如何在 MariaDB 10 中启用大索引?
在 Debian Jessie 中，我安装了 MariaDB 服务器 10.0.30，并尝试增加最大密钥长度.AFAIU 这取决于启用的配置参数 innodb_large_prefix.根据 docs，它还需要 barracuda 文件格式和 innodb_file_per_table.在配置中设置它们并重新启动服务器后，我在客户端看到这些参数设置正确:
In Debian Jessie I installed MariaDB server 10.0.30 and I try to increase max key length. AFAIU it depends of the config parameter innodb_large_prefix being enabled. According to the docs, it also requires barracuda file format and innodb_file_per_table. After setting them in config and restarting server I see in client, that those parameters are set correctly:
> SHOW GLOBAL VARIABLES LIKE 'innodb_large%';
+---------------------+-------+
| Variable_name | Value |
+---------------------+-------+
| innodb_large_prefix | ON |
+---------------------+-------+
1 row in set (0.00 sec)
> SHOW GLOBAL VARIABLES LIKE 'innodb_file%';
+--------------------------+-----------+
| Variable_name | Value |
+--------------------------+-----------+
| innodb_file_format | Barracuda |
| innodb_file_format_check | OFF |
| innodb_file_format_max | Antelope |
| innodb_file_per_table | ON |
+--------------------------+-----------+
4 rows in set (0.00 sec)
> SHOW GLOBAL VARIABLES LIKE 'innodb_page%';
+------------------+-------+
| Variable_name | Value |
+------------------+-------+
| innodb_page_size | 16384 |
+------------------+-------+
1 row in set (0.00 sec)
我不确定，为什么将 innodb_file_format_max 设置为 Antelope，但是当 innodb_file_format_check 为 OFF 时，应该没关系.其实即使我也设置了梭子鱼，也没什么区别.
I am not sure, why innodb_file_format_max is set Antelope, but while innodb_file_format_check is OFF, it should not matter. Actually, even if I had it also set Barracuda, it did not made difference.
如果我现在尝试创建具有大索引的表，例如:
If i try now create table with large index like:
CREATE TABLE `some_table` (
`some_tableID` int(10) unsigned NOT NULL AUTO_INCREMENT,
`column` varchar(750) COLLATE utf8mb4_estonian_ci NOT NULL DEFAULT '',
PRIMARY KEY (`some_tableID`),
KEY `column` (`column`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_estonian_ci;
我得到错误:
ERROR 1709 (HY000): Index column size too large. The maximum column size is 767 bytes.
在 Ubuntu 16.04 和 mysql 服务器 5.7.17 上，所有相关设置都相同(默认)，大索引没有问题(对于 utf8mb4，它是 750*4 = 3000).
On Ubuntu 16.04 with mysql server 5.7.17 are all related settings same (by default) and there is no problem with large index (for utf8mb4 it is 750*4 = 3000).
我的 MariaDB 设置有什么问题?
What is wrong with my MariaDB setup?
推荐答案
它需要的不仅仅是这两个设置...
It requires more than just those two settings...
SET GLOBAL innodb_file_format=Barracuda;
SET GLOBAL innodb_file_per_table=ON;
SET GLOBAL innodb_large_prefix=1;
logout & login (to get the global values);
ALTER TABLE tbl ROW_FORMAT=DYNAMIC; -- or COMPRESSED
也许您只需将 ROW_FORMAT=... 添加到您的 CREATE TABLE.
Perhaps all you need is to add ROW_FORMAT=... to your CREATE TABLE.
5.6.3 到 5.7.7 需要这些说明.从 5.7.7 开始，系统默认正确处理更大的字段.
These instructions are needed for 5.6.3 up to 5.7.7. Beginning with 5.7.7, the system defaults correctly to handle larger fields.
或者，您可以使用前缀"索引:
Alternatively, you could use a "prefix" index:
INDEX(column(191))
(但前缀索引在许多方面存在缺陷.)
(But prefix indexing is flawed in many ways.)
如果服务器稍后创建更高的表格式，则将 innodb_file_format_max 设置为该值"意味着该设置不是问题.
"If the server later creates a higher table format, innodb_file_format_max is set to that value" implies that that setting is not an issue.
相关文章