The reason for crash is that natural_sort_key(release_lock('a')) would
evaluate release_lock() twice, once in Item::is_null() and another time
in Item::val_str(). Second time it returns NULL, since lock was already
released.
Fixed to prevent double evaluation.
Leading zeros added a single byte overhead per numeric string,
even when they were. Sorting leading zeros offers only for little value
(except determinism in sort). I decided to drop it for now, we can be
like ICU, which drops leading zeros, in numeric sorting,
even with IDENTICAL collation strength.
Also, disabled virtual stored columns (thus also indexes), on Serg's request
Hopefully it is temporarily, and will be reenabled soon, when everyone is
as happy with key generation algorithm as I am.
- return error from natsort_encode_numeric_key, if it would need
to allocate memory. All needed memory was preallocated much earlier.
- Add test for sort order of leading zero vs numeric strings with suffix.
- Remove second optional parameter to natural_sort_key(), and all fraction
handling.
- Rename natsort_num2str() to natsort_encode_length() to show the intention
that it encodes string *lengths*, and not encode whitespaces and what not.
Handles lengths for which log10(len) >= 10, even if they do not happen for
MariaDB Strings (where length is limited by 32bit, and log10(len) is <= 9)
- Do not let natural sort key grow past max_packet_length.
- Split Item_func_natural_sort_key::val_str() further and add
natsort_encode_numeric_string(), which contains comment on how
whitespaces are handled.
- Simplify, and speedup to_natsort_key() in common case, by removing
handling of weird charsets utf16/32, that encode numbers in several bytes.
In rare cases utf16/32 is used, we'll convert to utf8 prior to
creating keys, and back to original charset afterwards.
The numbers should be compared as numbers, while the rest should be compared
as string.
Introduce natural_sort_key() function that transforms original string
so that the lexicographic order of such keys is suitable for
natural sort.
