From 3664868790fadc48f00ae65b15e682968f5a4e1d Mon Sep 17 00:00:00 2001
From: Boris Tyshkevich <btyshkevich@altinity.com>
Date: Thu, 24 Sep 2026 10:57:35 +0200
Subject: [PATCH] parser: recognize lowercase ARRAY JOIN as an expression list

---
 parser/altinity_array_join_test.go | 19 +++++++++++++++++++
 parser/parser_query.go             |  4 +++-
 2 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 parser/altinity_array_join_test.go

diff --git a/parser/altinity_array_join_test.go b/parser/altinity_array_join_test.go
new file mode 100644
index 0000000..2b43824
--- /dev/null
+++ b/parser/altinity_array_join_test.go
@@ -0,0 +1,19 @@
+package parser
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestLowercaseArrayJoinExpressionList(t *testing.T) {
+	for _, sql := range []string{
+		"SELECT 1 FROM t ARRAY JOIN arrayConcat(xs, [x]) AS ys",
+		"SELECT 1 FROM t array join arrayConcat(xs, [x]) AS ys",
+	} {
+		stmts, err := NewParser(sql).ParseStmts()
+		require.NoError(t, err)
+		require.Len(t, stmts, 1)
+		require.Equal(t, Format(stmts[0]), Format(parseOneStmt(t, Format(stmts[0]))))
+	}
+}
diff --git a/parser/parser_query.go b/parser/parser_query.go
index 41263f5..21cc57b 100644
--- a/parser/parser_query.go
+++ b/parser/parser_query.go
@@ -372,7 +372,9 @@ func (p *Parser) parseJoinRightExpr(pos Pos) (expr Expr, err error) {
 	modifiers = append(modifiers, KeywordJoin)
 
 	// Check if this is an ARRAY JOIN
-	if slices.Contains(modifiers, KeywordArray) {
+	if slices.ContainsFunc(modifiers, func(modifier string) bool {
+		return strings.EqualFold(modifier, KeywordArray)
+	}) {
 		// For ARRAY JOIN, parse column expression list instead of table expression
 		expr, err = p.parseColumnExprList(p.Pos())
 		if err != nil {