Copilot commented on code in PR #10992:
URL: https://github.com/apache/gravitino/pull/10992#discussion_r3218594889


##########
catalogs/catalog-lakehouse-iceberg/src/main/java/org/apache/gravitino/catalog/lakehouse/iceberg/IcebergViewCatalogOperations.java:
##########
@@ -0,0 +1,402 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.gravitino.catalog.lakehouse.iceberg;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.Maps;
+import java.time.Instant;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.stream.Collectors;
+import org.apache.commons.lang3.ArrayUtils;
+import org.apache.commons.lang3.StringUtils;
+import org.apache.gravitino.NameIdentifier;
+import org.apache.gravitino.Namespace;
+import org.apache.gravitino.catalog.lakehouse.iceberg.converter.ConvertUtil;
+import 
org.apache.gravitino.catalog.lakehouse.iceberg.ops.IcebergCatalogWrapperHelper;
+import org.apache.gravitino.exceptions.NoSuchSchemaException;
+import org.apache.gravitino.exceptions.NoSuchViewException;
+import org.apache.gravitino.exceptions.ViewAlreadyExistsException;
+import org.apache.gravitino.iceberg.common.ops.IcebergCatalogWrapper;
+import org.apache.gravitino.meta.AuditInfo;
+import org.apache.gravitino.rel.Column;
+import org.apache.gravitino.rel.Representation;
+import org.apache.gravitino.rel.SQLRepresentation;
+import org.apache.gravitino.rel.View;
+import org.apache.gravitino.rel.ViewChange;
+import org.apache.gravitino.utils.PrincipalUtils;
+import org.apache.iceberg.MetadataUpdate;
+import org.apache.iceberg.Schema;
+import org.apache.iceberg.catalog.TableIdentifier;
+import org.apache.iceberg.exceptions.AlreadyExistsException;
+import org.apache.iceberg.exceptions.NoSuchNamespaceException;
+import org.apache.iceberg.rest.requests.ImmutableCreateViewRequest;
+import org.apache.iceberg.rest.requests.RenameTableRequest;
+import org.apache.iceberg.rest.requests.UpdateTableRequest;
+import org.apache.iceberg.rest.responses.ListTablesResponse;
+import org.apache.iceberg.rest.responses.LoadViewResponse;
+import org.apache.iceberg.view.ImmutableSQLViewRepresentation;
+import org.apache.iceberg.view.ImmutableViewVersion;
+import org.apache.iceberg.view.SQLViewRepresentation;
+import org.apache.iceberg.view.ViewMetadata;
+import org.apache.iceberg.view.ViewRepresentation;
+import org.apache.iceberg.view.ViewVersion;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/** View catalog operations for Iceberg. */
+class IcebergViewCatalogOperations {
+
+  private static final Logger LOG = 
LoggerFactory.getLogger(IcebergViewCatalogOperations.class);
+
+  private final IcebergCatalogWrapper icebergCatalogWrapper;
+
+  IcebergViewCatalogOperations(IcebergCatalogWrapper icebergCatalogWrapper) {
+    this.icebergCatalogWrapper =
+        Preconditions.checkNotNull(icebergCatalogWrapper, 
"icebergCatalogWrapper must not be null");
+  }
+
+  public View loadView(NameIdentifier ident) throws NoSuchViewException {
+    try {
+      LoadViewResponse response =
+          icebergCatalogWrapper.loadView(
+              IcebergCatalogWrapperHelper.buildIcebergTableIdentifier(ident));
+      return IcebergView.fromLoadViewResponse(response, ident.name());
+    } catch (org.apache.iceberg.exceptions.NoSuchViewException e) {
+      throw new NoSuchViewException(e, "Iceberg view %s does not exist", 
ident);
+    }
+  }
+
+  public boolean viewExists(NameIdentifier ident) {
+    return icebergCatalogWrapper.viewExists(
+        IcebergCatalogWrapperHelper.buildIcebergTableIdentifier(ident));
+  }
+
+  public NameIdentifier[] listViews(Namespace namespace) throws 
NoSuchSchemaException {
+    org.apache.iceberg.catalog.Namespace icebergNamespace =
+        IcebergCatalogWrapperHelper.getIcebergNamespace(namespace);
+    if (!icebergCatalogWrapper.namespaceExists(icebergNamespace)) {
+      throw new NoSuchSchemaException("Schema %s does not exist", namespace);
+    }
+    try {
+      ListTablesResponse response = 
icebergCatalogWrapper.listView(icebergNamespace);
+      return response.identifiers().stream()
+          .map(id -> NameIdentifier.of(ArrayUtils.add(namespace.levels(), 
id.name())))
+          .toArray(NameIdentifier[]::new);
+    } catch (NoSuchNamespaceException e) {
+      throw new NoSuchSchemaException("Schema does not exist %s in Iceberg", 
namespace);
+    }
+  }
+
+  public View createView(
+      NameIdentifier ident,
+      String comment,
+      Column[] columns,
+      Representation[] representations,
+      String defaultCatalog,
+      String defaultSchema,
+      Map<String, String> properties)
+      throws NoSuchSchemaException, ViewAlreadyExistsException {
+    org.apache.iceberg.catalog.Namespace icebergNamespace =
+        IcebergCatalogWrapperHelper.getIcebergNamespace(
+            ident.namespace().level(ident.namespace().length() - 1));

Review Comment:
   This derives the Iceberg namespace using only the last namespace level. If 
`NameIdentifier` can contain multi-level namespaces, this will create the view 
in the wrong Iceberg namespace. Prefer converting the full `ident.namespace()` 
(or a clearly-defined schema namespace) rather than truncating to the last 
level.
   



##########
catalogs/catalog-lakehouse-iceberg/src/main/java/org/apache/gravitino/catalog/lakehouse/iceberg/IcebergViewCatalogOperations.java:
##########
@@ -0,0 +1,402 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.gravitino.catalog.lakehouse.iceberg;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.Maps;
+import java.time.Instant;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.stream.Collectors;
+import org.apache.commons.lang3.ArrayUtils;
+import org.apache.commons.lang3.StringUtils;
+import org.apache.gravitino.NameIdentifier;
+import org.apache.gravitino.Namespace;
+import org.apache.gravitino.catalog.lakehouse.iceberg.converter.ConvertUtil;
+import 
org.apache.gravitino.catalog.lakehouse.iceberg.ops.IcebergCatalogWrapperHelper;
+import org.apache.gravitino.exceptions.NoSuchSchemaException;
+import org.apache.gravitino.exceptions.NoSuchViewException;
+import org.apache.gravitino.exceptions.ViewAlreadyExistsException;
+import org.apache.gravitino.iceberg.common.ops.IcebergCatalogWrapper;
+import org.apache.gravitino.meta.AuditInfo;
+import org.apache.gravitino.rel.Column;
+import org.apache.gravitino.rel.Representation;
+import org.apache.gravitino.rel.SQLRepresentation;
+import org.apache.gravitino.rel.View;
+import org.apache.gravitino.rel.ViewChange;
+import org.apache.gravitino.utils.PrincipalUtils;
+import org.apache.iceberg.MetadataUpdate;
+import org.apache.iceberg.Schema;
+import org.apache.iceberg.catalog.TableIdentifier;
+import org.apache.iceberg.exceptions.AlreadyExistsException;
+import org.apache.iceberg.exceptions.NoSuchNamespaceException;
+import org.apache.iceberg.rest.requests.ImmutableCreateViewRequest;
+import org.apache.iceberg.rest.requests.RenameTableRequest;
+import org.apache.iceberg.rest.requests.UpdateTableRequest;
+import org.apache.iceberg.rest.responses.ListTablesResponse;
+import org.apache.iceberg.rest.responses.LoadViewResponse;
+import org.apache.iceberg.view.ImmutableSQLViewRepresentation;
+import org.apache.iceberg.view.ImmutableViewVersion;
+import org.apache.iceberg.view.SQLViewRepresentation;
+import org.apache.iceberg.view.ViewMetadata;
+import org.apache.iceberg.view.ViewRepresentation;
+import org.apache.iceberg.view.ViewVersion;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/** View catalog operations for Iceberg. */
+class IcebergViewCatalogOperations {
+
+  private static final Logger LOG = 
LoggerFactory.getLogger(IcebergViewCatalogOperations.class);
+
+  private final IcebergCatalogWrapper icebergCatalogWrapper;
+
+  IcebergViewCatalogOperations(IcebergCatalogWrapper icebergCatalogWrapper) {
+    this.icebergCatalogWrapper =
+        Preconditions.checkNotNull(icebergCatalogWrapper, 
"icebergCatalogWrapper must not be null");
+  }
+
+  public View loadView(NameIdentifier ident) throws NoSuchViewException {
+    try {
+      LoadViewResponse response =
+          icebergCatalogWrapper.loadView(
+              IcebergCatalogWrapperHelper.buildIcebergTableIdentifier(ident));
+      return IcebergView.fromLoadViewResponse(response, ident.name());
+    } catch (org.apache.iceberg.exceptions.NoSuchViewException e) {
+      throw new NoSuchViewException(e, "Iceberg view %s does not exist", 
ident);
+    }
+  }
+
+  public boolean viewExists(NameIdentifier ident) {
+    return icebergCatalogWrapper.viewExists(
+        IcebergCatalogWrapperHelper.buildIcebergTableIdentifier(ident));
+  }
+
+  public NameIdentifier[] listViews(Namespace namespace) throws 
NoSuchSchemaException {
+    org.apache.iceberg.catalog.Namespace icebergNamespace =
+        IcebergCatalogWrapperHelper.getIcebergNamespace(namespace);
+    if (!icebergCatalogWrapper.namespaceExists(icebergNamespace)) {
+      throw new NoSuchSchemaException("Schema %s does not exist", namespace);
+    }
+    try {
+      ListTablesResponse response = 
icebergCatalogWrapper.listView(icebergNamespace);
+      return response.identifiers().stream()
+          .map(id -> NameIdentifier.of(ArrayUtils.add(namespace.levels(), 
id.name())))
+          .toArray(NameIdentifier[]::new);
+    } catch (NoSuchNamespaceException e) {
+      throw new NoSuchSchemaException("Schema does not exist %s in Iceberg", 
namespace);
+    }
+  }
+
+  public View createView(
+      NameIdentifier ident,
+      String comment,
+      Column[] columns,
+      Representation[] representations,
+      String defaultCatalog,
+      String defaultSchema,
+      Map<String, String> properties)
+      throws NoSuchSchemaException, ViewAlreadyExistsException {
+    org.apache.iceberg.catalog.Namespace icebergNamespace =
+        IcebergCatalogWrapperHelper.getIcebergNamespace(
+            ident.namespace().level(ident.namespace().length() - 1));
+
+    Schema schema = ConvertUtil.toIcebergSchema(columns);
+    List<ViewRepresentation> viewRepresentations = new ArrayList<>();
+    for (Representation representation : representations) {
+      viewRepresentations.add(toSqlViewRepresentation(representation));
+    }
+    Representation[] sqlRepresentations =
+        viewRepresentations.stream()
+            .map(IcebergViewCatalogOperations::toSqlRepresentation)
+            .toArray(SQLRepresentation[]::new);
+
+    org.apache.iceberg.catalog.Namespace defaultNamespace =
+        defaultSchema != null
+            ? IcebergCatalogWrapperHelper.getIcebergNamespace(defaultSchema)
+            : icebergNamespace;
+
+    ViewVersion viewVersion =
+        ImmutableViewVersion.builder()
+            .versionId(1)
+            .timestampMillis(System.currentTimeMillis())
+            .schemaId(0)
+            .defaultNamespace(defaultNamespace)
+            .representations(viewRepresentations)
+            .putSummary("operation", "create")
+            .build();
+
+    Map<String, String> allProperties =
+        properties != null ? Maps.newHashMap(properties) : Maps.newHashMap();
+    if (comment != null) {
+      allProperties.put("comment", comment);
+    }
+    if (defaultCatalog != null) {
+      allProperties.put("default-catalog", defaultCatalog);
+    }
+
+    ImmutableCreateViewRequest request =
+        ImmutableCreateViewRequest.builder()
+            .name(ident.name())
+            .schema(schema)
+            .viewVersion(viewVersion)
+            .properties(allProperties)
+            .build();
+
+    try {
+      icebergCatalogWrapper.createView(icebergNamespace, request);
+      LOG.info("Created Iceberg view {}", ident);
+      return IcebergView.builder()
+          .withName(ident.name())
+          .withComment(comment)
+          .withColumns(columns)
+          .withRepresentations(sqlRepresentations)
+          .withProperties(allProperties)
+          .withAuditInfo(
+              
AuditInfo.builder().withCreator(currentUser()).withCreateTime(Instant.now()).build())
+          .build();
+    } catch (AlreadyExistsException e) {
+      throw new ViewAlreadyExistsException(e, "View %s already exists in 
Iceberg catalog", ident);
+    } catch (NoSuchNamespaceException e) {
+      throw new NoSuchSchemaException(
+          e, "Schema does not exist for view %s in Iceberg catalog", ident);
+    }
+  }
+
+  public View alterView(NameIdentifier ident, ViewChange... changes)
+      throws NoSuchViewException, IllegalArgumentException {
+    Optional<ViewChange> renameOptional =
+        Arrays.stream(changes).filter(c -> c instanceof 
ViewChange.RenameView).reduce((a, b) -> b);
+    if (renameOptional.isPresent()) {
+      String otherChange =
+          Arrays.stream(changes)
+              .filter(c -> !(c instanceof ViewChange.RenameView))
+              .map(String::valueOf)
+              .collect(Collectors.joining("\n"));
+      Preconditions.checkArgument(
+          StringUtils.isEmpty(otherChange),
+          "Rename cannot be combined with other view changes: " + otherChange);
+      return renameView(ident, (ViewChange.RenameView) renameOptional.get());
+    }
+    return internalUpdateView(ident, changes);
+  }
+
+  public boolean dropView(NameIdentifier ident) {
+    try {
+      icebergCatalogWrapper.dropView(
+          IcebergCatalogWrapperHelper.buildIcebergTableIdentifier(ident));
+      LOG.info("Dropped Iceberg view {}", ident);
+      return true;
+    } catch (org.apache.iceberg.exceptions.NoSuchViewException e) {
+      LOG.warn("Iceberg view {} does not exist, skip dropping", ident);
+      return false;
+    }
+  }
+
+  private View renameView(NameIdentifier ident, ViewChange.RenameView rename)
+      throws NoSuchViewException {
+    try {
+      RenameTableRequest request =
+          RenameTableRequest.builder()
+              
.withSource(IcebergCatalogWrapperHelper.buildIcebergTableIdentifier(ident))
+              .withDestination(
+                  IcebergCatalogWrapperHelper.buildIcebergTableIdentifier(
+                      ident.namespace(), rename.getNewName()))
+              .build();
+      icebergCatalogWrapper.renameView(request);
+      return loadView(
+          NameIdentifier.of(ArrayUtils.add(ident.namespace().levels(), 
rename.getNewName())));
+    } catch (org.apache.iceberg.exceptions.NoSuchViewException e) {
+      throw new NoSuchViewException(e, "Iceberg view %s does not exist", 
ident);
+    }
+  }
+
+  private View internalUpdateView(NameIdentifier ident, ViewChange... changes)
+      throws NoSuchViewException, IllegalArgumentException {
+    TableIdentifier viewId = 
IcebergCatalogWrapperHelper.buildIcebergTableIdentifier(ident);
+    try {
+      LoadViewResponse current = icebergCatalogWrapper.loadView(viewId);
+      ViewMetadata metadata = current.metadata();
+
+      List<MetadataUpdate> updates = new ArrayList<>();
+      Map<String, String> setProps = new HashMap<>();
+      Set<String> removeProps = new HashSet<>();
+      ViewChange.ReplaceView replace = null;
+
+      for (ViewChange change : changes) {
+        if (change instanceof ViewChange.SetProperty) {
+          ViewChange.SetProperty setProperty = (ViewChange.SetProperty) change;
+          String property = setProperty.getProperty();
+          setProps.put(property, setProperty.getValue());
+          removeProps.remove(property);
+        } else if (change instanceof ViewChange.RemoveProperty) {
+          String property = ((ViewChange.RemoveProperty) change).getProperty();
+          removeProps.add(property);
+          setProps.remove(property);
+        } else if (change instanceof ViewChange.ReplaceView) {
+          replace = (ViewChange.ReplaceView) change;
+        } else {
+          throw new IllegalArgumentException(
+              "Unsupported view change type: " + 
change.getClass().getSimpleName());
+        }
+      }
+
+      if (replace != null) {
+        setProps.put("replace.drop-dialect.allowed", "true");
+        if (replace.getComment() == null) {
+          removeProps.add("comment");
+          setProps.remove("comment");
+        } else {
+          setProps.put("comment", replace.getComment());
+          removeProps.remove("comment");
+        }
+        if (replace.getDefaultCatalog() == null) {
+          removeProps.add("default-catalog");
+          setProps.remove("default-catalog");
+        } else {
+          setProps.put("default-catalog", replace.getDefaultCatalog());
+          removeProps.remove("default-catalog");
+        }
+      }
+
+      if (!setProps.isEmpty()) {
+        updates.add(new MetadataUpdate.SetProperties(setProps));
+      }
+      if (!removeProps.isEmpty()) {
+        updates.add(new MetadataUpdate.RemoveProperties(removeProps));
+      }
+
+      if (replace != null) {
+        ViewVersion currentVersion = metadata.currentVersion();
+        List<ViewRepresentation> newRepresentations = new ArrayList<>();
+        for (Representation representation : replace.getRepresentations()) {
+          newRepresentations.add(toSqlViewRepresentation(representation));
+        }
+
+        int newVersionId = currentVersion != null ? currentVersion.versionId() 
+ 1 : 1;
+        int schemaId = currentVersion != null ? currentVersion.schemaId() : 0;
+        Schema replacementSchema = 
ConvertUtil.toIcebergSchema(replace.getColumns());
+        Optional<Schema> existingSchema =
+            metadata.schemas().stream()
+                .filter(schema -> schema.sameSchema(replacementSchema))
+                .findFirst();
+        if (existingSchema.isPresent()) {
+          schemaId = existingSchema.get().schemaId();
+        } else {
+          int newSchemaId =
+              
metadata.schemas().stream().mapToInt(Schema::schemaId).max().orElse(-1) + 1;
+          Schema newSchema =
+              new Schema(
+                  newSchemaId, replacementSchema.columns(), 
replacementSchema.identifierFieldIds());
+          updates.add(new MetadataUpdate.AddSchema(newSchema));
+          schemaId = newSchemaId;
+        }
+
+        org.apache.iceberg.catalog.Namespace defaultNamespace =
+            replace.getDefaultSchema() != null
+                ? 
IcebergCatalogWrapperHelper.getIcebergNamespace(replace.getDefaultSchema())
+                : (currentVersion != null
+                    ? currentVersion.defaultNamespace()
+                    : IcebergCatalogWrapperHelper.getIcebergNamespace(
+                        ident.namespace().level(ident.namespace().length() - 
1)));
+
+        ViewVersion newVersion =
+            ImmutableViewVersion.builder()
+                .versionId(newVersionId)
+                .timestampMillis(System.currentTimeMillis())
+                .schemaId(schemaId)
+                .defaultNamespace(defaultNamespace)
+                .representations(newRepresentations)
+                .putSummary("operation", "alter")
+                .build();
+
+        updates.add(new MetadataUpdate.AddViewVersion(newVersion));
+        updates.add(new MetadataUpdate.SetCurrentViewVersion(-1));

Review Comment:
   `SetCurrentViewVersion(-1)` is very likely an invalid current view version 
id and can leave the view pointing to a non-existent version (or failing loads 
/ returning unexpected versions). This should set the current view version to 
the `newVersionId` that was just added.
   



##########
catalogs/catalog-lakehouse-iceberg/src/main/java/org/apache/gravitino/catalog/lakehouse/iceberg/IcebergView.java:
##########
@@ -90,6 +125,41 @@ public static Builder builder() {
     return new Builder();
   }
 
+  private static Column[] extractColumns(ViewMetadata metadata) {
+    try {
+      Schema schema = metadata.schema();
+      if (schema != null && schema.columns() != null) {
+        return 
schema.columns().stream().map(ConvertUtil::fromNestedField).toArray(Column[]::new);
+      }
+    } catch (Exception e) {
+      LOG.warn("Failed to extract columns from Iceberg view metadata", e);
+    }
+    return new Column[0];
+  }
+
+  private static Representation[] extractRepresentations(ViewMetadata 
metadata) {
+    try {
+      ViewVersion currentVersion = metadata.currentVersion();
+      if (currentVersion != null && currentVersion.representations() != null) {
+        return currentVersion.representations().stream()
+            .filter(r -> r instanceof SQLViewRepresentation)
+            .map(
+                r -> {
+                  SQLViewRepresentation sqlRep = (SQLViewRepresentation) r;
+                  return (Representation)
+                      SQLRepresentation.builder()
+                          .withDialect(sqlRep.dialect())
+                          .withSql(sqlRep.sql())
+                          .build();
+                })
+            .toArray(Representation[]::new);
+      }
+    } catch (Exception e) {
+      LOG.warn("Failed to extract representations from Iceberg view metadata", 
e);

Review Comment:
   Catching a broad `Exception` and returning empty columns/representations can 
silently hide real incompatibilities/corruption in metadata, making failures 
harder to diagnose (callers will observe an apparently valid view with missing 
data). Consider narrowing the catch (e.g., specific Iceberg/serialization 
exceptions) and/or surfacing the failure to callers (or at least including view 
identity in the log) so debugging is actionable.
   



##########
catalogs/catalog-lakehouse-iceberg/src/main/java/org/apache/gravitino/catalog/lakehouse/iceberg/IcebergViewCatalogOperations.java:
##########
@@ -0,0 +1,402 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.gravitino.catalog.lakehouse.iceberg;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.Maps;
+import java.time.Instant;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.stream.Collectors;
+import org.apache.commons.lang3.ArrayUtils;
+import org.apache.commons.lang3.StringUtils;
+import org.apache.gravitino.NameIdentifier;
+import org.apache.gravitino.Namespace;
+import org.apache.gravitino.catalog.lakehouse.iceberg.converter.ConvertUtil;
+import 
org.apache.gravitino.catalog.lakehouse.iceberg.ops.IcebergCatalogWrapperHelper;
+import org.apache.gravitino.exceptions.NoSuchSchemaException;
+import org.apache.gravitino.exceptions.NoSuchViewException;
+import org.apache.gravitino.exceptions.ViewAlreadyExistsException;
+import org.apache.gravitino.iceberg.common.ops.IcebergCatalogWrapper;
+import org.apache.gravitino.meta.AuditInfo;
+import org.apache.gravitino.rel.Column;
+import org.apache.gravitino.rel.Representation;
+import org.apache.gravitino.rel.SQLRepresentation;
+import org.apache.gravitino.rel.View;
+import org.apache.gravitino.rel.ViewChange;
+import org.apache.gravitino.utils.PrincipalUtils;
+import org.apache.iceberg.MetadataUpdate;
+import org.apache.iceberg.Schema;
+import org.apache.iceberg.catalog.TableIdentifier;
+import org.apache.iceberg.exceptions.AlreadyExistsException;
+import org.apache.iceberg.exceptions.NoSuchNamespaceException;
+import org.apache.iceberg.rest.requests.ImmutableCreateViewRequest;
+import org.apache.iceberg.rest.requests.RenameTableRequest;
+import org.apache.iceberg.rest.requests.UpdateTableRequest;
+import org.apache.iceberg.rest.responses.ListTablesResponse;
+import org.apache.iceberg.rest.responses.LoadViewResponse;
+import org.apache.iceberg.view.ImmutableSQLViewRepresentation;
+import org.apache.iceberg.view.ImmutableViewVersion;
+import org.apache.iceberg.view.SQLViewRepresentation;
+import org.apache.iceberg.view.ViewMetadata;
+import org.apache.iceberg.view.ViewRepresentation;
+import org.apache.iceberg.view.ViewVersion;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/** View catalog operations for Iceberg. */
+class IcebergViewCatalogOperations {
+
+  private static final Logger LOG = 
LoggerFactory.getLogger(IcebergViewCatalogOperations.class);
+
+  private final IcebergCatalogWrapper icebergCatalogWrapper;
+
+  IcebergViewCatalogOperations(IcebergCatalogWrapper icebergCatalogWrapper) {
+    this.icebergCatalogWrapper =
+        Preconditions.checkNotNull(icebergCatalogWrapper, 
"icebergCatalogWrapper must not be null");
+  }
+
+  public View loadView(NameIdentifier ident) throws NoSuchViewException {
+    try {
+      LoadViewResponse response =
+          icebergCatalogWrapper.loadView(
+              IcebergCatalogWrapperHelper.buildIcebergTableIdentifier(ident));
+      return IcebergView.fromLoadViewResponse(response, ident.name());
+    } catch (org.apache.iceberg.exceptions.NoSuchViewException e) {
+      throw new NoSuchViewException(e, "Iceberg view %s does not exist", 
ident);
+    }
+  }
+
+  public boolean viewExists(NameIdentifier ident) {
+    return icebergCatalogWrapper.viewExists(
+        IcebergCatalogWrapperHelper.buildIcebergTableIdentifier(ident));
+  }
+
+  public NameIdentifier[] listViews(Namespace namespace) throws 
NoSuchSchemaException {
+    org.apache.iceberg.catalog.Namespace icebergNamespace =
+        IcebergCatalogWrapperHelper.getIcebergNamespace(namespace);
+    if (!icebergCatalogWrapper.namespaceExists(icebergNamespace)) {
+      throw new NoSuchSchemaException("Schema %s does not exist", namespace);
+    }
+    try {
+      ListTablesResponse response = 
icebergCatalogWrapper.listView(icebergNamespace);
+      return response.identifiers().stream()
+          .map(id -> NameIdentifier.of(ArrayUtils.add(namespace.levels(), 
id.name())))
+          .toArray(NameIdentifier[]::new);
+    } catch (NoSuchNamespaceException e) {
+      throw new NoSuchSchemaException("Schema does not exist %s in Iceberg", 
namespace);
+    }
+  }
+
+  public View createView(
+      NameIdentifier ident,
+      String comment,
+      Column[] columns,
+      Representation[] representations,
+      String defaultCatalog,
+      String defaultSchema,
+      Map<String, String> properties)
+      throws NoSuchSchemaException, ViewAlreadyExistsException {
+    org.apache.iceberg.catalog.Namespace icebergNamespace =
+        IcebergCatalogWrapperHelper.getIcebergNamespace(
+            ident.namespace().level(ident.namespace().length() - 1));
+
+    Schema schema = ConvertUtil.toIcebergSchema(columns);
+    List<ViewRepresentation> viewRepresentations = new ArrayList<>();
+    for (Representation representation : representations) {
+      viewRepresentations.add(toSqlViewRepresentation(representation));
+    }

Review Comment:
   `representations` is iterated without validation, so `null` (or an empty 
array) will cause NPEs or create an invalid Iceberg view version with no 
representations. Add an explicit argument check (non-null and non-empty) and 
fail fast with a clear `IllegalArgumentException`.



##########
catalogs/catalog-lakehouse-iceberg/src/main/java/org/apache/gravitino/catalog/lakehouse/iceberg/IcebergCatalogOperations.java:
##########
@@ -658,6 +736,13 @@ private static Distribution getIcebergDefaultDistribution(
     return Distributions.NONE;
   }
 
+  private IcebergViewCatalogOperations viewCatalogOperations() {
+    if (icebergViewCatalogOperations == null) {
+      icebergViewCatalogOperations = new 
IcebergViewCatalogOperations(icebergCatalogWrapper);
+    }
+    return icebergViewCatalogOperations;
+  }

Review Comment:
   This lazy initialization is not thread-safe. If `IcebergCatalogOperations` 
is accessed concurrently, multiple threads can race and create multiple 
`IcebergViewCatalogOperations` instances (and potentially observe 
partially-initialized state). Prefer initializing it eagerly in 
`initialize(...)`, or make the field `final`, or guard with 
synchronization/volatile if lazy init is required.



##########
catalogs/catalog-lakehouse-iceberg/src/main/java/org/apache/gravitino/catalog/lakehouse/iceberg/IcebergViewCatalogOperations.java:
##########
@@ -0,0 +1,402 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *  http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.gravitino.catalog.lakehouse.iceberg;
+
+import com.google.common.base.Preconditions;
+import com.google.common.collect.Maps;
+import java.time.Instant;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Optional;
+import java.util.Set;
+import java.util.stream.Collectors;
+import org.apache.commons.lang3.ArrayUtils;
+import org.apache.commons.lang3.StringUtils;
+import org.apache.gravitino.NameIdentifier;
+import org.apache.gravitino.Namespace;
+import org.apache.gravitino.catalog.lakehouse.iceberg.converter.ConvertUtil;
+import 
org.apache.gravitino.catalog.lakehouse.iceberg.ops.IcebergCatalogWrapperHelper;
+import org.apache.gravitino.exceptions.NoSuchSchemaException;
+import org.apache.gravitino.exceptions.NoSuchViewException;
+import org.apache.gravitino.exceptions.ViewAlreadyExistsException;
+import org.apache.gravitino.iceberg.common.ops.IcebergCatalogWrapper;
+import org.apache.gravitino.meta.AuditInfo;
+import org.apache.gravitino.rel.Column;
+import org.apache.gravitino.rel.Representation;
+import org.apache.gravitino.rel.SQLRepresentation;
+import org.apache.gravitino.rel.View;
+import org.apache.gravitino.rel.ViewChange;
+import org.apache.gravitino.utils.PrincipalUtils;
+import org.apache.iceberg.MetadataUpdate;
+import org.apache.iceberg.Schema;
+import org.apache.iceberg.catalog.TableIdentifier;
+import org.apache.iceberg.exceptions.AlreadyExistsException;
+import org.apache.iceberg.exceptions.NoSuchNamespaceException;
+import org.apache.iceberg.rest.requests.ImmutableCreateViewRequest;
+import org.apache.iceberg.rest.requests.RenameTableRequest;
+import org.apache.iceberg.rest.requests.UpdateTableRequest;
+import org.apache.iceberg.rest.responses.ListTablesResponse;
+import org.apache.iceberg.rest.responses.LoadViewResponse;
+import org.apache.iceberg.view.ImmutableSQLViewRepresentation;
+import org.apache.iceberg.view.ImmutableViewVersion;
+import org.apache.iceberg.view.SQLViewRepresentation;
+import org.apache.iceberg.view.ViewMetadata;
+import org.apache.iceberg.view.ViewRepresentation;
+import org.apache.iceberg.view.ViewVersion;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/** View catalog operations for Iceberg. */
+class IcebergViewCatalogOperations {
+
+  private static final Logger LOG = 
LoggerFactory.getLogger(IcebergViewCatalogOperations.class);
+
+  private final IcebergCatalogWrapper icebergCatalogWrapper;
+
+  IcebergViewCatalogOperations(IcebergCatalogWrapper icebergCatalogWrapper) {
+    this.icebergCatalogWrapper =
+        Preconditions.checkNotNull(icebergCatalogWrapper, 
"icebergCatalogWrapper must not be null");
+  }
+
+  public View loadView(NameIdentifier ident) throws NoSuchViewException {
+    try {
+      LoadViewResponse response =
+          icebergCatalogWrapper.loadView(
+              IcebergCatalogWrapperHelper.buildIcebergTableIdentifier(ident));
+      return IcebergView.fromLoadViewResponse(response, ident.name());
+    } catch (org.apache.iceberg.exceptions.NoSuchViewException e) {
+      throw new NoSuchViewException(e, "Iceberg view %s does not exist", 
ident);
+    }
+  }
+
+  public boolean viewExists(NameIdentifier ident) {
+    return icebergCatalogWrapper.viewExists(
+        IcebergCatalogWrapperHelper.buildIcebergTableIdentifier(ident));
+  }
+
+  public NameIdentifier[] listViews(Namespace namespace) throws 
NoSuchSchemaException {
+    org.apache.iceberg.catalog.Namespace icebergNamespace =
+        IcebergCatalogWrapperHelper.getIcebergNamespace(namespace);
+    if (!icebergCatalogWrapper.namespaceExists(icebergNamespace)) {
+      throw new NoSuchSchemaException("Schema %s does not exist", namespace);
+    }
+    try {
+      ListTablesResponse response = 
icebergCatalogWrapper.listView(icebergNamespace);
+      return response.identifiers().stream()
+          .map(id -> NameIdentifier.of(ArrayUtils.add(namespace.levels(), 
id.name())))
+          .toArray(NameIdentifier[]::new);
+    } catch (NoSuchNamespaceException e) {
+      throw new NoSuchSchemaException("Schema does not exist %s in Iceberg", 
namespace);
+    }
+  }
+
+  public View createView(
+      NameIdentifier ident,
+      String comment,
+      Column[] columns,
+      Representation[] representations,
+      String defaultCatalog,
+      String defaultSchema,
+      Map<String, String> properties)
+      throws NoSuchSchemaException, ViewAlreadyExistsException {
+    org.apache.iceberg.catalog.Namespace icebergNamespace =
+        IcebergCatalogWrapperHelper.getIcebergNamespace(
+            ident.namespace().level(ident.namespace().length() - 1));
+
+    Schema schema = ConvertUtil.toIcebergSchema(columns);
+    List<ViewRepresentation> viewRepresentations = new ArrayList<>();
+    for (Representation representation : representations) {
+      viewRepresentations.add(toSqlViewRepresentation(representation));
+    }
+    Representation[] sqlRepresentations =
+        viewRepresentations.stream()
+            .map(IcebergViewCatalogOperations::toSqlRepresentation)
+            .toArray(SQLRepresentation[]::new);
+
+    org.apache.iceberg.catalog.Namespace defaultNamespace =
+        defaultSchema != null
+            ? IcebergCatalogWrapperHelper.getIcebergNamespace(defaultSchema)
+            : icebergNamespace;
+
+    ViewVersion viewVersion =
+        ImmutableViewVersion.builder()
+            .versionId(1)
+            .timestampMillis(System.currentTimeMillis())
+            .schemaId(0)
+            .defaultNamespace(defaultNamespace)
+            .representations(viewRepresentations)
+            .putSummary("operation", "create")
+            .build();
+
+    Map<String, String> allProperties =
+        properties != null ? Maps.newHashMap(properties) : Maps.newHashMap();
+    if (comment != null) {
+      allProperties.put("comment", comment);
+    }
+    if (defaultCatalog != null) {
+      allProperties.put("default-catalog", defaultCatalog);
+    }
+
+    ImmutableCreateViewRequest request =
+        ImmutableCreateViewRequest.builder()
+            .name(ident.name())
+            .schema(schema)
+            .viewVersion(viewVersion)
+            .properties(allProperties)
+            .build();
+
+    try {
+      icebergCatalogWrapper.createView(icebergNamespace, request);
+      LOG.info("Created Iceberg view {}", ident);
+      return IcebergView.builder()
+          .withName(ident.name())
+          .withComment(comment)
+          .withColumns(columns)
+          .withRepresentations(sqlRepresentations)
+          .withProperties(allProperties)
+          .withAuditInfo(
+              
AuditInfo.builder().withCreator(currentUser()).withCreateTime(Instant.now()).build())
+          .build();
+    } catch (AlreadyExistsException e) {
+      throw new ViewAlreadyExistsException(e, "View %s already exists in 
Iceberg catalog", ident);
+    } catch (NoSuchNamespaceException e) {
+      throw new NoSuchSchemaException(
+          e, "Schema does not exist for view %s in Iceberg catalog", ident);
+    }
+  }
+
+  public View alterView(NameIdentifier ident, ViewChange... changes)
+      throws NoSuchViewException, IllegalArgumentException {
+    Optional<ViewChange> renameOptional =
+        Arrays.stream(changes).filter(c -> c instanceof 
ViewChange.RenameView).reduce((a, b) -> b);
+    if (renameOptional.isPresent()) {
+      String otherChange =
+          Arrays.stream(changes)
+              .filter(c -> !(c instanceof ViewChange.RenameView))
+              .map(String::valueOf)
+              .collect(Collectors.joining("\n"));
+      Preconditions.checkArgument(
+          StringUtils.isEmpty(otherChange),
+          "Rename cannot be combined with other view changes: " + otherChange);
+      return renameView(ident, (ViewChange.RenameView) renameOptional.get());
+    }
+    return internalUpdateView(ident, changes);
+  }
+
+  public boolean dropView(NameIdentifier ident) {
+    try {
+      icebergCatalogWrapper.dropView(
+          IcebergCatalogWrapperHelper.buildIcebergTableIdentifier(ident));
+      LOG.info("Dropped Iceberg view {}", ident);
+      return true;
+    } catch (org.apache.iceberg.exceptions.NoSuchViewException e) {
+      LOG.warn("Iceberg view {} does not exist, skip dropping", ident);
+      return false;
+    }
+  }
+
+  private View renameView(NameIdentifier ident, ViewChange.RenameView rename)
+      throws NoSuchViewException {
+    try {
+      RenameTableRequest request =
+          RenameTableRequest.builder()
+              
.withSource(IcebergCatalogWrapperHelper.buildIcebergTableIdentifier(ident))
+              .withDestination(
+                  IcebergCatalogWrapperHelper.buildIcebergTableIdentifier(
+                      ident.namespace(), rename.getNewName()))
+              .build();
+      icebergCatalogWrapper.renameView(request);
+      return loadView(
+          NameIdentifier.of(ArrayUtils.add(ident.namespace().levels(), 
rename.getNewName())));
+    } catch (org.apache.iceberg.exceptions.NoSuchViewException e) {
+      throw new NoSuchViewException(e, "Iceberg view %s does not exist", 
ident);
+    }
+  }
+
+  private View internalUpdateView(NameIdentifier ident, ViewChange... changes)
+      throws NoSuchViewException, IllegalArgumentException {
+    TableIdentifier viewId = 
IcebergCatalogWrapperHelper.buildIcebergTableIdentifier(ident);
+    try {
+      LoadViewResponse current = icebergCatalogWrapper.loadView(viewId);
+      ViewMetadata metadata = current.metadata();
+
+      List<MetadataUpdate> updates = new ArrayList<>();
+      Map<String, String> setProps = new HashMap<>();
+      Set<String> removeProps = new HashSet<>();
+      ViewChange.ReplaceView replace = null;
+
+      for (ViewChange change : changes) {
+        if (change instanceof ViewChange.SetProperty) {
+          ViewChange.SetProperty setProperty = (ViewChange.SetProperty) change;
+          String property = setProperty.getProperty();
+          setProps.put(property, setProperty.getValue());
+          removeProps.remove(property);
+        } else if (change instanceof ViewChange.RemoveProperty) {
+          String property = ((ViewChange.RemoveProperty) change).getProperty();
+          removeProps.add(property);
+          setProps.remove(property);
+        } else if (change instanceof ViewChange.ReplaceView) {
+          replace = (ViewChange.ReplaceView) change;
+        } else {
+          throw new IllegalArgumentException(
+              "Unsupported view change type: " + 
change.getClass().getSimpleName());
+        }
+      }
+
+      if (replace != null) {
+        setProps.put("replace.drop-dialect.allowed", "true");
+        if (replace.getComment() == null) {
+          removeProps.add("comment");
+          setProps.remove("comment");
+        } else {
+          setProps.put("comment", replace.getComment());
+          removeProps.remove("comment");
+        }
+        if (replace.getDefaultCatalog() == null) {
+          removeProps.add("default-catalog");
+          setProps.remove("default-catalog");
+        } else {
+          setProps.put("default-catalog", replace.getDefaultCatalog());
+          removeProps.remove("default-catalog");
+        }
+      }
+
+      if (!setProps.isEmpty()) {
+        updates.add(new MetadataUpdate.SetProperties(setProps));
+      }
+      if (!removeProps.isEmpty()) {
+        updates.add(new MetadataUpdate.RemoveProperties(removeProps));
+      }
+
+      if (replace != null) {
+        ViewVersion currentVersion = metadata.currentVersion();
+        List<ViewRepresentation> newRepresentations = new ArrayList<>();
+        for (Representation representation : replace.getRepresentations()) {
+          newRepresentations.add(toSqlViewRepresentation(representation));
+        }
+
+        int newVersionId = currentVersion != null ? currentVersion.versionId() 
+ 1 : 1;
+        int schemaId = currentVersion != null ? currentVersion.schemaId() : 0;
+        Schema replacementSchema = 
ConvertUtil.toIcebergSchema(replace.getColumns());
+        Optional<Schema> existingSchema =
+            metadata.schemas().stream()
+                .filter(schema -> schema.sameSchema(replacementSchema))
+                .findFirst();
+        if (existingSchema.isPresent()) {
+          schemaId = existingSchema.get().schemaId();
+        } else {
+          int newSchemaId =
+              
metadata.schemas().stream().mapToInt(Schema::schemaId).max().orElse(-1) + 1;
+          Schema newSchema =
+              new Schema(
+                  newSchemaId, replacementSchema.columns(), 
replacementSchema.identifierFieldIds());
+          updates.add(new MetadataUpdate.AddSchema(newSchema));
+          schemaId = newSchemaId;
+        }
+
+        org.apache.iceberg.catalog.Namespace defaultNamespace =
+            replace.getDefaultSchema() != null
+                ? 
IcebergCatalogWrapperHelper.getIcebergNamespace(replace.getDefaultSchema())
+                : (currentVersion != null
+                    ? currentVersion.defaultNamespace()
+                    : IcebergCatalogWrapperHelper.getIcebergNamespace(
+                        ident.namespace().level(ident.namespace().length() - 
1)));

Review Comment:
   The fallback default namespace also uses only the last namespace level from 
`ident`. This has the same truncation problem as create-view and can result in 
an incorrect default namespace for replaced views in multi-level namespaces. 
Use the full intended namespace instead of `level(length - 1)`.
   



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