This property specifies the size that the OracleDataReader internal cache needs to store result set data.

Declaration

// C#
public long FetchSize {get; set;}

Property Value

A long that specifies the size (in bytes) of the OracleRefCursor internal cache.

Exceptions

ArgumentException - The FetchSize value specified is invalid.

Remarks

Default = 131072.

The FetchSize property value is inherited by the OracleCommand that created the OracleRefCursor object. The FetchSize property on the OracleDataReader object determines the amount of data the OracleRefCursor fetches into its internal cache for each database round-trip.

This property is useful if the OracleRefCursor is explicitly used to fill the DataSet or DataTable through the OracleDataAdapter, because it can provide control on how the data of the REF CURSOR is fetched.

If an OracleDataReader object is created from the OracleRefCursor, the resulting OracleDataReader object inherits the FetchSize value of the OracleDataReader object. However, the inherited value can be overridden, if it is set before the first invocation of the OracleDataReader Read method for the given result set, by setting the OracleDataReader FetchSize property.

The RowSize and FetchSize properties handle UDT and XMLType data differently than other scalar data types. Because only a reference to the UDT and XMLType data is stored in the ODP.NET's internal cache, the RowSize property accounts for only the memory needed for the reference (which is very small) and not the actual size of the UDT and XMLType data. Thus, applications can inadvertently fetch a large number of UDT or XMLType instances from the database in a single database round-trip. This is because the actual size of UDT and XMLType data does not count against the FetchSize, and it would require numerous UDT and XMLType references to fill up the default cache size of 131072 bytes. Therefore, when fetching UDT or XMLType data, the FetchSize property must be appropriately configured to control the number of UDT and XMLType instances that are to be fetched, rather than the amount of the actual UDT and XMLType data to be fetched.

NOTE: For LOB and LONG data types, only the sizes specified in the InitialLOBFetchSize and InitialLONGFetchSize properties are accounted for by the RowSize property in addition to the metadata and reference information that is maintained by the cache for each LOB in the select list.