{{toc numerate=1}}
##Ðỉäçȑîṭĭčś##
===Current situation===
%%(info type="note" title="BINARY")
For some reason ((https://github.com/WackoWiki/wackowiki/blob/4.3.0/wacko/setup/database_mysql_updates.php#L53 we changed)) in **!!(green)R4.3!!** the ##tag## in the page table from
##VARCHAR(250) BINARY## to ##VARCHAR(250)##.
Til **!!(green)R6.0!!** WackoWiki used ((/Dev/Projects/Translit Translit)) and the ##supertag## (Latin1, case-insensitive) as cross charset reference.
%%
Currently you could create any tag you like, but then you couldn't rename it or create a new page with or without diacritics of the same word.
* ##Português## / ##Portugues## (same)
* ##Krąków## / ##Kraków## (different locations)
Either way it directed to the existing version since the default SQL coalition treats diacritics as not significant (##_ci## versus ##_bin##).
#|
*| Link | Page | Note |*
|| ##_ci##: ||
|| PrawaDostępu
PrawaDostepu
Prawadostępu
Prawadostepu
prawadostępu
prawadostepu
| PrawaDostępu | accent-insensitive, case-insensitive ||
|| ##_bin##: ||
|| PrawaDostępu
PrawaDostepu
Prawadostępu
Prawadostepu
prawadostępu
prawadostepu | PrawaDostępu
PrawaDostepu
Prawadostępu
Prawadostepu
prawadostępu
prawadostepu | accent-sensitive, case-sensitive ||
|#
===Make the page tag accent and case-sensitive===
%%(info type="important")
This may render existing **internal** and **incoming external links** invalid.
%%
%%(sql)
ALTER TABLE {$pref}page CHANGE tag tag VARCHAR(250) BINARY NOT NULL DEFAULT '';
%%
commit:0c346e9
translates with current defaults into ##utf8mb4_bin##:
%%(sql)
ALTER TABLE `prefix_page` CHANGE `tag` `tag` VARCHAR(250) CHARACTER SET utf8mb4 COLLATE utf8mb4_bin NOT NULL DEFAULT '';
%%
====Backup script====
Backup script ignored COLUMNS collation, but page tag columns require the ##BINARY## collation. The ##tag## must be **((BinaryTag accent and case-sensitive))**.
* ((https://dev.mysql.com/doc/refman/8.0/en/charset-column.html Column Character Set and Collation))
* ((https://dev.mysql.com/doc/refman/8.0/en/binary-varbinary.html The BINARY and VARBINARY Types))
Set back collation via ##VARCHAR BINARY## manually
%%(sql)
ALTER TABLE `wacko_page` CHANGE `tag` `tag` VARCHAR(250) BINARY NOT NULL;
ALTER TABLE `wacko_page` CHANGE `keywords` `keywords` VARCHAR(250) BINARY NOT NULL;
ALTER TABLE `wacko_revision` CHANGE `tag` `tag` VARCHAR(250) BINARY NOT NULL;
ALTER TABLE `wacko_revision` CHANGE `keywords` `keywords` VARCHAR(250) BINARY NOT NULL;
ALTER TABLE `wacko_page_link` CHANGE `to_tag` `to_tag` VARCHAR(250) BINARY NOT NULL;
%%
FIXED: commit:833adea67dde8a1b9fe64ea8c4563e1660018ef5
===Considerations===
We could show a hint / warning if someone creates a similar page with just different diacritics or case folding:
%%(info type="example" title="Hint")
A similar page already exists:
-> Krąków
%%
There are the following cases to consider:
* user_name
* file_name
* tag
All three can constitute a part of a internal link.
How we should deal, proceed, with the issue, what behavior is desired for each case, e.g. avoid user_name misuse.
====Search & Sorting====
Make search and sorting accent and case-insensitive.
COLLATE tag column case-insensitive for ORDER BY and LIKE
* %%(sql) ORDER BY tag COLLATE utf8mb4_unicode_520_ci ASC %%
* %%(sql) WHERE tag COLLATE utf8mb4_unicode_520_ci LIKE %%
====Tag naming policies====
===VARCHAR BINARY versus VARBINARY===
((https://dev.mysql.com/doc/refman/8.0/en/binary-varbinary.html The BINARY and VARBINARY Types))
The ##BINARY## attribute cause the binary collation for the column character set to be used, and the column itself contains nonbinary character strings rather than binary byte strings.
===Collation===
Collation Suffix Meanings
#|
*| Suffix | Meaning |*
|| _ai | Accent-insensitive ||
|| _as | Accent-sensitive ||
|| _ci | Case-insensitive ||
|| _cs | Case-sensitive ||
|| _bin | Binary ||
|#
Examples (MySQL 8.0)
* ##utf8mb4_0900_ai_ci##
* ##utf8mb4_0900_as_ci##
* ##utf8mb4_0900_as_cs##
* ##utf8mb4_0900_bin##
* ##utf8mb4_bin##
Unicode Collation Algorithm (UCA)
* ((https://dev.mysql.com/doc/refman/8.0/en/charset-collation-names.html Collation Naming Conventions))
* ((https://dev.mysql.com/doc/refman/8.0/en/charset-mysql.html Character Sets and Collations in MySQL))
* ((https://dev.mysql.com/doc/refman/8.0/en/charset-binary-collations.html The binary Collation Compared to _bin Collations))