expression: speed up Column.VecEvalReal by using MergeNulls (#22191)

pingcap · Feb 17, 2021 · c9af430 · c9af430
1 parent d6a2b9a
commit c9af430
Showing 1 changed file with 4 additions and 5 deletions.
diff --git a/expression/column.go b/expression/column.go
@@ -257,13 +257,12 @@ func (col *Column) VecEvalReal(ctx sessionctx.Context, input *chunk.Chunk, resul
 			}
 			return nil
 		}
+		result.MergeNulls(src)
 		for i := range f32s {
-			// TODO(zhangyuanjia): speed up the way to manipulate null-bitmaps.
-			if src.IsNull(i) {
-				result.SetNull(i, true)
-			} else {
-				f64s[i] = float64(f32s[i])
+			if result.IsNull(i) {
+				continue
 			}
+			f64s[i] = float64(f32s[i])
 		}
 		return nil
 	}