load.c

linux 下用c++ 开发的一个小型数据库系统

#include <unistd.h>
#include <fcntl.h>
#include "catalog.h"
#include "utility.h"
#include <stdlib.h>

//
// Loads a file of (binary) tuples from a standard file into the relation.
// Any indices on the relation are updated appropriately.
//
// Returns:
// 	OK on success
// 	an error code otherwise
//

const Status UT_Load(const string & relation, const string & fileName)
{
  Status status;
  RelDesc rd;
  AttrDesc *attrs;
  int attrCnt,fopen;
  int size = 0;
  RID rid;
  Record myrec ;
  char *mydata = NULL ;

  if (relation.empty() || fileName.empty() || relation == string(RELCATNAME)
      || relation == string(ATTRCATNAME))
    return BADCATPARM;


  if((fopen=open( fileName.c_str(), O_RDONLY, 0)) < 0)
    return UNIXERR;

  if((status = relCat->getInfo( relation, rd)) != OK) return status;
  if((status = attrCat->getRelInfo( rd.relName, attrCnt, attrs)) != OK) return status;

  InsertFileScan* ifs = new InsertFileScan( rd.relName, status);
  if (status != OK) return status;

  for(int i=0; i<attrCnt; i++) size += attrs[i].attrLen;

  mydata = new char[size];
  while(read( fopen, mydata, size) == size){
    myrec.data = mydata;
    myrec.length=size;
    if((status=ifs->insertRecord( myrec, rid)) != OK) return status;
  }

  delete [] mydata;

  if(close(fopen)<0) return UNIXERR;
  else return OK;
}