feat: support show columns and show index in sharding mode (#269)

pkg/optimize/optimize_show_table_meta.go

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2022 CECTC, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package optimize
+
+import (
+	"context"
+
+	"github.com/pkg/errors"
+
+	"github.com/cectc/dbpack/pkg/plan"
+	"github.com/cectc/dbpack/pkg/proto"
+	"github.com/cectc/dbpack/third_party/parser/ast"
+)
+
+func (o Optimizer) optimizeShowTableMeta(ctx context.Context, stmt *ast.ShowStmt, args []interface{}) (proto.Plan, error) {
+	if stmt.Tp != ast.ShowColumns && stmt.Tp != ast.ShowIndex {
+		return nil, errors.New("statement must be show columns stmt or show index stmt")
+	}
+
+	executor := o.executors[0]
+	tableName := stmt.Table.Name.O
+	if topology, exists := o.topologies[tableName]; exists {
+		stmt.Table.Name.O = topology.DBs[executor.GroupName()][0]
+		return &plan.ShowTableMetaPlan{
+			Stmt:     stmt,
+			Args:     args,
+			Executor: executor,
+		}, nil
+	}
+	return &plan.ShowTableMetaPlan{
+		Stmt:     stmt,
+		Args:     args,
+		Executor: executor,
+	}, nil
+}

pkg/optimize/optimize_show_table_status.go

@@ -41,15 +41,15 @@ func (o Optimizer) optimizeShowTableStatus(ctx context.Context, stmt *ast.ShowSt
 	pattern := stmt.Pattern.Pattern.(*driver.ValueExpr)
 	tableName := pattern.GetDatumString()
 	if topology, exists = o.topologies[tableName]; !exists {
-		return &plan.ShowTableStatusPlan{
+		return &plan.ShowTableMetaPlan{
 			Stmt:     stmt,
 			Args:     args,
 			Executor: o.executors[0],
 		}, nil
 	} else {
 		table := topology.DBs[o.executors[0].GroupName()][0]
 		pattern.SetValue(table)
-		return &plan.ShowTableStatusPlan{
+		return &plan.ShowTableMetaPlan{
 			Stmt:     stmt,
 			Args:     args,
 			Executor: o.executors[0],

pkg/optimize/optimizer.go

@@ -69,6 +69,8 @@ func (o Optimizer) Optimize(ctx context.Context, stmt ast.StmtNode, args ...inte
 		switch t.Tp {
 		case ast.ShowTableStatus:
 			return o.optimizeShowTableStatus(ctx, t, args)
+		case ast.ShowColumns, ast.ShowIndex:
+			return o.optimizeShowTableMeta(ctx, t, args)
 		}
 	}
 	sqlText := proto.SqlText(ctx)

pkg/plan/show_table_status.go → pkg/plan/show_table_meta.go

@@ -28,13 +28,13 @@ import (
 	"github.com/cectc/dbpack/third_party/parser/format"
 )
 
-type ShowTableStatusPlan struct {
+type ShowTableMetaPlan struct {
 	Stmt     *ast.ShowStmt
 	Args     []interface{}
 	Executor proto.DBGroupExecutor
 }
 
-func (p *ShowTableStatusPlan) Execute(ctx context.Context, _ ...*ast.TableOptimizerHint) (proto.Result, uint16, error) {
+func (p *ShowTableMetaPlan) Execute(ctx context.Context, _ ...*ast.TableOptimizerHint) (proto.Result, uint16, error) {
 	var (
 		sb  strings.Builder
 		sql string

test/shd/sharding_test.go

@@ -276,6 +276,37 @@ func (suite *_ShardingSuite) TestShowTableStatus() {
 	}
 }
 
+func (suite *_ShardingSuite) TestShowTableMeta() {
+	rows, err := suite.db.Query("SHOW COLUMNS FROM city")
+	if suite.NoErrorf(err, "show columns error: %v", err) {
+		var (
+			field, sqlType, null, key, defaultValue, extra interface{}
+		)
+		suite.T().Log("table city columns:")
+		for rows.Next() {
+			err := rows.Scan(&field, &sqlType, &null, &key, &defaultValue, &extra)
+			suite.NoError(err)
+			suite.T().Logf("%s	%s	%s	%s	%s	%s", field, sqlType, null, key, defaultValue, extra)
+		}
+	}
+	rows, err = suite.db.Query("SHOW INDEX FROM city")
+	if suite.NoErrorf(err, "show index error: %v", err) {
+		var (
+			table, non_unique, key_name, seq_in_index, column_name, collation, cardinality, sub_part, packed, null,
+			index_type, comment, index_comment, visible, expression interface{}
+		)
+		suite.T().Log("table city index:")
+		for rows.Next() {
+			err := rows.Scan(&table, &non_unique, &key_name, &seq_in_index, &column_name, &collation, &cardinality,
+				&sub_part, &packed, &null, &index_type, &comment, &index_comment, &visible, &expression)
+			suite.NoError(err)
+			suite.T().Logf("%s	%s	%s	%s	%s	%s %s	%s	%s	%s	%s	%s	%s	%s 	%s", table, non_unique,
+				key_name, seq_in_index, column_name, collation, cardinality, sub_part, packed, null, index_type,
+				comment, index_comment, visible, expression)
+		}
+	}
+}
+
 func (suite *_ShardingSuite) TestDeleteCity() {
 	result, err := suite.db.Exec(deleteCity, 10, 20)
 	suite.Assert().Nil(err)