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什么是blob,mysql blob大小配置介绍

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Jun 07, 2016 pm 06:05 PM

blobmysql

BLOB (binary large object)，二进制大对象，是一个可以存储二进制文件的容器。在计算机中，BLOB常常是数据库中用来存储二进制文件的字段类型

BLOB是一个大文件，典型的BLOB是一张图片或一个声音文件，由于它们的尺寸，必须使用特殊的方式来处理（例如：上传、下载或者存放到一个数据库）。根据Eric Raymond的说法，处理BLOB的主要思想就是让文件处理器（如数据库管理器）不去理会文件是什么，而是关心如何去处理它。但也有专家强调，这种处理大数据对象的方法是把双刃剑，它有可能引发一些问题，如存储的二进制文件过大，会使数据库的性能下降。在数据库中存放体积较大的多媒体对象就是应用程序处理BLOB的典型例子。

mysql BLOB类型

MySQL中，BLOB是个类型系列，包括：TinyBlob、Blob、MediumBlob、LongBlob，这几个类型之间的唯一区别是在存储文件的最大大小上不同。
　　MySQL的四种BLOB类型
　　类型大小(单位：字节)
　　TinyBlob 最大 255
　　Blob 最大 65K
　　MediumBlob 最大 16M
　　LongBlob 最大 4G

linux修改etc/my.cnf
[mysqld]
max_allowed_packet = 16M //不同于[mysqldump]下的max_allowed_packet

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