Fix null-safe comparison exception with const Dynamic/Variant columns#98553
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alexey-milovidov merged 4 commits intomasterfrom Mar 3, 2026
Merged
Fix null-safe comparison exception with const Dynamic/Variant columns#98553alexey-milovidov merged 4 commits intomasterfrom
alexey-milovidov merged 4 commits intomasterfrom
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The `executeForVariantOrDynamicAndNull` function tried to cast columns directly to `ColumnDynamic`/`ColumnVariant`, but the column could be wrapped in `ColumnConst` when only one argument is constant. Fixed by unwrapping via `convertToFullColumnIfConst` before the cast. Also fixed a pre-existing bug where `IS DISTINCT FROM` with Dynamic/Variant vs NULL always returned 0 due to `ele_is_null && false` always evaluating to `false`. https://s3.amazonaws.com/clickhouse-test-reports/json.html?REF=master&sha=337832154ed77a0f80ca69c428a5932fb7212c77&name_0=MasterCI&name_1=AST%20fuzzer%20%28amd_msan%29 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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src/Functions/FunctionsNullSafeCmp.h
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| { | ||
| bool ele_is_null = column_variant_or_dynamic.isNullAt(i); | ||
| data[i] = is_equal_mode ? ele_is_null && true : ele_is_null && false; | ||
| data[i] = is_equal_mode ? ele_is_null : !ele_is_null; |
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Who writes "element" as "ele"? 🤢
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No wonder this code has a bug.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
The fix for `IS DISTINCT FROM` with `Dynamic`/`Variant` vs `NULL` changes the result from always 0 to correctly returning 1 for non-null values. Update the existing test reference to reflect the correct behavior. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
Bad cast from type ColumnConst to ColumnDynamicwhen using<=>/IS NOT DISTINCT FROMwith a constDynamicorVariantcolumn vsNULL. The column is now unwrapped viaconvertToFullColumnIfConstbefore casting.IS DISTINCT FROMwithDynamic/VariantvsNULLalways returned 0 due toele_is_null && falsealways evaluating tofalse.Found by AST fuzzer (MSan): https://s3.amazonaws.com/clickhouse-test-reports/json.html?REF=master&sha=337832154ed77a0f80ca69c428a5932fb7212c77&name_0=MasterCI&name_1=AST%20fuzzer%20%28amd_msan%29
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04010_null_safe_cmp_dynamic_constChangelog category:
Changelog entry:
Fixed exception
Bad cast from type ColumnConst to ColumnDynamicin null-safe comparison (<=>/IS NOT DISTINCT FROM) with constDynamicorVariantcolumns andNULL. Also fixedIS DISTINCT FROMwithDynamic/VariantvsNULLalways incorrectly returning 0.🤖 Generated with Claude Code