/// <summary>
/// Determines whether a column set is covered by an index.
/// </summary>
/// <param name="columns">A set of columns.</param>
/// <param name="indexColumns">The index columns.</param>
/// <param name="indexIncludedColumns">The index columns.</param>
/// <returns><c>true</c> if <paramref name="columns"/> is covered by <paramref name="indexColumns"/>; otherwise <c>false</c>.</returns>
/// <exception cref="ArgumentNullException"><paramref name="columns"/> or <paramref name="indexColumns"/> or <paramref name="indexIncludedColumns"/> is <c>null</c>.</exception>
protected static bool ColumnsHaveIndexWithIncludedColumns(IEnumerable <IDatabaseColumn> columns, IEnumerable <IDatabaseIndexColumn> indexColumns, IEnumerable <IDatabaseColumn> indexIncludedColumns)
{
if (columns == null)
{
throw new ArgumentNullException(nameof(columns));
}
if (indexColumns == null)
{
throw new ArgumentNullException(nameof(indexColumns));
}
if (indexIncludedColumns == null)
{
throw new ArgumentNullException(nameof(indexIncludedColumns));
}
if (indexIncludedColumns.Empty())
{
return(false);
}
var columnList = columns.ToList();
var indexColumnList = indexColumns.ToList();
var dependentColumns = indexColumnList.SelectMany(ic => ic.DependentColumns).ToList();
var includedColumnList = indexIncludedColumns.ToList();
// can only check for regular indexes, not functional ones (functions may be composed of multiple columns)
if (indexColumnList.Count != dependentColumns.Count)
{
return(false);
}
var columnNames = new System.Collections.Generic.HashSet <Identifier>(columnList.Select(c => c.Name));
var indexColumnNames = new System.Collections.Generic.HashSet <Identifier>(dependentColumns.Select(ic => ic.Name));
// index won't be completely used or there are extra columns in it
if (indexColumnNames.Count > columnNames.Count || indexColumnNames.Any(ic => !columnNames.Contains(ic)))
{
return(false);
}
indexColumnNames.UnionWith(includedColumnList.Select(ic => ic.Name));
return(columnNames.IsSubsetOf(indexColumnNames));
}
protected bool IsSelectMode() => _selectedItems.Any();
