database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-08-05 13:16:09 +03:00
Code Activity

MDEV-30164 System variable for default collations

Browse Source 
This patch adds a way to override default collations
(or "character set collations") for desired character sets.

The SQL standard says:
> Each collation known in an SQL-environment is applicable to one
> or more character sets, and for each character set, one or more
> collations are applicable to it, one of which is associated with
> it as its character set collation.

In MariaDB, character set collations has been hard-coded so far,
e.g. utf8mb4_general_ci has been a hard-coded character set collation
for utf8mb4.

This patch allows to override (globally per server, or per session)
character set collations, so for example, uca1400_ai_ci can be set as a
character set collation for Unicode character sets
(instead of compiled xxx_general_ci).

The array of overridden character set collations is stored in a new
(session and global) system variable @@character_set_collations and
can be set as a comma separated list of charset=collation pairs, e.g.:

SET @@character_set_collations='utf8mb3=uca1400_ai_ci,utf8mb4=uca1400_ai_ci';

The variable is empty by default, which mean use the hard-coded
character set collations (e.g. utf8mb4_general_ci for utf8mb4).

The variable can also be set globally by passing to the server startup command
line, and/or in my.cnf.
This commit is contained in:
Alexander Barkov
2022-12-14 18:46:27 +04:00
parent 584c2351de
commit 75f25e4ca7
59 changed files with 2228 additions and 111 deletions
Download Patch File Download Diff File Expand all files Collapse all files

26
sql/sql_parse.cc
View File

@@ -5812,6 +5812,32 @@ finish:
}
thd->reset_kill_query();
}
/*
Binary logging is now done. Unset the "used" flags to avoid
flags leaking to the next event (and to the COMMIT statement
in the end of the current event).
Example:
Suppose a non-default collation (in @@character_set_collations)
was used during the statement, the mysqlbinlog output for
the current statement will contain a sequence like this:
SET character_set_collations='utf8mb3=utf8mb3_bin';
INSERT INTO t1 VALUES (_utf8mb3'test');
COMMIT;
The statment (INSERT in this example) is already in binlog at this point, and the
and the "SET character_set_collations" is written inside a
Q_CHARACTER_SET_COLLATIONS chunk in its log entry header.
The flag CHARACTER_SET_COLLATIONS_USED is not needed any more.
The COMMIT can be printed without "SET character_set_collations".
The same logic applies to the other _USED flags.
*/
thd->used= 0;
if (unlikely(thd->is_error()) ||
(thd->variables.option_bits & OPTION_MASTER_SQL_ERROR))
{