Alexander Barkov 8020b1bd73 MDEV-30034 UNIQUE USING HASH accepts duplicate entries for tricky collations ... - 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.		2023-04-04 12:30:50 +04:00
..
CMakeLists.txt	MDEV-5313 Improving audit api.	2019-01-17 03:52:52 +04:00
json-t.c	stricter json unit tests	2019-02-04 15:54:10 +01:00
strings-t.c	MDEV-30034 UNIQUE USING HASH accepts duplicate entries for tricky collations	2023-04-04 12:30:50 +04:00