysEvaluatedInputs}} are recursed into)
> and {{HigherOrderFunction}}.
> When {{spark.sql.subexpressionElimination.skipForShortcutExpr}} is enabled,
> {{skipForShortcut}} first peels the leading {{And}}/{{Or}} operands to reach
> the one operand that is always evaluated. {{And}}/{{Or}} are not
> {{ConditionalExpression}}s, so the peel walks past those cases, and the code
> then took {{peeled.children}} directly -- recursing into every child of the
> expression the peel landed on, conditional branches included.
> Repro, with ANSI mode on and both
> {{spark.sql.subexpressionElimination.enabled}} and
> {{spark.sql.subexpressionElimination.skipForShortcutExpr}} set to true:
> {code:sql}
> select (case when id = 0 then false else (1 / id + 1 / id) > 0 end) and id >= > 0
> from range(0, 1, 1, 1)
> {code}
> {{1 / id}} is repeated inside one branch body only, so it is shared with no
> other branch and should be evaluated only when that branch runs. For id = 0
> the other branch runs. Instead {{1 / id}} is collected as a common
> subexpression, hoisted to the top of the projection and evaluated for id = 0,
> raising DIVIDE_BY_ZERO.
> The fix is to compute the always-evaluated operand once and ask both
> {{childrenToRecurse}} and {{commonChildrenToRecurse}} about that operand.
> Only the {{skipForShortcutExpr}} path changes, and the config default (false)
> stays.
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