go-mssqldb: Azure SQL. long query - driver: bad connection

got a headache with a strange behavior when working with SQL Azure.

this code causes “driver: bad connection” error when executing second select

var dbConnString = "server=ttt.database.windows.net;port=1433;user id=user;password=pass;database=db;log=63"

func connect() (*sql.DB, error) {
    db, err := sql.Open("mssql", dbConnString)
    if err != nil {
        return nil, err
    }
    err = db.Ping()
    if err != nil {
        return nil, err
    }
    return db, nil
}

func main() {
    // open db in this function
    db, err := connect()
    if err != nil {
        return
    }
    defer db.Close() // close db in this function

    fmt.Println("SEL 1")
    _, err = db.Exec("SELECT 1")
    if err != nil {
                fmt.Println("Sel error: " + err.Error())
        return
    }

    fmt.Println("SEL bad")

    _, err = db.Exec(`SELECT 2 -- long query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
        `)
    if err != nil {
        fmt.Println("error: " + err.Error())
    }
}

log:

2016/08/31 16:46:36 (1 row(s) affected) 2016/08/31 16:46:36 (1 row(s) affected) 2016/08/31 16:46:36 SELECT 1 2016/08/31 16:46:36 (1 row(s) affected) 2016/08/31 16:46:36 SELECT 2 – long query FFD8FFE000104A46494600010100000100010000FFDB004300030202030202030303030403030 … cut … … cut … … cut … … cut … 78A28D551A49247629C2A468EE700B10B85566201E03C3FF0013758F0CF85AFF0040B4B3F0F4D617BE679B2EA1E1BD3AF2ED77A046F2

2016/08/31 16:46:36 got error: read tcp 172.17.0.35:49981->191.235.193.75:1433: wsarecv: An existing connection was forcibly closed by the remote host. 2016/08/31 16:46:36 (1 row(s) affected) 2016/08/31 16:46:36 (1 row(s) affected) 2016/08/31 16:46:36 SELECT 2 – long query FFD8FFE000104A46494600010100000100010000FFDB004300030202030202030303030403030 4050805050404050A070706080C0A0C0C0B0A0B0B0D0E12100D0E110E0B0B1016101113141515150C0F171816141812141514FFDB004301030404050 … cut … … cut … … cut … … cut … 78A28D551A49247629C2A468EE700B10B85566201E03C3FF0013758F0CF85AFF0040B4B3F0F4D617BE679B2EA1E1BD3AF2ED77A046F2

2016/08/31 16:46:36 got error: read tcp 172.17.0.35:49982->191.235.193.75:1433: wsarecv: An existing connection was forcibly closed by the remote host. 2016/08/31 16:46:37 (1 row(s) affected) 2016/08/31 16:46:37 (1 row(s) affected) 2016/08/31 16:46:37 SELECT 2 – long query FFD8FFE000104A46494600010100000100010000FFDB004300030202030202030303030403030 4050805050404050A070706080C0A0C0C0B0A0B0B0D0E12100D0E110E0B0B1016101113141515150C0F171816141812141514FFDB004301030404050 … cut … … cut … … cut … … cut … 78A28D551A49247629C2A468EE700B10B85566201E03C3FF0013758F0CF85AFF0040B4B3F0F4D617BE679B2EA1E1BD3AF2ED77A046F2

2016/08/31 16:46:37 got error: read tcp 172.17.0.35:49983->191.235.193.75:1433: wsarecv: An existing connection was forcibly closed by the remote host.

error: driver: bad connection

so as we see there is 3 attempt to execute long query (why???) and we have “wsarecv error by unknown reason” for each of them

tried to connect and run with SQL2005 - no problems at all. wireshark doesn’t hep because connection with sql azure is encrypted

got problem only with long queries (I’m inserting images into database like 0x123456…), all the rest of db routine working well