The patch for "MDEV-25440: Indexed CHAR ... broken with NO_PAD collations"
fixed these scenarios from MDEV-26743:
- Basic latin letter vs equal accented letter
- Two letters vs equal (but space padded) expansion
However, this scenario was still broken:
- Basic latin letter (but followed by an ignorable character)
vs equal accented letter
Fix:
When processing for a NOPAD collation a string with trailing ignorable
characters, like:
'<non-ignorable><ignorable><ignorable>'
the string gets virtually converted to:
'<non-ignorable><ignorable><ignorable><space><space><space>...'
After the fix the code works differently in these two cases:
1. <space> fits into the "nchars" limit
2. <space> does not fit into the "nchars" limit
Details:
1. If "nchars" is large enough (4+ in this example),
return weights as follows:
'[weight-for-non-ignorable, 1 char] [weight-for-space-character, 3 chars]'
i.e. the weight for the virtual trailing space character now indicates
that it corresponds to total 3 characters:
- two ignorable characters
- one virtual trailing space character
2. If "nchars" is small (3), then the virtual trailing space character
does not fit into the "nchar" limit, so return 0x00 as weight, e.g.:
'[weight-for-non-ignorable, 1 char] [0x00, 2 chars]'
Adding corresponding MTR tests and unit tests.
- Adding a new argument "flag" to MY_COLLATION_HANDLER::strnncollsp_nchars()
and a flag MY_STRNNCOLLSP_NCHARS_EMULATE_TRIMMED_TRAILING_SPACES.
The flag defines if strnncollsp_nchars() should emulate trailing spaces
which were possibly trimmed earlier (e.g. in InnoDB CHAR compression).
This is important for NOPAD collations.
For example, with this input:
- str1= 'a ' (Latin letter a followed by one space)
- str2= 'a ' (Latin letter a followed by two spaces)
- nchars= 3
if the flag is given, strnncollsp_nchars() will virtually restore
one trailing space to str1 up to nchars (3) characters and compare two
strings as equal:
- str1= 'a ' (one extra trailing space emulated)
- str2= 'a ' (as is)
If the flag is not given, strnncollsp_nchars() does not add trailing
virtual spaces, so in case of a NOPAD collation, str1 will be compared
as less than str2 because it is shorter.
- Field_string::cmp_prefix() now passes the new flag.
Field_varstring::cmp_prefix() and Field_blob::cmp_prefix() do
not pass the new flag.
- The branch in cmp_whole_field() in storage/innobase/rem/rem0cmp.cc
(which handles the CHAR data type) now also passed the new flag.
- Fixing UCA collations to respect the new flag.
Other collations are possibly also affected, however
I had no success in making an SQL script demonstrating the problem.
Other collations will be extended to respect this flags in a separate
patch later.
- Changing the meaning of the last parameter of Field::cmp_prefix()
from "number of bytes" (internal length)
to "number of characters" (user visible length).
The code calling cmp_prefix() from handler.cc was wrong.
After this change, the call in handler.cc became correct.
The code calling cmp_prefix() from key_rec_cmp() in key.cc
was adjusted according to this change.
- Old strnncollsp_nchar() related tests in unittest/strings/strings-t.c
now pass the new flag.
A few new tests also were added, without the flag.
Also fixes:
MDEV-27768 MDEV-25440: Assertion `(cs->state & 0x20000) == 0' failed in my_strnncollsp_nchars_generic_8bit
The "strnncollsp_nchars" virtual function pointer for tis620_thai_nopad_ci
was incorrectly initialized to a generic function
my_strnncollsp_nchars_generic_8bit(), which crashed on assert.
Implementing a tis620 specific function version.
- Removing the "diff_if_only_endspace_difference" argument from
MY_COLLATION_HANDLER::strnncollsp(), my_strnncollsp_simple(),
as well as in the function template MY_FUNCTION_NAME(strnncollsp)
in strcoll.ic
- Removing the "diff_if_only_space_different" from ha_compare_text(),
hp_rec_key_cmp().
- Adding a new function my_strnncollsp_padspace_bin() and reusing
it instead of duplicate code pieces in my_strnncollsp_8bit_bin(),
my_strnncollsp_latin1_de(), my_strnncollsp_tis620(),
my_strnncollsp_utf8_cs().
- Adding more tests for better coverage of the trailing space handling.
- Removing the unused definition of HA_END_SPACE_ARE_EQUAL
mysql-test/t/bug46080-master.opt:
Lower limits to be able to run tests
regex/main.c:
Fixed compiler warnings
storage/maria/ma_key_recover.c:
Fixed compiler warnings
storage/maria/ma_recovery.c:
Fixed compiler warnings
storage/maria/ma_unique.c:
Fixed compiler warnings
strings/ctype-uca.c:
Added comment
strings/xml.c:
Fixed compiler warnings
support-files/compiler_warnings.supp:
Added suppressions for windows
unittest/strings/strings-t.c:
Added ifdef to fix compilation failure when compiling without UCA
Problem: The functions my_like_range_xxx() returned
badly formed maximum strings for Asian character sets,
which made problems for storage engines.
Fix:
- Removed a number my_like_range_xxx() implementations,
which were in fact dumplicate code pieces.
- Using generic my_like_range_mb() instead.
- Setting max_sort_char member properly for Asian character sets
- Adding unittest/strings/strings-t.c,
to test that my_like_range_xxx() return well-formed
min and max strings.
Notes:
- No additional tests in mysql/t/ available.
Old tests cover the affected code well enough.
