Add support for SETTINGS clause in ALTER TABLE ADD COLUMN (#232)

Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: Lance726

parser/ast.go

@@ -605,13 +605,17 @@ type AlterTableAddColumn struct {
 	Column      *ColumnDef
 	IfNotExists bool
 	After       *NestedIdentifier
+	Settings    *SettingsClause
 }
 
 func (a *AlterTableAddColumn) Pos() Pos {
 	return a.AddPos
 }
 
 func (a *AlterTableAddColumn) End() Pos {
+	if a.Settings != nil {
+		return a.Settings.End()
+	}
 	return a.StatementEnd
 }
 
@@ -622,14 +626,18 @@ func (a *AlterTableAddColumn) AlterType() string {
 func (a *AlterTableAddColumn) String() string {
 	var builder strings.Builder
 	builder.WriteString("ADD COLUMN ")
-	builder.WriteString(a.Column.String())
 	if a.IfNotExists {
 		builder.WriteString("IF NOT EXISTS ")
 	}
+	builder.WriteString(a.Column.String())
 	if a.After != nil {
 		builder.WriteString(" AFTER ")
 		builder.WriteString(a.After.String())
 	}
+	if a.Settings != nil {
+		builder.WriteByte(' ')
+		builder.WriteString(a.Settings.String())
+	}
 	return builder.String()
 }
 
@@ -644,6 +652,11 @@ func (a *AlterTableAddColumn) Accept(visitor ASTVisitor) error {
 			return err
 		}
 	}
+	if a.Settings != nil {
+		if err := a.Settings.Accept(visitor); err != nil {
+			return err
+		}
+	}
 	return visitor.VisitAlterTableAddColumn(a)
 }
 

parser/parser_alter.go

@@ -117,12 +117,21 @@ func (p *Parser) parseAlterTableAddColumn(pos Pos) (*AlterTableAddColumn, error)
 		statementEnd = after.End()
 	}
 
+	settings, err := p.tryParseSettingsClause(p.Pos())
+	if err != nil {
+		return nil, err
+	}
+	if settings != nil {
+		statementEnd = settings.End()
+	}
+
 	return &AlterTableAddColumn{
 		AddPos:       pos,
 		StatementEnd: statementEnd,
 		Column:       column,
 		IfNotExists:  ifNotExists,
 		After:        after,
+		Settings:     settings,
 	}, nil
 }
 

parser/testdata/ddl/alter_table_add_column.sql

@@ -1 +1 @@
-ALTER TABLE test.events_local ON CLUSTER 'default_cluster' ADD COLUMN f1 String AFTER f0;
+ALTER TABLE test.events_local ON CLUSTER 'default_cluster' ADD COLUMN f1 String AFTER f0 SETTINGS alter_sync = 2;

parser/testdata/ddl/format/alter_table_add_column.sql

@@ -1,6 +1,6 @@
 -- Origin SQL:
-ALTER TABLE test.events_local ON CLUSTER 'default_cluster' ADD COLUMN f1 String AFTER f0;
+ALTER TABLE test.events_local ON CLUSTER 'default_cluster' ADD COLUMN f1 String AFTER f0 SETTINGS alter_sync = 2;
 
 
 -- Format SQL:
-ALTER TABLE test.events_local ON CLUSTER 'default_cluster' ADD COLUMN f1 String AFTER f0;
+ALTER TABLE test.events_local ON CLUSTER 'default_cluster' ADD COLUMN f1 String AFTER f0 SETTINGS alter_sync=2;

parser/testdata/ddl/output/alter_table_add_column.sql.golden.json

@@ -1,7 +1,7 @@
 [
   {
     "AlterPos": 0,
-    "StatementEnd": 88,
+    "StatementEnd": 112,
     "TableIdentifier": {
       "Database": {
         "Name": "test",
@@ -27,7 +27,7 @@
     "AlterExprs": [
       {
         "AddPos": 59,
-        "StatementEnd": 88,
+        "StatementEnd": 112,
         "Column": {
           "NamePos": 70,
           "ColumnEnd": 79,
@@ -67,6 +67,27 @@
             "NameEnd": 88
           },
           "DotIdent": null
+        },
+        "Settings": {
+          "SettingsPos": 89,
+          "ListEnd": 112,
+          "Items": [
+            {
+              "SettingsPos": 98,
+              "Name": {
+                "Name": "alter_sync",
+                "QuoteType": 1,
+                "NamePos": 98,
+                "NameEnd": 108
+              },
+              "Expr": {
+                "NumPos": 111,
+                "NumEnd": 112,
+                "Literal": "2",
+                "Base": 10
+              }
+            }
+          ]
         }
       }
     ]

parser/testdata/dml/output/alter_table_with_comment.sql.golden.json

@@ -72,7 +72,8 @@
           "CompressionCodec": null
         },
         "IfNotExists": false,
-        "After": null
+        "After": null,
+        "Settings": null
       }
     ]
   },
@@ -140,7 +141,8 @@
           "CompressionCodec": null
         },
         "IfNotExists": false,
-        "After": null
+        "After": null,
+        "Settings": null
       }
     ]
   }

parser/walk.go

@@ -831,6 +831,9 @@ func Walk(node Expr, fn WalkFunc) bool {
 		if !Walk(n.After, fn) {
 			return false
 		}
+		if !Walk(n.Settings, fn) {
+			return false
+		}
 	case *AlterTableAddIndex:
 		if !Walk(n.Index, fn) {
 			return false