Add IF NOT EXISTS to CREATE VIEW

Author: liianghuang

core/trino-grammar/src/main/antlr4/io/trino/grammar/sql/SqlBase.g4

@@ -109,7 +109,8 @@ statement
         (WHEN STALE (INLINE | FAIL))?
         (COMMENT string)?
         (WITH properties)? AS rootQuery                                #createMaterializedView
-    | CREATE (OR REPLACE)? VIEW qualifiedName
+    | CREATE (OR REPLACE)? VIEW
+        (IF NOT EXISTS)? qualifiedName
         (COMMENT string)?
         (SECURITY (DEFINER | INVOKER))?
         (WITH properties)? AS rootQuery                                #createView

core/trino-main/src/main/java/io/trino/execution/CreateViewTask.java

@@ -25,6 +25,7 @@
 import io.trino.metadata.ViewDefinition;
 import io.trino.metadata.ViewPropertyManager;
 import io.trino.security.AccessControl;
+import io.trino.spi.connector.SaveMode;
 import io.trino.spi.security.Identity;
 import io.trino.sql.PlannerContext;
 import io.trino.sql.analyzer.Analysis;
@@ -99,9 +100,12 @@ public ListenableFuture<Void> execute(
             throw semanticException(TABLE_ALREADY_EXISTS, statement, "Materialized view already exists: '%s'", name);
         }
         if (metadata.isView(session, name)) {
-            if (!statement.isReplace()) {
+            if (!statement.isReplace() && !statement.isNotExists()) {
                 throw semanticException(TABLE_ALREADY_EXISTS, statement, "View already exists: '%s'", name);
             }
+            if (statement.isNotExists()) {
+                return immediateVoidFuture();
+            }
         }
         else if (metadata.getTableHandle(session, name).isPresent()) {
             throw semanticException(TABLE_ALREADY_EXISTS, statement, "Table already exists: '%s'", name);
@@ -148,11 +152,20 @@ else if (metadata.getTableHandle(session, name).isPresent()) {
                         .filter(element -> !element.getCatalogName().equals(GlobalSystemConnector.NAME))
                         .collect(toImmutableList()));
 
-        metadata.createView(session, name, definition, properties, statement.isReplace());
+        metadata.createView(session, name, definition, properties, toConnectorSaveMode(statement.getSaveMode()));
 
         stateMachine.setOutput(analysis.getTarget());
         stateMachine.setReferencedTables(analysis.getReferencedTables());
 
         return immediateVoidFuture();
     }
+
+    private static SaveMode toConnectorSaveMode(io.trino.sql.tree.SaveMode saveMode)
+    {
+        return switch (saveMode) {
+            case FAIL -> SaveMode.FAIL;
+            case IGNORE -> SaveMode.IGNORE;
+            case REPLACE -> SaveMode.REPLACE;
+        };
+    }
 }

core/trino-main/src/main/java/io/trino/metadata/Metadata.java

@@ -548,7 +548,7 @@ Optional<ConnectorOutputMetadata> finishRefreshMaterializedView(
     /**
      * Creates the specified view with the specified view definition.
      */
-    void createView(Session session, QualifiedObjectName viewName, ViewDefinition definition, Map<String, Object> properties, boolean replace);
+    void createView(Session session, QualifiedObjectName viewName, ViewDefinition definition, Map<String, Object> properties, SaveMode saveMode);
 
     /**
      * Rename the specified view.

core/trino-main/src/main/java/io/trino/metadata/MetadataManager.java

@@ -1670,13 +1670,13 @@ private Optional<ConnectorViewDefinition> getViewInternal(Session session, Quali
     }
 
     @Override
-    public void createView(Session session, QualifiedObjectName viewName, ViewDefinition definition, Map<String, Object> viewProperties, boolean replace)
+    public void createView(Session session, QualifiedObjectName viewName, ViewDefinition definition, Map<String, Object> viewProperties, SaveMode saveMode)
     {
         CatalogMetadata catalogMetadata = getCatalogMetadataForWrite(session, viewName.catalogName());
         CatalogHandle catalogHandle = catalogMetadata.getCatalogHandle();
         ConnectorMetadata metadata = catalogMetadata.getMetadata(session);
 
-        metadata.createView(session.toConnectorSession(catalogHandle), viewName.asSchemaTableName(), definition.toConnectorViewDefinition(), viewProperties, replace);
+        metadata.createView(session.toConnectorSession(catalogHandle), viewName.asSchemaTableName(), definition.toConnectorViewDefinition(), viewProperties, saveMode);
         if (catalogMetadata.getSecurityManagement() == SYSTEM) {
             systemSecurityMetadata.tableCreated(session, viewName.asCatalogSchemaTableName());
         }

core/trino-main/src/main/java/io/trino/sql/analyzer/StatementAnalyzer.java

@@ -1064,6 +1064,9 @@ protected Scope visitCreateView(CreateView node, Optional<Scope> scope)
         {
             QualifiedObjectName viewName = createQualifiedObjectName(session, node, node.getName());
 
+            if (node.isReplace() && node.isNotExists()) {
+                throw semanticException(NOT_SUPPORTED, node, "'CREATE OR REPLACE' and 'IF NOT EXISTS' clauses can not be used together");
+            }
             node.getQuery().getFunctions().stream().findFirst().ifPresent(function -> {
                 throw semanticException(NOT_SUPPORTED, function, "Views cannot contain inline functions");
             });

core/trino-main/src/main/java/io/trino/sql/rewrite/ShowQueriesRewrite.java

@@ -83,6 +83,7 @@
 import io.trino.sql.tree.QuerySpecification;
 import io.trino.sql.tree.Relation;
 import io.trino.sql.tree.Row;
+import io.trino.sql.tree.SaveMode;
 import io.trino.sql.tree.SelectItem;
 import io.trino.sql.tree.ShowBranches;
 import io.trino.sql.tree.ShowCatalogs;
@@ -614,7 +615,7 @@ private Query showCreateView(ShowCreate node)
                     node.getLocation().orElseThrow(),
                     QualifiedName.of(ImmutableList.of(catalogName, schemaName, tableName)),
                     query,
-                    false,
+                    SaveMode.FAIL,
                     viewDefinition.get().getComment(),
                     Optional.of(security),
                     propertyNodes))

core/trino-main/src/main/java/io/trino/testing/TestingMetadata.java

@@ -205,10 +205,10 @@ public void dropTable(ConnectorSession session, ConnectorTableHandle tableHandle
     }
 
     @Override
-    public void createView(ConnectorSession session, SchemaTableName viewName, ConnectorViewDefinition definition, Map<String, Object> viewProperties, boolean replace)
+    public void createView(ConnectorSession session, SchemaTableName viewName, ConnectorViewDefinition definition, Map<String, Object> viewProperties, SaveMode saveMode)
     {
         checkArgument(viewProperties.isEmpty(), "This connector does not support creating views with properties");
-        if (replace) {
+        if (saveMode == saveMode.REPLACE) {
             views.put(viewName, definition);
         }
         else if (views.putIfAbsent(viewName, definition) != null) {

core/trino-main/src/main/java/io/trino/tracing/TracingConnectorMetadata.java

@@ -802,11 +802,11 @@ public void finishMerge(ConnectorSession session, ConnectorMergeTableHandle tabl
     }
 
     @Override
-    public void createView(ConnectorSession session, SchemaTableName viewName, ConnectorViewDefinition definition, Map<String, Object> viewProperties, boolean replace)
+    public void createView(ConnectorSession session, SchemaTableName viewName, ConnectorViewDefinition definition, Map<String, Object> viewProperties, SaveMode saveMode)
     {
         Span span = startSpan("createView", viewName);
         try (var _ = scopedSpan(span)) {
-            delegate.createView(session, viewName, definition, viewProperties, replace);
+            delegate.createView(session, viewName, definition, viewProperties, saveMode);
         }
     }
 

core/trino-main/src/main/java/io/trino/tracing/TracingMetadata.java

@@ -992,11 +992,11 @@ public Optional<TrinoPrincipal> getSchemaOwner(Session session, CatalogSchemaNam
     }
 
     @Override
-    public void createView(Session session, QualifiedObjectName viewName, ViewDefinition definition, Map<String, Object> properties, boolean replace)
+    public void createView(Session session, QualifiedObjectName viewName, ViewDefinition definition, Map<String, Object> properties, SaveMode saveMode)
     {
         Span span = startSpan("createView", viewName);
         try (var _ = scopedSpan(span)) {
-            delegate.createView(session, viewName, definition, properties, replace);
+            delegate.createView(session, viewName, definition, properties, saveMode);
         }
     }
 

core/trino-main/src/test/java/io/trino/connector/MockConnector.java

@@ -711,7 +711,7 @@ public void renameField(ConnectorSession session, ConnectorTableHandle tableHand
         public void dropColumn(ConnectorSession session, ConnectorTableHandle tableHandle, ColumnHandle column) {}
 
         @Override
-        public void createView(ConnectorSession session, SchemaTableName viewName, ConnectorViewDefinition definition, Map<String, Object> viewProperties, boolean replace) {}
+        public void createView(ConnectorSession session, SchemaTableName viewName, ConnectorViewDefinition definition, Map<String, Object> viewProperties, SaveMode saveMode) {}
 
         @Override
         public void renameView(ConnectorSession session, SchemaTableName source, SchemaTableName target) {}