MySQL-SQL_BIG_SELECTS [英] MySQL - SQL_BIG_SELECTS
问题描述
嘿，我一直在研究SQL_BIG_SELECTS，但是到目前为止，MySQL文档一直没有帮助.我正在寻找一些预防方法，以防止出现以下错误.
Hey, I've been investigating SQL_BIG_SELECTS, but the MySQL documentation so far has been pretty unhelpful. I'm looking for some insight as to preventing errors like the one below from appearing.
错误1104:SELECT将检查太多记录，可能会花费很长时间. 检查您的WHERE，如果SELECT没问题，请使用SET OPTION SQL_BIG_SELECTS = 1
ERROR 1104: The SELECT would examine too many records and probably take a very long time. Check your WHERE and use SET OPTION SQL_BIG_SELECTS=1 if the SELECT is ok
- MySQL决定查询多少行为大选择"?
- 适当的索引编制通常可以解决此问题吗?
- 是将SQL_BIG_SELECTS视为万不得已"，还是好的做法?
- 有人将如何在配置中设置"SQL_BIG_SELECTS = 1"(无需执行查询)?
- 还有其他值得了解的替代方法吗?
提前谢谢！
推荐答案
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MySQL根据"max_join_size"的值确定查询是否为大选择".如果查询可能需要检查的行数超过此数目，它将认为它是大选择".使用显示变量"查看最大连接大小的值.
MySQL determines whether or not a query is a 'big select' based on the value of 'max_join_size'. If the query is likely to have to examine more than this number of rows, it will consider it a 'big select'. Use 'show variables' to view the value of the max join size.
我相信索引以及特别好的where子句可以防止出现此问题.
I believe that indexing and particular a good where clause will prevent this problem from occuring.
SQL_BIG_SELECTS用于防止用户意外执行过大的查询.可以在mysql.cnf中将其设置为ON或在启动时使用命令行选项.
SQL_BIG_SELECTS is used to prevent users from accidentally executing excessively large queries. It is okay to set it to ON in mysql.cnf or using the command-line option at startup.
您可以在my.cnf或服务器启动时设置SQL_BIG_SELECTS.也可以使用SET SESSION SQL_BIG_SELECTS=1在会话的基础上进行设置.
You can set SQL_BIG_SELECTS in my.cnf or at server startup. It can also be set on a session basis with SET SESSION SQL_BIG_SELECTS=1.
我想不到.我只是检查您的查询，以确保您确实需要使用它.我们的服务器默认情况下将其打开，并且max_join_size非常大.
Not that I can think of. I would just check your query to make sure that you really need to use it. Our servers have it turned on by default, and max_join_size is very large.
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