/// <summary>
/// prase the filter collection and get an execution plan.
/// </summary>
/// <returns></returns>
public static ExecutionPlan GetExecutionPlan(Query query)
{
ExecutionPlan executionplan = new ExecutionPlan();
ITableIndex startindex = null;
if (!string.IsNullOrEmpty(query.OrderByFieldName))
{
startindex = query.table.Indexs.Find(o => o.FieldName == query.OrderByFieldName);
if (startindex == null)
{
executionplan.RequireOrderBy = true;
}
}
// find other where fields......
if (startindex == null)
{
startindex = query.table.Indexs.Find(o => o.IsSystem);
}
if (!string.IsNullOrEmpty(query.OrderByFieldName) && !executionplan.RequireOrderBy)
{
Range <byte[]> range = getRange(query.OrderByFieldName, query.items);
if (range != null)
{
executionplan.startCollection = startindex.GetCollection(range.lower, range.upper, range.lowerOpen, range.upperOpen, query.Ascending);
}
else
{
executionplan.startCollection = startindex.AllItems(query.Ascending);
}
}
else
{
executionplan.startCollection = startindex.AllItems(query.Ascending);
}
// check all index fields that has been used in the filter.
foreach (var item in query.table.Indexs)
{
if (item.FieldName != startindex.FieldName)
{
Range <byte[]> indexrange = getRange(item.FieldName, query.items);
if (indexrange != null)
{
executionplan.indexRanges.Add(item.FieldName, indexrange);
}
}
}
// now the left columns..
foreach (var item in query.items)
{
var column = query.table.ObjectConverter.Fields.Find(o => o.FieldName == item.FieldOrProperty);
if (column != null)
{
ColumnScan colplan = new ColumnScan();
colplan.ColumnName = column.FieldName;
colplan.relativeStartPosition = column.RelativePosition;
colplan.length = column.Length;
colplan.Evaluator = ColumnEvaluator.GetEvaluator(column.ClrType, item.Compare, item.Value, column.Length);
executionplan.scanColumns.Add(colplan);
}
else
{
throw new Exception("filter field must be column with fixed len");
}
}
// the left column query.
foreach (var item in query.InItems)
{
var column = query.table.ObjectConverter.Fields.Find(o => o.FieldName == item.Key);
if (column != null)
{
ColumnScan colplan = new ColumnScan();
colplan.ColumnName = column.FieldName;
colplan.relativeStartPosition = column.RelativePosition;
colplan.length = column.Length;
colplan.Evaluator = ColumnInEvaluator.GetInEvaluator(column.ClrType, item.Value, column.Length);
executionplan.scanColumns.Add(colplan);
}
else
{
throw new Exception("filter field must be a column with fixed length");
}
}
/// for the methods calls.
foreach (var item in query.calls)
{
MemberExpression memberaccess = null;
foreach (var xitem in item.Arguments)
{
if (xitem.NodeType == ExpressionType.MemberAccess)
{
memberaccess = xitem as MemberExpression;
}
}
if (memberaccess == null)
{
throw new Exception("Method call require use one of the Fields or Property as parameters");
}
string fieldname = memberaccess.Member.Name;
var column = query.table.ObjectConverter.Fields.Find(o => o.FieldName == fieldname);
if (column != null)
{
ColumnScan colplan = new ColumnScan();
colplan.ColumnName = column.FieldName;
colplan.relativeStartPosition = column.RelativePosition;
colplan.length = column.Length;
colplan.Evaluator = ColumnMethodCallEvaluator.GetMethodEvaluator(column.ClrType, column.Length, item);
executionplan.scanColumns.Add(colplan);
}
else
{
throw new Exception("methed call parameter must be a column, add the field to colomn creating creating the store, otherwise use the fullscan option");
}
}
return(executionplan);
}