placement: quorum number done right (#31188)

close #31186
pingcap · Dec 30, 2021 · 1cc0b51 · 1cc0b51
1 parent f40bfa1
commit 1cc0b51
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Showing 2 changed files with 3 additions and 3 deletions.
diff --git a/ddl/placement/bundle.go b/ddl/placement/bundle.go
@@ -174,7 +174,7 @@ func NewBundleFromSugarOptions(options *model.PlacementSettings) (*Bundle, error
 		primaryCount = uint64(math.Ceil(float64(followers+1) / float64(len(regions))))
 	case "majority_in_primary":
 		// calculate how many replicas need to be in the primary region for quorum
-		primaryCount = uint64(math.Ceil(float64(followers+1)/2 + 1))
+		primaryCount = (followers+1)/2 + 1
 	default:
 		return nil, fmt.Errorf("%w: unsupported schedule %s", ErrInvalidPlacementOptions, schedule)
 	}

diff --git a/ddl/placement/bundle_test.go b/ddl/placement/bundle_test.go
@@ -517,11 +517,11 @@ func (s *testBundleSuite) TestNewBundleFromOptions(c *C) {
 		input: &model.PlacementSettings{
 			PrimaryRegion: "sh",
 			Regions:       "bj,sh",
-			Followers:     5,
+			Followers:     4,
 			Schedule:      "majority_in_primary",
 		},
 		output: []*Rule{
-			NewRule(Voter, 4, NewConstraintsDirect(
+			NewRule(Voter, 3, NewConstraintsDirect(
 				NewConstraintDirect("region", In, "sh"),
 			)),
 			NewRule(Follower, 2, NewConstraintsDirect(