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MDEV-32203 Raise notes when an index cannot be used on data type mismatch

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Raise notes if indexes cannot be used:
- in case of data type or collation mismatch (diferent error messages).
- in case if a table field was replaced to something else
  (e.g. Item_func_conv_charset) during a condition rewrite.

Added option to write warnings and notes to the slow query log for
slow queries.

New variables added/changed:

- note_verbosity, with is a set of the following options:
  basic            - All old notes
  unusable_keys    - Print warnings about keys that cannot be used
                     for select, delete or update.
  explain          - Print unusable_keys warnings for EXPLAIN querys.

The default is 'basic,explain'. This means that for old installations
the only notable new behavior is that one will get notes about
unusable keys when one does an EXPLAIN for a query. One can turn all
of all notes by either setting note_verbosity to "" or setting sql_notes=0.

- log_slow_verbosity has a new option 'warnings'. If this is set
  then warnings and notes generated are printed in the slow query log
  (up to log_slow_max_warnings times per statement).

- log_slow_max_warnings   - Max number of warnings written to
                            slow query log.

Other things:
- One can now use =ALL for any 'set' variable to set all options at once.
  For example using "note_verbosity=ALL" in a config file or
  "SET @@note_verbosity=ALL' in SQL.
- mysqldump will in the future use @@note_verbosity=""' instead of
  @sql_notes=0 to disable notes.
- Added "enum class Data_type_compatibility" and changing the return type
  of all Field::can_optimize*() methods from "bool" to this new data type.

Reviewer & Co-author: Alexander Barkov <bar@mariadb.com>
- The code that prints out the notes comes mainly from Alexander
This commit is contained in:
Monty
2023-09-20 15:46:55 +03:00
parent 4c8d2410b6
commit 4e9322e2ff
79 changed files with 4328 additions and 310 deletions
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34
sql/sql_type.h
View File

@ -124,6 +124,40 @@ enum scalar_comparison_op
};
/*
This enum is intentionally defined as "class" to disallow its implicit
cast as "bool". This is needed to avoid pre-MDEV-32203 constructs like:
if (field->can_optimize_range(...))
do_optimization();
to merge automatically as such - that would change the meaning
to the opposite. The pre-MDEV-32203 code must to be changed to:
if (field->can_optimize_range(...) == Data_type_compatibility::OK)
do_optimization();
*/
enum class Data_type_compatibility
{
OK,
INCOMPATIBLE_DATA_TYPE,
INCOMPATIBLE_COLLATION
};
static inline const LEX_CSTRING
scalar_comparison_op_to_lex_cstring(scalar_comparison_op op)
{
switch (op) {
case SCALAR_CMP_EQ: return LEX_CSTRING{STRING_WITH_LEN("=")};
case SCALAR_CMP_EQUAL: return LEX_CSTRING{STRING_WITH_LEN("<=>")};
case SCALAR_CMP_LT: return LEX_CSTRING{STRING_WITH_LEN("<")};
case SCALAR_CMP_LE: return LEX_CSTRING{STRING_WITH_LEN("<=")};
case SCALAR_CMP_GE: return LEX_CSTRING{STRING_WITH_LEN(">")};
case SCALAR_CMP_GT: return LEX_CSTRING{STRING_WITH_LEN(">=")};
}
DBUG_ASSERT(0);
return LEX_CSTRING{STRING_WITH_LEN("<?>")};
}
class Hasher
{
ulong m_nr1;