IDatasetModelField.IsSparse

Fore Syntax

IsSparse: Boolean;

Fore.NET Syntax

IsSparse: boolean;

Description

The IsSparse property returns whether sparse columns are used to store data

Comments

Available values:

True. Sparse columns are used. Sparse columns are regular columns that have an optimized storage for Null values. Sparse columns reduce the space required to store Null values, but more resources are spent to get values that are different from Null. Use sparse columns only if the saved space will be 20-40%.
False. Sparse columns are not used.

Fore Example

Executing the example requires that the repository contains a table with the T_ISSPARSE identifier.

Add links to the Db and Metabase system assemblies.

Sub UserProc;
Var
    MB: IMetabase;
    DSInst: IDatasetInstance;
    DSModel: IDatasetModel;
    Fields: IDatasetModelFields;
    i: Integer;
    Field: IDatasetModelField;
Begin
    MB := MetabaseClass.Active;
    // Get table
    DSInst := MB.ItemById("T_ISSPARSE").Open(Null) As IDatasetInstance;
    // Get table fields
    DSModel := DSInst.Dataset;
    Fields := DSModel.Fields;
    For i := 0 To Fields.Count - 1 Do
        Field := Fields.Item(i);
        // Display names of the fields using
        // sparse columns to store data
        If Field.IsSparse Then
            Debug.WriteLine(Field.Name);
        End If;
    End For;
End Sub UserProc;

After executing the example the console window displays names of the fields using sparse columns to store data.

Fore.NET Example

The requirements and result of the Fore.NET example execution match with those in the Fore example.

Imports Prognoz.Platform.Interop.Db;
…
Public Shared Sub Main(Params: StartParams);
Var
    MB: IMetabase;
    DSInst: IDatasetInstance;
    DSModel: IDatasetModel;
    Fields: IDatasetModelFields;
    i: Integer;
    Field: IDatasetModelField;
Begin
    MB := Params.Metabase;
    // Get table
    DSInst := MB.ItemById["T_ISSPARSE"].Open(Null) As IDatasetInstance;
    // Get table fields
    DSModel := DSInst.Dataset;
    Fields := DSModel.Fields;
    For i := 0 To Fields.Count - 1 Do
        Field := Fields.Item[i];
        // Display names of the fields using
        // sparse columns to store data
        If Field.IsSparse Then
            System.Diagnostics.Debug.WriteLine(Field.Name);
        End If;
    End For;
End Sub;