Enable unusable key notes for non-equality predicates:
<, <=, =>, >, BETWEEN, IN, LIKE
Note, in some scenarios it displays duplicate notes, e.g.
for queries with ORDER BY:
SELECT * FROM t1
WHERE indexed_string_column >= 10
ORDER BY indexed_string_column
LIMIT 5;
This should be tolarable. Getting rid of the diplicate note
completely would need a much more complex patch, which is
not desiable in 10.6.
Details:
- Changing RANGE_OPT_PARAM::note_unusable_keys from bool
to a new data type Item_func::Bitmap, so the caller can
choose with a better granuality which predicates
should raise unusable key notes inside the range optimizer:
a. all predicates (=, <=>, <, <=, =>, >, BETWEEN, IN, LIKE)
b. all predicates except equality (=, <=>)
c. none of the predicates
"b." is needed because in some scenarios equality predicates (=, <=>)
send unusable key notes at an earlier stage, before the range optimizer,
during update_ref_and_keys(). Calling the range optimizer with
"all predicates" would produce duplicate notes for = and <=> in such cases.
- Fixing get_quick_record_count() to call the range optimizer
with "all predicates except equality" instead of "none of the predicates".
Before this change the range optimizer suppressed all notes for
non-equality predicates: <, <=, =>, >, BETWEEN, IN, LIKE.
This actually fixes the reported problem.
- Fixing JOIN::make_range_rowid_filters() to call the range optimizer
with "all predicates except equality" instead of "all predicates".
Before this change the range optimizer produced duplicate notes
for = and <=> during a rowid_filter optimization.
- Cleanup:
Adding the op_collation argument to Field::raise_note_cannot_use_key_part()
and displaying the operation collation rather than the argument collation
in the unusable key note. This is important for operations with more than
two arguments: BETWEEN and IN, e.g.:
SELECT * FROM t1
WHERE column_utf8mb3_general_ci
BETWEEN 'a' AND 'b' COLLATE utf8mb3_unicode_ci;
SELECT * FROM t1
WHERE column_utf8mb3_general_ci
IN ('a', 'b' COLLATE utf8mb3_unicode_ci);
The note for 'a' now prints utf8mb3_unicode_ci as the collation.
which is the collation of the entire operation:
Cannot use key key1 part[0] for lookup:
"`column_utf8mb3_general_ci`" of collation `utf8mb3_general_ci` >=
"'a'" of collation `utf8mb3_unicode_ci`
Before this change it printed the collation of 'a',
so the note was confusing:
Cannot use key key1 part[0] for lookup:
"`column_utf8mb3_general_ci`" of collation `utf8mb3_general_ci` >=
"'a'" of collation `utf8mb3_general_ci`"
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 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.
So to push index condition for each join tab we have calculate the index condition that can be pushed and then
remove this index condition from the original condition. This is done through the function make_cond_remainder.
The problem is the function make_cond_remainder does not remove index condition when there is an OR operator.
Fixed this by making the function make_cond_remainder to keep in mind of the OR operator.
Also updated results for multiple test files which were incorrectly updated by the commit e0c1b3f242
code which was supposed to remove the condition present in the index
condition was not getting executed when the condition had OR operator, with AND the pushed
index condition was getting removed from where.
This problem affects all versions starting from 5.5 but this is a performance improvement, so fixing it in 10.4
This patch contains a full implementation of the optimization
that allows to use in-memory rowid / primary filters built for range
conditions over indexes. In many cases usage of such filters reduce
the number of disk seeks spent for fetching table rows.
In this implementation the choice of what possible filter to be applied
(if any) is made purely on cost-based considerations.
This implementation re-achitectured the partial implementation of
the feature pushed by Galina Shalygina in the commit
8d5a11122c.
Besides this patch contains a better implementation of the generic
handler function handler::multi_range_read_info_const() that
takes into account gaps between ranges when calculating the cost of
range index scans. It also contains some corrections of the
implementation of the handler function records_in_range() for MyISAM.
This patch supports the feature for InnoDB and MyISAM.
