Illegal type Nullable(Nothing) of argument of function json_extract

[aytrack]

Bug Report

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

drop table if exists t;
create table t(a int, b json);

insert into t values (1, '{ "one potato" : 1 }'), (2, '{ "a.b" : 1 }'), (3, '{ "\\"a\\"": 1}'), (4, '{ "\\"a\\"": 1}'), (5, '{ "a": 1}'), (6, '{ "a": 1}'), (7,  '{ "a": [ [ 3, 2 ], [ { "c" : "d" }, 1 ] ], "b": { "c" : 6 }, "one potato": 7, "b.c" : 8 }'), (9, NULL);

alter table t set tiflash replica 1;
set tidb_enforce_mpp = 1;
select sleep(1);
select /*+ read_from_storage(tiflash[t]) */ json_extract(b, '$.b'), json_extract(NULL, NULL) from t;
explain select /*+ read_from_storage(tiflash[t]) */ json_extract(b, '$.b'), json_extract(NULL, NULL) from t;

introduced by #48550

2. What did you expect to see? (Required)

query success

3. What did you see instead (Required)

[11:03:28]TiDB root:test> select /*+ read_from_storage(tiflash[t]) */ json_extract(b, '$.b'), json_extract(NULL, NULL) from t;
(1105, 'other error for mpp stream: Code: 43, e.displayText() = DB::Exception: Illegal type Nullable(Nothing) of argument of function json_extract, e.what() = DB::Exception,')

4. What is your TiDB version? (Required)

[11:05:08]TiDB root:test> select type,version,git_hash  from information_schema.cluster_info;
+---------+-----------------------------+------------------------------------------+
| type    | version                     | git_hash                                 |
+---------+-----------------------------+------------------------------------------+
| tidb    | 7.6.0-alpha-299-gd0feede759 | d0feede7598640dd58038ce56590ccf0b0c76dd6 |
| pd      | 7.6.0-alpha                 | 995fcef820f43758b94a2eeef8cdd91fa08deaea |
| tiflash | 7.6.0-alpha                 | 713bca0a4f65c3217192baf00dc00b8ea7c9dccc |
| tikv    | 7.6.0-alpha                 | 213299221806959c95d05d0f2d7368e597fa9281 |
+---------+-----------------------------+------------------------------------------+

[SeaRise]

The reason is that json_extract does not handle only null column, not related to cast null as json
/cc @yibin87

[yibin87]

The reason is that json_extract does not handle only null column, not related to cast null as json /cc @yibin87

Got, I'll check it

[yibin87]

Should be fixed by pingcap/tiflash#8489