Type_handler::partition_field_append_value() erroneously
passed the address of my_collation_contextually_typed_binary
to conversion functions copy_and_convert() and my_convert().
This happened because generate_partition_syntax_for_frm()
was called from mysql_create_frm_image() in the stage when
the fields in List<Create_field> can still contain unresolved
contextual collations, like "binary" in the reported crash scenario:
ALTER TABLE t CHANGE COLUMN a a CHAR BINARY;
Fix:
1. Splitting mysql_prepare_create_table() into two parts:
- mysql_prepare_create_table_stage1() interates through
List<Create_field> and calls Create_field::prepare_stage1(),
which performs basic attribute initialization, including
context collation resolution.
- mysql_prepare_create_table_finalize() - the rest of the
old mysql_prepare_create_table() code.
2. Changing mysql_create_frm_image():
It now calls:
- mysql_prepare_create_table_stage1() in the very
beginning, before the partition related code.
- mysql_prepare_create_table_finalize() in the end,
instead of the old mysql_prepare_create_table() call
3. Adding mysql_prepare_create_table() as a wrapper
for two calls:
mysql_prepare_create_table_stage1() ||
mysql_prepare_create_table_finalize()
so the code stays unchanged in the other places
where mysql_prepare_create_table() was used.
4. Changing prototype for Type_handler::Column_definition_prepare_stage1()
Removing arguments:
- handler *file
- ulonglong table_flags
Adding a new argument instead:
- column_definition_type_t type
This allows to call Column_definition_prepare_stage1() and
therefore to call mysql_prepare_create_table_stage1()
before instantiation of a handler.
This simplifies the code, because in case of a partitioned table,
mysql_create_frm_image() creates a handler of the underlying
partition first, the frees it and created a ha_partition
instance instead.
mysql_prepare_create_table() before the fix was called with the final
(ha_partition) handler.
5. Moving parts of Column_definition_prepare_stage1() which
need a pointer to handler and table_flags to
Column_definition_prepare_stage2().
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.
