Fix filter pushdown through legacy JoinStep with join_use_nulls#98337
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alexey-milovidov merged 4 commits intomasterfrom Mar 1, 2026
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Fix filter pushdown through legacy JoinStep with join_use_nulls#98337alexey-milovidov merged 4 commits intomasterfrom
alexey-milovidov merged 4 commits intomasterfrom
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When `join_use_nulls` is enabled, the join output header has Nullable column types for the outer side. The filter expression (e.g. `k < 10`) is built with these Nullable types. When filter pushdown moves this filter to the join input side (where columns are non-nullable), it causes a type mismatch exception: "Unexpected return type from `less`. Expected `Nullable(UInt8)`. Got `UInt8`." Commit 5557b5e removed the type equality check in `get_available_columns_for_filter` to support `join_use_nulls` with `JoinStepLogical`, which has `fix_predicate_for_join_logical_step` to adjust types. But the legacy `JoinStep` has no such adjustment, so removing the check broke it. Restore the type check specifically for the legacy `JoinStep` path. Closes #98167 https://s3.amazonaws.com/clickhouse-test-reports/json.html?REF=master&sha=ededb4c6063844d24eee5d3023dfe17912307ffa&name_0=MasterCI&name_1=Stress%20test%20%28azure%2C%20amd_msan%29 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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A straightforward fix - just inhibit the optimization in certain cases for the obsolete legacy JOIN step.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
tests/queries/0_stateless/03835_filter_pushdown_join_use_nulls_legacy.sql
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…r path The bug only triggers with the old `InterpreterSelectQuery` which always uses the legacy `JoinStep`. With the new analyzer, even `query_plan_use_new_logical_join_step = 0` doesn't reproduce it because the query analysis differs. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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…e-nulls-legacy Fix filter pushdown through legacy JoinStep with join_use_nulls
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Summary
less. ExpectedNullable(UInt8). GotUInt8" that occurs when filter pushdown moves a filter expression through a legacyJoinStepwithjoin_use_nullsenabledget_available_columns_for_filterspecifically for the legacyJoinSteppath, which was inadvertently removed in Support convert OUTER to INNER join optimization with join_use_nulls #95968JoinStepLogicalpath is unaffected — it has its own type adjustment mechanism viafix_predicate_for_join_logical_stepCloses #98167
CI report: https://s3.amazonaws.com/clickhouse-test-reports/json.html?REF=master&sha=ededb4c6063844d24eee5d3023dfe17912307ffa&name_0=MasterCI&name_1=Stress%20test%20%28azure%2C%20amd_msan%29
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