GreenPlumorca优化器在何处产生执行计划并进行分发

CTranslatorDXLToPlStmt::TranslateDXLTblScan
if (IMDRelation::ErelstorageExternal == md_rel->RetrieveRelStorageType()){
ForeignScan *foreign_scan...
...
}else{//创建一个SeqScan节点
SeqScan *seq_scan = MakeNode(SeqScan);
seq_scan->scanrelid = index;
plan = &(seq_scan->plan);
plan_return = (Plan *) seq_scan;
plan->targetlist = targetlist;
plan->qual = qual;
}
...

standard_planner
top_plan = create_plan(root, best_path, top_slice);
Gather *gather = makeNode(Gather);//创建一个Gather节点
...
top_plan = &gather->plan;