ddl: split partition region when add a new partition (#16537)

ddl/ddl_api.go

@@ -1451,7 +1451,6 @@ func (d *ddl) CreateTable(ctx sessionctx.Context, s *ast.CreateTableStmt) (err e
 				go preSplit()
 			}
 		}
-
 		if tbInfo.AutoIncID > 1 {
 			// Default tableAutoIncID base is 0.
 			// If the first ID is expected to greater than 1, we need to do rebase.
@@ -1495,6 +1494,37 @@ func (d *ddl) RecoverTable(ctx sessionctx.Context, tbInfo *model.TableInfo, sche
 	return errors.Trace(err)
 }
 
+// preSplitAndScatter performs pre-split and scatter of the table's regions.
+func (d *ddl) preSplitAndScatter(ctx sessionctx.Context, tbInfo *model.TableInfo, pi *model.PartitionInfo) {
+	sp, ok := d.store.(kv.SplitableStore)
+	if !ok || atomic.LoadUint32(&EnableSplitTableRegion) == 0 {
+		return
+	}
+	var (
+		preSplit      func()
+		scatterRegion bool
+	)
+	val, err := variable.GetGlobalSystemVar(ctx.GetSessionVars(), variable.TiDBScatterRegion)
+	if err != nil {
+		logutil.Logger(context.Background()).Warn("[ddl] won't scatter region", zap.Error(err))
+	} else {
+		scatterRegion = variable.TiDBOptOn(val)
+	}
+	if pi == nil {
+		pi = tbInfo.GetPartitionInfo()
+	}
+	if pi != nil {
+		preSplit = func() { splitPartitionTableRegion(sp, pi, scatterRegion) }
+	} else {
+		preSplit = func() { splitTableRegion(sp, tbInfo, scatterRegion) }
+	}
+	if scatterRegion {
+		preSplit()
+	} else {
+		go preSplit()
+	}
+}
+
 func (d *ddl) CreateView(ctx sessionctx.Context, s *ast.CreateViewStmt) (err error) {
 	ident := ast.Ident{Name: s.ViewName.Name, Schema: s.ViewName.Schema}
 	is := d.GetInfoSchemaWithInterceptor(ctx)
@@ -2238,6 +2268,9 @@ func (d *ddl) AddTablePartitions(ctx sessionctx.Context, ident ast.Ident, spec *
 	}
 
 	err = d.doDDLJob(ctx, job)
+	if err == nil {
+		d.preSplitAndScatter(ctx, meta, partInfo)
+	}
 	err = d.callHookOnChanged(err)
 	return errors.Trace(err)
 }
@@ -3153,6 +3186,14 @@ func (d *ddl) TruncateTable(ctx sessionctx.Context, ti ast.Ident) error {
 		}
 		return errors.Trace(err)
 	}
+
+	oldTblInfo := tb.Meta()
+	if oldTblInfo.PreSplitRegions > 0 {
+		if _, tb, err := d.getSchemaAndTableByIdent(ctx, ti); err == nil {
+			d.preSplitAndScatter(ctx, tb.Meta(), tb.Meta().GetPartitionInfo())
+		}
+	}
+
 	if !config.TableLockEnabled() {
 		return nil
 	}

executor/executor_test.go

@@ -4122,6 +4122,24 @@ func (s *testSuite) TestShowTableRegion(c *C) {
 	c.Assert(rows[1][1], Matches, fmt.Sprintf("t_%d_.*", partitionDef[1].ID))
 	c.Assert(rows[2][1], Matches, fmt.Sprintf("t_%d_.*", partitionDef[2].ID))
 
+	// Test split partition region when add new partition.
+	tk.MustExec("drop table if exists partition_t;")
+	tk.MustExec(`create table partition_t (a int, b int,index(a)) PARTITION BY RANGE (a) (
+		PARTITION p0 VALUES LESS THAN (10),
+		PARTITION p1 VALUES LESS THAN (20),
+		PARTITION p2 VALUES LESS THAN (30));`)
+	tk.MustExec(`alter table partition_t add partition ( partition p3 values less than (40), partition p4 values less than (50) );`)
+	re = tk.MustQuery("show table partition_t regions")
+	rows = re.Rows()
+	c.Assert(len(rows), Equals, 5)
+	tbl = testGetTableByName(c, tk.Se, "test", "partition_t")
+	partitionDef = tbl.Meta().GetPartitionInfo().Definitions
+	c.Assert(rows[0][1], Matches, fmt.Sprintf("t_%d_.*", partitionDef[0].ID))
+	c.Assert(rows[1][1], Matches, fmt.Sprintf("t_%d_.*", partitionDef[1].ID))
+	c.Assert(rows[2][1], Matches, fmt.Sprintf("t_%d_.*", partitionDef[2].ID))
+	c.Assert(rows[3][1], Matches, fmt.Sprintf("t_%d_.*", partitionDef[3].ID))
+	c.Assert(rows[4][1], Matches, fmt.Sprintf("t_%d_.*", partitionDef[4].ID))
+
 	// Test pre-split table region when create table.
 	tk.MustExec("drop table if exists t_pre")
 	tk.MustExec("create table t_pre (a int, b int) shard_row_id_bits = 2 pre_split_regions=2;")