From 9bddf7180e9e76e1cabc580eee23962dd66f84c3 Mon Sep 17 00:00:00 2001
From: Udbhav30 <u.agrawal30@gmail.com>
Date: Wed, 6 Mar 2019 09:06:10 -0800
Subject: [PATCH] [SPARK-24669][SQL] Invalidate tables in case of DROP DATABASE
 CASCADE

  ## What changes were proposed in this pull request?
Before dropping database refresh the tables of that database, so as to refresh all cached entries associated with those tables.
We follow the same when dropping a table.

## How was this patch tested?
UT is added

Closes #23905 from Udbhav30/SPARK-24669.

Authored-by: Udbhav30 <u.agrawal30@gmail.com>
Signed-off-by: Dongjoon Hyun <dhyun@apple.com>
---
 .../sql/catalyst/catalog/SessionCatalog.scala |  5 +++
 .../sql/execution/command/DDLSuite.scala      | 38 ++++++++++++++++++-
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/catalog/SessionCatalog.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/catalog/SessionCatalog.scala
index 1dbe946503e51..4b862a579cc36 100644
--- a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/catalog/SessionCatalog.scala
+++ b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/catalog/SessionCatalog.scala
@@ -218,6 +218,11 @@ class SessionCatalog(
     if (dbName == DEFAULT_DATABASE) {
       throw new AnalysisException(s"Can not drop default database")
     }
+    if (cascade && databaseExists(dbName)) {
+      listTables(dbName).foreach { t =>
+        invalidateCachedTable(QualifiedTableName(dbName, t.table))
+      }
+    }
     externalCatalog.dropDatabase(dbName, ignoreIfNotExists, cascade)
   }
 
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/DDLSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/DDLSuite.scala
index 052a5e757c445..001e4aca22daf 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/command/DDLSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/command/DDLSuite.scala
@@ -17,7 +17,7 @@
 
 package org.apache.spark.sql.execution.command
 
-import java.io.File
+import java.io.{File, PrintWriter}
 import java.net.URI
 import java.util.Locale
 
@@ -2715,4 +2715,40 @@ abstract class DDLSuite extends QueryTest with SQLTestUtils {
     }
     assert(ex.getMessage.contains("Spark config"))
   }
+
+  test("Refresh table before drop database cascade") {
+    withTempDir { tempDir =>
+      val file1 = new File(tempDir + "/first.csv")
+      val writer1 = new PrintWriter(file1)
+      writer1.write("first")
+      writer1.close()
+
+      val file2 = new File(tempDir + "/second.csv")
+      val writer2 = new PrintWriter(file2)
+      writer2.write("second")
+      writer2.close()
+
+      withDatabase("foo") {
+        withTable("foo.first") {
+          sql("CREATE DATABASE foo")
+          sql(
+            s"""CREATE TABLE foo.first (id STRING)
+               |USING csv OPTIONS (path='${file1.toURI}')
+             """.stripMargin)
+          sql("SELECT * FROM foo.first")
+          checkAnswer(spark.table("foo.first"), Row("first"))
+
+          // Dropping the database and again creating same table with different path
+          sql("DROP DATABASE foo CASCADE")
+          sql("CREATE DATABASE foo")
+          sql(
+            s"""CREATE TABLE foo.first (id STRING)
+               |USING csv OPTIONS (path='${file2.toURI}')
+             """.stripMargin)
+          sql("SELECT * FROM foo.first")
+          checkAnswer(spark.table("foo.first"), Row("second"))
+        }
+      }
+    }
+  }
 }