refine table optimizer hint and make it more generic (#747)

* refine table optimizer hint and make it more generic

Signed-off-by: Lonng <heng@lonng.org>

* implement the restore

Signed-off-by: Lonng <heng@lonng.org>

* address comment

Signed-off-by: Lonng <heng@lonng.org>

* address comment

Signed-off-by: Lonng <heng@lonng.org>

* fix typo

Signed-off-by: Lonng <heng@lonng.org>

ast/misc.go

@@ -2198,17 +2198,31 @@ type TableOptimizerHint struct {
 	// Table hints has no schema info
 	// It allows only table name or alias (if table has an alias)
 	HintName model.CIStr
-	// QBName is the default effective query block of this hint.
-	QBName    model.CIStr
-	Tables    []HintTable
-	Indexes   []model.CIStr
-	StoreType model.CIStr
+	// HintData is the payload of the hint. The actual type of this field
+	// is defined differently as according `HintName`. Define as following:
+	//
 	// Statement Execution Time Optimizer Hints
 	// See https://dev.mysql.com/doc/refman/5.7/en/optimizer-hints.html#optimizer-hints-execution-time
-	MaxExecutionTime uint64
-	MemoryQuota      int64
-	QueryType        model.CIStr
-	HintFlag         bool
+	// - MAX_EXECUTION_TIME  => uint64
+	// - MEMORY_QUOTA        => int64
+	// - QUERY_TYPE          => model.CIStr
+	//
+	// Time Range is used to hint the time range of inspection tables
+	// e.g: select /*+ time_range('','') */ * from information_schema.inspection_result.
+	// - TIME_RANGE          => ast.HintTimeRange
+	// - READ_FROM_STORAGE   => model.CIStr
+	// - USE_TOJA            => bool
+	HintData interface{}
+	// QBName is the default effective query block of this hint.
+	QBName  model.CIStr
+	Tables  []HintTable
+	Indexes []model.CIStr
+}
+
+// HintTimeRange is the payload of `TIME_RANGE` hint
+type HintTimeRange struct {
+	From string
+	To   string
 }
 
 // HintTable is table in the hint. It may have query block info.
@@ -2252,7 +2266,7 @@ func (n *TableOptimizerHint) Restore(ctx *format.RestoreCtx) error {
 	// Hints with args except query block.
 	switch n.HintName.L {
 	case "max_execution_time":
-		ctx.WritePlainf("%d", n.MaxExecutionTime)
+		ctx.WritePlainf("%d", n.HintData.(uint64))
 	case "tidb_hj", "tidb_smj", "tidb_inlj", "hash_join", "sm_join", "inl_join":
 		for i, table := range n.Tables {
 			if i != 0 {
@@ -2270,17 +2284,17 @@ func (n *TableOptimizerHint) Restore(ctx *format.RestoreCtx) error {
 			ctx.WriteName(index.String())
 		}
 	case "use_toja", "enable_plan_cache":
-		if n.HintFlag {
+		if n.HintData.(bool) {
 			ctx.WritePlain("TRUE")
 		} else {
 			ctx.WritePlain("FALSE")
 		}
 	case "query_type":
-		ctx.WriteKeyWord(n.QueryType.String())
+		ctx.WriteKeyWord(n.HintData.(model.CIStr).String())
 	case "memory_quota":
-		ctx.WritePlainf("%d MB", n.MemoryQuota/1024/1024)
+		ctx.WritePlainf("%d MB", n.HintData.(int64)/1024/1024)
 	case "read_from_storage":
-		ctx.WriteKeyWord(n.StoreType.String())
+		ctx.WriteKeyWord(n.HintData.(model.CIStr).String())
 		for i, table := range n.Tables {
 			if i == 0 {
 				ctx.WritePlain("[")
@@ -2292,6 +2306,11 @@ func (n *TableOptimizerHint) Restore(ctx *format.RestoreCtx) error {
 				ctx.WritePlain(", ")
 			}
 		}
+	case "time_range":
+		hintData := n.HintData.(HintTimeRange)
+		ctx.WriteString(hintData.From)
+		ctx.WritePlain(", ")
+		ctx.WriteString(hintData.To)
 	}
 	ctx.WritePlain(")")
 	return nil

ast/misc_test.go

@@ -255,6 +255,7 @@ func (ts *testMiscSuite) TestTableOptimizerHintRestore(c *C) {
 		{"READ_CONSISTENT_REPLICA(@sel1)", "READ_CONSISTENT_REPLICA(@`sel1`)"},
 		{"QB_NAME(sel1)", "QB_NAME(`sel1`)"},
 		{"READ_FROM_STORAGE(@sel TIFLASH[t1, t2])", "READ_FROM_STORAGE(@`sel` TIFLASH[`t1`, `t2`])"},
+		{"TIME_RANGE('2020-02-02 10:10:10','2020-02-02 11:10:10')", "TIME_RANGE('2020-02-02 10:10:10', '2020-02-02 11:10:10')"},
 	}
 	extractNodeFunc := func(node Node) Node {
 		return node.(*SelectStmt).TableHints[0]