feat: Enable expressions as default value in lead/lag function#22134
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sandugood wants to merge 8 commits into
Open
feat: Enable expressions as default value in lead/lag function#22134sandugood wants to merge 8 commits into
sandugood wants to merge 8 commits into
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comphead
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May 12, 2026
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Added the tests in the window.slt file |
comphead
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May 13, 2026
| SELECT | ||
| employee_id, | ||
| salary, | ||
| lag(salary, 1, 0) OVER (ORDER BY employee_id) AS prev_salary |
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we still need examples with literal
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Which issue does this PR close?
ColumnExprin LAG/LEAD for default parameter #22082.Rationale for this change
In the current DataFusion implementation we can only use a
ScalarValueas the default value in bothLAGandLEADwindow functions. That means that users can't reference other columns' values from the table as default value and create various combinations of them.It means that currently we cannot perform something like:
lead(col1, 1, col1 / col2) as lead_resultWhat changes are included in this PR?
DefaultValueenum that can be either aLiteralvalue or anExpressionparse_default_valuefunction to takedefault_value's type into considerationshift_with_array_defaultandevaluate_all_with_ignore_null_and_array_defaultfor the situations, whendefault_valueis ofDefaultValue::ExpressiontypeAre these changes tested?
Yes, changes were tested:
Are there any user-facing changes?
There are user-facing changes in terms of documentation and DataFusion usage (no syntax changes per se). Also, docs were updated