[SPARK-33667][SQL] Respect the spark.sql.caseSensitive config while…

… resolving partition spec in v1 `SHOW PARTITIONS`

Preprocess the partition spec passed to the V1 SHOW PARTITIONS implementation `ShowPartitionsCommand`, and normalize the passed spec according to the partition columns w.r.t the case sensitivity flag  **spark.sql.caseSensitive**.

V1 SHOW PARTITIONS is case sensitive in fact, and doesn't respect the SQL config **spark.sql.caseSensitive** which is false by default, for instance:
```sql
spark-sql> CREATE TABLE tbl1 (price int, qty int, year int, month int)
         > USING parquet
         > PARTITIONED BY (year, month);
spark-sql> INSERT INTO tbl1 PARTITION(year = 2015, month = 1) SELECT 1, 1;
spark-sql> SHOW PARTITIONS tbl1 PARTITION(YEAR = 2015, Month = 1);
Error in query: Non-partitioning column(s) [YEAR, Month] are specified for SHOW PARTITIONS;
```
The `SHOW PARTITIONS` command must show the partition `year = 2015, month = 1` specified by `YEAR = 2015, Month = 1`.

Yes. After the changes, the command above works as expected:
```sql
spark-sql> SHOW PARTITIONS tbl1 PARTITION(YEAR = 2015, Month = 1);
year=2015/month=1
```

By running the affected test suites:
- `v1/ShowPartitionsSuite`
- `v2/ShowPartitionsSuite`

Closes apache#30615 from MaxGekk/show-partitions-case-sensitivity-test.

Authored-by: Max Gekk <max.gekk@gmail.com>
Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>
(cherry picked from commit 4829781)
Signed-off-by: Max Gekk <max.gekk@gmail.com>

sql/core/src/main/scala/org/apache/spark/sql/execution/command/tables.scala

@@ -1012,20 +1012,18 @@ case class ShowPartitionsCommand(
     DDLUtils.verifyPartitionProviderIsHive(sparkSession, table, "SHOW PARTITIONS")
 
     /**
-     * Validate the partitioning spec by making sure all the referenced columns are
+     * Normalizes the partition spec w.r.t the partition columns and case sensitivity settings,
+     * and validates the spec by making sure all the referenced columns are
      * defined as partitioning columns in table definition. An AnalysisException exception is
      * thrown if the partitioning spec is invalid.
      */
-    if (spec.isDefined) {
-      val badColumns = spec.get.keySet.filterNot(table.partitionColumnNames.contains)
-      if (badColumns.nonEmpty) {
-        val badCols = badColumns.mkString("[", ", ", "]")
-        throw new AnalysisException(
-          s"Non-partitioning column(s) $badCols are specified for SHOW PARTITIONS")
-      }
-    }
+    val normalizedSpec = spec.map(partitionSpec => PartitioningUtils.normalizePartitionSpec(
+      partitionSpec,
+      table.partitionColumnNames,
+      table.identifier.quotedString,
+      sparkSession.sessionState.conf.resolver))
 
-    val partNames = catalog.listPartitionNames(tableName, spec)
+    val partNames = catalog.listPartitionNames(tableName, normalizedSpec)
     partNames.map(Row(_))
   }
 }

sql/core/src/test/scala/org/apache/spark/sql/execution/command/DDLSuite.scala

@@ -3032,7 +3032,7 @@ abstract class DDLSuite extends QueryTest with SQLTestUtils {
     }
   }
 
-  test("SPARK-33588: case sensitivity of partition spec") {
+  test("SPARK-33588: case sensitivity of partition spec in SHOW TABLE") {
     val t = "part_table"
     withTable(t) {
       sql(s"""
@@ -3052,6 +3052,27 @@ abstract class DDLSuite extends QueryTest with SQLTestUtils {
       }
     }
   }
+
+  test("SPARK-33667: case sensitivity of partition spec in SHOW PARTITIONS") {
+    val t = "part_table"
+    withTable(t) {
+      sql(s"""
+        |CREATE TABLE $t (price int, qty int, year int, month int)
+        |USING $dataSource
+        |PARTITIONED BY (year, month)""".stripMargin)
+      sql(s"INSERT INTO $t PARTITION(year = 2015, month = 1) SELECT 1, 1")
+      Seq(
+        true -> "PARTITION(year = 2015, month = 1)",
+        false -> "PARTITION(YEAR = 2015, Month = 1)"
+      ).foreach { case (caseSensitive, partitionSpec) =>
+        withSQLConf(SQLConf.CASE_SENSITIVE.key -> caseSensitive.toString) {
+          checkAnswer(
+            sql(s"SHOW PARTITIONS $t $partitionSpec"),
+            Row("year=2015/month=1"))
+        }
+      }
+    }
+  }
 }
 
 object FakeLocalFsFileSystem {