change default leaf size and fanout configuration
change default leaf size and fanout configuration

BohuTANG/cascadb,weicao/cascadb,BohuTANG/cascadb,tempbottle/cascadb,li0000/cascadb,tempbottle/cascadb,weicao/cascadb,li0000/cascadb,lilothar/cascadb,lilothar/cascadb