MySQL中的最大JSON列长度 [英] Max JSON column length in MySQL

问题描述

我可以在MySQL的JSON列中存储的最大字符数是多少?我没有在MySQL手册中看到这一点.

What's the max number of characters I can store in a JSON column in MySQL? I don't see this mentioned in the MySQL manual.

推荐答案

这里是@JorgeLondoño谈论的演示.

Here's a demo of what @JorgeLondoño is talking about.

设置服务器允许的最大数据包大小:

Set the server's max allowed packet size:

mysql> set global max_allowed_packet=1024*1024*1024;

退出并再次打开mysql客户端，这次将客户端的最大数据包大小设置为匹配:

Exit and open the mysql client again, this time setting the client max packet size to match:

$ mysql --max-allowed-packet=$((1024*1024*1024*))

使用JSON列创建测试表，并用最长的JSON文档填充它:

Create a test table with a JSON column and fill it with the longest JSON document you can:

mysql> create table test.jtest ( j json );

mysql> insert into test.jtest 
  set j = concat('[', repeat('"word",', 100000000), '"word"]');
Query OK, 1 row affected (1 min 49.67 sec)

mysql> select length(j) from test.jtest;
+-----------+
| length(j) |
+-----------+
| 800000008 |
+-----------+

这表明我能够创建一个包含1亿个元素的JSON文档，而MySQL将其存储在大约800MB中.

This shows that I was able to create a single JSON document with 100 million elements, and MySQL stores this in approximately 800MB.

我没有尝试更长的文档.我假设它最大为1 GB，这是您可以为max_allowed_pa​​cket设置的最大值.

I didn't try a longer document. I assume it maxes out at 1 GB, which is the largest value you can set for max_allowed_packet.

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