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<h1 class="refname">mysqlnd_qc_get_core_stats</h1>
<p class="verinfo">(PECL mysqlnd_qc >= 1.0.0)</p><p class="refpurpose"><span class="refname">mysqlnd_qc_get_core_stats</span> — <span class="dc-title">Statistics collected by the core of the query cache</span></p>
</div>
<div class="refsect1 description" id="refsect1-function.mysqlnd-qc-get-core-stats-description">
<h3 class="title">Description</h3>
<div class="methodsynopsis dc-description">
<span class="type">array</span>
<span class="methodname"><strong>mysqlnd_qc_get_core_stats</strong></span>
( <span class="methodparam">void</span>
)</div>
<p class="para rdfs-comment">
Returns an array of statistics collected by the core of the cache plugin.
The same data fields will be reported for any storage handler because the
data is collected by the core.
</p>
<p class="para">
The
<em>PHP</em> configuration setting
<em>mysqlnd_qc.collect_statistics</em>
controls the collection of statistics. The collection of statistics
is disabled by default for performance reasons.
Disabling the collection of statistics will also disable the collection
of time related statistics.
</p>
<p class="para">
The
<em>PHP</em> configuration setting
<em>mysqlnd_qc.collect_time_statistics</em> controls the
collection of time related statistics.
</p>
<p class="para">
The scope of the core statistics is the
<em>PHP</em> process.
Depending on your deployment model a
<em>PHP</em> process may handle one or multiple requests.
</p>
<p class="para">
Statistics are aggregated for all cache entries and all storage handler.
It is not possible
to tell how much queries originating from
<em>mysqli</em>,
<em>PDO_MySQL</em> or
<em>mysql</em> API calls have
contributed to the aggregated data values.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-function.mysqlnd-qc-get-core-stats-parameters">
<h3 class="title">Parameters</h3>
<p class="para">This function has no parameters.</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-function.mysqlnd-qc-get-core-stats-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Array of core statistics
</p>
<table class="doctable informaltable">
<col style="width: 10%;" />
<col style="width: 70%;" />
<col style="width: 20%;" />
<thead>
<tr>
<th>Statistic</th>
<th>Description</th>
<th>Version</th>
</tr>
</thead>
<tbody class="tbody">
<tr>
<td>
<em>cache_hit</em>
</td>
<td>
Statement is considered cacheable and cached data has been reused.
Statement is considered cacheable and a cache miss happened but
the statement got cached by someone else while we process it and thus
we can fetch the result from the refreshed cache.
</td>
<td>Since 1.0.0.</td>
</tr>
<tr>
<td>
<em>cache_miss</em>
</td>
<td>
Statement is considered cacheable...
<ul class="itemizedlist">
<li class="listitem">
<p class="para">
... and has been added to the cache
</p>
</li>
<li class="listitem">
<p class="para">
... but the
<em>PHP</em>
configuration directive setting of
<em>mysqlnd_qc.cache_no_table = 1</em> has prevented caching.
</p>
</li>
<li class="listitem">
<p class="para">
... but an unbuffered result set is requested.
</p>
</li>
<li class="listitem">
<p class="para">
... but a buffered result set was empty.
</p>
</li>
</ul>
</td>
<td>Since 1.0.0.</td>
</tr>
<tr>
<td>
<em>cache_put</em>
</td>
<td>
Statement is considered cacheable and has been added to the cache.
Take care when calculating derived statistics. Storage handler
with a storage life time beyond process scope may report
<em>cache_put = 0</em> together with
<em>cache_hit > 0</em>, if another process has filled
the cache. You may want to use
<em>num_entries</em> from
<span class="function"><a href="function.mysqlnd-qc-get-cache-info.html" class="function">mysqlnd_qc_get_cache_info()</a></span> if the handler
supports it (
<em>default</em>,
<em>APC</em>).
</td>
<td>Since 1.0.0.</td>
</tr>
<tr>
<td>
<em>query_should_cache</em>
</td>
<td>
Statement is considered cacheable based on query string analysis.
The statement may or may not be added to the cache. See also
<em>cache_put</em>.
</td>
<td>Since 1.0.0.</td>
</tr>
<tr>
<td>
<em>query_should_not_cache</em>
</td>
<td>
Statement is considered not cacheable based on query string analysis.
</td>
<td>Since 1.0.0.</td>
</tr>
<tr>
<td>
<em>query_not_cached</em>
</td>
<td>
Statement is considered not cacheable or it is
considered cachable but the storage handler has not returned a
hash key for it.
</td>
<td>Since 1.0.0.</td>
</tr>
<tr>
<td>
<em>query_could_cache</em>
</td>
<td>
Statement is considered cacheable...
<ul class="itemizedlist">
<li class="listitem">
<p class="para">
... and statement has been run without errors
</p>
</li>
<li class="listitem">
<p class="para">
... and meta data shows at least one column in the result set
</p>
</li>
</ul>
The statement may or may not be in the cache already.
It may or may not be added to the cache later on.
</td>
<td>Since 1.0.0.</td>
</tr>
<tr>
<td>
<em>query_found_in_cache</em>
</td>
<td>
Statement is considered cacheable and we have found it in the cache
but we have not replayed the cached data yet and we have not send
the result set to the client yet. This is not considered
a cache hit because the client might not fetch the result or
the cached data may be faulty.
</td>
<td>Since 1.0.0.</td>
</tr>
<tr>
<td>
<em>query_uncached_other</em>
</td>
<td>
Statement is considered cacheable and it may or may not be in
the cache already but either replaying cached data has failed,
no result set is available or some other error has happened.
</td>
</tr>
<tr>
<td>
<em>query_uncached_no_table</em>
</td>
<td>
Statement has not been cached because the result set has at least
one column which has no table name in its meta data. An example of
such a query is
<em>SELECT SLEEP(1)</em>. To cache those
statements you have to change default value of the PHP configuration directive
<em>mysqlnd_qc.cache_no_table</em> and set
<em>mysqlnd_qc.cache_no_table = 1</em>. Often, it is not
desired to cache such statements.
</td>
<td>Since 1.0.0.</td>
</tr>
<tr>
<td>
<em>query_uncached_use_result</em>
</td>
<td>
Statement would have been cached if a buffered result set
had been used. The situation is also considered as a cache miss and
<em>cache_miss</em> will be incremented as well.
</td>
<td>Since 1.0.0.</td>
</tr>
<tr>
<td>
<em>query_aggr_run_time_cache_hit</em>
</td>
<td>
Aggregated run time (ms) of all cached queries.
Cached queries are those which have incremented
<em>cache_hit</em>.
</td>
<td>Since 1.0.0.</td>
</tr>
<tr>
<td>
<em>query_aggr_run_time_cache_put</em>
</td>
<td>
Aggregated run time (ms) of all uncached queries that
have been put into the cache. See also
<em>cache_put</em>.
</td>
<td>Since 1.0.0.</td>
</tr>
<tr>
<td>
<em>query_aggr_run_time_total</em>
</td>
<td>
Aggregated run time (ms) of all uncached and cached queries
that have been inspected and executed by the query cache.
</td>
<td>Since 1.0.0.</td>
</tr>
<tr>
<td>
<em>query_aggr_store_time_cache_hit</em>
</td>
<td>
Aggregated store time (ms) of all cached queries.
Cached queries are those which have incremented
<em>cache_hit</em>.
</td>
<td>Since 1.0.0.</td>
</tr>
<tr>
<td>
<em>query_aggr_store_time_cache_put</em>
</td>
<td>
Aggregated store time (
<em>ms</em>) of all uncached queries that
have been put into the cache. See also
<em>cache_put</em>.
</td>
<td>Since 1.0.0.</td>
</tr>
<tr>
<td>
<em>query_aggr_store_time_total</em>
</td>
<td>
Aggregated store time (ms) of all uncached and cached queries
that have been inspected and executed by the query cache.
</td>
<td>Since 1.0.0.</td>
</tr>
<tr>
<td>
<em>receive_bytes_recorded</em>
</td>
<td>
Recorded incoming network traffic (
<em>bytes</em>) send from MySQL to PHP.
The traffic may or may not have been added to the cache. The
traffic is the total for all queries regardless if cached or not.
</td>
<td>Since 1.0.0.</td>
</tr>
<tr>
<td>
<em>receive_bytes_replayed</em>
</td>
<td>
Network traffic replayed during cache. This is the total amount of
incoming traffic saved because of the usage of the query cache plugin.
</td>
<td>Since 1.0.0.</td>
</tr>
<tr>
<td>
<em>send_bytes_recorded</em>
</td>
<td>
Recorded outgoing network traffic (
<em>bytes</em>) send from MySQL to PHP.
The traffic may or may not have been added to the cache. The
traffic is the total for all queries regardless if cached or not.
</td>
<td>Since 1.0.0.</td>
</tr>
<tr>
<td>
<em>send_bytes_replayed</em>
</td>
<td>
Network traffic replayed during cache. This is the total amount of
outgoing traffic saved because of the usage of the query cache plugin.
</td>
<td>Since 1.0.0.</td>
</tr>
<tr>
<td>
<em>slam_stale_refresh</em>
</td>
<td>
Number of cache misses which triggered serving stale data until
the client causing the cache miss has refreshed the cache entry.
</td>
<td>Since 1.0.0.</td>
</tr>
<tr>
<td>
<em>slam_stale_hit</em>
</td>
<td>
Number of cache hits while a stale cache entry gets refreshed.
</td>
<td>Since 1.0.0.</td>
</tr>
</tbody>
</table>
</div>
<div class="refsect1 examples" id="refsect1-function.mysqlnd-qc-get-core-stats-examples">
<h3 class="title">Examples</h3>
<div class="example" id="example-1864">
<p><strong>Example #1 <span class="function"><strong>mysqlnd_qc_get_core_stats()</strong></span> example</strong></p>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /></span><span style="color: #FF8000">/* Enable collection of statistics - default: disabled */<br /></span><span style="color: #0000BB">ini_set</span><span style="color: #007700">(</span><span style="color: #DD0000">"mysqlnd_qc.collect_statistics"</span><span style="color: #007700">, </span><span style="color: #0000BB">1</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">/* Enable collection of all timing related statistics -<br />default: enabled but overruled by mysqlnd_qc.collect_statistics = 0 */<br /></span><span style="color: #0000BB">ini_set</span><span style="color: #007700">(</span><span style="color: #DD0000">"mysqlnd_qc.collect_time_statistics"</span><span style="color: #007700">, </span><span style="color: #0000BB">1</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">/* Populate the cache, e.g. using mysqli */<br /></span><span style="color: #0000BB">$mysqli </span><span style="color: #007700">= new </span><span style="color: #0000BB">mysqli</span><span style="color: #007700">(</span><span style="color: #DD0000">'host'</span><span style="color: #007700">, </span><span style="color: #DD0000">'user'</span><span style="color: #007700">, </span><span style="color: #DD0000">'password'</span><span style="color: #007700">, </span><span style="color: #DD0000">'schema'</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">/* Cache miss and cache put */<br /></span><span style="color: #0000BB">$mysqli</span><span style="color: #007700">-></span><span style="color: #0000BB">query</span><span style="color: #007700">(</span><span style="color: #DD0000">"/*qc=on*/SELECT id FROM test"</span><span style="color: #007700">);<br /></span><span style="color: #FF8000">/* Cache hit */<br /></span><span style="color: #0000BB">$mysqli</span><span style="color: #007700">-></span><span style="color: #0000BB">query</span><span style="color: #007700">(</span><span style="color: #DD0000">"/*qc=on*/SELECT id FROM test"</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">/* Display core statistics */<br /></span><span style="color: #0000BB">var_dump</span><span style="color: #007700">(</span><span style="color: #0000BB">mysqlnd_qc_get_core_stats</span><span style="color: #007700">());<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>The above examples will output:</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
array(26) {
["cache_hit"]=>
string(1) "1"
["cache_miss"]=>
string(1) "1"
["cache_put"]=>
string(1) "1"
["query_should_cache"]=>
string(1) "2"
["query_should_not_cache"]=>
string(1) "0"
["query_not_cached"]=>
string(1) "0"
["query_could_cache"]=>
string(1) "2"
["query_found_in_cache"]=>
string(1) "1"
["query_uncached_other"]=>
string(1) "0"
["query_uncached_no_table"]=>
string(1) "0"
["query_uncached_no_result"]=>
string(1) "0"
["query_uncached_use_result"]=>
string(1) "0"
["query_aggr_run_time_cache_hit"]=>
string(1) "4"
["query_aggr_run_time_cache_put"]=>
string(3) "395"
["query_aggr_run_time_total"]=>
string(3) "399"
["query_aggr_store_time_cache_hit"]=>
string(1) "2"
["query_aggr_store_time_cache_put"]=>
string(1) "8"
["query_aggr_store_time_total"]=>
string(2) "10"
["receive_bytes_recorded"]=>
string(2) "65"
["receive_bytes_replayed"]=>
string(2) "65"
["send_bytes_recorded"]=>
string(2) "29"
["send_bytes_replayed"]=>
string(2) "29"
["slam_stale_refresh"]=>
string(1) "0"
["slam_stale_hit"]=>
string(1) "0"
["request_counter"]=>
int(1)
["process_hash"]=>
int(3547549858)
}
</pre></div>
</div>
</div>
</div>
<div class="refsect1 seealso" id="refsect1-function.mysqlnd-qc-get-core-stats-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member">
<a href="mysqlnd-qc.configuration.html" class="link">Runtime configuration</a>
</li>
<li class="member">
<a href="mysqlnd-qc.configuration.html#ini.mysqlnd-qc.collect-statistics" class="link">mysqlnd_qc.collect_statistics</a>
</li>
<li class="member">
<a href="mysqlnd-qc.configuration.html#ini.mysqlnd-qc.time-statistics" class="link">mysqlnd_qc.time_statistics</a>
</li>
<li class="member">
<span class="function"><a href="function.mysqlnd-qc-get-cache-info.html" class="function" rel="rdfs-seeAlso">mysqlnd_qc_get_cache_info()</a> - Returns information on the current handler, the number of cache entries and cache entries, if available</span>
</li>
</ul>
</p>
</div>
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