Alexander Barkov 4ced4898fd MDEV-32958 Unusable key notes do not get reported for some operations ...

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`"

2023-12-11 08:55:27 +04:00

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