avoid regression

Author: wangyum

docs/sql-migration-guide-upgrade.md

@@ -24,22 +24,6 @@ license: |
 
 ## Upgrading From Spark SQL 2.4 to 3.0
 
-  - Since Spark 3.0, we upgraded the built-in Hive to 2.3 when enabling the Hadoop 3.2+ profile. This upgrade fixes the following issues:
-
-     - [HIVE-6727](https://issues.apache.org/jira/browse/HIVE-6727): Table level stats for external tables are set incorrectly.
-
-     - [HIVE-15653](https://issues.apache.org/jira/browse/HIVE-15653): Some ALTER TABLE commands drop table stats.
-
-     - [SPARK-12014](https://issues.apache.org/jira/browse/SPARK-12014): Spark SQL query containing semicolon is broken in Beeline.
-
-     - [SPARK-25193](https://issues.apache.org/jira/browse/SPARK-25193): insert overwrite doesn't throw exception when drop old data fails.
-
-     - [SPARK-25919](https://issues.apache.org/jira/browse/SPARK-25919): Date value corrupts when tables are "ParquetHiveSerDe" formatted and target table is Partitioned.
-
-     - [SPARK-26332](https://issues.apache.org/jira/browse/SPARK-26332): Spark sql write orc table on viewFS throws exception.
-
-     - [SPARK-26437](https://issues.apache.org/jira/browse/SPARK-26437): Decimal data becomes bigint to query, unable to query.
-
   - Since Spark 3.0, the Dataset and DataFrame API `unionAll` is not deprecated any more. It is an alias for `union`.
 
   - In PySpark, when creating a `SparkSession` with `SparkSession.builder.getOrCreate()`, if there is an existing `SparkContext`, the builder was trying to update the `SparkConf` of the existing `SparkContext` with configurations specified to the builder, but the `SparkContext` is shared by all `SparkSession`s, so we should not update them. Since 3.0, the builder comes to not update the configurations. This is the same behavior as Java/Scala API in 2.3 and above. If you want to update them, you need to update them prior to creating a `SparkSession`.

sql/hive/src/main/scala/org/apache/spark/sql/hive/client/HiveClientImpl.scala

@@ -52,6 +52,7 @@ import org.apache.spark.sql.catalyst.parser.{CatalystSqlParser, ParseException}
 import org.apache.spark.sql.execution.QueryExecutionException
 import org.apache.spark.sql.execution.command.DDLUtils
 import org.apache.spark.sql.hive.HiveExternalCatalog.{DATASOURCE_SCHEMA, DATASOURCE_SCHEMA_NUMPARTS, DATASOURCE_SCHEMA_PART_PREFIX}
+import org.apache.spark.sql.hive.HiveUtils
 import org.apache.spark.sql.hive.client.HiveClientImpl._
 import org.apache.spark.sql.types._
 import org.apache.spark.util.{CircularBuffer, Utils}
@@ -191,7 +192,9 @@ private[hive] class HiveClientImpl(
   }
 
   /** Returns the configuration for the current session. */
-  def conf: HiveConf = {
+  def conf: HiveConf = if (!HiveUtils.isHive23) {
+    state.getConf
+  } else {
     val hiveConf = state.getConf
     // Hive changed the default of datanucleus.schema.autoCreateAll from true to false
     // and hive.metastore.schema.verification from false to true since Hive 2.0.