Add IF EXISTS and IF NOT EXISTS checks to ALTER TABLE

presto-docs/src/main/sphinx/sql/alter-table.rst

@@ -7,35 +7,57 @@ Synopsis
 
 .. code-block:: none
 
-    ALTER TABLE name RENAME TO new_name
-    ALTER TABLE name ADD COLUMN column_name data_type [ COMMENT comment ] [ WITH ( property_name = expression [, ...] ) ]
-    ALTER TABLE name DROP COLUMN column_name
-    ALTER TABLE name RENAME COLUMN column_name TO new_column_name
+    ALTER TABLE [ IF EXISTS ] name RENAME TO new_name
+    ALTER TABLE [ IF EXISTS ] name ADD COLUMN [ IF NOT EXISTS ] column_name data_type [ COMMENT comment ] [ WITH ( property_name = expression [, ...] ) ]
+    ALTER TABLE [ IF EXISTS ] name DROP COLUMN column_name
+    ALTER TABLE [ IF EXISTS ] name RENAME COLUMN [ IF EXISTS ] column_name TO new_column_name
 
 Description
 -----------
 
 Change the definition of an existing table.
 
+The optional ``IF EXISTS`` (when used before the table name) clause causes the error to be suppressed if the table does not exists.
+
+The optional ``IF EXISTS`` (when used before the column name) clause causes the error to be suppressed if the column does not exists.
+
+The optional ``IF NOT EXISTS`` clause causes the error to be suppressed if the column already exists.
+
 Examples
 --------
 
 Rename table ``users`` to ``people``::
 
     ALTER TABLE users RENAME TO people;
 
+Rename table ``users`` to ``people`` if table ``users`` exists::
+
+    ALTER TABLE IF EXISTS users RENAME TO people;
+
 Add column ``zip`` to the ``users`` table::
 
     ALTER TABLE users ADD COLUMN zip varchar;
 
+Add column ``zip`` to the ``users`` table if table ``users`` exists and column ``zip`` not already exists::
+
+    ALTER TABLE IF EXISTS users ADD COLUMN IF NOT EXISTS zip varchar;
+
 Drop column ``zip`` from the ``users`` table::
 
     ALTER TABLE users DROP COLUMN zip;
 
+Drop column ``zip`` from the ``users`` table if table ``users`` and column ``zip`` exists::
+
+    ALTER TABLE IF EXISTS users DROP COLUMN IF EXISTS zip;
+
 Rename column ``id`` to ``user_id`` in the ``users`` table::
 
     ALTER TABLE users RENAME COLUMN id TO user_id;
 
+Rename column ``id`` to ``user_id`` in the ``users`` table if table ``users`` and column ``id`` exists::
+
+    ALTER TABLE IF EXISTS users RENAME column IF EXISTS id to user_id;
+
 See Also
 --------
 

presto-main/src/main/java/com/facebook/presto/execution/AddColumnTask.java

@@ -63,7 +63,10 @@ public ListenableFuture<?> execute(AddColumn statement, TransactionManager trans
         QualifiedObjectName tableName = createQualifiedObjectName(session, statement, statement.getName());
         Optional<TableHandle> tableHandle = metadata.getTableHandle(session, tableName);
         if (!tableHandle.isPresent()) {
-            throw new SemanticException(MISSING_TABLE, statement, "Table '%s' does not exist", tableName);
+            if (!statement.isTableExists()) {
+                throw new SemanticException(MISSING_TABLE, statement, "Table '%s' does not exist", tableName);
+            }
+            return immediateFuture(null);
         }
 
         ConnectorId connectorId = metadata.getCatalogHandle(session, tableName.getCatalogName())
@@ -85,7 +88,10 @@ public ListenableFuture<?> execute(AddColumn statement, TransactionManager trans
             throw new SemanticException(TYPE_MISMATCH, element, "Unknown type '%s' for column '%s'", element.getType(), element.getName());
         }
         if (columnHandles.containsKey(element.getName().getValue().toLowerCase(ENGLISH))) {
-            throw new SemanticException(COLUMN_ALREADY_EXISTS, statement, "Column '%s' already exists", element.getName());
+            if (!statement.isColumnNotExists()) {
+                throw new SemanticException(COLUMN_ALREADY_EXISTS, statement, "Column '%s' already exists", element.getName());
+            }
+            return immediateFuture(null);
         }
         if (!element.isNullable() && !metadata.getConnectorCapabilities(session, connectorId).contains(NOT_NULL_COLUMN_CONSTRAINT)) {
             throw new SemanticException(NOT_SUPPORTED, element, "Catalog '%s' does not support NOT NULL for column '%s'", connectorId.getCatalogName(), element.getName());

presto-main/src/main/java/com/facebook/presto/execution/DropColumnTask.java

@@ -26,6 +26,7 @@
 import com.google.common.util.concurrent.ListenableFuture;
 
 import java.util.List;
+import java.util.Optional;
 
 import static com.facebook.presto.metadata.MetadataUtil.createQualifiedObjectName;
 import static com.facebook.presto.sql.analyzer.SemanticErrorCode.MISSING_COLUMN;
@@ -48,16 +49,26 @@ public ListenableFuture<?> execute(DropColumn statement, TransactionManager tran
     {
         Session session = stateMachine.getSession();
         QualifiedObjectName tableName = createQualifiedObjectName(session, statement, statement.getTable());
-        TableHandle tableHandle = metadata.getTableHandle(session, tableName)
-                .orElseThrow(() -> new SemanticException(MISSING_TABLE, statement, "Table '%s' does not exist", tableName));
+        Optional<TableHandle> tableHandleOptional = metadata.getTableHandle(session, tableName);
+
+        if (!tableHandleOptional.isPresent()) {
+            if (!statement.isTableExists()) {
+                throw new SemanticException(MISSING_TABLE, statement, "Table '%s' does not exist", tableName);
+            }
+            return immediateFuture(null);
+        }
+        TableHandle tableHandle = tableHandleOptional.get();
 
         String column = statement.getColumn().getValue().toLowerCase(ENGLISH);
 
         accessControl.checkCanDropColumn(session.getRequiredTransactionId(), session.getIdentity(), session.getAccessControlContext(), tableName);
 
         ColumnHandle columnHandle = metadata.getColumnHandles(session, tableHandle).get(column);
         if (columnHandle == null) {
-            throw new SemanticException(MISSING_COLUMN, statement, "Column '%s' does not exist", column);
+            if (!statement.isColumnExists()) {
+                throw new SemanticException(MISSING_COLUMN, statement, "Column '%s' does not exist", column);
+            }
+            return immediateFuture(null);
         }
 
         if (metadata.getColumnMetadata(session, tableHandle, columnHandle).isHidden()) {

presto-main/src/main/java/com/facebook/presto/execution/RenameColumnTask.java

@@ -27,6 +27,7 @@
 
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 
 import static com.facebook.presto.metadata.MetadataUtil.createQualifiedObjectName;
 import static com.facebook.presto.sql.analyzer.SemanticErrorCode.COLUMN_ALREADY_EXISTS;
@@ -50,8 +51,14 @@ public ListenableFuture<?> execute(RenameColumn statement, TransactionManager tr
     {
         Session session = stateMachine.getSession();
         QualifiedObjectName tableName = createQualifiedObjectName(session, statement, statement.getTable());
-        TableHandle tableHandle = metadata.getTableHandle(session, tableName)
-                .orElseThrow(() -> new SemanticException(MISSING_TABLE, statement, "Table '%s' does not exist", tableName));
+        Optional<TableHandle> tableHandleOptional = metadata.getTableHandle(session, tableName);
+        if (!tableHandleOptional.isPresent()) {
+            if (!statement.isTableExists()) {
+                throw new SemanticException(MISSING_TABLE, statement, "Table '%s' does not exist", tableName);
+            }
+            return immediateFuture(null);
+        }
+        TableHandle tableHandle = tableHandleOptional.get();
 
         String source = statement.getSource().getValue().toLowerCase(ENGLISH);
         String target = statement.getTarget().getValue().toLowerCase(ENGLISH);
@@ -61,7 +68,10 @@ public ListenableFuture<?> execute(RenameColumn statement, TransactionManager tr
         Map<String, ColumnHandle> columnHandles = metadata.getColumnHandles(session, tableHandle);
         ColumnHandle columnHandle = columnHandles.get(source);
         if (columnHandle == null) {
-            throw new SemanticException(MISSING_COLUMN, statement, "Column '%s' does not exist", source);
+            if (!statement.isColumnExists()) {
+                throw new SemanticException(MISSING_COLUMN, statement, "Column '%s' does not exist", source);
+            }
+            return immediateFuture(null);
         }
 
         if (columnHandles.containsKey(target)) {

presto-main/src/main/java/com/facebook/presto/execution/RenameTableTask.java

@@ -50,7 +50,10 @@ public ListenableFuture<?> execute(RenameTable statement, TransactionManager tra
         QualifiedObjectName tableName = createQualifiedObjectName(session, statement, statement.getSource());
         Optional<TableHandle> tableHandle = metadata.getTableHandle(session, tableName);
         if (!tableHandle.isPresent()) {
-            throw new SemanticException(MISSING_TABLE, statement, "Table '%s' does not exist", tableName);
+            if (!statement.isExists()) {
+                throw new SemanticException(MISSING_TABLE, statement, "Table '%s' does not exist", tableName);
+            }
+            return immediateFuture(null);
         }
 
         QualifiedObjectName target = createQualifiedObjectName(session, statement, statement.getTarget());

presto-parser/src/main/antlr4/com/facebook/presto/sql/parser/SqlBase.g4

@@ -49,13 +49,14 @@ statement
     | DROP TABLE (IF EXISTS)? qualifiedName                            #dropTable
     | INSERT INTO qualifiedName columnAliases? query                   #insertInto
     | DELETE FROM qualifiedName (WHERE booleanExpression)?             #delete
-    | ALTER TABLE from=qualifiedName RENAME TO to=qualifiedName        #renameTable
-    | ALTER TABLE tableName=qualifiedName
-        RENAME COLUMN from=identifier TO to=identifier                 #renameColumn
-    | ALTER TABLE tableName=qualifiedName
-        DROP COLUMN column=qualifiedName                               #dropColumn
-    | ALTER TABLE tableName=qualifiedName
-        ADD COLUMN column=columnDefinition                             #addColumn
+    | ALTER TABLE (IF EXISTS)? from=qualifiedName
+        RENAME TO to=qualifiedName                                     #renameTable
+    | ALTER TABLE (IF EXISTS)? tableName=qualifiedName
+        RENAME COLUMN (IF EXISTS)? from=identifier TO to=identifier    #renameColumn
+    | ALTER TABLE (IF EXISTS)? tableName=qualifiedName
+        DROP COLUMN (IF EXISTS)? column=qualifiedName                  #dropColumn
+    | ALTER TABLE (IF EXISTS)? tableName=qualifiedName
+        ADD COLUMN (IF NOT EXISTS)? column=columnDefinition            #addColumn
     | ANALYZE qualifiedName (WITH properties)?                         #analyze
     | CREATE (OR REPLACE)? VIEW qualifiedName
             (SECURITY (DEFINER | INVOKER))? AS query                       #createView

presto-parser/src/main/java/com/facebook/presto/sql/SqlFormatter.java

@@ -1067,8 +1067,11 @@ protected Void visitDropTable(DropTable node, Integer context)
         @Override
         protected Void visitRenameTable(RenameTable node, Integer context)
         {
-            builder.append("ALTER TABLE ")
-                    .append(node.getSource())
+            builder.append("ALTER TABLE ");
+            if (node.isExists()) {
+                builder.append("IF EXISTS ");
+            }
+            builder.append(node.getSource())
                     .append(" RENAME TO ")
                     .append(node.getTarget());
 
@@ -1078,10 +1081,16 @@ protected Void visitRenameTable(RenameTable node, Integer context)
         @Override
         protected Void visitRenameColumn(RenameColumn node, Integer context)
         {
-            builder.append("ALTER TABLE ")
-                    .append(node.getTable())
-                    .append(" RENAME COLUMN ")
-                    .append(node.getSource())
+            builder.append("ALTER TABLE ");
+            if (node.isTableExists()) {
+                builder.append("IF EXISTS ");
+            }
+            builder.append(node.getTable())
+                    .append(" RENAME COLUMN ");
+            if (node.isColumnExists()) {
+                builder.append("IF EXISTS ");
+            }
+            builder.append(node.getSource())
                     .append(" TO ")
                     .append(node.getTarget());
 
@@ -1091,10 +1100,16 @@ protected Void visitRenameColumn(RenameColumn node, Integer context)
         @Override
         protected Void visitDropColumn(DropColumn node, Integer context)
         {
-            builder.append("ALTER TABLE ")
-                    .append(formatName(node.getTable()))
-                    .append(" DROP COLUMN ")
-                    .append(formatExpression(node.getColumn(), parameters));
+            builder.append("ALTER TABLE ");
+            if (node.isTableExists()) {
+                builder.append("IF EXISTS ");
+            }
+            builder.append(formatName(node.getTable()))
+                    .append(" DROP COLUMN ");
+            if (node.isColumnExists()) {
+                builder.append("IF EXISTS ");
+            }
+            builder.append(formatExpression(node.getColumn(), parameters));
 
             return null;
         }
@@ -1111,10 +1126,16 @@ protected Void visitAnalyze(Analyze node, Integer context)
         @Override
         protected Void visitAddColumn(AddColumn node, Integer indent)
         {
-            builder.append("ALTER TABLE ")
-                    .append(node.getName())
-                    .append(" ADD COLUMN ")
-                    .append(formatColumnDefinition(node.getColumn()));
+            builder.append("ALTER TABLE ");
+            if (node.isTableExists()) {
+                builder.append("IF EXISTS ");
+            }
+            builder.append(node.getName())
+                    .append(" ADD COLUMN ");
+            if (node.isColumnNotExists()) {
+                builder.append("IF NOT EXISTS ");
+            }
+            builder.append(formatColumnDefinition(node.getColumn()));
 
             return null;
         }

presto-parser/src/main/java/com/facebook/presto/sql/parser/AstBuilder.java

@@ -372,7 +372,7 @@ public Node visitDelete(SqlBaseParser.DeleteContext context)
     @Override
     public Node visitRenameTable(SqlBaseParser.RenameTableContext context)
     {
-        return new RenameTable(getLocation(context), getQualifiedName(context.from), getQualifiedName(context.to));
+        return new RenameTable(getLocation(context), getQualifiedName(context.from), getQualifiedName(context.to), context.EXISTS() != null);
     }
 
     @Override
@@ -382,7 +382,9 @@ public Node visitRenameColumn(SqlBaseParser.RenameColumnContext context)
                 getLocation(context),
                 getQualifiedName(context.tableName),
                 (Identifier) visit(context.from),
-                (Identifier) visit(context.to));
+                (Identifier) visit(context.to),
+                context.EXISTS().stream().anyMatch(node -> node.getSymbol().getTokenIndex() < context.COLUMN().getSymbol().getTokenIndex()),
+                context.EXISTS().stream().anyMatch(node -> node.getSymbol().getTokenIndex() > context.COLUMN().getSymbol().getTokenIndex()));
     }
 
     @Override
@@ -401,13 +403,21 @@ public Node visitAnalyze(SqlBaseParser.AnalyzeContext context)
     @Override
     public Node visitAddColumn(SqlBaseParser.AddColumnContext context)
     {
-        return new AddColumn(getLocation(context), getQualifiedName(context.qualifiedName()), (ColumnDefinition) visit(context.columnDefinition()));
+        return new AddColumn(getLocation(context),
+                getQualifiedName(context.qualifiedName()),
+                (ColumnDefinition) visit(context.columnDefinition()),
+                context.EXISTS().stream().anyMatch(node -> node.getSymbol().getTokenIndex() < context.COLUMN().getSymbol().getTokenIndex()),
+                context.EXISTS().stream().anyMatch(node -> node.getSymbol().getTokenIndex() > context.COLUMN().getSymbol().getTokenIndex()));
     }
 
     @Override
     public Node visitDropColumn(SqlBaseParser.DropColumnContext context)
     {
-        return new DropColumn(getLocation(context), getQualifiedName(context.tableName), (Identifier) visit(context.column));
+        return new DropColumn(getLocation(context),
+                getQualifiedName(context.tableName),
+                (Identifier) visit(context.column),
+                context.EXISTS().stream().anyMatch(node -> node.getSymbol().getTokenIndex() < context.COLUMN().getSymbol().getTokenIndex()),
+                context.EXISTS().stream().anyMatch(node -> node.getSymbol().getTokenIndex() > context.COLUMN().getSymbol().getTokenIndex()));
     }
 
     @Override

presto-parser/src/main/java/com/facebook/presto/sql/tree/AddColumn.java

@@ -27,22 +27,27 @@ public class AddColumn
 {
     private final QualifiedName name;
     private final ColumnDefinition column;
+    private final boolean tableExists;
+    private final boolean columnNotExists;
+
+    public AddColumn(QualifiedName name, ColumnDefinition column, boolean tableExists, boolean columnNotExists)
 
-    public AddColumn(QualifiedName name, ColumnDefinition column)
     {
-        this(Optional.empty(), name, column);
+        this(Optional.empty(), name, column, tableExists, columnNotExists);
     }
 
-    public AddColumn(NodeLocation location, QualifiedName name, ColumnDefinition column)
+    public AddColumn(NodeLocation location, QualifiedName name, ColumnDefinition column, boolean tableExists, boolean columnNotExists)
     {
-        this(Optional.of(location), name, column);
+        this(Optional.of(location), name, column, tableExists, columnNotExists);
     }
 
-    private AddColumn(Optional<NodeLocation> location, QualifiedName name, ColumnDefinition column)
+    private AddColumn(Optional<NodeLocation> location, QualifiedName name, ColumnDefinition column, boolean tableExists, boolean columnNotExists)
     {
         super(location);
         this.name = requireNonNull(name, "table is null");
         this.column = requireNonNull(column, "column is null");
+        this.tableExists = tableExists;
+        this.columnNotExists = columnNotExists;
     }
 
     public QualifiedName getName()
@@ -55,6 +60,16 @@ public ColumnDefinition getColumn()
         return column;
     }
 
+    public boolean isTableExists()
+    {
+        return tableExists;
+    }
+
+    public boolean isColumnNotExists()
+    {
+        return columnNotExists;
+    }
+
     @Override
     public <R, C> R accept(AstVisitor<R, C> visitor, C context)
     {