Online DDL: set migration's progress to 100% once it's ready_to_complete (#18544)

Signed-off-by: Shlomi Noach <[email protected]>

Author: shlomi-noach

go/test/endtoend/onlineddl/scheduler/onlineddl_scheduler_test.go

@@ -569,6 +569,7 @@ func testScheduler(t *testing.T) {
 			require.NotNil(t, rs)
 			for _, row := range rs.Named().Rows {
 				assert.True(t, row["shadow_analyzed_timestamp"].IsNull())
+				assert.Equal(t, 100.0, row.AsFloat64("progress", 0))
 			}
 		})
 
@@ -619,6 +620,7 @@ func testScheduler(t *testing.T) {
 			require.NotNil(t, rs)
 			for _, row := range rs.Named().Rows {
 				assert.True(t, row["shadow_analyzed_timestamp"].IsNull())
+				assert.Equal(t, 100.0, row.AsFloat64("progress", 0))
 			}
 		})
 

go/vt/vttablet/onlineddl/executor.go

@@ -4041,6 +4041,15 @@ func (e *Executor) updateMigrationReadyToComplete(ctx context.Context, uuid stri
 			atomic.StoreInt64(&runningMigration.ReadyToComplete, storeValue)
 		}
 	}
+
+	if isReady {
+		// We set progress to 100%. Remember that progress is based on table rows estimation. We can get here
+		// with progress 87% or another value that is way off. But once we realize the migration is ready to complete,
+		// we know row copy is fully complete _and_ that vplayer is not far behind. So it's a better DX to report 100%.
+		if err = e.updateMigrationProgress(ctx, uuid, progressPctFull); err != nil {
+			return err
+		}
+	}
 	return nil
 }