Parse ON CLUSTER before column definitions in CREATE MATERIALIZED VIEW

ClickHouse allows ON CLUSTER to appear either before or after column
definitions in CREATE MATERIALIZED VIEW statements. The parser was only
checking after column definitions, causing parsing failures for syntax
like: CREATE MATERIALIZED VIEW v ON CLUSTER c (x Int) ENGINE=...

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: kyleconroy

parser/parser.go

@@ -2807,6 +2807,15 @@ func (p *Parser) parseCreateView(create *ast.CreateQuery) {
 		}
 	}
 
+	// Handle ON CLUSTER (can appear before or after column definitions)
+	if p.currentIs(token.ON) {
+		p.nextToken()
+		if p.currentIs(token.CLUSTER) {
+			p.nextToken()
+			create.OnCluster = p.parseIdentifierName()
+		}
+	}
+
 	// Parse column definitions (e.g., CREATE VIEW v (x UInt64) AS SELECT ...)
 	// For MATERIALIZED VIEW, this can also include INDEX, PROJECTION, and PRIMARY KEY
 	if p.currentIs(token.LPAREN) {
@@ -2850,8 +2859,8 @@ func (p *Parser) parseCreateView(create *ast.CreateQuery) {
 		p.expect(token.RPAREN)
 	}
 
-	// Handle ON CLUSTER
-	if p.currentIs(token.ON) {
+	// Handle ON CLUSTER (if it appears after column definitions instead of before)
+	if create.OnCluster == "" && p.currentIs(token.ON) {
 		p.nextToken()
 		if p.currentIs(token.CLUSTER) {
 			p.nextToken()

parser/testdata/03460_alter_materialized_view_on_cluster/metadata.json

@@ -1,5 +1 @@
-{
-  "explain_todo": {
-    "stmt6": true
-  }
-}
+{}