From 75c6b642b5ff1ed171bc1d1a758a70098539c48e Mon Sep 17 00:00:00 2001
From: Miguel Pragier <miguelpragier@gmail.com>
Date: Fri, 15 Dec 2023 20:03:18 +0100
Subject: [PATCH] GH-39238:[Go] PATCH Prevents empty record to be appended to
 empty resultset (#39239)

### Rationale for this change
When having an empty resultset, the driver tries to include an empty record referece, that cannot be scanned.

So, any operation that relies on the returned Row(s) will trigger a "Index out of Range" error.

### What changes are included in this PR?
We're preventing to include an invalid record (that can't be scanned) in an empty resultset

### Are these changes tested?
Yes, there's a new test included

### Are there any user-facing changes?
No

**This PR contains a "Critical Fix".**
* Closes: #39238

Authored-by: miguel pragier <miguel.pragier@ebnerstolz.de>
Signed-off-by: Matt Topol <zotthewizard@gmail.com>
---
 go/arrow/flight/flightsql/driver/driver.go    |  7 +--
 .../flight/flightsql/driver/driver_test.go    | 44 +++++++++++++++++++
 2 files changed, 48 insertions(+), 3 deletions(-)

diff --git a/go/arrow/flight/flightsql/driver/driver.go b/go/arrow/flight/flightsql/driver/driver.go
index e31e572586557..f74bfa378a303 100644
--- a/go/arrow/flight/flightsql/driver/driver.go
+++ b/go/arrow/flight/flightsql/driver/driver.go
@@ -487,9 +487,10 @@ func readEndpoint(ctx context.Context, client *flightsql.Client, endpoint *fligh
 	schema := reader.Schema()
 	var records []arrow.Record
 	for reader.Next() {
-		record := reader.Record()
-		record.Retain()
-		records = append(records, record)
+		if record := reader.Record(); record.NumRows() > 0 {
+			record.Retain()
+			records = append(records, record)
+		}
 	}
 
 	if err := reader.Err(); err != nil && !errors.Is(err, io.EOF) {
diff --git a/go/arrow/flight/flightsql/driver/driver_test.go b/go/arrow/flight/flightsql/driver/driver_test.go
index a388bf155ec99..24eb5ee6812c0 100644
--- a/go/arrow/flight/flightsql/driver/driver_test.go
+++ b/go/arrow/flight/flightsql/driver/driver_test.go
@@ -273,6 +273,50 @@ func (s *SqlTestSuite) TestQuery() {
 	wg.Wait()
 }
 
+func (s *SqlTestSuite) TestQueryWithEmptyResultset() {
+	t := s.T()
+
+	// Create and start the server
+	server, addr, err := s.createServer()
+	require.NoError(t, err)
+
+	var wg sync.WaitGroup
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		require.NoError(s.T(), s.startServer(server))
+	}()
+	defer s.stopServer(server)
+	time.Sleep(100 * time.Millisecond)
+
+	// Configure client
+	cfg := s.Config
+	cfg.Address = addr
+	db, err := sql.Open("flightsql", cfg.DSN())
+	require.NoError(t, err)
+	defer db.Close()
+
+	// Create the table
+	_, err = db.Exec(fmt.Sprintf(s.Statements["create table"], s.TableName))
+	require.NoError(t, err)
+
+	rows, err := db.Query(fmt.Sprintf(s.Statements["query"], s.TableName))
+	require.NoError(t, err)
+	require.False(t, rows.Next())
+
+	row := db.QueryRow(fmt.Sprintf(s.Statements["query"], s.TableName))
+	require.NotNil(t, row)
+	require.NoError(t, row.Err())
+
+	target := make(map[string]any)
+	err = row.Scan(&target)
+	require.ErrorIs(t, err, sql.ErrNoRows)
+
+	// Tear-down server
+	s.stopServer(server)
+	wg.Wait()
+}
+
 func (s *SqlTestSuite) TestPreparedQuery() {
 	t := s.T()