Dictionary <int, List <List <long> > > idDict = new Dictionary <int, List <List <long> > >(); //收集cellid消息
#region 邹开发 select
public override void SelectFromClientHandler(SelectMessageReader request, SelectResponseWriter response)
{
idDict.Clear();
for (int i = 0; i < Global.ServerCount; i++)
{
//每个服务器挨个发送
SelectMessageWriter smw = new SelectMessageWriter(request.columnNameList,
request.columnTypeList, request.cellIds, request.usedIndex, request.condition);
Global.CloudStorage.SelectFromProxyToDatabaseServer(i, smw);
}
sem.WaitOne(); //等待服务器全部返回信息
response.cellIds = new List <List <long> >();
//将信息合并
for (int i = 0; i < Global.ServerCount; i++)
{
response.cellIds.AddRange(idDict[i]);
}
}
/// <summary>
/// 无into的select语句
/// </summary>
/// <param name="fields">三元组数组，第一个表示字段，第二个表示别名</param>
/// <param name="con">条件表达式</param>
/// <returns></returns>
public Table select(Tuple <string, string>[] fields, string con)
{
//新表的结构
List <string> newColumnNames = new List <string>();
List <int> newColumnTypes = new List <int>();
List <int> usedIndexes = new List <int>(); //标记被select的索引
//先检查字段是否符合
if (fields.Length == 1 && fields[0].Item1.Equals("*"))
{
newColumnNames = columnNames;
newColumnTypes = columnTypes;
}
else
{
foreach (Tuple <string, string> field in fields)
{
string fieldName = field.Item1; //字段名
if (columnNames.Contains(fieldName)) //直接能识别出该字段
{
newColumnNames.Add((field.Item2 == null) || (field.Item2.Equals("")) ?
fieldName : field.Item2); //别名
newColumnTypes.Add(columnTypes[columnNames.IndexOf(fieldName)]);
usedIndexes.Add(columnNames.IndexOf(fieldName));
}
else //说明要么该字段不存在，要么没有使用表名直接使用字段名
{
int count = 0;
int fieldIndex = 0;
for (int i = 0; i < columnNames.Count; i++)
{
if (columnNames.Contains("." + fieldName)) //统计是否重复了
{
count++;
fieldIndex = i;
}
}
if (count == 0)
{
throw new Exception(String.Format("字段{0}不存在", fieldName));
}
else if (count > 1)
{
throw new Exception(String.Format("字段{0}重复，需要指明表名", fieldName));
}
else
{
newColumnNames.Add((field.Item2 == null) || (field.Item2.Equals("")) ?
columnNames[fieldIndex] : field.Item2); //别名
newColumnTypes.Add(fieldIndex);
usedIndexes.Add(fieldIndex);
}
}
}
}
usedIndexes.Sort();
//此时，新表的结构构建完成，向proxy发送查询任务
SelectMessageWriter smw = new SelectMessageWriter(columnNames, columnTypes, cellIds, usedIndexes, con);
List <List <long> > newCellIds = Global.CloudStorage.SelectFromClientToDatabaseProxy(0, smw).cellIds;
return(new Table(newCellIds, newColumnTypes, newColumnNames, this.primaryIndexs,
this.defaultValues, this.tableNames));
}
