从视图中选择*比直接通过MySQL 5.7执行视图create语句慢10倍以上

Question

我创建了一个视图，将多个表连接起来以隐藏复杂性。

现在，当我执行select * from view时，它花费了直接执行select语句（定义视图）的执行时间的10倍以上（大约70毫秒vs 900毫秒）。

此行为在MySQL 5.7.23服务器上发生。

我比较了两个查询的执行计划，唯一的区别（如预期的那样）是派生表：

这是视图的正常行为还是我该如何解决？

P.S .： 根据请求创建视图语句（混淆的名称）：

create view vrs as select
rs."id" as "id",
l."language" as "language",
rss."t" as "discriminator",
rss."type" as "type",
coalesce(lt3."text", concat('!',s3."textkey",'(',l."language",')')) as "typeText",
rss."model" as "model",
coalesce(lt2."text", concat('!',s2."textkey",'(',l."language",')')) as "modelText",
rs."name"  as "name",
rs."reqCATGroup" as "CATGroup",
rs."devID" as "devID",
case s."builtIn"
    when 0 then s."displayName"
    else (select lt1."text"
        from loctext lt1
        where lt1."language"=l."language"
        and lt1."textkey"=s."displayName")
end as "sName",
s."id" as "sId",
s."postcode" as "sPostcode",
s."place" as "sPlace",
s."street" as "sStreet",
s."streetNumber" as "sStreetNumber",
s."tId" as "tId",
t."tName" as "tName",
rss."CCVMajor" as "CCVMajor",
rss."CCVMinor" as "CCVMinor",
rss."CCVPatch" as "CCVPatch",
rss."CCHV" as "CCHV",
coalesce(lHw."text", concat('!',sHw."textkey",'(',l."language",')')) as "CCHVText",
rss."MCVMajor" as "MCVMajor",
rss."MCVMinor" as "MCVMinor",
rss."MCVPatch" as "MCVPatch",
rss."level",
coalesce(lLevel."text", concat('!', sLevel."textkey", '(', l."language", ')')) as "levelText",
rss."event",
coalesce(lEvent."text", concat('!', sEvent."textkey", '(', l."language", ')')) as "eventText",
rss."isBusy" as "isBusy",
rss."tsLastComIn" as "tsLastCom",
rss."tsBT" AS "tsBT",
b1."ordinal" as "isSending",
coalesce(ltSend."text", concat('!',b1."textkey",'(',l."language",')')) as "isSendingText",
b2."ordinal" as "isReceiving",
coalesce(ltReceive."text", concat('!',b2."textkey",'(',l."language",')')) as "isReceivingText",
rs."historyCreateDevTs",
rs."historyCreateDevUserId",
rs."historyCreateDevUserLoginName",
rs."historyModifyDevLinkTs",
rs."historyModifyDevLinkUserId",
rs."historyModifyDevLinkUserLoginName",
rs."monitorStartTs",
rs."monitorEndTs"
from synch rss
cross join loclanguages l
join cfgrs rs on rs."id" = rss."id"
join cfgs s on s."id" = rs."sId"
join cfgt t on t."id" = s."tId"
left join locmodel s2 on s2."ordinal" = rss."model"
left join loctext lt2 on lt2."textkey" = s2."textkey" and lt2."language" = l."language"
left join loctype s3 on s3."ordinal" = rss."type"
left join loctext lt3 on lt3."textkey" = s3."textkey" and lt3."language" = l."language"
left join locbooleanrange b1 on rs."sending"+1 = b1."ordinal"
left join loctext ltSend on ltSend."textkey" = b1."textkey" and ltSend."language" = l."language"
left join locbooleanrange b2 on rs."receiving"+1 = b2."ordinal"
left join loctext ltReceive on ltReceive."textkey" = b2."textkey" and ltReceive."language" = l."language"
left join loceventlevel sLevel on sLevel."ordinal" = rss."level"
left join loctext lLevel on lLevel."textkey" = sLevel."textkey" and lLevel."language" = l."language"
left join locevent sEvent on sEvent."ordinal" = rss."event" and sEvent."type" = rss."type"
left join loctext lEvent on lEvent."textkey" = sEvent."textkey" and lEvent."language" = l."language"
left join loccchv sHw on sHw."ordinal" = rss."CCHV"
left join loctext lHw on lHw."textkey" = sHw."textkey" and lHw."language" = l."language"
where rs."deleted" = 0
;

P.P.S .：完整的执行计划如下：

直接通话：

视图：

Answer 1

此链接适用于MySQL 8.0，但是当我上次遇到MySQL 5.6、5.7中的Views的性能问题并进行挖掘时，我得到了相同的答案：使用Views时，您基本上不能利用索引。

https://dev.mysql.com/doc/refman/8.0/en/view-restrictions.html

我个人发现，由于上述限制，特别是由于性能下降，MySQL中的视图总体上没有用。

读者-如果以某种方式可以在MySQL中执行View，那么我肯定在某个地方错过了重要备忘录。如果是这种情况，请纠正我。