[SPARK-38236][SQL][3.2][3.1] Check if table location is absolute by "…

…new Path(locationUri).isAbsolute" in create/alter table

### What changes were proposed in this pull request?
After #28527, we change to create table under the database location when the table location is relative. However the criteria to determine if a table location is relative/absolute is `URI.isAbsolute`, which basically checks if the table location URI has a scheme defined. So table URIs like `/table/path` are treated as relative and the scheme and authority of the database location URI are used to create the table. For example, when the database location URI is `s3a://bucket/db`, the table will be created at `s3a://bucket/table/path`, while it should be created under the file system defined in `SessionCatalog.hadoopConf` instead.

This change fixes that by treating table location as absolute when the first letter of its path is slash.

This also applies to alter table.

### Why are the changes needed?
This is to fix the behavior described above.

### Does this PR introduce _any_ user-facing change?
Yes. When users try to create/alter a table with a location that starts with a slash but without a scheme defined, the table will be created under/altered to the file system defined in `SessionCatalog.hadoopConf`, instead of the one defined in the database location URI.

### How was this patch tested?
Updated unit tests.

Closes #35591 from bozhang2820/spark-31709-3.2.

Authored-by: Bo Zhang <bo.zhang@databricks.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>

external/avro/src/test/scala/org/apache/spark/sql/avro/AvroSuite.scala

@@ -68,6 +68,8 @@ abstract class AvroSuite
 
   override protected def beforeAll(): Unit = {
     super.beforeAll()
+    // initialize SessionCatalog here so it has a clean hadoopConf
+    spark.sessionState.catalog
     spark.conf.set(SQLConf.FILES_MAX_PARTITION_BYTES.key, 1024)
   }
 

mllib/src/test/scala/org/apache/spark/mllib/util/MLlibTestSparkContext.scala

@@ -40,6 +40,8 @@ trait MLlibTestSparkContext extends TempDirectory { self: Suite =>
       .appName("MLlibUnitTest")
       .getOrCreate()
     sc = spark.sparkContext
+    // initialize SessionCatalog here so it has a clean hadoopConf
+    spark.sessionState.catalog
 
     checkpointDir = Utils.createDirectory(tempDir.getCanonicalPath, "checkpoints").toString
     sc.setCheckpointDir(checkpointDir)

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/catalog/SessionCatalog.scala

@@ -393,6 +393,8 @@ class SessionCatalog(
   private def makeQualifiedTablePath(locationUri: URI, database: String): URI = {
     if (locationUri.isAbsolute) {
       locationUri
+    } else if (new Path(locationUri).isAbsolute) {
+      makeQualifiedPath(locationUri)
     } else {
       val dbName = formatDatabaseName(database)
       val dbLocation = makeQualifiedDBPath(getDatabaseMetadata(dbName).locationUri)

sql/core/src/test/scala/org/apache/spark/sql/execution/datasources/v2/V2SessionCatalogSuite.scala

@@ -29,7 +29,7 @@ import org.scalatest.BeforeAndAfter
 import org.apache.spark.sql.AnalysisException
 import org.apache.spark.sql.catalyst.analysis.{NamespaceAlreadyExistsException, NoSuchNamespaceException, NoSuchTableException, TableAlreadyExistsException}
 import org.apache.spark.sql.catalyst.parser.CatalystSqlParser
-import org.apache.spark.sql.connector.catalog.{CatalogV2Util, Identifier, NamespaceChange, TableCatalog, TableChange, V1Table}
+import org.apache.spark.sql.connector.catalog.{CatalogV2Util, Identifier, NamespaceChange, SupportsNamespaces, TableCatalog, TableChange, V1Table}
 import org.apache.spark.sql.test.SharedSparkSession
 import org.apache.spark.sql.types.{DoubleType, IntegerType, LongType, StringType, StructField, StructType, TimestampType}
 import org.apache.spark.sql.util.CaseInsensitiveStringMap
@@ -60,7 +60,8 @@ class V2SessionCatalogTableSuite extends V2SessionCatalogBaseSuite {
     super.beforeAll()
     val catalog = newCatalog()
     catalog.createNamespace(Array("db"), emptyProps)
-    catalog.createNamespace(Array("db2"), emptyProps)
+    catalog.createNamespace(Array("db2"),
+      Map(SupportsNamespaces.PROP_LOCATION -> "file:///db2.db").asJava)
     catalog.createNamespace(Array("ns"), emptyProps)
     catalog.createNamespace(Array("ns2"), emptyProps)
   }
@@ -186,10 +187,17 @@ class V2SessionCatalogTableSuite extends V2SessionCatalogBaseSuite {
     assert(t2.catalogTable.location === makeQualifiedPathWithWarehouse("db.db/relative/path"))
     catalog.dropTable(testIdent)
 
-    // absolute path
+    // absolute path without scheme
     properties.put(TableCatalog.PROP_LOCATION, "/absolute/path")
     val t3 = catalog.createTable(testIdent, schema, Array.empty, properties).asInstanceOf[V1Table]
-    assert(t3.catalogTable.location.toString === "file:/absolute/path")
+    assert(t3.catalogTable.location.toString === "file:///absolute/path")
+    catalog.dropTable(testIdent)
+
+    // absolute path with scheme
+    properties.put(TableCatalog.PROP_LOCATION, "file:/absolute/path")
+    val t4 = catalog.createTable(testIdent, schema, Array.empty, properties).asInstanceOf[V1Table]
+    assert(t4.catalogTable.location.toString === "file:/absolute/path")
+    catalog.dropTable(testIdent)
   }
 
   test("tableExists") {
@@ -686,10 +694,15 @@ class V2SessionCatalogTableSuite extends V2SessionCatalogBaseSuite {
       TableChange.setProperty(TableCatalog.PROP_LOCATION, "relative/path")).asInstanceOf[V1Table]
     assert(t2.catalogTable.location === makeQualifiedPathWithWarehouse("db.db/relative/path"))
 
-    // absolute path
+    // absolute path without scheme
     val t3 = catalog.alterTable(testIdent,
       TableChange.setProperty(TableCatalog.PROP_LOCATION, "/absolute/path")).asInstanceOf[V1Table]
-    assert(t3.catalogTable.location.toString === "file:/absolute/path")
+    assert(t3.catalogTable.location.toString === "file:///absolute/path")
+
+    // absolute path with scheme
+    val t4 = catalog.alterTable(testIdent, TableChange.setProperty(
+      TableCatalog.PROP_LOCATION, "file:/absolute/path")).asInstanceOf[V1Table]
+    assert(t4.catalogTable.location.toString === "file:/absolute/path")
   }
 
   test("dropTable") {