planner: fix PointGet working with list columns partition table with only one partition (#61141)

close #61134

Author: Defined2014

pkg/planner/core/casetest/partition/BUILD.bazel

@@ -10,7 +10,7 @@ go_test(
     ],
     data = glob(["testdata/**"]),
     flaky = True,
-    shard_count = 13,
+    shard_count = 14,
     deps = [
         "//pkg/config",
         "//pkg/planner/util/coretestsdk",

pkg/planner/core/casetest/partition/partition_pruner_test.go

@@ -634,3 +634,18 @@ func TestIssue59827RangeColumns(t *testing.T) {
 	tk.MustQuery("explain select * from t where a = 'a' and b = '2'").CheckContain("partition:p2")
 	tk.MustQuery("explain select * from t where a = 'a' and (b = '2')").CheckContain("partition:p2")
 }
+
+func TestIssue61134(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test")
+	tk.MustExec("create table t (" +
+		"a varchar(291)," +
+		"b int," +
+		"primary key(a)) partition by list columns (a)" +
+		"(partition p0 values in ('', '1'))")
+
+	tk.MustExec("insert into t values ('', 1)")
+	tk.MustQuery("explain select * from t where a in ('')").CheckContain("Point_Get")
+	tk.MustQuery("select * from t where a in ('')").Check(testkit.Rows(" 1"))
+}

pkg/planner/core/point_get_plan.go

@@ -388,9 +388,16 @@ func needsPartitionPruning(sctx sessionctx.Context, tblInfo *model.TableInfo, pt
 	}
 
 	partIdx, err := PartitionPruning(sctx.GetPlanCtx(), pt, conds, partitionNames, tblCols, partNameSlice)
-	if err != nil || len(partIdx) != 1 {
+	if err != nil {
 		return nil, true, err
 	}
+	if len(partIdx) == 1 && partIdx[0] == FullRange {
+		ret := make([]int, len(tblInfo.Partition.Definitions))
+		for i := range len(tblInfo.Partition.Definitions) {
+			ret[i] = i
+		}
+		return ret, true, nil
+	}
 	return partIdx, true, nil
 }