plusplusjiajia opened a new pull request, #753:
URL: https://github.com/apache/paimon-rust/pull/753
### Purpose
PaimonRelationPlanner handed every version clause it did not recognize back
to DataFusion, which drops it: FOR SYSTEM_TIME AS OF planned against the
current snapshot, so an explicitly historical query returned today's rows.
System tables and views were dropped the same way — each has a provider of its
own, so the downcast missed them and even VERSION AS OF over t$files was
ignored.
Reachable from a plain SessionContext with a dialect that parses version
clauses. SQLContext resolves them before planning and is unaffected.
### Brief change log
- Error on a version clause this planner cannot resolve, instead of
returning the relation unchanged.
- Mark system tables and views with PaimonOwnedProvider and refuse time
travel over them: this planner rewrites a table onto another snapshot, and
there is no equivalent for something built over one. A marker
rather than the name, since another engine may hold a table called x$files.
- A genuinely foreign provider still falls through untouched — relation
planners are session-global.
- The read path classifies through load_table, so a table a query engine
must serve reports its declared type at load time rather than deeper in the
scan.
### Tests
- time_travel_on_a_system_table_is_rejected_in_a_raw_session
- a_foreign_table_named_like_a_system_table_is_left_alone — same $files
name, opposite outcome, which is what pins the discriminator.
### API and Format
No public API change(PaimonOwnedProvider 是 pub(crate)),no format change.
### Documentation
None needed.
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