(arrow) branch main updated: GH-39238:[Go] PATCH Prevents empty record to be appended to empty resultset (#39239)

[zeroshade]

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The following commit(s) were added to refs/heads/main by this push:
     new 75c6b642b5 GH-39238:[Go] PATCH Prevents empty record to be appended to 
empty resultset (#39239)
75c6b642b5 is described below

commit 75c6b642b5ff1ed171bc1d1a758a70098539c48e
Author: Miguel Pragier <miguelprag...@gmail.com>
AuthorDate: Fri Dec 15 20:03:18 2023 +0100

    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.prag...@ebnerstolz.de>
    Signed-off-by: Matt Topol <zotthewiz...@gmail.com>
---
 go/arrow/flight/flightsql/driver/driver.go      |  7 ++--
 go/arrow/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 e31e572586..f74bfa378a 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 a388bf155e..24eb5ee681 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()