db.Query with NULL *LOB fields hangs about go-hdb

[stfnmllr]

Ok - as the error clearly states, that the table cannot be found in schema SYSTEM:

• each db. takes a (most probably different) connection out of the connection pool
  --> db.Exec("SET SCHEMA....") is most probably executed not in the same connection as the following db.Query(...)
• to guarantee the same connection, please use whether schema.tableName syntax in the query, a transaction or (golang > 1.9) a sql.Conn object

Please share the results after the change - thanks!

...Thanks for writing the go-hdb library!!
my pleasure

[stfnmllr]

Didn't hear back, so closing the issue

[petar-iv]

I also observe that the process hangs when trying to fetch a LOB with a value of NULL (with current state of master branch, go version: 1.10.1, HANA 2 SPS 2). Here is a scenario to reproduce:

create schema test;

create table test.table_1 (col clob not null);
insert into test.table_1 values('some-text');

create table test.table_2 (col clob);
insert into test.table_2 values(null);

package main

import (
	"bytes"
	"database/sql"
	"fmt"

	"github.com/SAP/go-hdb/driver"
)

func main() {
	db, err := sql.Open("hdb", "hdb://<user>:<password>@<host>:<port>")
	if err != nil {
		panic(err)
	}
	defer db.Close()

	fetchLob(db, "non-null", "table_1")
	fetchLob(db, "null", "table_2")
}

func fetchLob(db *sql.DB, scenario string, tableName string) {
	fmt.Printf("Fetching %s LOB value ...\n", scenario)
	lob := new(driver.Lob)
	b := new(bytes.Buffer)
	lob.SetWriter(b)
	if err := db.QueryRow(fmt.Sprintf("select col from test.%s", tableName)).Scan(lob); err != nil {
		panic(err)
	}
	fmt.Printf("Fetched value: %v\n\n\n", b)
}

The output is:

Fetching non-null LOB value ...
Fetched value: some-text


Fetching null LOB value ...

There is no value from the second fetch because the process hangs.

Let me know if there is anything wrong in my coding or this is an issue in the library.

Many thanks

[stfnmllr]

thanks a lot for providing the example - the code looks good, so most probably we are going to provide a fix asap

[stfnmllr]

should work with the newest release (v0.11.1) - please see new NullLob for scanning Lob null values

[petar-iv]

Works as expected now, thanks a lot