StatsMathUtil.java

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package org.apache.doris.nereids.stats;

/**
 * Math util for statistics derivation
 */
public class StatsMathUtil {

    public static double nonZeroDivisor(double d) {
        return d == 0.0 ? 1 : d;
    }

    /**
     *  Try to find non NaN min.
     */
    public static double minNonNaN(double a, double b) {
        if (Double.isNaN(a)) {
            return b;
        }
        if (Double.isNaN(b)) {
            return a;
        }
        return Math.min(a, b);
    }

    /**
     *  Try to find non NaN max.
     */
    public static double maxNonNaN(double a, double b) {
        if (Double.isNaN(a)) {
            return b;
        }
        if (Double.isNaN(b)) {
            return a;
        }
        return Math.max(a, b);
    }

    public static double divide(double a, double b) {
        if (Double.isNaN(a) || Double.isNaN(b)) {
            return Double.NaN;
        }
        return a / nonZeroDivisor(b);
    }

    // TODO: add more protection at other stats estimation
    public static double normalizeRowCountOrNdv(double value) {
        return value >= 0 && value < 1 ? 1 : value;
    }
}