stats: fix index_length in information_schema

pkg/statistics/handle/cache/stats_table_row_cache.go

@@ -147,10 +147,12 @@ func (c *StatsTableRowCache) Update(sctx sessionctx.Context) error {
 // Returns row count, average row length, total data length, and all indexed column length.
 func (c *StatsTableRowCache) EstimateDataLength(table *model.TableInfo) (
 	rowCount uint64, avgRowLength uint64, dataLength uint64, indexLength uint64) {
-	if table.GetPartitionInfo() == nil {
-		rowCount = c.GetTableRows(table.ID)
-		dataLength, indexLength = c.GetDataAndIndexLength(table, table.ID, rowCount)
-	} else {
+	rowCount = c.GetTableRows(table.ID)
+	dataLength, indexLength = c.GetDataAndIndexLength(table, table.ID, rowCount)
+	if table.GetPartitionInfo() != nil {
+		// For partition table, data only stores in partition level.
+		// Keep `indexLength` for global index.
+		rowCount, dataLength = 0, 0
 		for _, pi := range table.GetPartitionInfo().Definitions {
 			piRowCnt := c.GetTableRows(pi.ID)
 			rowCount += piRowCnt
@@ -257,6 +259,16 @@ func (c *StatsTableRowCache) GetDataAndIndexLength(info *model.TableInfo, physic
 		if idx.State != model.StatePublic {
 			continue
 		}
+		if info.GetPartitionInfo() != nil {
+			// Global indexes calcuated in table level.
+			if idx.Global && info.ID != physicalID {
+				continue
+			}
+			// Normal indexes calculated in partition level.
+			if !idx.Global && info.ID == physicalID {
+				continue
+			}
+		}
 		for _, col := range idx.Columns {
 			if col.Length == types.UnspecifiedLength {
 				indexLength += columnLength[col.Name.L]

tests/integrationtest/r/globalindex/information_schema.result

@@ -7,8 +7,20 @@ UNIQUE KEY `idx1` (`b`),
 KEY `idx` (`b`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin
 PARTITION BY HASH (`a`) PARTITIONS 5;
+insert into t values (1, 1);
+analyze table t;
 select key_name, is_global from information_schema.tidb_indexes where table_name='t' and table_schema='globalindex__information_schema' order by key_name;
 key_name	is_global
 idx	0
 idx1	1
+select partition_name, data_length, index_length from information_schema.PARTITIONS where table_name='t' and table_schema='globalindex__information_schema' order by partition_name;
+partition_name	data_length	index_length
+p0	0	0
+p1	16	8
+p2	0	0
+p3	0	0
+p4	0	0
+select table_name, data_length, index_length from information_schema.tables where table_name='t' and table_schema='globalindex__information_schema';
+table_name	data_length	index_length
+t	16	16
 set tidb_enable_global_index=default;

tests/integrationtest/t/globalindex/information_schema.test

@@ -9,7 +9,13 @@ CREATE TABLE `t` (
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin
 PARTITION BY HASH (`a`) PARTITIONS 5;
 
+insert into t values (1, 1);
+analyze table t;
+
 select key_name, is_global from information_schema.tidb_indexes where table_name='t' and table_schema='globalindex__information_schema' order by key_name;
 
+select partition_name, data_length, index_length from information_schema.PARTITIONS where table_name='t' and table_schema='globalindex__information_schema' order by partition_name;
+select table_name, data_length, index_length from information_schema.tables where table_name='t' and table_schema='globalindex__information_schema';
+
 set tidb_enable_global_index=default;