With compress=true, cannot query DB after calling Ping

[evanelias]

Issue description

When connecting to a database using compress=true, any use of DB.Ping() seems to cause subsequent queries to not return rows.

Ping itself does not return an error.

Example code

package main

import (
	"database/sql"
	"fmt"
	_ "github.com/go-sql-driver/mysql"
)

func main(){
	db, err := sql.Open("mysql", "root:mypw@tcp(127.0.0.1:3306)/?compress=1")
	if err != nil{
		panic(err)
	}
	defer db.Close()
	if err = db.Ping(); err != nil{
		panic("Ping error: " + err.Error())
	}
	var version string
	query := "SELECT @@global.version"
	err = db.QueryRow(query).Scan(&version)
	if err != nil{
		panic("QueryRow error: " + err.Error())
	}
	fmt.Println(version)
}

Error log

panic: QueryRow error: sql: no rows in result set

If I replace the call to QueryRow with Query and a loop over rows, the loop does not execute (there are no rows, even though selecting a global variable should always result in 1 row).

If I change compress=1 to compress=0, the code works properly and prints the server version.

Alternatively, if I comment-out the Ping call, the code works properly.

Configuration

Driver version (or git SHA): 1.9.2

Go version: go version go1.24.4 darwin/arm64

Server version: Tested with both MySQL 8.0.40 and MariaDB 11.4.5, same behavior with both

Server OS: Linux (VM via Docker Desktop for Mac) - MySQL was on Oracle Linux, MariaDB was on Debian

[evanelias]

Just to rule out environmental causes (e.g. any weirdness from Docker Desktop networking between my Mac and Linux VM), I also reproduced this natively on a Linux client, same issue exists there.

[methane]

I confirmed and investigated too.
Please wait a week.