DivCostVer2 is div utility func of CostVer2.

HasCostFlag indicates whether the costFlag has the flag.

MulCostVer2 is mul utility func of CostVer2.

NewCostVer2 is the constructor of CostVer2.

NewZeroCostVer2 return a new zero costVer2.

SumCostVer2 sum the cost up of all the passed args.

TraceCost indicates whether to trace cost.

CostFlagRecalculate indicates the optimizer to ignore cached cost and recalculate it again.

CostFlagTrace indicates whether to trace the cost calculation.

CostFlagUseTrueCardinality indicates the optimizer to use true cardinality to calculate the cost.

ZeroCostVer2 is a pre-defined zero CostVer2.

CostTrace record the basic factor and formula in cost est.

CostVer2 is a structure of cost basic of version2.

CostVer2Factor is a record of internal cost factor.