RC QL_JoinNode::GetNext(RM_Record &rec) {
RM_Record leftRec;
RM_Record rightRec;
while(true) {
if (bRightNodeEOF) {
if (lSubNode.GetNext(leftRec) == QL_EOF)
return QL_EOF;
memcpy(buffer, leftRec.GetContent(), leftRec.GetRecordSize());
bRightNodeEOF = false;
}
if (rSubNode.GetNext(rightRec) == QL_EOF) {
bRightNodeEOF = true;
rSubNode.Reset();
continue;
}
memcpy(buffer + lSubNode.GetTupleLength(), rightRec.GetContent(), rSubNode.GetTupleLength());
RID rid(-1, -1);
rec = RM_Record(buffer, rid, tupleLength);
return 0;
}
}
RC QL_ProjNode::GetNext(RM_Record &rec) {
RM_Record record;
if (prevNode.GetNext(record) == QL_EOF) {
return QL_EOF;
}
int i;
int base = 0;
char *prevRecord = record.GetContent();
//投影操作
for(i = 0; i < nAttrInfos; i++) {
memcpy(buffer + base, prevRecord + offsetInPrev[i], attrInfos[i].attrLength);
base += attrInfos[i].attrLength;
}
RID rid(-1, -1);
rec = RM_Record(buffer, rid, tupleLength);
return 0;
}
