Remove incorrect UNION ALL simplification in EXPLAIN output#81
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kyleconroy merged 2 commits intomainfrom Dec 29, 2025
Merged
Remove incorrect UNION ALL simplification in EXPLAIN output#81kyleconroy merged 2 commits intomainfrom
kyleconroy merged 2 commits intomainfrom
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The simplifyUnionSelects function was incorrectly collapsing UNION ALL queries when selects had identical expressions but different aliases. ClickHouse's EXPLAIN AST output keeps all SELECT queries in a UNION, so this optimization was incorrect. Fixes test 00592_union_all_different_aliases.
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The simplifyUnionSelects function was incorrectly collapsing UNION ALL
queries when selects had identical expressions but different aliases.
ClickHouse's EXPLAIN AST output keeps all SELECT queries in a UNION,
so this optimization was incorrect.
Fixes test 00592_union_all_different_aliases.