title: query cache doesn't work
body: <p>I have turned on query_cache, and allocated memory for it:</p>
  
  <pre><code>| query_cache_limit            | 1048576    |
  | query_cache_min_res_unit     | 4096       |
  | query_cache_size             | 16777216   |
  | query_cache_type             | ON         |
  | query_cache_wlock_invalidate | OFF        |
  </code></pre>
  
  <p>But queries are not cached:</p>
  
  <pre><code>| Qcache_free_blocks             | 1        |
  | Qcache_free_memory             | 16768400 |
  | Qcache_hits                    | 0        |
  | Qcache_inserts                 | 0        |
  | Qcache_lowmem_prunes           | 0        |
  | Qcache_not_cached              | 163      |
  | Qcache_queries_in_cache        | 0        |
  | Qcache_total_blocks            | 1        |
  </code></pre>
  
  <p>I use Innodb as storage engine, without transactions. The sample query which is not cached:</p>
  
  <pre><code>select * from `feed-ts`.feeds where id &lt; 10;
  </code></pre>
  
  <p>It returns just one row.</p>
  
  <p>Any ideas?</p>