unsigned long IndexManager::getIndexID(Attribute attr)
{
if (isIndexExist(attr))
return column_attribute_to_id[attr];
cout << "[ERROR: IndexManager.cpp->getIndexID()]: The index for column " << attr.attrName << " is not exist!\n";
return -1;
}
bool Index::createIndex()
{
if (isIndexExist()){
//索引名已存在
throw Table_Index_Error("index", index_name);
}
Table T(table_name);
if (!T.isTableExist()){
//表不存在
throw Table_Index_Error("table", table_name);
}
T.getTableInfo();
if (!T.isAttriExist(attr_name)){
//属性不存在
throw Table_Index_Error("attribute", attr_name);
}
if (!T.isAttriUnique(attr_name)){
//属性不是unique属性
throw Multip_Error(attr_name);
}
//满足创建索引的条件
//向indexlist.txt中追加索引名
ofstream outfile;
outfile.open("indexlist.txt", ios::app);
if (!outfile) throw File_openfail("indexlist.txt");
outfile << index_name << endl;
outfile.close();
//新建记录该索引信息的文件
string filename;
filename = index_name + "_indexinfo.txt";
outfile.open(filename.c_str(), ios::app);
if (!outfile) throw File_openfail(filename.c_str());
outfile << index_name << " ";
outfile << table_name << " ";
outfile << attr_name << endl;
outfile.close();
//新建记录该表所有索引信息的文件
filename = table_name + "_tableindexinfo.txt";
outfile.open(filename.c_str(), ios::app);
if (!outfile) throw File_openfail(filename.c_str());
outfile << index_name << " ";
outfile << attr_name << endl;
outfile.close();
//新建储存该索引的B+树的文件
filename = index_name;
outfile.open(filename.c_str(), ios::app);
if (!outfile) throw File_openfail(filename.c_str());
outfile.close();
return true;
}
//删除索引
bool Index::dropIndex()
{
if (!isIndexExist()){
//索引不存在，无法删除
cerr << "The index doesn't exist!" << endl;
return false;
}
//索引存在，则删除或更新相关文件
//删除indexlist.txt中索引名
ifstream infile;
infile.open("indexlist.txt", ios::in); //以只读模式打开文件，读取其中信息
if (!infile) throw File_openfail("indexlist.txt");
string indexname;
string newIndexList = "";
while (!infile.eof()){
getline(infile, indexname); //每行只储存一个索引信息
if (indexname != "" && indexname != index_name){
//过滤掉要删除的索引，保留其余的索引信息，存在newIndexList中
newIndexList = newIndexList + indexname + '\n';
}
}
infile.close();
ofstream outfile;
outfile.open("indexlist.txt", ios::out); //打开indexlist.txt并清空
if (!outfile) throw File_openfail("indexlist.txt");
outfile << newIndexList; //将保留的索引信息存入文件中
outfile.close();
string filename;
string tbname;
string idname;
//删除记录索引信息的文件
filename = index_name + "_indexinfo.txt";
infile.open(filename.c_str(), ios::in);
//读取索引所在的表名和字段信息
{
infile >> indexname >>tbname >>idname;
}
string thisIndexinfo = indexname + " " + idname;
infile.close();
remove(filename.c_str()); //移除文件
//删除_tableindexinfo.txt中索引信息
filename = tbname + "_tableindexinfo.txt";
infile.open(filename.c_str(), ios::in); //以只读模式打开文件，读取其中信息
if (!infile) throw File_openfail(filename.c_str());
string newIndexinfo = "";
string indexinfo;
while (!infile.eof()){
getline(infile, indexinfo); //每行只储存一个索引信息
if (indexinfo != "" && indexinfo != thisIndexinfo){
//过滤掉要删除的索引信息，保留其余的索引信息，存在newIndexList中
newIndexinfo = newIndexinfo + indexinfo + '\n';
}
}
infile.close();
outfile.open(filename.c_str(), ios::out); //打开_tableindexlist.txt并清空
if (!outfile) throw File_openfail(filename.c_str());
outfile << newIndexinfo; //将保留的该表的索引信息存入文件中
outfile.close();
//删除储存该索引B+树的文件
filename = index_name;
remove(filename.c_str()); //移除文件
return true;
}
