This patch changes the main name of 3 byte character set from utf8 to
utf8mb3. New old_mode UTF8_IS_UTF8MB3 is added and set TRUE by default,
so that utf8 would mean utf8mb3. If not set, utf8 would mean utf8mb4.
The old code to print partition values was too complicated:
- it created new Items for character set conversion purposes.
- it mixed string conversion and partition error reporting
in the same code blocks.
Simplifying the code as follows:
- Adding helper methods String::can_be_safely_convert_to() and
String::append_introducer_and_hex().
- Adding DBUG_EXECUTE_IF("generate_partition_syntax_for_frm", push_warning...)
into generate_partition_syntax_for_frm(), to test the PARTITON
clause written to FRM. Adding test partition_utf8-debug.test for this.
- Removing functions get_cs_converted_part_value_from_string() and
get_cs_converted_string_value. Changing get_partition_column_description()
to use Type_handler::partition_field_append_value() instead.
This makes SHOW CREATE TABLE and SELECT FROM I_S.PARTITIONS
use the same code path.
- Changing Type_handler::partition_field_append_value() not to
call convert_charset_partition_constant(), to avoid creating a new Item
for string conversion pursposes.
Rewritting the code to use only String methods.
- Removing error reporting code (ER_PARTITION_FUNCTION_IS_NOT_ALLOWED)
from Type_handler::partition_field_append_value().
The error is correctly detected and reported on the caller level.
So error reporting was redundant here.
Also:
- Moving methods Type_handler::partition_field_*() from sql_partition.cc
to sql_type.cc. This fixes compilation problem with -DPLUGIN_PARTITION=NO,
earlier introduced by the patch for MDEV-20831.
