Result length not requested length

[nghiaminhle]

Dear all,

Today, i've got a exception:
Result length not requested length:
Expected=8643. Actual=6. Position: 595. Data Length: 601

The exception tracing:
Result length not requested length:
Expected=8643. Actual=6. Position: 595. Data Length: 601
Traceback (most recent call last):

for row in binlogevent.rows:
File "/python3.6/site-packages/pymysqlreplication/row_event.py", line 428, in rows
self._fetch_rows()
File "/python3.6/site-packages/pymysqlreplication/row_event.py", line 423, in _fetch_rows
self.__rows.append(self._fetch_one_row())
File "/python3.6/site-packages/pymysqlreplication/row_event.py", line 512, in _fetch_one_row
row["before_values"] = self._read_column_data(self.columns_present_bitmap)
File "/python3.6/site-packages/pymysqlreplication/row_event.py", line 130, in _read_column_data
values[name] = self.__read_string(2, column)
File "/python3.6/site-packages/pymysqlreplication/row_event.py", line 218, in __read_string
string = self.packet.read_length_coded_pascal_string(size)
File "/python3.6/site-packages/pymysqlreplication/packet.py", line 253, in read_length_coded_pascal_string
return self.read(length)
File "/python3.6/site-packages/pymysqlreplication/packet.py", line 153, in read
return self.packet.read(size)
File "/python3.6/site-packages/pymysql/connections.py", line 250, in read
raise AssertionError(error)
AssertionError: Result length not requested length:
Expected=8643. Actual=6. Position: 595. Data Length: 601

When i remove the update rows event, the problem is gone away.
My configuration:

stream = BinLogStreamReader(
                connection_settings=mysql_settings,
                server_id=121
                ,only_events=[DeleteRowsEvent, WriteRowsEvent, UpdateRowsEvent]
                ,freeze_schema = False
                ,log_file='bin.002877'
                ,log_pos=753583192
                ,resume_stream = True
                ,auto_position = False
            )

I don't know the reason. Please help to figure out the solution for this solution

[baloo]

can you share the pymysql verion and the version of pymysqlreplication?

[tferreira]

I just got the same issue with WriteRowsEvent.

mysql-replication==0.15
PyMySQL==0.8.0

I tried with older versions of PyMySQL but had the same errors.

[lumenghe]

I got the same error with

mysql-replication==0.19
PyMySql==0.9.2

[juravlikk]

Got the same with

mysql-replication==0.19
PyMySql==0.8.2

After some investigation found that it doesn't depend on the library version and caused by wrong value retrieving for JSONB_TYPE_LITERAL type (true, false, null). It occurs only for large JSON documents and works well for small.
https://github.com/noplay/python-mysql-replication/blob/master/pymysqlreplication/packet.py#L389

I've raised PR to fix this - #307

[MintooJinnu]

The above issue is not specifically raised for JSON Literal method correct? It is still happening in reading varchar data(read_length_coded_pascal_string) @baloo for your refereference #610