gengliangwang opened a new pull request #23648: [BRANCH-2.3][SPARK-26709][SQL] OptimizeMetadataOnlyQuery does not handle empty records correctly URL: https://github.com/apache/spark/pull/23648 ## What changes were proposed in this pull request? When reading from empty tables, the optimization `OptimizeMetadataOnlyQuery` may return wrong results: ``` sql("CREATE TABLE t (col1 INT, p1 INT) USING PARQUET PARTITIONED BY (p1)") sql("INSERT INTO TABLE t PARTITION (p1 = 5) SELECT ID FROM range(1, 1)") sql("SELECT MAX(p1) FROM t") ``` The result is supposed to be `null`. However, with the optimization the result is `5`. The rule is originally ported from https://issues.apache.org/jira/browse/HIVE-1003 in #13494. In Hive, the rule is disabled by default in a later release(https://issues.apache.org/jira/browse/HIVE-15397), due to the same problem. It is hard to completely avoid the correctness issue. Because data sources like Parquet can be metadata-only. Spark can't tell whether it is empty or not without actually reading it. This PR disable the optimization by default. ## How was this patch tested? Unit test
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