postgres v crdb float checker

main.go

package main

import (
	"database/sql"
	"fmt"
	"log"
	"math"
	"math/rand"

	"github.com/cockroachdb/cockroach/pkg/util/randutil"
	_ "github.com/lib/pq"
)

func main() {
	r, _ := randutil.NewPseudoRand()
	pg, err := sql.Open("postgres", "user=postgres sslmode=disable")
	if err != nil {
		log.Fatal(err)
	}
	cr, err := sql.Open("postgres", "port=26257 sslmode=disable")
	if err != nil {
		log.Fatal(err)
	}

	dbs := []*sql.DB{pg, cr}
	res := make([]string, len(dbs))
	const query = "SELECT ln(%f)"
	for {
		q := fmt.Sprintf("SELECT ln(%v::decimal)", Float64(r))
		for i, db := range dbs {
			var s string
			if err := db.QueryRow(q).Scan(&s); err != nil {
				panic(fmt.Errorf("%s: %s", q, err))
			}
			res[i] = s
		}
		sd := sameDigits(res[0], res[1])
		if sd < 12 {
			fmt.Printf("%s\n\t%v\n\t%v (pg)\n\t%v (cr)\n", q, sd, res[0], res[1])
		}
	}
}

func sameDigits(a, b string) int {
	s := 0
	m := 0
	for s < len(a) && s < len(b) && a[s] == b[s] {
		switch a[s] {
		case '-', '.':
			m++
		}
		s++
	}
	return s - m
}

func Float64(r *rand.Rand) float64 {
	v := r.Float64()
	switch r.Intn(3) {
	case 0:
		i := r.Intn(75)
		v *= math.Pow10(i)
	case 1:
		i := r.Intn(50)
		v *= math.Pow10(-i)
	case 2:
		// ignore
	default:
		panic("nope")
	}
	return v
}