add integration test for "outfile append.."

1 files changed, 21 insertions, 9 deletions

diff --git a/internal/mapr/groupsetresult.go b/internal/mapr/groupsetresult.go
index 40c10fe..4b86025 100644
--- a/internal/mapr/groupsetresult.go
+++ b/internal/mapr/groupsetresult.go
@@ -187,13 +187,23 @@ func (g *GroupSet) WriteResult(query *Query) error {
 		return err
 	}
 
+	// By default, also write the CSV header.
+	writeHeader := true
+
+	// In append mode, only write CSV header when file doesn't exist yet or is empty.
+	if query.Outfile.AppendMode {
+		if info, err := os.Stat(query.Outfile.FilePath); err == nil && info.Size() > 0 {
+			writeHeader = false
+		}
+	}
+
 	fd, err := g.getOutfileFD(query)
 	if err != nil {
 		return err
 	}
 	defer fd.Close()
 
-	return g.resultWriteUnformatted(query, rows, fd)
+	return g.resultWriteUnformatted(query, rows, fd, writeHeader)
 }
 
 func (g *GroupSet) getOutfileFD(query *Query) (*os.File, error) {
@@ -208,17 +218,19 @@ func (g *GroupSet) getOutfileFD(query *Query) (*os.File, error) {
 	return os.OpenFile(query.Outfile.FilePath, os.O_CREATE|os.O_WRONLY|os.O_APPEND, 0644)
 }
 
-func (g *GroupSet) resultWriteUnformatted(query *Query, rows []result, fd *os.File) error {
-	// Generate header now
+func (g *GroupSet) resultWriteUnformatted(query *Query, rows []result, fd *os.File, writeHeader bool) error {
 	lastColumn := len(query.Select) - 1
-	for i, sc := range query.Select {
-		fd.WriteString(sc.FieldStorage)
-		if i == lastColumn {
-			continue
+
+	if writeHeader {
+		for i, sc := range query.Select {
+			fd.WriteString(sc.FieldStorage)
+			if i == lastColumn {
+				continue
+			}
+			fd.WriteString(protocol.CSVDelimiter)
 		}
-		fd.WriteString(protocol.CSVDelimiter)
+		fd.WriteString("\n")
 	}
-	fd.WriteString("\n")
 
 	// And now write the data
 	for i, r := range rows {