MySQL Variables concurrent_insert 数据库 参数变量解释及正确配置使用
本站中文解释
concurrent_insert是MySQL服务器的一个参数变量，它指示MySQL在执行INSERTS语句时是否允许并发插入行。它允许多个客户端在同一张表中同时向数据库插入行。角色默认值是2，它可以用以下语句进行设置：
SET GLOBAL concurrent_insert = mode_value;
mode_value可以是以下值之一：
1：不允许concurrent_insert
2： 允许当前INSERT语句继续，但不允许其它INSERT语句。
0： 允许并发插入行。
一旦改变，这个变量的更改是永久的，直到服务器重新启动。
官方英文解释
concurrent_insert
| Command-Line Format | --concurrent-insert[=value] |
|---|---|
| System Variable | concurrent_insert |
| Scope | Global |
| Dynamic | Yes |
| Type | Enumeration |
| Default Value | AUTO |
| Valid Values |
|
If AUTO (the default), MySQL permits
INSERT and
SELECT statements to run
concurrently for MyISAM tables that have no
free blocks in the middle of the data file.
This variable can take the values shown in the following
table. The variable can be assigned using either the name
values or corresponding integer values.
| Value | Description |
|---|---|
NEVER (or 0) |
Disables concurrent inserts |
AUTO (or 1) |
(Default) Enables concurrent insert for MyISAM tablesthat do not have holes |
ALWAYS (or 2) |
Enables concurrent inserts for all MyISAM tables,even those that have holes. For a table with a hole, new rows are inserted at the end of the table if it is in use by another thread. Otherwise, MySQL acquires a normal write lock and inserts the row into the hole. |
If you start mysqld with
--skip-new,
concurrent_insert is set to
NEVER.
See also Section 8.11.3, “Concurrent Inserts”.
