bool NestLoopExecutor::p_execute(const NValueArray ¶ms, ReadWriteTracker *tracker) {
VOLT_DEBUG("executing NestLoop...");
NestLoopPlanNode* node = dynamic_cast<NestLoopPlanNode*>(abstract_node);
assert(node);
assert(node->getInputTables().size() == 2);
Table* output_table_ptr = node->getOutputTable();
assert(output_table_ptr);
// output table must be a temp table
TempTable* output_table = dynamic_cast<TempTable*>(output_table_ptr);
assert(output_table);
Table* outer_table = node->getInputTables()[0];
assert(outer_table);
Table* inner_table = node->getInputTables()[1];
assert(inner_table);
VOLT_TRACE ("input table left:\n %s", outer_table->debug().c_str());
VOLT_TRACE ("input table right:\n %s", inner_table->debug().c_str());
//
// Join Expression
//
AbstractExpression *predicate = node->getPredicate();
if (predicate) {
predicate->substitute(params);
VOLT_TRACE ("predicate: %s", predicate == NULL ?
"NULL" : predicate->debug(true).c_str());
}
int outer_cols = outer_table->columnCount();
int inner_cols = inner_table->columnCount();
TableTuple outer_tuple(node->getInputTables()[0]->schema());
TableTuple inner_tuple(node->getInputTables()[1]->schema());
TableTuple &joined = output_table->tempTuple();
TableIterator iterator0(outer_table);
while (iterator0.next(outer_tuple)) {
// populate output table's temp tuple with outer table's values
// probably have to do this at least once - avoid doing it many
// times per outer tuple
for (int col_ctr = 0; col_ctr < outer_cols; col_ctr++) {
joined.setNValue(col_ctr, outer_tuple.getNValue(col_ctr));
}
TableIterator iterator1(inner_table);
while (iterator1.next(inner_tuple)) {
if (predicate == NULL || predicate->eval(&outer_tuple, &inner_tuple).isTrue()) {
// Matched! Complete the joined tuple with the inner column values.
for (int col_ctr = 0; col_ctr < inner_cols; col_ctr++) {
joined.setNValue(col_ctr + outer_cols, inner_tuple.getNValue(col_ctr));
}
output_table->insertTupleNonVirtual(joined);
}
}
}
return (true);
}
bool NestLoopExecutor::p_init(AbstractPlanNode* abstract_node, const catalog::Database* catalog_db, int* tempTableMemoryInBytes) {
VOLT_TRACE("init NestLoop Executor");
assert(tempTableMemoryInBytes);
NestLoopPlanNode* node = dynamic_cast<NestLoopPlanNode*>(abstract_node);
assert(node);
// produce the fully joined schema relying on a later projection
// to narrow the output later as required.
assert(node->getInputTables().size() == 2);
const TupleSchema *first = node->getInputTables()[0]->schema();
const TupleSchema *second = node->getInputTables()[1]->schema();
TupleSchema *schema = TupleSchema::createTupleSchema(first, second);
int combinedColumnCount = first->columnCount() + second->columnCount();
std::string *columnNames = new std::string[combinedColumnCount];
std::vector<int> outputColumnGuids;
int index = 0;
for (int ctr = 0; ctr < 2; ctr++) {
assert(node->getInputTables()[ctr]);
for (int col_ctr = 0, col_cnt = node->getInputTables()[ctr]->columnCount();
col_ctr < col_cnt;
col_ctr++, index++)
{
outputColumnGuids.
push_back(node->getChildren()[ctr]->getOutputColumnGuids()[col_ctr]);
columnNames[index] = node->getInputTables()[ctr]->columnName(col_ctr);
}
}
// Set the mapping of column names to column indexes in output tables
node->setOutputColumnGuids(outputColumnGuids);
// create the output table
node->setOutputTable(
TableFactory::getTempTable(
node->getInputTables()[0]->databaseId(), "temp", schema, columnNames, tempTableMemoryInBytes));
// for each tuple value expression in the predicate, determine
// which tuple is being represented. Tuple could come from outer
// table or inner table. Configure the predicate to use the correct
// eval() tuple parameter. By convention, eval's first parameter
// will always be the outer table and its second parameter the inner
const AbstractExpression *predicate = node->getPredicate();
std::stack<const AbstractExpression*> stack;
while (predicate != NULL) {
const AbstractExpression *left = predicate->getLeft();
const AbstractExpression *right = predicate->getRight();
if (right != NULL) {
if (right->getExpressionType() == EXPRESSION_TYPE_VALUE_TUPLE) {
if (!assignTupleValueIndex(const_cast<AbstractExpression*>(right),
node->getInputTables()[0]->name(),
node->getInputTables()[1]->name())) {
delete [] columnNames;
return false;
}
}
// remember the right node - must visit its children
stack.push(right);
}
if (left != NULL) {
if (left->getExpressionType() == EXPRESSION_TYPE_VALUE_TUPLE) {
if (!assignTupleValueIndex(const_cast<AbstractExpression*>(left),
node->getInputTables()[0]->name(),
node->getInputTables()[1]->name())) {
delete [] columnNames;
return false;
}
}
}
predicate = left;
if (!predicate && !stack.empty()) {
predicate = stack.top();
stack.pop();
}
}
delete[] columnNames;
return true;
}
