mirror of https://github.com/citusdata/citus.git
a6161f5a21
fixes #8105 This change lets `FindReferencedTableColumn()` correctly resolve columns through a CTE even when the expression comes from an outer query level (`varlevelsup > 0`, `skipOuterVars = false`). Before, we hit an `Assert(skipOuterVars)` in this path. **Problem** * Hitting a CTE after walking outer Vars triggered `Assert(skipOuterVars)`. * Cause: we modified `parentQueryList` in place and didn’t rebuild the correct parent chain before recursing into the CTE, so the path was considered unsafe. **Fix** * Remove the `Assert(skipOuterVars)` in the `RTE_CTE` branch. * Find the CTE’s owning level via `ctelevelsup` and compute `cteParentListIndex`. * Rebuild a private parent list for recursion: `list_copy` → `list_truncate` → `lappend(current query)`. * Add a bounds check before indexing the CTE’s `targetList`. **Why it works** ```diff -parentQueryList = lappend(parentQueryList, query); -FindReferencedTableColumn(targetEntry->expr, parentQueryList, - cteQuery, column, rteContainingReferencedColumn, - skipOuterVars); + /* hand a private, bounded parent list to the recursion */ + List *newParent = list_copy(parentQueryList); + newParent = list_truncate(newParent, cteParentListIndex + 1); + newParent = lappend(newParent, query); + + FindReferencedTableColumn(targetEntry->expr, + newParent, + cteQuery, + column, + rteContainingReferencedColumn, + skipOuterVars); +} ``` **Before:** We changed `parentQueryList` in place (`parentQueryList = lappend(...)`) and didn’t trim it to the CTE’s owner level. **After:** We copy the list, trim it to the CTE’s owner level, then append the current query. This keeps the parent list accurate for the current recursion and safe when following outer Vars. **Example: Nested subquery referencing the CTE (two levels down)** ``` WITH c AS MATERIALIZED (SELECT user_id FROM raw_events_first) SELECT 1 FROM raw_events_first t WHERE EXISTS ( SELECT 1 FROM (SELECT user_id FROM c) c2 WHERE c2.user_id = t.user_id ); ``` Levels: Q0 = top SELECT Q1 = EXISTS subquery Q2 = inner (SELECT user_id FROM c) When resolving c2.user_id inside Q2: - parentQueryList is [Q0, Q1, Q2]. - `ctelevelsup`: 2 `cteParentListIndex = length(parentQueryList) - ctelevelsup - 1` - Recurse into the CTE’s query with [Q0, Q2]. **Tests (added in `multi_insert_select`)** * **T1:** Correlated subquery that references a CTE (one level down) Verifies that resolving through `RTE_CTE` after following an outer `Var` succeeds, row count matches source table. * **T2:** Nested subquery that references a CTE (two levels down) Exercises deeper recursion and confirms identical to T1. * **T3:** Scalar subquery in a target list that reads from the outer CTE Checks expected row count and that no NULLs are inserted. These tests cover the cases that previously hit `Assert(skipOuterVars)` and confirm CTE references while following outer Vars. |
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