plan: less allocation (#5302)
plan: less allocation (#5302)


Cofyc/tidb,ngaut/tidb,c4pt0r/tidb,XuHuaiyu/tidb,kyle-wang/tidb,CodeRushing/tidb,c4pt0r/tidb,coocood/tidb,Cofyc/tidb,kyle-wang/tidb,ming-relax/tidb,kyle-wang/tidb,kyle-wang/tidb,tiancaiamao/tidb,wusphinx/tidb,wusphinx/tidb,ngaut/tidb,mccxj/tidb,c4pt0r/tidb,ming-relax/tidb,c4pt0r/tidb,pingcap/tidb,yangwenmai/tidb,ngaut/tidb,tiancaiamao/tidb,cosmtrek/tidb,spongedu/tidb,qiuyesuifeng/tidb,XuHuaiyu/tidb,c4pt0r/tidb,pingcap/tidb,spongedu/tidb,kyle-wang/tidb,ngaut/tidb,coocood/tidb,mccxj/tidb,pingcap/tidb,CodeRushing/tidb,pingcap/tidb,c4pt0r/tidb,yangwenmai/tidb,pingcap/tidb,ngaut/tidb,kyle-wang/tidb,Nify/tidb,Nify/tidb,qiuyesuifeng/tidb,EvilMcJerkface/tidb,pingcap/tidb,cosmtrek/tidb,EvilMcJerkface/tidb,ngaut/tidb