executor: fix character_octet_length from information_schema.columns (p…

…ingcap#25476)
CheneyDing · Jun 25, 2021 · 46a0385 · 46a0385
1 parent 93333b6
commit 46a0385
Show file tree

Hide file tree

Showing 3 changed files with 46 additions and 4 deletions.
diff --git a/executor/infoschema_reader.go b/executor/infoschema_reader.go
@@ -629,7 +629,7 @@ func (e *hugeMemTableRetriever) dataForColumnsInTable(ctx context.Context, sctx
 				colLen += (len(col.Elems) - 1)
 			}
 			charMaxLen = colLen
-			charOctLen = colLen
+			charOctLen = calcCharOctLength(colLen, col.Charset)
 		} else if col.Tp == mysql.TypeEnum {
 			// Example: In MySQL enum('a', 'ab', 'cdef') has length 4, because
 			// the longest string in the enum is 'cdef'
@@ -641,10 +641,10 @@ func (e *hugeMemTableRetriever) dataForColumnsInTable(ctx context.Context, sctx
 				}
 			}
 			charMaxLen = colLen
-			charOctLen = colLen
+			charOctLen = calcCharOctLength(colLen, col.Charset)
 		} else if types.IsString(col.Tp) {
 			charMaxLen = colLen
-			charOctLen = colLen
+			charOctLen = calcCharOctLength(colLen, col.Charset)
 		} else if types.IsTypeFractionable(col.Tp) {
 			datetimePrecision = decimal
 		} else if types.IsTypeNumeric(col.Tp) {
@@ -688,6 +688,14 @@ func (e *hugeMemTableRetriever) dataForColumnsInTable(ctx context.Context, sctx
 	}
 }
 
+func calcCharOctLength(lenInChar int, cs string) int {
+	lenInBytes := lenInChar
+	if desc, err := charset.GetCharsetDesc(cs); err == nil {
+		lenInBytes = desc.Maxlen * lenInChar
+	}
+	return lenInBytes
+}
+
 func (e *memtableRetriever) setDataFromPartitions(ctx sessionctx.Context, schemas []*model.DBInfo) error {
 	tableRowsMap, colLengthMap, err := tableStatsCache.get(ctx)
 	if err != nil {

diff --git a/executor/infoschema_reader_test.go b/executor/infoschema_reader_test.go
@@ -232,6 +232,40 @@ func (s *testInfoschemaTableSuite) TestCharacterSetCollations(c *C) {
 		testkit.Rows("utf8mb4_bin utf8mb4"))
 }
 
+// https://github.com/pingcap/tidb/issues/25467.
+func (s *testInfoschemaTableSuite) TestDataTypesMaxLengthAndOctLength(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("drop database if exists test_oct_length;")
+	tk.MustExec("create database test_oct_length;")
+	tk.MustExec("use test_oct_length;")
+
+	testCases := []struct {
+		colTp  string
+		maxLen int
+		octLen int
+	}{
+		{"varchar(255) collate ascii_bin", 255, 255},
+		{"varchar(255) collate utf8mb4_bin", 255, 255 * 4},
+		{"varchar(255) collate utf8_bin", 255, 255 * 3},
+		{"char(10) collate ascii_bin", 10, 10},
+		{"char(10) collate utf8mb4_bin", 10, 10 * 4},
+		{"set('a', 'b', 'cccc') collate ascii_bin", 8, 8},
+		{"set('a', 'b', 'cccc') collate utf8mb4_bin", 8, 8 * 4},
+		{"enum('a', 'b', 'cccc') collate ascii_bin", 4, 4},
+		{"enum('a', 'b', 'cccc') collate utf8mb4_bin", 4, 4 * 4},
+	}
+	for _, tc := range testCases {
+		createSQL := fmt.Sprintf("create table t (a %s);", tc.colTp)
+		tk.MustExec(createSQL)
+		result := tk.MustQuery("select character_maximum_length, character_octet_length " +
+			"from information_schema.columns " +
+			"where table_schema=(select database()) and table_name='t';")
+		expectedRows := testkit.Rows(fmt.Sprintf("%d %d", tc.maxLen, tc.octLen))
+		result.Check(expectedRows)
+		tk.MustExec("drop table t;")
+	}
+}
+
 func (s *testInfoschemaTableSuite) TestDDLJobs(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 	tk.MustExec("create database if not exists test_ddl_jobs")

diff --git a/infoschema/tables_test.go b/infoschema/tables_test.go
@@ -241,7 +241,7 @@ func (s *testTableSuite) TestInfoschemaFieldValue(c *C) {
 	tk.MustQuery("select CHARACTER_MAXIMUM_LENGTH,CHARACTER_OCTET_LENGTH,NUMERIC_PRECISION,NUMERIC_SCALE,DATETIME_PRECISION from information_schema.COLUMNS where table_name='timeschema'").
 		Check(testkit.Rows("<nil> <nil> <nil> <nil> <nil>", "<nil> <nil> <nil> <nil> 3", "<nil> <nil> <nil> <nil> 3", "<nil> <nil> <nil> <nil> 4", "<nil> <nil> <nil> <nil> <nil>"))
 	tk.MustQuery("select CHARACTER_MAXIMUM_LENGTH,CHARACTER_OCTET_LENGTH,NUMERIC_PRECISION,NUMERIC_SCALE,DATETIME_PRECISION from information_schema.COLUMNS where table_name='strschema'").
-		Check(testkit.Rows("3 3 <nil> <nil> <nil>", "3 3 <nil> <nil> <nil>", "255 255 <nil> <nil> <nil>", "255 255 <nil> <nil> <nil>"))
+		Check(testkit.Rows("3 12 <nil> <nil> <nil>", "3 12 <nil> <nil> <nil>", "255 255 <nil> <nil> <nil>", "255 1020 <nil> <nil> <nil>"))
 	tk.MustQuery("select NUMERIC_SCALE from information_schema.COLUMNS where table_name='floatschema'").
 		Check(testkit.Rows("<nil>", "3"))