Question

MySQL服务器5.6

innodb_buffer_pool_size = 6GB
key_buffer_size = 20M

这是我的架构：

TBL_1    TBL_2    TBL_3    TBL_4    TBL_5    TBL_6
id       id       id       id       id       id      (int, primary key, auto increment)
uid      uid      uid      uid      uid      uid     (varchar 100, key index)
dev      dev      dev      dev      dev      dev     (varchar 80)
intf     intf     intf     intf     intf     intf    (varchar 100)
stat1    stat2    stat3    stat4    stat5    stat6   (float, 11)

uid字段提供跨表行的唯一关系。所有表中的count（*）是~52K

我希望的观点：

VIEW_1
dev   intf   stat1   stat2   stat3   stat4   stat5   stat6

这是我迄今为止尝试过的视图选择sql的一个例子：

select a.dev, a.intf, a.stat1, b.stat2, c.stat3, d.stat4, e.stat_5, f.stat_6
from TBL_1 a
inner join TBL_2 b on b.uid = a.uid
inner join TBL_3 c on c.uid = a.uid
inner join TBL_4 d on d.uid = a.uid
inner join TBL_5 e on e.uid = a.uid
inner join TBL_6 f on f.uid = a.uid

一旦我超过2个连接，查询就会变得无法响应。对于上面的查询说明return

|| *id* || *select_type* || *table* || *type* || *possible_keys* || *key* || *key_len* ||    *ref* || *rows* || *Extra*               ||
|| 1    || SIMPLE        || e       || ALL    || uid             ||       ||           ||          || 51391  ||                       ||
|| 1    || SIMPLE        || c       || ref    || uid             || uid   || 102       || db.e.uid || 1      || Using index condition ||
|| 1    || SIMPLE        || a       || ref    || uid             || uid   || 102       || db.c.uid || 1      ||                       ||
|| 1    || SIMPLE        || b       || ref    || uid             || uid   || 257       || db.c.uid || 1      || Using index condition ||
|| 1    || SIMPLE        || f       || ref    || uid             || uid   || 257       || db.c.uid || 1      || Using index condition ||
|| 1    || SIMPLE        || d       || ref    || uid             || uid   || 102       || db.e.uid || 1      || Using index condition ||

有关如何改进的建议吗？

Answer 1

检查查询的解释计划

EXPLAIN SELECT * from ABC;

选中此Understanding the Query Execution Plan

根据解释输出，请考虑添加indexes或使用其他Optimizing techniques

如果这无法帮助您解释您的解释计划，请继续关注。

干杯!!

MySQL视图永远

1 个答案: