Fix logical error in ReadFromMerge::addFilter when child plan is not initialized#95047
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alexey-milovidov merged 2 commits intomasterfrom Jan 24, 2026
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…itialized
In `ReadFromMerge::addFilter`, when iterating over `child_plans` to
propagate a filter, the code called `getCurrentHeader()` without
checking if the plan was initialized. Child plans can be uninitialized
because `createPlanForTable` returns an empty `ChildPlan` when
`storage->read()` doesn't initialize the plan.
This caused a "QueryPlan was not initialized" exception found by the
AST fuzzer with the following query:
```
SELECT explain FROM (SELECT * FROM viewExplain('EXPLAIN', '', (
SELECT count() FROM foo_merge INNER JOIN t2 USING (Val)
SETTINGS enable_join_runtime_filters = 1, parallel_replicas_local_plan = 1
)))
```
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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Workflow [PR], commit [8ab3e5b] Summary: ❌
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The test successfully reproduces the issue on the debug build: https://pastila.nl/?004b0bb8/658891c0b623d91f48d541203783472f#GRdNrf2XU7N4e5SJYiTuoA==GCM |
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In
ReadFromMerge::addFilter, when iterating overchild_plansto propagate a filter, the code calledgetCurrentHeader()without checking if the plan was initialized. Child plans can be uninitialized becausecreatePlanForTablereturns an emptyChildPlanwhenstorage->read()doesn't initialize the plan.This caused a "QueryPlan was not initialized" exception found by the AST fuzzer with the following query:
See https://s3.amazonaws.com/clickhouse-test-reports/json.html?REF=master&sha=637b383d0c472f3cb3df4371274c9b9c390b3785&name_0=MasterCI&name_1=AST%20fuzzer%20%28amd_ubsan%29&name_1=AST%20fuzzer%20%28amd_ubsan%29
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