planner: reject invalid conversion from like to =

go.sum

@@ -3,6 +3,7 @@ github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/StackExchange/wmi v0.0.0-20180725035823-b12b22c5341f h1:5ZfJxyXo8KyX8DgGXC5B7ILL8y51fci/qYz2B4j8iLY=
 github.com/StackExchange/wmi v0.0.0-20180725035823-b12b22c5341f/go.mod h1:3eOhrUMpNV+6aFIbp5/iudMxNCF27Vw2OZgy4xEx0Fg=
+github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf h1:qet1QNfXsQxTZqLG4oE62mJzwPIB8+Tee4RNCL9ulrY=
 github.com/alecthomas/units v0.0.0-20151022065526-2efee857e7cf/go.mod h1:ybxpYRFXyAe+OPACYpWeL0wqObRcbAqCMya13uyzqw0=
 github.com/beorn7/perks v0.0.0-20180321164747-3a771d992973 h1:xJ4a3vCFaGF/jqvzLMYoU8P317H5OQ+Via4RmuPwCS0=
 github.com/beorn7/perks v0.0.0-20180321164747-3a771d992973/go.mod h1:Dwedo/Wpr24TaqPxmxbtue+5NUziq4I4S80YR8gNf3Q=

planner/core/expression_rewriter.go

@@ -1237,7 +1237,7 @@ func (er *expressionRewriter) patternLikeToExpression(v *ast.PatternLikeExpr) {
 		}
 		if !isNull {
 			patValue, patTypes := stringutil.CompilePattern(patString, v.Escape)
-			if stringutil.IsExactMatch(patTypes) {
+			if stringutil.IsExactMatch(patTypes) && er.ctxStack[l-2].GetType().EvalType() == types.ETString {
 				op := ast.EQ
 				if v.Not {
 					op = ast.NE

planner/core/expression_rewriter_test.go

@@ -242,3 +242,21 @@ func (s *testExpressionRewriterSuite) TestCheckFullGroupBy(c *C) {
 	err = tk.ExecToErr("select t1.a, (select t2.a, max(t2.b) from t t2) from t t1")
 	c.Assert(terror.ErrorEqual(err, core.ErrMixOfGroupFuncAndFields), IsTrue, Commentf("err %v", err))
 }
+
+func (s *testExpressionRewriterSuite) TestPatternLikeToExpression(c *C) {
+	defer testleak.AfterTest(c)()
+	store, dom, err := newStoreWithBootstrap()
+	c.Assert(err, IsNil)
+	tk := testkit.NewTestKit(c, store)
+	defer func() {
+		dom.Close()
+		store.Close()
+	}()
+	tk.MustQuery("select 0 like 'a string';").Check(testkit.Rows("0"))
+	tk.MustQuery("select 0.0 like 'a string';").Check(testkit.Rows("0"))
+	tk.MustQuery("select 0 like '0.00';").Check(testkit.Rows("0"))
+	tk.MustQuery("select cast(\"2011-5-3\" as datetime) like \"2011-05-03\";").Check(testkit.Rows("0"))
+	tk.MustQuery("select 1 like '1';").Check(testkit.Rows("1"))
+	tk.MustQuery("select 0 like '0';").Check(testkit.Rows("1"))
+	tk.MustQuery("select 0.00 like '0.00';").Check(testkit.Rows("1"))
+}

planner/core/logical_plan_test.go

@@ -83,7 +83,7 @@ func (s *testPlanSuite) TestPredicatePushDown(c *C) {
 		},
 		{
 			sql:  "select * from t t1, t t2 where t1.a = t2.b and t2.b > 0 and t1.a = t1.c and t1.d like 'abc' and t2.d = t1.d",
-			best: "Join{DataScan(t1)->Sel([eq(cast(test.t1.d), cast(abc))])->DataScan(t2)->Sel([eq(cast(test.t2.d), cast(abc))])}(test.t1.a,test.t2.b)(test.t1.d,test.t2.d)->Projection",
+			best: "Join{DataScan(t1)->Sel([like(cast(test.t1.d), abc, 92)])->DataScan(t2)->Sel([like(cast(test.t2.d), abc, 92)])}(test.t1.a,test.t2.b)(test.t1.d,test.t2.d)->Projection",
 		},
 		{
 			sql:  "select * from t ta join t tb on ta.d = tb.d and ta.d > 1 where tb.a = 0",

planner/core/physical_plan_test.go

@@ -1170,12 +1170,6 @@ func (s *testPlanSuite) TestRefine(c *C) {
 			sql:  `select a from t where c_str like 123`,
 			best: "IndexReader(Index(t.c_d_e_str)[[\"123\",\"123\"]])->Projection",
 		},
-		// c is type int which will be added cast to specified type when building function signature,
-		// and rewrite predicate like to predicate '='  when exact match , index still can be used.
-		{
-			sql:  `select a from t where c like '1'`,
-			best: "IndexReader(Index(t.c_d_e)[[1,1]])->Projection",
-		},
 		{
 			sql:  `select a from t where c = 1.9 and d > 3`,
 			best: "Dual",