Merge branch 'master' into fix_bug_8700

pingcap · Jan 6, 2019 · 7b0e53d · 7b0e53d
2 parents 8993094 + 78a51a4
commit 7b0e53d
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Showing 3 changed files with 23 additions and 2 deletions.
diff --git a/executor/show.go b/executor/show.go
@@ -31,6 +31,7 @@ import (
 	"github.com/pingcap/parser/mysql"
 	"github.com/pingcap/parser/terror"
 	"github.com/pingcap/tidb/infoschema"
+	plannercore "github.com/pingcap/tidb/planner/core"
 	"github.com/pingcap/tidb/privilege"
 	"github.com/pingcap/tidb/sessionctx/stmtctx"
 	"github.com/pingcap/tidb/sessionctx/variable"
@@ -329,6 +330,22 @@ func (e *ShowExec) fetchShowColumns() error {
 	}
 
 	cols := tb.Cols()
+	if tb.Meta().IsView() {
+		// Because view's undertable's column could change or recreate, so view's column type may change overtime.
+		// To avoid this situation we need to generate a logical plan and extract current column types from Schema.
+		planBuilder := plannercore.NewPlanBuilder(e.ctx, e.is)
+		viewLogicalPlan, err := planBuilder.BuildDataSourceFromView(e.DBName, tb.Meta())
+		if err != nil {
+			return err
+		}
+		viewSchema := viewLogicalPlan.Schema()
+		for _, col := range cols {
+			viewColumn := viewSchema.FindColumnByName(col.Name.L)
+			if viewColumn != nil {
+				col.FieldType = *viewColumn.GetType()
+			}
+		}
+	}
 	for _, col := range cols {
 		if e.Column != nil && e.Column.Name.L != col.Name.L {
 			continue

diff --git a/executor/show_test.go b/executor/show_test.go
@@ -173,6 +173,9 @@ func (s *testSuite2) TestShow2(c *C) {
 	tk.MustExec(`create table if not exists t (c int) comment '注释'`)
 	tk.MustExec("create or replace view v as select * from t")
 	tk.MustQuery(`show columns from t`).Check(testutil.RowsWithSep(",", "c,int(11),YES,,<nil>,"))
+	tk.MustQuery(`describe t`).Check(testutil.RowsWithSep(",", "c,int(11),YES,,<nil>,"))
+	tk.MustQuery(`show columns from v`).Check(testutil.RowsWithSep(",", "c,int(11),YES,,<nil>,"))
+	tk.MustQuery(`describe v`).Check(testutil.RowsWithSep(",", "c,int(11),YES,,<nil>,"))
 	tk.MustQuery("show collation where Charset = 'utf8' and Collation = 'utf8_bin'").Check(testutil.RowsWithSep(",", "utf8_bin,utf8,83,,Yes,1"))
 
 	tk.MustQuery("show tables").Check(testkit.Rows("t", "v"))

diff --git a/planner/core/logical_plan_builder.go b/planner/core/logical_plan_builder.go
@@ -1984,7 +1984,7 @@ func (b *PlanBuilder) buildDataSource(tn *ast.TableName) (LogicalPlan, error) {
 	b.visitInfo = appendVisitInfo(b.visitInfo, mysql.SelectPriv, dbName.L, tableInfo.Name.L, "", nil)
 
 	if tableInfo.IsView() {
-		return b.buildDataSourceFromView(dbName, tableInfo)
+		return b.BuildDataSourceFromView(dbName, tableInfo)
 	}
 
 	if tableInfo.GetPartitionInfo() != nil {
@@ -2086,7 +2086,8 @@ func (b *PlanBuilder) buildDataSource(tn *ast.TableName) (LogicalPlan, error) {
 	return result, nil
 }
 
-func (b *PlanBuilder) buildDataSourceFromView(dbName model.CIStr, tableInfo *model.TableInfo) (LogicalPlan, error) {
+// BuildDataSourceFromView is used to build LogicalPlan from view
+func (b *PlanBuilder) BuildDataSourceFromView(dbName model.CIStr, tableInfo *model.TableInfo) (LogicalPlan, error) {
 	charset, collation := b.ctx.GetSessionVars().GetCharsetInfo()
 	selectNode, err := parser.New().ParseOneStmt(tableInfo.View.SelectStmt, charset, collation)
 	if err != nil {