Fix: index using closes #1751

sqlglot/expressions.py

@@ -1500,6 +1500,7 @@ class Index(Expression):
     arg_types = {
         "this": False,
         "table": False,
+        "using": False,
         "where": False,
         "columns": False,
         "unique": False,

sqlglot/generator.py

@@ -885,11 +885,14 @@ def index_sql(self, expression: exp.Index) -> str:
         name = f"{expression.name} " if expression.name else ""
         table = self.sql(expression, "table")
         table = f"{self.INDEX_ON} {table} " if table else ""
+        using = self.sql(expression, "using")
+        using = f"USING {using} " if using else ""
         index = "INDEX " if not table else ""
         columns = self.expressions(expression, key="columns", flat=True)
+        columns = f"({columns})" if columns else ""
         partition_by = self.expressions(expression, key="partition_by", flat=True)
         partition_by = f" PARTITION BY {partition_by}" if partition_by else ""
-        return f"{unique}{primary}{amp}{index}{name}{table}({columns}){partition_by}"
+        return f"{unique}{primary}{amp}{index}{name}{table}{using}{columns}{partition_by}"
 
     def identifier_sql(self, expression: exp.Identifier) -> str:
         text = expression.name

sqlglot/parser.py

@@ -2248,6 +2248,8 @@ def _parse_index(
             index = self._parse_id_var()
             table = None
 
+        using = self._parse_field() if self._match(TokenType.USING) else None
+
         if self._match(TokenType.L_PAREN, advance=False):
             columns = self._parse_wrapped_csv(self._parse_ordered)
         else:
@@ -2257,6 +2259,7 @@ def _parse_index(
             exp.Index,
             this=index,
             table=table,
+            using=using,
             columns=columns,
             unique=unique,
             primary=primary,

tests/fixtures/identity.sql

@@ -601,6 +601,7 @@ CREATE FUNCTION a.b.c()
 CREATE INDEX abc ON t (a)
 CREATE INDEX abc ON t (a, b, b)
 CREATE INDEX abc ON t (a NULLS LAST)
+CREATE INDEX pointloc ON points USING GIST(BOX(location, location))
 CREATE UNIQUE INDEX abc ON t (a, b, b)
 CREATE UNIQUE INDEX IF NOT EXISTS my_idx ON tbl (a, b)
 CREATE SCHEMA x