[release-17.0] BaseShowTablesWithSizes: optimize MySQL 8.0 query (#13375)

go/mysql/flavor_mysql.go

@@ -345,17 +345,41 @@ GROUP BY t.table_name, t.table_type, t.create_time, t.table_comment`
 // We join with a subquery that materializes the data from `information_schema.innodb_sys_tablespaces`
 // early for performance reasons. This effectively causes only a single read of `information_schema.innodb_tablespaces`
 // per query.
+// Note the following:
+//   - We use UNION ALL to deal differently with partitioned tables vs. non-partitioned tables.
+//     Originally, the query handled both, but that introduced "WHERE ... OR" conditions that led to poor query
+//     optimization. By separating to UNION ALL we remove all "OR" conditions.
+//   - We utilize `INFORMATION_SCHEMA`.`TABLES`.`CREATE_OPTIONS` column to do early pruning before the JOIN.
+//   - `TABLES`.`TABLE_NAME` has `utf8mb4_0900_ai_ci` collation.  `INNODB_TABLESPACES`.`NAME` has `utf8mb3_general_ci`.
+//     We normalize the collation to get better query performance (we force the casting at the time of our choosing)
+//   - `create_options` is NULL for views, and therefore we need an additional UNION ALL to include views
 const TablesWithSize80 = `SELECT t.table_name,
-	t.table_type,
-	UNIX_TIMESTAMP(t.create_time),
-	t.table_comment,
-	SUM(i.file_size),
-	SUM(i.allocated_size)
-FROM information_schema.tables t
-LEFT JOIN information_schema.innodb_tablespaces i
-	ON i.name LIKE CONCAT(database(), '/%') AND (i.name = CONCAT(t.table_schema, '/', t.table_name) OR i.name LIKE CONCAT(t.table_schema, '/', t.table_name, '#p#%'))
-WHERE t.table_schema = database()
-GROUP BY t.table_name, t.table_type, t.create_time, t.table_comment`
+		t.table_type,
+		UNIX_TIMESTAMP(t.create_time),
+		t.table_comment,
+		i.file_size,
+		i.allocated_size
+	FROM information_schema.tables t
+		LEFT JOIN information_schema.innodb_tablespaces i
+	ON i.name = CONCAT(t.table_schema, '/', t.table_name) COLLATE utf8_general_ci
+	WHERE
+		t.table_schema = database() AND not t.create_options <=> 'partitioned'
+UNION ALL
+	SELECT
+		t.table_name,
+		t.table_type,
+		UNIX_TIMESTAMP(t.create_time),
+		t.table_comment,
+		SUM(i.file_size),
+		SUM(i.allocated_size)
+	FROM information_schema.tables t
+		LEFT JOIN information_schema.innodb_tablespaces i
+	ON i.name LIKE (CONCAT(t.table_schema, '/', t.table_name, '#p#%') COLLATE utf8_general_ci )
+	WHERE
+		t.table_schema = database() AND t.create_options <=> 'partitioned'
+	GROUP BY
+		t.table_schema, t.table_name, t.table_type, t.create_time, t.table_comment
+`
 
 // baseShowTablesWithSizes is part of the Flavor interface.
 func (mysqlFlavor56) baseShowTablesWithSizes() string {

go/vt/vttablet/endtoend/misc_test.go

@@ -20,6 +20,7 @@ import (
 	"context"
 	"fmt"
 	"io"
+	"math"
 	"net/http"
 	"reflect"
 	"strings"
@@ -944,3 +945,52 @@ func TestHexAndBitBindVar(t *testing.T) {
 	require.NoError(t, err)
 	assert.Equal(t, `[[INT64(10) UINT64(10) INT64(2480) UINT64(2480)]]`, fmt.Sprintf("%v", qr.Rows))
 }
+
+// Test will validate drop view ddls.
+func TestShowTablesWithSizes(t *testing.T) {
+	ctx := context.Background()
+	conn, err := mysql.Connect(ctx, &connParams)
+	require.NoError(t, err)
+	defer conn.Close()
+
+	setupQueries := []string{
+		`drop view if exists show_tables_with_sizes_v1`,
+		`drop table if exists show_tables_with_sizes_t1`,
+		`drop table if exists show_tables_with_sizes_employees`,
+		`create table show_tables_with_sizes_t1 (id int primary key)`,
+		`create view show_tables_with_sizes_v1 as select * from show_tables_with_sizes_t1`,
+		`CREATE TABLE show_tables_with_sizes_employees (id INT NOT NULL, store_id INT) PARTITION BY HASH(store_id) PARTITIONS 4`,
+	}
+
+	defer func() {
+		_, _ = conn.ExecuteFetch(`drop view if exists show_tables_with_sizes_v1`, 1, false)
+		_, _ = conn.ExecuteFetch(`drop table if exists show_tables_with_sizes_t1`, 1, false)
+		_, _ = conn.ExecuteFetch(`drop table if exists show_tables_with_sizes_employees`, 1, false)
+	}()
+	for _, query := range setupQueries {
+		_, err := conn.ExecuteFetch(query, 1, false)
+		require.NoError(t, err)
+	}
+	expectTables := map[string]([]string){ // TABLE_TYPE, TABLE_COMMENT
+		"show_tables_with_sizes_t1":        {"BASE TABLE", ""},
+		"show_tables_with_sizes_v1":        {"VIEW", "VIEW"},
+		"show_tables_with_sizes_employees": {"BASE TABLE", ""},
+	}
+
+	rs, err := conn.ExecuteFetch(conn.BaseShowTablesWithSizes(), math.MaxInt, false)
+	require.NoError(t, err)
+	require.NotEmpty(t, rs.Rows)
+
+	assert.GreaterOrEqual(t, len(rs.Rows), len(expectTables))
+	matchedTables := map[string]bool{}
+	for _, row := range rs.Rows {
+		tableName := row[0].ToString()
+		vals, ok := expectTables[tableName]
+		if ok {
+			assert.Equal(t, vals[0], row[1].ToString()) // TABLE_TYPE
+			assert.Equal(t, vals[1], row[3].ToString()) // TABLE_COMMENT
+			matchedTables[tableName] = true
+		}
+	}
+	assert.Equalf(t, len(expectTables), len(matchedTables), "%v", matchedTables)
+}