Wrong/Improvable recommendations
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
mysqltuner |
New
|
Undecided
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Unassigned |
Bug Description
As mentioned in the questions area I am currently in the process of rewriting the rules file for my needs. I'm just half way through but I've noticed some recommendations that could need improvement, which I would like to pass on to your project as well:
> % query cache used|||
This calculates the wrong number, this the % of free query cache, not the % of used qc. It should be 100 - [above expr].
>Sort rows|||=~ /second|
Sort_rows, from what I was able to read, is also increased when sorting with indexes. Thus, this recommendation is incorrect.
> Query cache size|||eq "0 bytes"|
Query cache might also be turned off by setting query_cache_type to 'OFF' independent of what query_cache_size is set to.
>MySQL Architecture||| !~ /64/|||
From what I was able to read, the 64 bit version of mysql has no or even worse performance. The 64 bit version should only be used where the system memory is above 3 GiB, or there will be no gain at all.
>Query cache low memory prunes|||=~ /second|
Maybe this recommendation should note that a very big query cache (3 digit Mb) might cause serious slow down because of the overhead to manage the cache. So increasing it too much will be bad too.
>temp table rate|||=~ /second|
I couldn't find any source on the internet that suggests a direct relation to temporary tables and any of these variables. Several independent Blog entries suggest (http://