void CatalogManager::dropTable(string tableName)
{
if (!tableExisted(tableName))
{
printf("Table does not exist!\n");
}
else
{
BufferManager buffer;
IndexCatalogPage indexPage;
int n,nn,i,x,k;
string s, attrName;
indexPage.pageIndex=1;
buffer.readPage(indexPage);
n=*(int*)indexPage.pageData;
nn=n;
i=1;
k=0;
while (i<=n) //开始逐条检查，删除这张表上所有的索引
{
x=indexPage.readPrevDel(i);
if (x==0) //如果当前条未被删除
{
s=indexPage.readTableName(i);
if (s==tableName) //如果是这张表的索引，删掉
{
k++; //k用来记录删除了多少条索引
indexPage.deleteIndex(i);
attrName=indexPage.readAttrName(i);
BufferManager bm;
string filePath=bm.indexFilePath(tableName, attrName);
if (bm.indexFileIsExist(tableName, attrName))
bm.deleteIndexFile(tableName, attrName);
}
}
else //如果当前条已被删除，则最后一条位置后移
n++;
i++;
}
indexPage.pageIndex=1; //记录索引信息首页的索引总数也需要改
buffer.readPage(indexPage);
*(int*)indexPage.pageData=nn-k;
buffer.writePage(indexPage);
buffer.deleteTableCatalogFile(tableName); //删除当前表的文件
buffer.deleteTableFile(tableName); //删除当前表的record文件
printf("Dropped table %s successfully!\n",tableName.c_str());
}
}
void CatalogManager::deleteIndex(string indexName)
{
if (!indexExisted(indexName)) //如果没有这个索引
{
printf("Failed to delete index %s. Index does not existed.\n", indexName.c_str());
return;
}
else //有这个索引
{
BufferManager buffer;
CatalogPage catalog;
IndexCatalogPage indexPage;
string s,tableName,attrName;
int i,num,n,x;
s=indexLocation(indexName); //找到这个索引
tableName=""; //分割字符串
attrName="";
i=0;
while (s[i]!=' ')
{
tableName=tableName+s[i];
i++;
}
while (s[i]==' ')
i++;
while (s[i]!=0)
{
attrName=attrName+s[i];
i++;
}
printf("#%s# @%s@ *%s*\n",indexName.c_str(), tableName.c_str(), attrName.c_str());
printf("~%s~\n",primaryKey(tableName).c_str());
if (indexName == tableName+attrName && primaryKey(tableName) == attrName)
{
printf("Failed to delete index %s. Default index on primary key cannot be deleted.\n",indexName.c_str());
return;
}
indexPage.pageIndex=1;
buffer.readPage(indexPage);
n=*(int*)indexPage.pageData;
i=1;
while (i<=n) //开始在indexCatalogPage里逐条检查，删除这个索引
{
x=indexPage.readPrevDel(i);
if (x==0) //如果当前条未被删除
{
s=indexPage.readIndexName(i);
if (s==indexName) //如果找到要删的这条索引
{
indexPage.deleteIndex(i); //删掉它
break;
}
}
else //如果当前条已被删除，则最后一条位置后移
n++;
i++;
}
buffer.writePage(indexPage);
catalog.tableName = tableName; //在catalogPage里面的对应属性上修改索引总数
buffer.readPage(catalog);
num = (int)catalog.pageData[0];
for (i=0; i<num; i++) {
if (catalog.readAttrName(i) == attrName)
{
catalog.modifyAttrIndexNum(i,-1);
buffer.writePage(catalog);
if (catalog.readAttrIndexNum(i)==0)
{
BufferManager bm;
string filePath=bm.indexFilePath(tableName, attrName);
if (bm.indexFileIsExist(tableName, attrName))
bm.deleteIndexFile(tableName, attrName);
}
break;
}
}
printf("Deleted index %s successfully!\n",indexName.c_str());
}
}
