Update 1.1-overview.md

docs/MatrixOne/Develop/schema-design/1.1-overview.md

@@ -26,10 +26,9 @@ An index is a data structure used to find data in database tables quickly. It ca
 
 The indexes commonly used in databases include primary key indexes, secondary indexes, etc. Among them, unique indexes are used to ensure the uniqueness of specific columns or combinations of columns, ordinary indexes are used to improve query performance, and full-text indexes are used for full-text search in text data.
 
-There are two common types of indexes, namely:
+MatrixOne supports one type of index, namely:
 
-- **Primary Key**: Primary key index, that is, the index that identifies the primary key column. The primary key index uniquely identifies each row of data in the table.
-- **Secondary index**: Secondary index is the index identified on the non-primary key. The secondary index, also called a non-clustered index, is used to improve query performance and speed up data retrieval.
+- **Primary Key**: Primary key index, the index that identifies the primary key column. The primary key index uniquely identifies each row of data in the table.
 
 ## Vector
 
@@ -41,9 +40,9 @@ For more information, see [vector](vector.md)
 
 ## Other supported logical objects
 
-MatrixOne supports the following logical objects at the same level as table:
+MatrixOne supports the following logical objects at the same level as the table:
 
-- View: a view acts as a virtual table, whose schema is defined by the SELECT statement that creates the view.
+- View: a view acts as a virtual table whose schema is defined by the SELECT statement that creates the view.
 
 - Temporary table: a table whose data is not persistent.