From 3053540c5dc7199d84a6a9bfbe0d3e37efe87990 Mon Sep 17 00:00:00 2001
From: Eduard Tudenhoefner <etudenhoefner@gmail.com>
Date: Thu, 12 Dec 2024 18:07:04 +0100
Subject: [PATCH] Core: Use HEAD request to check if view exists (#11760)

---
 .../apache/iceberg/rest/CatalogHandlers.java  |  6 ++++
 .../iceberg/rest/RESTSessionCatalog.java      | 12 +++++++
 .../iceberg/rest/RESTCatalogAdapter.java      | 10 ++++++
 .../iceberg/rest/TestRESTViewCatalog.java     | 32 +++++++++++++++++++
 4 files changed, 60 insertions(+)

diff --git a/core/src/main/java/org/apache/iceberg/rest/CatalogHandlers.java b/core/src/main/java/org/apache/iceberg/rest/CatalogHandlers.java
index 563853e3f033..344308e4caf0 100644
--- a/core/src/main/java/org/apache/iceberg/rest/CatalogHandlers.java
+++ b/core/src/main/java/org/apache/iceberg/rest/CatalogHandlers.java
@@ -507,6 +507,12 @@ private static LoadViewResponse viewResponse(View view) {
         .build();
   }
 
+  public static void viewExists(ViewCatalog catalog, TableIdentifier viewIdentifier) {
+    if (!catalog.viewExists(viewIdentifier)) {
+      throw new NoSuchViewException("View does not exist: %s", viewIdentifier);
+    }
+  }
+
   public static LoadViewResponse loadView(ViewCatalog catalog, TableIdentifier viewIdentifier) {
     View view = catalog.loadView(viewIdentifier);
     return viewResponse(view);
diff --git a/core/src/main/java/org/apache/iceberg/rest/RESTSessionCatalog.java b/core/src/main/java/org/apache/iceberg/rest/RESTSessionCatalog.java
index 5c6fc49984a5..8e8bd2bb70c7 100644
--- a/core/src/main/java/org/apache/iceberg/rest/RESTSessionCatalog.java
+++ b/core/src/main/java/org/apache/iceberg/rest/RESTSessionCatalog.java
@@ -1212,6 +1212,18 @@ public List<TableIdentifier> listViews(SessionContext context, Namespace namespa
     return views.build();
   }
 
+  @Override
+  public boolean viewExists(SessionContext context, TableIdentifier identifier) {
+    checkViewIdentifierIsValid(identifier);
+
+    try {
+      client.head(paths.view(identifier), headers(context), ErrorHandlers.viewErrorHandler());
+      return true;
+    } catch (NoSuchViewException e) {
+      return false;
+    }
+  }
+
   @Override
   public View loadView(SessionContext context, TableIdentifier identifier) {
     Endpoint.check(
diff --git a/core/src/test/java/org/apache/iceberg/rest/RESTCatalogAdapter.java b/core/src/test/java/org/apache/iceberg/rest/RESTCatalogAdapter.java
index 87b693e206ae..94dd45d4f23d 100644
--- a/core/src/test/java/org/apache/iceberg/rest/RESTCatalogAdapter.java
+++ b/core/src/test/java/org/apache/iceberg/rest/RESTCatalogAdapter.java
@@ -156,6 +156,7 @@ enum Route {
         CommitTransactionRequest.class,
         null),
     LIST_VIEWS(HTTPMethod.GET, ResourcePaths.V1_VIEWS, null, ListTablesResponse.class),
+    VIEW_EXISTS(HTTPMethod.HEAD, ResourcePaths.V1_VIEW),
     LOAD_VIEW(HTTPMethod.GET, ResourcePaths.V1_VIEW, null, LoadViewResponse.class),
     CREATE_VIEW(
         HTTPMethod.POST, ResourcePaths.V1_VIEWS, CreateViewRequest.class, LoadViewResponse.class),
@@ -471,6 +472,15 @@ public <T extends RESTResponse> T handleRequest(
           break;
         }
 
+      case VIEW_EXISTS:
+        {
+          if (null != asViewCatalog) {
+            CatalogHandlers.viewExists(asViewCatalog, viewIdentFromPathVars(vars));
+            return null;
+          }
+          break;
+        }
+
       case LOAD_VIEW:
         {
           if (null != asViewCatalog) {
diff --git a/core/src/test/java/org/apache/iceberg/rest/TestRESTViewCatalog.java b/core/src/test/java/org/apache/iceberg/rest/TestRESTViewCatalog.java
index 85ccdc8f5ddd..40a206896be4 100644
--- a/core/src/test/java/org/apache/iceberg/rest/TestRESTViewCatalog.java
+++ b/core/src/test/java/org/apache/iceberg/rest/TestRESTViewCatalog.java
@@ -50,6 +50,7 @@
 import org.eclipse.jetty.servlet.ServletHolder;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.ValueSource;
@@ -226,6 +227,37 @@ public void testPaginationForListViews(int numberOfItems) {
             eq(ListTablesResponse.class));
   }
 
+  @Test
+  public void viewExistsViaHEADRequest() {
+    RESTCatalogAdapter adapter = Mockito.spy(new RESTCatalogAdapter(backendCatalog));
+    RESTCatalog catalog =
+        new RESTCatalog(SessionCatalog.SessionContext.createEmpty(), (config) -> adapter);
+    catalog.initialize("test", ImmutableMap.of());
+
+    catalog.createNamespace(Namespace.of("ns"));
+
+    assertThat(catalog.viewExists(TableIdentifier.of("ns", "view"))).isFalse();
+
+    Mockito.verify(adapter)
+        .execute(
+            eq(HTTPMethod.GET),
+            eq("v1/config"),
+            any(),
+            any(),
+            eq(ConfigResponse.class),
+            any(),
+            any());
+    Mockito.verify(adapter)
+        .execute(
+            eq(HTTPMethod.HEAD),
+            eq("v1/namespaces/ns/views/view"),
+            any(),
+            any(),
+            any(),
+            any(),
+            any());
+  }
+
   @Override
   protected RESTCatalog catalog() {
     return restCatalog;