Databases Reference
In-Depth Information
Advanced topics on view objects
In a view object, you will have the custom logic to work on SQL queries and the data that is
displayed in the UI layer. The following are some of the advanced concepts for view objects:
Tuning
: View object tuning plays an important role in the performance of an
applicaion. Some of the common tuning concepts are discussed here in this secion.
MaxFetchSize
:
MaxFetchSize
is the maximum number of rows fetched from a
database for the current view object.
-1
will retrieve an unlimited number of rows
or all the rows returned from a query. The value
0
will cause no query execuion and
no rows will be returned.
FetchSize
: This is the number of rows that is returned on a single database round
trip. This seing will determine how many rows will be returned for a paricular view
object at runime on a single query.
FetchMode
: This is the mode that controls how the rows are retrieved in a JDBC
result set. Some of the modes allowed for this funcion are as follows:
FETCH_ALL
: This mode will fetch all the rows at once
FETCH_AS_NEEDED
: This mode will fetch the number of rows defined by
FetchSize
first, and the rows are again fetched upon further request
RowFetchLimit
: This opion is provided in the
adf-config.xml
file to limit the
number of rows fetched by the view object query, and it is applied to the enire view
object in an applicaion.
Forward-only mode:
This seing is used to manage one row and the next row.
The navigaion proceeds in a linearly forward manner.
ListRangeSize
: This is the seing for the list of values that are added to the
atribute in the view object. The value of this seing will be set to a lesser value
to reduce a large number of rows being returned unnecessarily. The value
-1
will
retrieve all the rows.
RangeSize
: This is the seing that is added in combinaion with the
ListRangeSize
seing in the UI binding iterator. A value of
-1
will include all the
rows to be displayed in the iterator range.
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