[I] [Bug] A cached permanent view is re-read when referenced twice in one query [kyuubi]

["j1wonpark (via GitHub)" <gi...@apache.org>]

j1wonpark opened a new issue, #7738:
URL: https://github.com/apache/kyuubi/issues/7738

   ### Code of Conduct
   
   - [x] I agree to follow this project's [Code of Conduct](https://www.apache.org/foundation/policies/conduct)
   
   ### Search before asking
   
   - [x] I have searched in the [issues](https://github.com/apache/kyuubi/issues?q=is%3Aissue) and found no similar issues.
   
   ### Describe the bug
   
   Caching a permanent view and referencing it twice in one query makes the second reference miss
   the cache and read the view down to its base tables.
   
   ```scala
   sql("CREATE TABLE t (id int, k int)")
   sql("CREATE VIEW v AS SELECT id, k FROM t")
   
   val df = spark.table("v")
   df.cache()
   df.count()
   
   val optimized = df.join(df.select("k").distinct(), "k").queryExecution.optimizedPlan
   assert(optimized.collect { case r: InMemoryRelation => r }.size === 2)   // 1 did not equal 2
   ```
   
   `PermanentViewMarker` is a `MultiInstanceRelation`, so the analyzer calls `newInstance()` on the
   second occurrence. The contract is that a new instance stays `sameResult` with the original,
   which is what lets `CacheManager` find it. It does not: `newInstance()` wraps the child in a
   `Project` that survives canonicalization, for three reasons.
   
   - The `Cast` in `Alias(Cast(attr, attr.dataType), attr.name)` makes Spark's own rename-only
     `Project` stripping not apply.
   - `doCanonicalize`'s guard reads a `TreeNodeTag[Unit]` with `.contains(true)`, which is always
     false, so it never runs.
   - That guard also matches only one `Project` layer and only under a `View`, and neither holds
     for subquery markers or for a renewed marker that is reused in another query.
   
   Reproduced on Spark 3.5, 4.0 and 4.1.
   
   ### Affects Version(s)
   
   master, 1.11.x, 1.10.0
   
   ### Additional context
   
   The first point came in with #5884, the other two with #5937, which shipped without a test.
   A PR with the fix and unit tests follows.
   
   ### Are you willing to submit PR?
   
   - [x] Yes. I would be willing to submit a PR with guidance from the Kyuubi community to fix.
   


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Re: [I] [Bug] A cached permanent view is re-read when referenced twice in one query [kyuubi]

["pan3793 (via GitHub)" <gi...@apache.org>]

pan3793 closed issue #7738: [Bug] A cached permanent view is re-read when referenced twice in one query
URL: https://github.com/apache/kyuubi/issues/7738


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