planner: incorrect query result using ISNULL (#54819)

close #54803

pkg/planner/core/casetest/testdata/plan_normalized_suite_out.json

@@ -426,8 +426,8 @@
         "Plan": [
           " TableReader         root         ",
           " └─ExchangeSender    cop[tiflash] ",
-          "   └─Selection       cop[tiflash] gt(test.t1.b, ?)",
-          "     └─TableFullScan cop[tiflash] table:t1, range:[?,?], pushed down filter:gt(test.t1.a, ?), gt(test.t1.c, ?), keep order:false"
+          "   └─Selection       cop[tiflash] gt(test.t1.c, ?)",
+          "     └─TableFullScan cop[tiflash] table:t1, range:[?,?], pushed down filter:gt(test.t1.a, ?), gt(test.t1.b, ?), keep order:false"
         ]
       },
       {

pkg/planner/core/issuetest/BUILD.bazel

@@ -10,7 +10,7 @@ go_test(
     data = glob(["testdata/**"]),
     flaky = True,
     race = "on",
-    shard_count = 3,
+    shard_count = 4,
     deps = [
         "//pkg/parser",
         "//pkg/planner",

pkg/planner/core/issuetest/planner_issue_test.go

@@ -117,3 +117,30 @@ func TestIssue54535(t *testing.T) {
 	tk.MustQuery("select /*+ inl_join(tmp) */ * from t1 inner join (select col_1, group_concat(col_2) from t2 group by col_1) tmp on t1.col_1 = tmp.col_1;").Check(testkit.Rows())
 	tk.MustQuery("select /*+ inl_join(tmp) */ * from t1 inner join (select col_1, group_concat(distinct col_2 order by col_2) from t2 group by col_1) tmp on t1.col_1 = tmp.col_1;").Check(testkit.Rows())
 }
+
+func TestIssue54803(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec(`
+    CREATE TABLE t1db47fc1 (
+        col_67 time NOT NULL DEFAULT '16:58:45',
+        col_68 tinyint(3) unsigned DEFAULT NULL,
+        col_69 bit(6) NOT NULL DEFAULT b'11110',
+        col_72 double NOT NULL
+    ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci
+    PARTITION BY HASH (col_68) PARTITIONS 5;
+    `)
+	tk.MustQuery(`EXPLAIN SELECT TRIM(t1db47fc1.col_68) AS r0
+    FROM t1db47fc1
+    WHERE ISNULL(t1db47fc1.col_68)
+    GROUP BY t1db47fc1.col_68
+    HAVING ISNULL(t1db47fc1.col_68) OR t1db47fc1.col_68 IN (62, 200, 196, 99)
+    LIMIT 106149535;
+    `).Check(testkit.Rows("Projection_11 8.00 root  trim(cast(test.t1db47fc1.col_68, var_string(20)))->Column#7",
+		"└─Limit_14 8.00 root  offset:0, count:106149535",
+		"  └─HashAgg_17 8.00 root  group by:test.t1db47fc1.col_68, funcs:firstrow(test.t1db47fc1.col_68)->test.t1db47fc1.col_68",
+		"    └─TableReader_24 10.00 root partition:p0 data:Selection_23",
+		"      └─Selection_23 10.00 cop[tikv]  isnull(test.t1db47fc1.col_68), or(isnull(test.t1db47fc1.col_68), in(test.t1db47fc1.col_68, 62, 200, 196, 99))",
+		"        └─TableFullScan_22 10000.00 cop[tikv] table:t1db47fc1 keep order:false, stats:pseudo"))
+}

pkg/util/ranger/detacher.go

@@ -755,8 +755,11 @@ func ExtractEqAndInCondition(sctx *rangerctx.RangerContext, conditions []express
 			return nil, nil, nil, nil, true
 		} else {
 			// All Intervals are single points
-			accesses[i] = points2EqOrInCond(sctx.ExprCtx, points[i], cols[i])
-			newConditions = append(newConditions, accesses[i])
+			if f, ok := accesses[i].(*expression.ScalarFunction); !ok || (ok && f.FuncName.L != ast.IsNull) {
+				// isnull is not equal to a = NULL
+				accesses[i] = points2EqOrInCond(sctx.ExprCtx, points[i], cols[i])
+				newConditions = append(newConditions, accesses[i])
+			}
 			if f, ok := accesses[i].(*expression.ScalarFunction); ok && f.FuncName.L == ast.EQ {
 				// Actually the constant column value may not be mutable. Here we assume it is mutable to keep it simple.
 				// Maybe we can improve it later.