expression: Push down json_contains to tikv (#37840)

close #37839

expression/expression.go

@@ -1003,7 +1003,7 @@ func scalarExprSupportedByTiKV(sf *ScalarFunction) bool {
 		ast.JSONType, ast.JSONExtract, ast.JSONObject, ast.JSONArray, ast.JSONMerge, ast.JSONSet,
 		ast.JSONInsert /*ast.JSONReplace,*/, ast.JSONRemove, ast.JSONLength,
 		// FIXME: JSONUnquote is incompatible with Coprocessor
-		ast.JSONUnquote,
+		ast.JSONUnquote, ast.JSONContains,
 
 		// date functions.
 		ast.Date, ast.Week /* ast.YearWeek, ast.ToSeconds */, ast.DateDiff,

planner/core/integration_test.go

@@ -3065,7 +3065,7 @@ func TestScalarFunctionPushDown(t *testing.T) {
 	tk := testkit.NewTestKit(t, store)
 	tk.MustExec("use test")
 	tk.MustExec("create table t(id int signed, id2 int unsigned, c varchar(11), d datetime, b double, e bit(10))")
-	tk.MustExec("insert into t(id, id2, c, d) values (-1, 1, 'abc', '2021-12-12')")
+	tk.MustExec("insert into t(id, id2, c, d) values (-1, 1, '{\"a\":1}', '2021-12-12')")
 	rows := [][]interface{}{
 		{"TableReader_7", "root", "data:Selection_6"},
 		{"└─Selection_6", "cop[tikv]", "right(test.t.c, 1)"},
@@ -3178,6 +3178,10 @@ func TestScalarFunctionPushDown(t *testing.T) {
 	rows[1][2] = "ascii(cast(test.t.e, var_string(2)))"
 	tk.MustQuery("explain analyze select /*+read_from_storage(tikv[t])*/ * from t where ascii(e);").
 		CheckAt([]int{0, 3, 6}, rows)
+
+	rows[1][2] = "json_contains(cast(test.t.c, json BINARY), cast(\"1\", json BINARY))"
+	tk.MustQuery("explain analyze select /*+read_from_storage(tikv[t])*/ * from t where json_contains(c, '1');").
+		CheckAt([]int{0, 3, 6}, rows)
 }
 
 func TestDistinctScalarFunctionPushDown(t *testing.T) {