public int Count()
{
lock (this.store._Locker)
{
int skipped = 0;
int taken = 0;
ExecutionPlan executionplan = FilterParser <TKey, TValue> .GetExecutionPlan(this);
List <List <long> > rangelist = new List <List <long> >();
List <TValue> returnlist = new List <TValue>();
foreach (var item in executionplan.indexRanges)
{
/// check if the primary key is included.
List <long> blockpositionList = new List <long>();
ItemCollection collection = this.store.Indexes.getIndex(item.Key).GetCollection(item.Value.lower, item.Value.upper, item.Value.lowerOpen, item.Value.upperOpen, this.Ascending);
foreach (Int64 position in collection)
{
blockpositionList.Add(position);
}
rangelist.Add(blockpositionList);
}
bool itemMatch = true;
foreach (Int64 item in executionplan.startCollection)
{
/// check matches.
itemMatch = true;
foreach (List <long> rangeitem in rangelist)
{
if (!rangeitem.Contains(item))
{
itemMatch = false;
break;
}
}
if (!itemMatch)
{
continue;
}
/// check column matchs.
foreach (ColumnScan plan in executionplan.scanColumns)
{
byte[] columnbytes = this.store.getColumnsBytes(item, plan.relativeStartPosition, plan.length);
if (!plan.Evaluator.isMatch(columnbytes))
{
itemMatch = false;
break;
}
}
if (!itemMatch)
{
continue;
}
/// pass all tests.
if (skipped < this.SkipCount)
{
skipped += 1;
continue;
}
taken += 1;
}
executionplan = null;
return(taken);
}
}
/// <summary>
/// prase the filter collection and get an execution plan.
/// </summary>
/// <returns></returns>
public static ExecutionPlan GetExecutionPlan(Filter <TKey, TValue> filter)
{
ExecutionPlan executionplan = new ExecutionPlan();
//first check order by field.
if (filter.OrderByPrimaryKey)
{
// does not support range with primary key yet, will be supported later.
Range <byte[]> primaryrange = getRange(filter.store.StoreSetting.PrimaryKey, filter.items);
if (primaryrange != null)
{
executionplan.startCollection = filter.store.primaryIndex.getCollection(primaryrange.lower, primaryrange.upper, primaryrange.lowerOpen, primaryrange.upperOpen, filter.Ascending);
}
else
{
executionplan.startCollection = filter.store.primaryIndex.allItemCollection(filter.Ascending);
}
// executionplan.OrderBySettled = true;
executionplan.hasStartCollection = true;
}
else
{
if (!string.IsNullOrEmpty(filter.OrderByFieldName))
{
if (filter.store.Indexes.HasIndex(filter.OrderByFieldName))
{
Range <byte[]> range = getRange(filter.OrderByFieldName, filter.items);
if (range != null)
{
executionplan.startCollection = filter.store.Indexes.getIndex(filter.OrderByFieldName).GetCollection(range.lower, range.upper, range.lowerOpen, range.upperOpen, filter.Ascending);
}
else
{
executionplan.startCollection = filter.store.Indexes.getIndex(filter.OrderByFieldName).AllItems(filter.Ascending);
}
// executionplan.OrderBySettled = true;
executionplan.hasStartCollection = true;
}
}
}
// check the primary key index.
Range <byte[]> primarykeyrange = getRange(filter.store.StoreSetting.PrimaryKey, filter.items);
if (primarykeyrange != null)
{
executionplan.startCollection = filter.store.primaryIndex.getCollection(primarykeyrange.lower, primarykeyrange.upper, primarykeyrange.lowerOpen, primarykeyrange.upperOpen, filter.Ascending);
executionplan.hasStartCollection = true;
}
// check all index fields that has been used in the filter.
foreach (var item in filter.store.Indexes.items)
{
Range <byte[]> indexrange = getRange(item.FieldName, filter.items);
if (indexrange != null)
{
executionplan.indexRanges.Add(item.FieldName, indexrange);
}
}
// now parse columns. All query where condition item must be in columns, otherwise this will be a problem.
foreach (var item in filter.items)
{
Columns.IColumn <TValue> column;
column = filter.store.GetColumn(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.DataType, item.Compare, item.Value, column.Length);
executionplan.scanColumns.Add(colplan);
}
else
{
throw new Exception("filter field must be index or column, add them to colomn or index when creating the store, otherwise use the fullscan option");
}
}
foreach (var item in filter.InItems)
{
Columns.IColumn <TValue> column;
column = filter.store.GetColumn(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.DataType, item.Value, column.Length);
executionplan.scanColumns.Add(colplan);
}
else
{
throw new Exception("filter field must be index or column, add them to colomn or index when creating the store, otherwise use the fullscan option");
}
}
/// for the methods calls.
foreach (var item in filter.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;
Columns.IColumn <TValue> column;
column = filter.store.GetColumn(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.DataType, 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");
}
}
/// verify the plan. or optimize it.
if (!executionplan.hasStartCollection)
{
//make one of the range. pick any one now. should be pick by the optimizer.
foreach (var item in executionplan.indexRanges)
{
IIndex <TValue> index = filter.store.Indexes.getIndex(item.Key);
if (index != null)
{
executionplan.startCollection = index.GetCollection(item.Value.lower, item.Value.upper, item.Value.lowerOpen, item.Value.upperOpen, filter.Ascending);
executionplan.hasStartCollection = true;
executionplan.indexRanges.Remove(item.Key);
break;
}
}
if (!executionplan.hasStartCollection)
{
executionplan.startCollection = filter.store.primaryIndex.allItemCollection(filter.Ascending);
executionplan.hasStartCollection = true;
}
}
return(executionplan);
}
