infoschema: add TIDB_ROW_ID_SHARDING_INFO for table table. (pingc…

…ap#13418)

infoschema/tables.go

@@ -20,6 +20,7 @@ import (
 	"io/ioutil"
 	"net/http"
 	"sort"
+	"strconv"
 	"strings"
 	"sync"
 	"time"
@@ -177,6 +178,7 @@ var tablesCols = []columnInfo{
 	{"CREATE_OPTIONS", mysql.TypeVarchar, 255, 0, nil, nil},
 	{"TABLE_COMMENT", mysql.TypeVarchar, 2048, 0, nil, nil},
 	{"TIDB_TABLE_ID", mysql.TypeLonglong, 21, 0, nil, nil},
+	{"TIDB_ROW_ID_SHARDING_INFO", mysql.TypeVarchar, 255, 0, nil, nil},
 }
 
 // See: http://dev.mysql.com/doc/refman/5.7/en/columns-table.html
@@ -1303,6 +1305,8 @@ func dataForTables(ctx sessionctx.Context, schemas []*model.DBInfo) ([][]types.D
 				if rowCount != 0 {
 					avgRowLength = dataLength / rowCount
 				}
+
+				shardingInfo := GetShardingInfo(schema, table)
 				record := types.MakeDatums(
 					catalogVal,    // TABLE_CATALOG
 					schema.Name.O, // TABLE_SCHEMA
@@ -1326,6 +1330,7 @@ func dataForTables(ctx sessionctx.Context, schemas []*model.DBInfo) ([][]types.D
 					createOptions, // CREATE_OPTIONS
 					table.Comment, // TABLE_COMMENT
 					table.ID,      // TIDB_TABLE_ID
+					shardingInfo,  // TIDB_ROW_ID_SHARDING_INFO
 				)
 				rows = append(rows, record)
 			} else {
@@ -1352,6 +1357,7 @@ func dataForTables(ctx sessionctx.Context, schemas []*model.DBInfo) ([][]types.D
 					nil,           // CREATE_OPTIONS
 					"VIEW",        // TABLE_COMMENT
 					table.ID,      // TIDB_TABLE_ID
+					nil,           // TIDB_ROW_ID_SHARDING_INFO
 				)
 				rows = append(rows, record)
 			}
@@ -1360,6 +1366,28 @@ func dataForTables(ctx sessionctx.Context, schemas []*model.DBInfo) ([][]types.D
 	return rows, nil
 }
 
+// GetShardingInfo returns a nil or description string for the sharding information of given TableInfo.
+// The returned description string may be:
+//  - "NOT_SHARDED": for tables that SHARD_ROW_ID_BITS is not specified.
+//  - "NOT_SHARDED(PK_IS_HANDLE)": for tables that is primary key is row id.
+//  - "SHARD_BITS={bit_number}": for tables that with SHARD_ROW_ID_BITS.
+// The returned nil indicates that sharding information is not suitable for the table(for example, when the table is a View).
+// This function is exported for unit test.
+func GetShardingInfo(dbInfo *model.DBInfo, tableInfo *model.TableInfo) interface{} {
+	if dbInfo == nil || tableInfo == nil || tableInfo.IsView() || util.IsMemOrSysDB(dbInfo.Name.L) {
+		return nil
+	}
+	shardingInfo := "NOT_SHARDED"
+	if tableInfo.PKIsHandle {
+		shardingInfo = "NOT_SHARDED(PK_IS_HANDLE)"
+	} else {
+		if tableInfo.ShardRowIDBits > 0 {
+			shardingInfo = "SHARD_BITS=" + strconv.Itoa(int(tableInfo.ShardRowIDBits))
+		}
+	}
+	return shardingInfo
+}
+
 func dataForIndexes(ctx sessionctx.Context, schemas []*model.DBInfo) ([][]types.Datum, error) {
 	checker := privilege.GetPrivilegeManager(ctx)
 	var rows [][]types.Datum

infoschema/tables_test.go

@@ -463,6 +463,48 @@ func (s *testTableSuite) TestTableIDAndIndexID(c *C) {
 	tk.MustQuery("select * from information_schema.tidb_indexes where table_schema = 'test' and table_name = 't'").Check(testkit.Rows("test t 0 PRIMARY 1 a <nil>  0", "test t 1 k1 1 b <nil>  1"))
 }
 
+func (s *testTableSuite) TestTableRowIDShardingInfo(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("DROP DATABASE IF EXISTS `sharding_info_test_db`")
+	tk.MustExec("CREATE DATABASE `sharding_info_test_db`")
+
+	assertShardingInfo := func(tableName string, expectInfo interface{}) {
+		querySQL := fmt.Sprintf("select tidb_row_id_sharding_info from information_schema.tables where table_schema = 'sharding_info_test_db' and table_name = '%s'", tableName)
+		info := tk.MustQuery(querySQL).Rows()[0][0]
+		if expectInfo == nil {
+			c.Assert(info, Equals, "<nil>")
+		} else {
+			c.Assert(info, Equals, expectInfo)
+		}
+	}
+	tk.MustExec("CREATE TABLE `sharding_info_test_db`.`t1` (a int)")
+	assertShardingInfo("t1", "NOT_SHARDED")
+
+	tk.MustExec("CREATE TABLE `sharding_info_test_db`.`t2` (a int key)")
+	assertShardingInfo("t2", "NOT_SHARDED(PK_IS_HANDLE)")
+
+	tk.MustExec("CREATE TABLE `sharding_info_test_db`.`t3` (a int) SHARD_ROW_ID_BITS=4")
+	assertShardingInfo("t3", "SHARD_BITS=4")
+
+	tk.MustExec("CREATE VIEW `sharding_info_test_db`.`tv` AS select 1")
+	assertShardingInfo("tv", nil)
+
+	testFunc := func(dbName string, expectInfo interface{}) {
+		dbInfo := model.DBInfo{Name: model.NewCIStr(dbName)}
+		tableInfo := model.TableInfo{}
+
+		info := infoschema.GetShardingInfo(&dbInfo, &tableInfo)
+		c.Assert(info, Equals, expectInfo)
+	}
+
+	testFunc("information_schema", nil)
+	testFunc("mysql", nil)
+	testFunc("performance_schema", nil)
+	testFunc("uucc", "NOT_SHARDED")
+
+	tk.MustExec("DROP DATABASE `sharding_info_test_db`")
+}
+
 func (s *testTableSuite) TestSlowQuery(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 	// Prepare slow log file.