如何在MariaDB 10中启用大型索引？ [英] How to enable large index in MariaDB 10?

问题描述

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取决于启用配置参数 innodb_large_prefix 。根据文档，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 innodb_file_format_max 设置为羚羊，但是当 innodb_file_format_check 为OFF时，无关紧要。实际上，即使我还设置了 Barracuda ，它也没有什么区别。

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：

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;

我收到错误：

ERROR 1709 (HY000): Index column size too large. The maximum column size is 767 bytes.

在带有mysql服务器5.7.17的Ubuntu 16.04上，所有相关设置都是相同的（默认情况下）并且有没有大索引的问题（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

也许您只需要添加 ROW_FORMAT = .. 。到您的 CREATE TABLE 。

Perhaps all you need is to add ROW_FORMAT=... to your CREATE TABLE.

5.6.3 up需要这些说明到5.7.7。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))

（但前缀索引在很多方面存在缺陷。）

(But prefix indexing is flawed in many ways.)

如果服务器稍后创建更高的表格格式，则将innodb_file_format_max设置为该值意味着该设置为不是问题。

"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.

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