From b765ad00401c5ccfe043582c4b5038be5c9a2bc6 Mon Sep 17 00:00:00 2001
From: tiancaiamao <tiancaiamao@gmail.com>
Date: Wed, 22 Dec 2021 22:26:55 +0800
Subject: [PATCH] executor: display 'show create table' and INFOSCHEMA for
 cached table correctly

---
 executor/infoschema_reader.go |  2 ++
 executor/show.go              |  6 ++++++
 executor/show_test.go         | 21 +++++++++++++++++++++
 3 files changed, 29 insertions(+)

diff --git a/executor/infoschema_reader.go b/executor/infoschema_reader.go
index 06d35d24fce1d..b5eee15e32600 100644
--- a/executor/infoschema_reader.go
+++ b/executor/infoschema_reader.go
@@ -543,6 +543,8 @@ func (e *memtableRetriever) setDataFromTables(ctx context.Context, sctx sessionc
 			if !table.IsView() {
 				if table.GetPartitionInfo() != nil {
 					createOptions = "partitioned"
+				} else if table.TableCacheStatusType == model.TableCacheStatusEnable {
+					createOptions = "cached=on"
 				}
 				var autoIncID interface{}
 				hasAutoIncID, _ := infoschema.HasAutoIncrementColumn(table)
diff --git a/executor/show.go b/executor/show.go
index ea4bdf4f1aee8..066d819cc9b80 100644
--- a/executor/show.go
+++ b/executor/show.go
@@ -1077,6 +1077,12 @@ func ConstructResultOfShowCreateTable(ctx sessionctx.Context, tableInfo *model.T
 		fmt.Fprintf(buf, " /*T![placement] PLACEMENT POLICY=%s */", stringutil.Escape(tableInfo.PlacementPolicyRef.Name.String(), sqlMode))
 	}
 
+	if tableInfo.TableCacheStatusType == model.TableCacheStatusEnable {
+		// This is not meant to be understand by other components, so it's not written as /*T![cached] */
+		// For all external components, cached table is just a normal table.
+		fmt.Fprintf(buf, " /* CACHED ON */")
+	}
+
 	// add direct placement info here
 	appendDirectPlacementInfo(tableInfo.DirectPlacementOpts, buf)
 	// add partition info here.
diff --git a/executor/show_test.go b/executor/show_test.go
index 34db4d54ae962..229d4399dae4d 100644
--- a/executor/show_test.go
+++ b/executor/show_test.go
@@ -1674,3 +1674,24 @@ func (s *testSuite5) TestShowTemporaryTable(c *C) {
 		") ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin AUTO_INCREMENT=2"
 	tk.MustQuery("show create table t7").Check(testkit.Rows("t7 " + expect))
 }
+
+func (s *testSuite5) TestShowCachedTable(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("create table t1 (id int)")
+	tk.MustExec("alter table t1 cache")
+	tk.MustQuery("show create table t1").Check(
+		testkit.Rows("t1 CREATE TABLE `t1` (\n" +
+			"  `id` int(11) DEFAULT NULL\n" +
+			") ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin /* CACHED ON */"))
+	tk.MustQuery("select create_options from information_schema.tables where table_schema = 'test' and table_name = 't1'").Check(
+		testkit.Rows("cached=on"))
+
+	tk.MustExec("alter table t1 nocache")
+	tk.MustQuery("show create table t1").Check(
+		testkit.Rows("t1 CREATE TABLE `t1` (\n" +
+			"  `id` int(11) DEFAULT NULL\n" +
+			") ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin"))
+	tk.MustQuery("select create_options from information_schema.tables where table_schema = 'test' and table_name = 't1'").Check(
+		testkit.Rows(""))
+}