* Kristofer Pettersson <Kristofer.Pettersson@stripped> [08/10/09 15:12]:
> 2768 Kristofer Pettersson 2008-10-09
> Bug#38551 query cache can still consume [very little] cpu time even when it is
> off.
>
> When the query cache size is zero, all query cache functionallity should be
> skipped.
>
> By checking query_cache_size before attempting to invalidate a table or
> db we avoid grabbing the query cache mutex. If the rare cases the query cache
> size would change so we get a false read the cache has either been cleared or
> modified:
What's worse, we'll fail to invalidate a query, since you added it
to ::invalidate().
Which is a potential semantical problem.
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