Status Operators::IndexSelect(const string& result, // Name of the output relation
const int projCnt, // Number of attributes in the projection
const AttrDesc projNames[], // Projection list (as AttrDesc)
const AttrDesc* attrDesc, // Attribute in the selection predicate
const Operator op, // Predicate operator
const void* attrValue, // Pointer to the literal value in the predicate
const int reclen) // Length of a tuple in the output relation
{
cout << "Algorithm: Index Select" << endl;
/* Your solution goes here */
Status indexStatus;
Index scanIndex(attrDesc->relName, attrDesc->attrOffset, attrDesc->attrLen, (Datatype)attrDesc->attrType, 0, indexStatus);
if (indexStatus != OK)
return indexStatus;
HeapFile indexHeapFile(result, indexStatus);
if (indexStatus != OK)
return indexStatus;
HeapFileScan indexHeapScan (attrDesc->relName, indexStatus);
if (indexStatus != OK)
return indexStatus;
Record newRecord, oldRecord;
newRecord.length = reclen;
newRecord.data = malloc (reclen);
RID rid1, rid2;
scanIndex.startScan(attrValue);
while(scanIndex.scanNext(rid1)==OK){
int offset = 0;
indexStatus = indexHeapScan.getRandomRecord(rid1, oldRecord);
if (indexStatus != OK){
free(newRecord.data);
return indexStatus;
}
for (int i = 0; i < projCnt; i++){
memcpy((char*)(newRecord.data) + offset, (char*)(oldRecord.data) + projNames[i].attrOffset, projNames[i].attrLen);
offset += projNames[i].attrLen;
}
indexStatus = indexHeapFile.insertRecord(newRecord, rid2);
if (indexStatus != OK){
free(newRecord.data);
return indexStatus;
}
}
scanIndex.endScan();
free(newRecord.data);
return OK;
}
Status SortedFile::generateRun(int items)
{
Status status;
// Sort buffer using library function qsort (quick sort). Use
// the appropriate comparison function for integers, floats,
// or strings (qsort can't take type as a parameter).
if (type == INTEGER)
qsort(buffer, items, sizeof(SORTREC), intcmp);
else if (type == DOUBLE)
qsort(buffer, items, sizeof(SORTREC), floatcmp);
else
qsort(buffer, items, sizeof(SORTREC), stringcmp);
// If this is the first sub-run, malloc space for a RUN object,
// otherwise realloc more space. Note that on most systems
// realloc(NULL) could be used even when runs == NULL, but
// this doesn't work on all systems.
RUN newRun;
runs.push_back(newRun);
// If failed to create space for an additional run.
RUN & run = runs.back();
// Generate file name for temporary file.
ostringstream outputString;
outputString << fileName << ".sort." << runs.size() << ends;
run.name = outputString.str();
/*
char *tmpString = outputString.str();
run.name = string(tmpString);
delete [] tmpString;
*/
#ifdef DEBUGSORT
cout << "%% Writing " << items << " tuples to file " << run->name
<< endl;
#endif
// Make sure temporary file does not exist already. We don't
// want to corrupt somebody else's sorted files (on another
// attribute, for example).
if ((status = db.createFile(run.name)) != OK)
return status; // file must not exist already
if ((status = db.destroyFile(run.name)) != OK)
return status; // delete if successful
// Open a heap file. This will also create the temporary file.
if (!(run.file = new HeapFileScan(run.name, 0, 0, STRING, NULL, EQ, status)))
return INSUFMEM;
if (status != OK)
return status;
// Open an unfiltered sequential scan on the source file. The scan
// is not actually needed for anything else than just getting
// a scanId which getRandomRecord requires.
HeapFileScan scan (fileName, 0, 0, STRING, NULL, EQ, status);
if (status != OK)
return status;
// For each sort record (attribute plus RID) in the buffer, fetch
// the whole record from the source file and then insert it into
// the temporary file.
for(int i = 0; i < items; i++) {
SORTREC* rec = &buffer[i];
RID rid;
Record record;
if ((status = scan.getRandomRecord(rec->rid, record)) != OK)
return status;
if ((status = run.file->insertRecord(record, rid)) != OK)
return status;
}
delete run.file;
return OK;
}
