You can use Fetch Size to change the row fetch size to change the number of rows retrieved each time the database cursor is accessed.
By default, when the OceanBase JDBC driver runs a query, it retrieves a result set of 10 rows from the database cursor at a time.
The standard JDBC also allows you to specify the number of rows to be retrieved from the database during each round trip, which is called the fetch size. In OceanBase JDBC, the row-prefetch value is the default fetch size for the statement object. The fetch size configured will override the row-prefetch value and takes effect on subsequent queries of the statement object.
Fetch Size also applies to result sets. When a statement object runs a query, the fetch size of the statement object is passed to the result set object of the query. However, you can also specify the fetch size in the result set object to override the statement fetch size passed to it. Notice
After the result set is generated, changes made to the fetch size of the statement object does not take effect on the result set.
The fetch size of the result set, no matter explicitly set or by default equal to the statement fetch size passed to the result set, can determine the number of rows retrieved during subsequent database access for the result set, including all the trips still required to complete the query and all the trips to refetch the data into the result set. You can refetch data explicitly or implicitly to update a scroll-sensitive result set or a scroll-insensitive/updatable result set.
Set the fetch size
You can use the following method to set and obtain the fetch size for all Statement, PreparedStatement, CallableStatement, and ResultSet objects:
void setFetchSize(int rows) throws SQLExceptionint getFetchSize() throws SQLException
To set the fetch size for a query, call setFetchSize on the statement object before you run the query . If you set the fetch size to N, N rows are obtained during each access to the database.
After you run the query, you can call setFetchSize on the result set object to override the statement object fetch size passed to it. The setting takes effect on subsequent trips to the database to obtain more rows for the original query and on subsequent row refetching.
Preset the fetch direction
standard JDBC allows you to pre-specify the result set processing direction, also known as the fetch direction. Use the following result set methods:
void setFetchDirection(int direction) throws SQLExceptionint getFetchDirection() throws SQLException
The OceanBase JDBC driver supports only a forward preset value, which can be specified by entering the ResultSet.FETCH_FORWARD static constant value.
Values such as ResultSet.FETCH_REVERSE and ResultSet.FETCH_UNKNOWN are not supported. If you attempt to use these values, an SQL warning is returned and the setting will be ignored.