feat(mysql): parse hints on UPDATE and DELETE. (#7523)

MySQL allows optimizer hints (`/*+ ... */`) on all DML statements.
sqlglot parsed them on `SELECT` and `INSERT` but not `UPDATE` or
`DELETE`.

Author: burnison

sqlglot/expressions/dml.py

@@ -79,6 +79,7 @@ class Delete(Expression, DML):
         "limit": False,
         "tables": False,  # Multiple-Table Syntax (MySQL)
         "cluster": False,  # Clickhouse
+        "hint": False,
     }
 
     def delete(
@@ -301,6 +302,7 @@ class Update(Expression, DML):
         "order": False,
         "limit": False,
         "options": False,
+        "hint": False,
     }
 
     def table(

sqlglot/generator.py

@@ -1685,6 +1685,7 @@ def directory_sql(self, expression: exp.Directory) -> str:
         return f"{local}DIRECTORY {self.sql(expression, 'this')}{row_format}"
 
     def delete_sql(self, expression: exp.Delete) -> str:
+        hint = self.sql(expression, "hint")
         this = self.sql(expression, "this")
         this = f" FROM {this}" if this else ""
         using = self.expressions(expression, key="using")
@@ -1701,7 +1702,7 @@ def delete_sql(self, expression: exp.Delete) -> str:
             expression_sql = f"{this}{using}{cluster}{where}{returning}{order}{limit}"
         else:
             expression_sql = f"{returning}{this}{using}{cluster}{where}{order}{limit}"
-        return self.prepend_ctes(expression, f"DELETE{tables}{expression_sql}")
+        return self.prepend_ctes(expression, f"DELETE{hint}{tables}{expression_sql}")
 
     def drop_sql(self, expression: exp.Drop) -> str:
         this = self.sql(expression, "this")
@@ -2467,6 +2468,7 @@ def _update_from_joins_sql(self, expression: exp.Update) -> tuple[str, str]:
         return (join_sql, "")
 
     def update_sql(self, expression: exp.Update) -> str:
+        hint = self.sql(expression, "hint")
         this = self.sql(expression, "this")
         join_sql, from_sql = self._update_from_joins_sql(expression)
         set_sql = self.expressions(expression, flat=True)
@@ -2480,7 +2482,7 @@ def update_sql(self, expression: exp.Update) -> str:
             expression_sql = f"{returning}{from_sql}{where_sql}"
         options = self.expressions(expression, key="options")
         options = f" OPTION({options})" if options else ""
-        sql = f"UPDATE {this}{join_sql} SET {set_sql}{expression_sql}{order}{limit}{options}"
+        sql = f"UPDATE{hint} {this}{join_sql} SET {set_sql}{expression_sql}{order}{limit}{options}"
         return self.prepend_ctes(expression, sql)
 
     def values_sql(self, expression: exp.Values, values_as_table: bool = True) -> str:

sqlglot/parser.py

@@ -3580,6 +3580,8 @@ def _parse_load(self) -> exp.LoadData | exp.Command:
         return self._parse_as_command(self._prev)
 
     def _parse_delete(self) -> exp.Delete:
+        hint = self._parse_hint()
+
         # This handles MySQL's "Multiple-Table Syntax"
         # https://dev.mysql.com/doc/refman/8.0/en/delete.html
         tables = None
@@ -3590,6 +3592,7 @@ def _parse_delete(self) -> exp.Delete:
 
         return self.expression(
             exp.Delete(
+                hint=hint,
                 tables=tables,
                 this=self._match(TokenType.FROM) and self._parse_table(joins=True),
                 using=self._match(TokenType.USING)
@@ -3603,7 +3606,9 @@ def _parse_delete(self) -> exp.Delete:
         )
 
     def _parse_update(self) -> exp.Update:
+        hint = self._parse_hint()
         kwargs: dict[str, object] = {
+            "hint": hint,
             "this": self._parse_table(joins=True, alias_tokens=self.UPDATE_ALIAS_TOKENS),
         }
         while self._curr:

tests/dialects/test_mysql.py

@@ -22,7 +22,9 @@ def test_ddl(self):
         self.validate_identity("CREATE TABLE 00f (1d BIGINT)")
         self.validate_identity("CREATE TABLE temp (id SERIAL PRIMARY KEY)")
         self.validate_identity("UPDATE items SET items.price = 0 WHERE items.id >= 5 LIMIT 10")
+        self.validate_identity("UPDATE /*+ MAX_EXECUTION_TIME(1) */ t SET a = 1")
         self.validate_identity("DELETE FROM t WHERE a <= 10 LIMIT 10")
+        self.validate_identity("DELETE /*+ MAX_EXECUTION_TIME(1) */ FROM t WHERE a = 1")
         self.validate_identity("DELETE FROM t FORCE INDEX (idx) WHERE a > 5 ORDER BY id")
         self.validate_identity("CREATE TABLE foo (a BIGINT, INDEX USING BTREE (b))")
         self.validate_identity("CREATE TABLE foo (a BIGINT, FULLTEXT INDEX (b))")