Some optimizations and fixes

[kolya7k]

1. Row Constructor Expression eventually not used even by MySQL 8.1+ and so (col_a, col_b) > (a, b) leads to INDEX scan instead of RANGE scan when col_a > a OR (col_a = a AND col_b > b) used.
   Speedup for queries about 20x in huge tables

2. We have to convert date as string ('2025-02-02') to date type because python can't compare str with date

[bakwc]

We should only attempt to convert for datetime or date types, not for arbitrary strings. Please do the following:

1. Get MySQL field types for primary keys (add it after line 300):

   field_types_mysql = [field.field_type for field in mysql_table_structure.fields]
   primary_key_types_mysql = [field_types[key_idx] for key_idx in primary_key_ids]
   

2. Check if the type is datetime and only in this case try to convert it to dates.

[bakwc]

It would be great to add some unit tests if you have time. See running tests section in README.md (it's optional)

[bakwc]

Please note that some existing tests seem to be failing; could you please take a look?

[kolya7k]

I'm coding on python first time and on vacation atm :)
Test failure was fixed in last commits.

[bakwc]

They still failing.. here is a stack trace:

 Traceback (most recent call last):
  File "/app/mysql_ch_replicator/db_replicator.py", line 210, in run
    self.perform_initial_replication()
  File "/app/mysql_ch_replicator/db_replicator.py", line 254, in perform_initial_replication
    self.perform_initial_replication_table(table)
  File "/app/mysql_ch_replicator/db_replicator.py", line 358, in perform_initial_replication_table
    self.clickhouse_api.insert(table_name, records, table_structure=clickhouse_table_structure)
  File "/app/mysql_ch_replicator/clickhouse_api.py", line 244, in insert
    records=len(records_to_insert),
                ^^^^^^^^^^^^^^^^^
NameError: name 'records_to_insert' is not defined

[kolya7k]

Forgot the last commit, did it

[bakwc]

Tests still failing (this time another test), see the build run, test is called test_datetime_exception:

Traceback (most recent call last):
  File "/usr/local/lib/python3.12/site-packages/clickhouse_connect/driver/transform.py", line 99, in chunk_gen
    col_type.write_column(data, output, context)
  File "/usr/local/lib/python3.12/site-packages/clickhouse_connect/datatypes/base.py", line 214, in write_column
    self.write_column_data(column, dest, ctx)
  File "/usr/local/lib/python3.12/site-packages/clickhouse_connect/datatypes/base.py", line 229, in write_column_data
    self._write_column_binary(column, dest, ctx)
  File "/usr/local/lib/python3.12/site-packages/clickhouse_connect/datatypes/temporal.py", line 223, in _write_column_binary
    column = [((int(x.timestamp()) * 1000000 + x.microsecond) * prec) // 1000000 for x in column]

Anyway thanks a lot for the PR! Will merge it as soon as all test resolved.