branch-4.1: [fix](mv) Prevent snapshot reads from using current MVs #67700 - #67729
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## Problem An external-table query that explicitly reads an older snapshot can still enter materialized view rewrite. The candidate materialized view represents the table state at its refresh snapshot, so using a current materialized view for a historical query can silently return data from the wrong point in time. ## Root cause `LogicalFileScan` stores standard `FOR TIME AS OF` and `FOR VERSION AS OF` clauses in `tableSnapshot`. The materialized-view eligibility checker rejected scans with table samples or scan parameters, but did not inspect `tableSnapshot`. As a result, the historical scan was treated like an ordinary latest-snapshot scan. ## How to reproduce 1. Create an Iceberg table and insert an initial row, then record that snapshot ID. 2. Insert newer data and refresh a materialized view over the table at the current snapshot. 3. Enable materialized-view rewrite and query the Iceberg table with `FOR VERSION AS OF <old_snapshot_id>` (the same issue applies to `FOR TIME AS OF`). 4. Before this change, the historical query can be considered eligible for rewrite by the current-snapshot materialized view, producing current rather than historical results. The same condition can be reproduced directly in the optimizer by building a `LogicalFileScan` with a non-empty `tableSnapshot`: the table-query-operator checker previously returned false. ## Fix Treat a non-empty `LogicalFileScan.tableSnapshot` as a table-level query operator, alongside table samples and scan parameters. This conservatively prevents materialized-view rewrite until the optimizer can prove that the query snapshot and materialized-view refresh snapshot are semantically equivalent. Add a unit test that constructs a file scan with a version snapshot and verifies that the checker rejects it from ordinary rewrite eligibility.
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yiguolei
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Sep 9, 2026
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Cherry-picked from #67700