@Override
public List<ByteString> getNextRows(int fetchRowNum) throws IOException {
List<ByteString> rows = new ArrayList<ByteString>();
int startRow = currentRow;
int endRow = startRow + fetchRowNum;
if (physicalExec == null) {
return rows;
}
while (currentRow < endRow) {
Tuple currentTuple = physicalExec.next();
if (currentTuple == null) {
physicalExec.close();
physicalExec = null;
break;
}
currentRow++;
rows.add(ByteString.copyFrom(encoder.toBytes(currentTuple)));
if (currentRow >= maxRow) {
physicalExec.close();
physicalExec = null;
break;
}
}
return rows;
}
@Override
public void init() throws IOException {
QueryContext queryContext = new QueryContext(masterContext.getConf());
currentRow = 0;
MasterPlan masterPlan = new MasterPlan(queryId, queryContext, logicalPlan);
GlobalPlanner globalPlanner =
new GlobalPlanner(masterContext.getConf(), masterContext.getCatalog());
try {
globalPlanner.build(queryContext, masterPlan);
} catch (PlanningException e) {
throw new RuntimeException(e);
}
ExecutionBlockCursor cursor = new ExecutionBlockCursor(masterPlan);
ExecutionBlock leafBlock = null;
for (ExecutionBlock block : cursor) {
if (masterPlan.isLeaf(block)) {
leafBlock = block;
break;
}
}
if (leafBlock == null) {
throw new InvalidQueryException("Global planner could not find any leaf block.");
}
taskContext =
new TaskAttemptContext(
queryContext, null, new TaskAttemptId(new TaskId(leafBlock.getId(), 0), 0), null, null);
physicalExec =
new SimplePhysicalPlannerImpl(masterContext.getConf())
.createPlan(taskContext, leafBlock.getPlan());
tableDesc =
new TableDesc(
"table_" + System.currentTimeMillis(),
physicalExec.getSchema(),
new TableMeta("SYSTEM", new KeyValueSet()),
null);
outSchema = physicalExec.getSchema();
encoder = RowStoreUtil.createEncoder(getLogicalSchema());
physicalExec.init();
}
@Override
public void close() throws Exception {
tableDesc = null;
outSchema = null;
encoder = null;
if (physicalExec != null) {
try {
physicalExec.close();
} catch (Exception ignored) {
}
}
physicalExec = null;
currentRow = -1;
}