Chapter 8 Mysqlnd query result cache plugin

mysqlnd_qc.enable_qc=1

mysqlnd_qc.enable_qc=1

    

<?php
/* Connect, create and populate test table */
$mysqli = new mysqli("host", "user", "password", "schema", "port", "socket");
$mysqli->query("DROP TABLE IF EXISTS test");
$mysqli->query("CREATE TABLE test(id INT)");
$mysqli->query("INSERT INTO test(id) VALUES (1), (2)");

/* Will be cached because of the SQL hint */
$start = microtime(true);
$res   = $mysqli->query("/*" . MYSQLND_QC_ENABLE_SWITCH . "*/" . "SELECT id FROM test WHERE id = 1");

var_dump($res->fetch_assoc());
$res->free();

printf("Total time uncached query: %.6fs\n", microtime(true) - $start);

/* Cache hit */
$start = microtime(true);
$res   = $mysqli->query("/*" . MYSQLND_QC_ENABLE_SWITCH . "*/" . "SELECT id FROM test WHERE id = 1");

var_dump($res->fetch_assoc());
$res->free();

printf("Total time cached query: %.6fs\n", microtime(true) - $start);
?>

    

The above examples will output something similar to:

array(1) {
  ["id"]=>
  string(1) "1"
}
Total time uncached query: 0.000740s
array(1) {
  ["id"]=>
  string(1) "1"
}
Total time cached query: 0.000098s

mysqlnd_qc.enable_qc=1
mysqlnd_qc.cache_by_default=1

    

<?php
/* Connect, create and populate test table */
$mysqli = new mysqli("host", "user", "password", "schema", "port", "socket");
$mysqli->query("DROP TABLE IF EXISTS test");
$mysqli->query("CREATE TABLE test(id INT)");
$mysqli->query("INSERT INTO test(id) VALUES (1), (2)");

/* Will be cached although no SQL hint is present because of mysqlnd_qc.cache_by_default = 1*/
$res = $mysqli->query("SELECT id FROM test WHERE id = 1");
var_dump($res->fetch_assoc());
$res->free();

$mysqli->query("DELETE FROM test WHERE id = 1");

/* Cache hit - no automatic invalidation and still valid! */
$res = $mysqli->query("SELECT id FROM test WHERE id = 1");
var_dump($res->fetch_assoc());
$res->free();

/* Cache miss - query must not be cached because of the SQL hint */
$res = $mysqli->query("/*" . MYSQLND_QC_DISABLE_SWITCH . "*/SELECT id FROM test WHERE id = 1");
var_dump($res->fetch_assoc());
$res->free();
?>

    

The above examples will output:

array(1) {
  ["id"]=>
  string(1) "1"
}
array(1) {
  ["id"]=>
  string(1) "1"
}
NULL

mysqlnd_qc.enable_qc=1
mysqlnd_qc.cache_by_default=1

    

<?php
/* Connect, create and populate test table */
$mysqli = new mysqli("host", "user", "password", "schema", "port", "socket");
$mysqli->query("DROP TABLE IF EXISTS test");
$mysqli->query("CREATE TABLE test(id INT)");
$mysqli->query("INSERT INTO test(id) VALUES (1)");

for ($i = 0; $i < 3; $i++) {

    $start = microtime(true);

    /* Note: statement will not be cached because of NOW() use */
    $res = $mysqli->query("SELECT id, NOW() AS _time FROM test");
    $row = $res->fetch_assoc();

    /* dump results */
    var_dump($row);

    printf("Total time: %.6fs\n", microtime(true) - $start);

    /* pause one second */
    sleep(1);
}
?>

    

The above examples will output something similar to:

array(2) {
  ["id"]=>
  string(1) "1"
  ["_time"]=>
  string(19) "2012-01-11 15:43:10"
}
Total time: 0.000540s
array(2) {
  ["id"]=>
  string(1) "1"
  ["_time"]=>
  string(19) "2012-01-11 15:43:11"
}
Total time: 0.000555s
array(2) {
  ["id"]=>
  string(1) "1"
  ["_time"]=>
  string(19) "2012-01-11 15:43:12"
}
Total time: 0.000549s

mysqlnd_qc.enable_qc=1
mysqlnd_qc.cache_by_default=1
mysqlnd_qc.cache_no_table=1

    

<?php
/* Connect, create and populate test table */
$mysqli = new mysqli("host", "user", "password", "schema", "port", "socket");
$mysqli->query("DROP TABLE IF EXISTS test");
$mysqli->query("CREATE TABLE test(id INT)");
$mysqli->query("INSERT INTO test(id) VALUES (1)");

for ($i = 0; $i < 3; $i++) {

    $start = microtime(true);

    /* Note: statement will not be cached because of NOW() use */
    $res = $mysqli->query("SELECT id, NOW() AS _time FROM test");
    $row = $res->fetch_assoc();

    /* dump results */
    var_dump($row);

    printf("Total time: %.6fs\n", microtime(true) - $start);

    /* pause one second */
    sleep(1);
}
?>

    

The above examples will output something similar to:

array(2) {
  ["id"]=>
  string(1) "1"
  ["_time"]=>
  string(19) "2012-01-11 15:47:45"
}
Total time: 0.000546s
array(2) {
  ["id"]=>
  string(1) "1"
  ["_time"]=>
  string(19) "2012-01-11 15:47:45"
}
Total time: 0.000187s
array(2) {
  ["id"]=>
  string(1) "1"
  ["_time"]=>
  string(19) "2012-01-11 15:47:45"
}
Total time: 0.000167s

mysqlnd_qc.enable_qc=1
mysqlnd_qc.ttl=3

    

<?php
/* Connect, create and populate test table */
$mysqli = new mysqli("host", "user", "password", "schema", "port", "socket");
$mysqli->query("DROP TABLE IF EXISTS test");
$mysqli->query("CREATE TABLE test(id VARCHAR(255))");

for ($i = 0; $i < 7; $i++) {

    /* update DB row  */
    if (!$mysqli->query("DELETE FROM test") ||
        !$mysqli->query("INSERT INTO test(id) VALUES (NOW())"))
      /* Of course, a real-life script should do better error handling */
      die(sprintf("[%d] %s\n", $mysqli->errno, $mysqli->error));

    /* select latest row but cache results */
    $query  = "/*" . MYSQLND_QC_ENABLE_SWITCH . "*/";
    $query .= "SELECT id AS _time FROM test";
    if (!($res = $mysqli->query($query)) ||
        !($row = $res->fetch_assoc()))
    {
      printf("[%d] %s\n", $mysqli->errno, $mysqli->error);
    }
    $res->free();
    printf("Wall time %s - DB row time %s\n", date("H:i:s"), $row['_time']);

    /* pause one second */
    sleep(1);
}
?>

    

The above examples will output something similar to:

Wall time 14:55:59 - DB row time 2012-01-11 14:55:59
Wall time 14:56:00 - DB row time 2012-01-11 14:55:59
Wall time 14:56:01 - DB row time 2012-01-11 14:55:59
Wall time 14:56:02 - DB row time 2012-01-11 14:56:02
Wall time 14:56:03 - DB row time 2012-01-11 14:56:02
Wall time 14:56:04 - DB row time 2012-01-11 14:56:02
Wall time 14:56:05 - DB row time 2012-01-11 14:56:05

<?php
$start = microtime(true);

/* Connect, create and populate test table */
$mysqli = new mysqli("host", "user", "password", "schema", "port", "socket");
$mysqli->query("DROP TABLE IF EXISTS test");
$mysqli->query("CREATE TABLE test(id INT)");
$mysqli->query("INSERT INTO test(id) VALUES (1), (2)");

printf("Default TTL\t: %d seconds\n", ini_get("mysqlnd_qc.ttl"));

/* Will be cached for 2 seconds */
$sql = sprintf("/*%s*//*%s%d*/SELECT id FROM test WHERE id = 1", MYSQLND_QC_ENABLE_SWITCH, MYSQLND_QC_TTL_SWITCH, 2);
$res = $mysqli->query($sql);

var_dump($res->fetch_assoc());
$res->free();

$mysqli->query("DELETE FROM test WHERE id = 1");
sleep(1);

/* Cache hit - no automatic invalidation and still valid! */
$res = $mysqli->query($sql);
var_dump($res->fetch_assoc());
$res->free();

sleep(2);

/* Cache miss - cache entry has expired */
$res = $mysqli->query($sql);
var_dump($res->fetch_assoc());
$res->free();

printf("Script runtime\t: %d seconds\n", microtime(true) - $start);
?>

    

The above examples will output something similar to:

Default TTL     : 30 seconds
array(1) {
  ["id"]=>
  string(1) "1"
}
array(1) {
  ["id"]=>
  string(1) "1"
}
NULL
Script runtime  : 3 seconds

mysqlnd_qc.enable_qc=1
mysqlnd_qc.collect_statistics=1

    

<?php
/* callback which decides if query is cached */
function is_select($query) {
    static $patterns = array(
      /* true - use default from mysqlnd_qc.ttl */
      "@SELECT\s+.*\s+FROM\s+test@ismU" => true,
      /* 3 - use TTL = 3 seconds */
      "@SELECT\s+.*\s+FROM\s+news@ismU" => 3
    );

    /* check if query does match pattern */
    foreach ($patterns as $pattern => $ttl) {
        if (preg_match($pattern, $query)) {
            printf("is_select(%45s): cache\n", $query);
            return $ttl;
        }
    }
    printf("is_select(%45s): do not cache\n", $query);
    return false;
}
/* install callback */
mysqlnd_qc_set_is_select("is_select");

/* Connect, create and populate test table */
$mysqli = new mysqli("host", "user", "password", "schema", "port", "socket");
$mysqli->query("DROP TABLE IF EXISTS test");
$mysqli->query("CREATE TABLE test(id INT)");
$mysqli->query("INSERT INTO test(id) VALUES (1), (2), (3)");

/* cache put */
$mysqli->query("SELECT id FROM test WHERE id = 1");
/* cache hit */
$mysqli->query("SELECT id FROM test WHERE id = 1");
/* cache put */
$mysqli->query("SELECT * FROM test");

$stats = mysqlnd_qc_get_core_stats();
printf("Cache put: %d\n", $stats['cache_put']);
printf("Cache hit: %d\n", $stats['cache_hit']);
?>

    

The above examples will output something similar to:

is_select(                    DROP TABLE IF EXISTS test): do not cache
is_select(                    CREATE TABLE test(id INT)): do not cache
is_select(    INSERT INTO test(id) VALUES (1), (2), (3)): do not cache
is_select(             SELECT id FROM test WHERE id = 1): cache
is_select(             SELECT id FROM test WHERE id = 1): cache
is_select(                           SELECT * FROM test): cache
Cache put: 2
Cache hit: 1

mysqlnd_qc.slam_defense=1
mysqlnd_qc.slam_defense_ttl=1

mysqlnd_qc.enable_qc=1
mysqlnd_qc.collect_query_trace=1

    

<?php
/* connect to MySQL */
$mysqli = new mysqli("host", "user", "password", "schema", "port", "socket");

/* dummy queries to fill the query trace */
for ($i = 0; $i < 2; $i++) {
    $res = $mysqli->query("SELECT 1 AS _one FROM DUAL");
    $res->free();
}

/* dump trace */
var_dump(mysqlnd_qc_get_query_trace_log());
?>

    

The above examples will output:

array(2) {
  [0]=>
  array(8) {
    ["query"]=>
    string(26) "SELECT 1 AS _one FROM DUAL"
    ["origin"]=>
    string(102) "#0 qc.php(7): mysqli->query('SELECT 1 AS _on...')
#1 {main}"
    ["run_time"]=>
    int(0)
    ["store_time"]=>
    int(25)
    ["eligible_for_caching"]=>
    bool(false)
    ["no_table"]=>
    bool(false)
    ["was_added"]=>
    bool(false)
    ["was_already_in_cache"]=>
    bool(false)
  }
  [1]=>
  array(8) {
    ["query"]=>
    string(26) "SELECT 1 AS _one FROM DUAL"
    ["origin"]=>
    string(102) "#0 qc.php(7): mysqli->query('SELECT 1 AS _on...')
#1 {main}"
    ["run_time"]=>
    int(0)
    ["store_time"]=>
    int(8)
    ["eligible_for_caching"]=>
    bool(false)
    ["no_table"]=>
    bool(false)
    ["was_added"]=>
    bool(false)
    ["was_already_in_cache"]=>
    bool(false)
  }
}

mysqlnd_qc.enable_qc=1
mysqlnd_qc.collect_query_trace=1

    

<?php
/* connect to MySQL */
$mysqli = new mysqli("host", "user", "password", "schema", "port", "socket");
$mysqli->query("DROP TABLE IF EXISTS test");
$mysqli->query("CREATE TABLE test(id INT)");
$mysqli->query("INSERT INTO test(id) VALUES (1), (2), (3)");

/* dummy queries to fill the query trace */
for ($i = 0; $i < 3; $i++) {
    $res = $mysqli->query("SELECT id FROM test WHERE id = " . $mysqli->real_escape_string($i));
    $res->free();
}

$trace = mysqlnd_qc_get_query_trace_log();
$summary = array();
foreach ($trace as $entry) {
    if (!isset($summary[$entry['query']])) {
        $summary[$entry['query']] = array(
            "executions" => 1,
            "time"       => $entry['run_time'] + $entry['store_time'],
        );
    } else {
        $summary[$entry['query']]['executions']++;
        $summary[$entry['query']]['time'] += $entry['run_time'] + $entry['store_time'];
    }
}

foreach ($summary as $query => $details) {
    printf("%45s: %5dms (%dx)\n",
    $query, $details['time'], $details['executions']);
}
?>

    

The above examples will output something similar to:

                    DROP TABLE IF EXISTS test:     0ms (1x)
                    CREATE TABLE test(id INT):     0ms (1x)
    INSERT INTO test(id) VALUES (1), (2), (3):     0ms (1x)
             SELECT id FROM test WHERE id = 0:    25ms (1x)
             SELECT id FROM test WHERE id = 1:    10ms (1x)
             SELECT id FROM test WHERE id = 2:     9ms (1x)

mysqlnd_qc.enable_qc=1
mysqlnd_qc.collect_statistics=1

    

<?php
/* connect to MySQL */
$mysqli = new mysqli("host", "user", "password", "schema", "port", "socket");
$mysqli->query("DROP TABLE IF EXISTS test");
$mysqli->query("CREATE TABLE test(id INT)");
$mysqli->query("INSERT INTO test(id) VALUES (1), (2), (3)");

/* dummy queries */
for ($i = 1; $i <= 4; $i++) {
    $query = sprintf("/*%s*/SELECT id FROM test WHERE id = %d", MYSQLND_QC_ENABLE_SWITCH, $i % 2);
    $res   = $mysqli->query($query);
    
    $res->free();
}

var_dump(mysqlnd_qc_get_core_stats());
?>

    

The above examples will output something similar to:

array(26) {
  ["cache_hit"]=>
  string(1) "2"
  ["cache_miss"]=>
  string(1) "2"
  ["cache_put"]=>
  string(1) "2"
  ["query_should_cache"]=>
  string(1) "4"
  ["query_should_not_cache"]=>
  string(1) "3"
  ["query_not_cached"]=>
  string(1) "3"
  ["query_could_cache"]=>
  string(1) "4"
  ["query_found_in_cache"]=>
  string(1) "2"
  ["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(2) "28"
  ["query_aggr_run_time_cache_put"]=>
  string(3) "900"
  ["query_aggr_run_time_total"]=>
  string(3) "928"
  ["query_aggr_store_time_cache_hit"]=>
  string(2) "14"
  ["query_aggr_store_time_cache_put"]=>
  string(2) "40"
  ["query_aggr_store_time_total"]=>
  string(2) "54"
  ["receive_bytes_recorded"]=>
  string(3) "136"
  ["receive_bytes_replayed"]=>
  string(3) "136"
  ["send_bytes_recorded"]=>
  string(2) "84"
  ["send_bytes_replayed"]=>
  string(2) "84"
  ["slam_stale_refresh"]=>
  string(1) "0"
  ["slam_stale_hit"]=>
  string(1) "0"
  ["request_counter"]=>
  int(1)
  ["process_hash"]=>
  int(1929695233)
}

mysqlnd_qc.enable_qc=1

    

<?php
/* connect to MySQL */
$mysqli = new mysqli("host", "user", "password", "schema", "port", "socket");
$mysqli->query("DROP TABLE IF EXISTS test");
$mysqli->query("CREATE TABLE test(id INT)");
$mysqli->query("INSERT INTO test(id) VALUES (1), (2), (3)");

/* dummy queries to fill the query trace */
for ($i = 1; $i <= 4; $i++) {
    $query = sprintf("/*%s*/SELECT id FROM test WHERE id = %d", MYSQLND_QC_ENABLE_SWITCH, $i % 2);
    $res   = $mysqli->query($query);
  
    $res->free();
}

var_dump(mysqlnd_qc_get_cache_info());
?>

    

The above examples will output something similar to:

array(4) {
  ["num_entries"]=>
  int(2)
  ["handler"]=>
  string(7) "default"
  ["handler_version"]=>
  string(5) "1.0.0"
  ["data"]=>
  array(2) {
    ["Localhost via UNIX socket
3306
root
test|/*qc=on*/SELECT id FROM test WHERE id = 1"]=>
    array(2) {
      ["statistics"]=>
      array(11) {
        ["rows"]=>
        int(1)
        ["stored_size"]=>
        int(71)
        ["cache_hits"]=>
        int(1)
        ["run_time"]=>
        int(391)
        ["store_time"]=>
        int(27)
        ["min_run_time"]=>
        int(16)
        ["max_run_time"]=>
        int(16)
        ["min_store_time"]=>
        int(8)
        ["max_store_time"]=>
        int(8)
        ["avg_run_time"]=>
        int(8)
        ["avg_store_time"]=>
        int(4)
      }
      ["metadata"]=>
      array(1) {
        [0]=>
        array(8) {
          ["name"]=>
          string(2) "id"
          ["orig_name"]=>
          string(2) "id"
          ["table"]=>
          string(4) "test"
          ["orig_table"]=>
          string(4) "test"
          ["db"]=>
          string(4) "test"
          ["max_length"]=>
          int(1)
          ["length"]=>
          int(11)
          ["type"]=>
          int(3)
        }
      }
    }
    ["Localhost via UNIX socket
3306
root
test|/*qc=on*/SELECT id FROM test WHERE id = 0"]=>
    array(2) {
      ["statistics"]=>
      array(11) {
        ["rows"]=>
        int(0)
        ["stored_size"]=>
        int(65)
        ["cache_hits"]=>
        int(1)
        ["run_time"]=>
        int(299)
        ["store_time"]=>
        int(13)
        ["min_run_time"]=>
        int(11)
        ["max_run_time"]=>
        int(11)
        ["min_store_time"]=>
        int(6)
        ["max_store_time"]=>
        int(6)
        ["avg_run_time"]=>
        int(5)
        ["avg_store_time"]=>
        int(3)
      }
      ["metadata"]=>
      array(1) {
        [0]=>
        array(8) {
          ["name"]=>
          string(2) "id"
          ["orig_name"]=>
          string(2) "id"
          ["table"]=>
          string(4) "test"
          ["orig_table"]=>
          string(4) "test"
          ["db"]=>
          string(4) "test"
          ["max_length"]=>
          int(0)
          ["length"]=>
          int(11)
          ["type"]=>
          int(3)
        }
      }
    }
  }
}

mysqlnd_qc.enable_qc=1
mysqlnd_qc.collect_normalized_query_trace=1

    

<?php
/* connect to MySQL */
$mysqli = new mysqli("host", "user", "password", "schema", "port", "socket");
$mysqli->query("DROP TABLE IF EXISTS test");
$mysqli->query("CREATE TABLE test(id INT)");
$mysqli->query("INSERT INTO test(id) VALUES (1), (2), (3)");

/* dummy queries to fill the query trace */
for ($i = 1; $i <= 4; $i++) {
    $query = sprintf("/*%s*/SELECT id FROM test WHERE id = %d", MYSQLND_QC_ENABLE_SWITCH, $i % 2);
    $res   = $mysqli->query($query);
  
    $res->free();
}

var_dump(mysqlnd_qc_get_normalized_query_trace_log());
?>

    

The above examples will output something similar to:

array(4) {
  [0]=>
  array(9) {
    ["query"]=>
    string(25) "DROP TABLE IF EXISTS test"
    ["occurences"]=>
    int(0)
    ["eligible_for_caching"]=>
    bool(false)
    ["avg_run_time"]=>
    int(0)
    ["min_run_time"]=>
    int(0)
    ["max_run_time"]=>
    int(0)
    ["avg_store_time"]=>
    int(0)
    ["min_store_time"]=>
    int(0)
    ["max_store_time"]=>
    int(0)
  }
  [1]=>
  array(9) {
    ["query"]=>
    string(27) "CREATE TABLE test (id INT )"
    ["occurences"]=>
    int(0)
    ["eligible_for_caching"]=>
    bool(false)
    ["avg_run_time"]=>
    int(0)
    ["min_run_time"]=>
    int(0)
    ["max_run_time"]=>
    int(0)
    ["avg_store_time"]=>
    int(0)
    ["min_store_time"]=>
    int(0)
    ["max_store_time"]=>
    int(0)
  }
  [2]=>
  array(9) {
    ["query"]=>
    string(46) "INSERT INTO test (id ) VALUES (? ), (? ), (? )"
    ["occurences"]=>
    int(0)
    ["eligible_for_caching"]=>
    bool(false)
    ["avg_run_time"]=>
    int(0)
    ["min_run_time"]=>
    int(0)
    ["max_run_time"]=>
    int(0)
    ["avg_store_time"]=>
    int(0)
    ["min_store_time"]=>
    int(0)
    ["max_store_time"]=>
    int(0)
  }
  [3]=>
  array(9) {
    ["query"]=>
    string(31) "SELECT id FROM test WHERE id =?"
    ["occurences"]=>
    int(4)
    ["eligible_for_caching"]=>
    bool(true)
    ["avg_run_time"]=>
    int(179)
    ["min_run_time"]=>
    int(11)
    ["max_run_time"]=>
    int(393)
    ["avg_store_time"]=>
    int(12)
    ["min_store_time"]=>
    int(7)
    ["max_store_time"]=>
    int(25)
  }
}

<?php
/* Enable default caching of all statements */
ini_set("mysqlnd_qc.cache_by_default", 1);

/* Procedural user defined storage handler functions */

$__cache = array();

function get_hash($host_info, $port, $user, $db, $query) {
    global $__cache;
    printf("\t%s(%d)\n", __FUNCTION__, func_num_args());

    return md5(sprintf("%s%s%s%s%s", $host_info, $port, $user, $db, $query));
}

function find_query_in_cache($key) {
    global $__cache;
    printf("\t%s(%d)\n", __FUNCTION__, func_num_args());

    if (isset($__cache[$key])) {
        $tmp = $__cache[$key];
        if ($tmp["valid_until"] < time()) {
            unset($__cache[$key]);
            $ret = NULL;
        } else {
            $ret = $__cache[$key]["data"];
        }
    } else {
        $ret = NULL;
    }

    return $ret;
}

function return_to_cache($key) {
    /*
     Called on cache hit after cached data has been processed,
     may be used for reference counting
    */
    printf("\t%s(%d)\n", __FUNCTION__, func_num_args());
}

function add_query_to_cache_if_not_exists($key, $data, $ttl, $run_time, $store_time, $row_count) {
    global $__cache;
    printf("\t%s(%d)\n", __FUNCTION__, func_num_args());

    $__cache[$key] = array(
        "data"               => $data,
        "row_count"          => $row_count,
        "valid_until"        => time() + $ttl,
        "hits"               => 0,
        "run_time"           => $run_time,
        "store_time"         => $store_time,
        "cached_run_times"   => array(),
        "cached_store_times" => array(),
    );

    return TRUE;
}

function query_is_select($query) {
    printf("\t%s('%s'): ", __FUNCTION__, $query);

    $ret = FALSE;
    if (stristr($query, "SELECT") !== FALSE) {
        /* cache for 5 seconds */
        $ret = 5;
    }

    printf("%s\n", (FALSE === $ret) ? "FALSE" : $ret);
    return $ret;
}

function update_query_run_time_stats($key, $run_time, $store_time) {
    global $__cache;
    printf("\t%s(%d)\n", __FUNCTION__, func_num_args());

    if (isset($__cache[$key])) {
        $__cache[$key]['hits']++;
        $__cache[$key]["cached_run_times"][] = $run_time;
        $__cache[$key]["cached_store_times"][] = $store_time;
    }
}

function get_stats($key = NULL) {
    global $__cache;
    printf("\t%s(%d)\n", __FUNCTION__, func_num_args());

    if ($key && isset($__cache[$key])) {
        $stats = $__cache[$key];
    } else {
        $stats = array();
        foreach ($__cache as $key => $details) {
            $stats[$key] = array(
               'hits'              => $details['hits'],
               'bytes'             => strlen($details['data']),
               'uncached_run_time' => $details['run_time'],
               'cached_run_time'   => (count($details['cached_run_times']))
                                      ? array_sum($details['cached_run_times']) / count($details['cached_run_times'])
                                      : 0,
            );
        }
    }

    return $stats;
}

function clear_cache() {
    global $__cache;
    printf("\t%s(%d)\n", __FUNCTION__, func_num_args());

    $__cache = array();
    return TRUE;
}

/* Install procedural user-defined storage handler */
if (!mysqlnd_qc_set_user_handlers("get_hash", "find_query_in_cache",
    "return_to_cache", "add_query_to_cache_if_not_exists",
    "query_is_select", "update_query_run_time_stats", "get_stats", "clear_cache")) {
  
        printf("Failed to install user-defined storage handler\n");
}


/* Connect, create and populate test table */
$mysqli = new mysqli("host", "user", "password", "schema", "port", "socket");
$mysqli->query("DROP TABLE IF EXISTS test");
$mysqli->query("CREATE TABLE test(id INT)");
$mysqli->query("INSERT INTO test(id) VALUES (1), (2)");

printf("\nCache put/cache miss\n");

$res = $mysqli->query("SELECT id FROM test WHERE id = 1");
var_dump($res->fetch_assoc());
$res->free();

/* Delete record to verify we get our data from the cache */
$mysqli->query("DELETE FROM test WHERE id = 1");

printf("\nCache hit\n");

$res = $mysqli->query("SELECT id FROM test WHERE id = 1");
var_dump($res->fetch_assoc());
$res->free();

printf("\nDisplay cache statistics\n");
var_dump(mysqlnd_qc_get_cache_info());

printf("\nFlushing cache, cache put/cache miss");
var_dump(mysqlnd_qc_clear_cache());

$res = $mysqli->query("SELECT id FROM test WHERE id = 1");
var_dump($res->fetch_assoc());
$res->free();
?>

    

The above examples will output something similar to:

        query_is_select('DROP TABLE IF EXISTS test'): FALSE
        query_is_select('CREATE TABLE test(id INT)'): FALSE
        query_is_select('INSERT INTO test(id) VALUES (1), (2)'): FALSE

Cache put/cache miss
        query_is_select('SELECT id FROM test WHERE id = 1'): 5
        get_hash(5)
        find_query_in_cache(1)
        add_query_to_cache_if_not_exists(6)
array(1) {
  ["id"]=>
  string(1) "1"
}
        query_is_select('DELETE FROM test WHERE id = 1'): FALSE

Cache hit
        query_is_select('SELECT id FROM test WHERE id = 1'): 5
        get_hash(5)
        find_query_in_cache(1)
        return_to_cache(1)
        update_query_run_time_stats(3)
array(1) {
  ["id"]=>
  string(1) "1"
}

Display cache statistics
        get_stats(0)
array(4) {
  ["num_entries"]=>
  int(1)
  ["handler"]=>
  string(4) "user"
  ["handler_version"]=>
  string(5) "1.0.0"
  ["data"]=>
  array(1) {
    ["18683c177dc89bb352b29965d112fdaa"]=>
    array(4) {
      ["hits"]=>
      int(1)
      ["bytes"]=>
      int(71)
      ["uncached_run_time"]=>
      int(398)
      ["cached_run_time"]=>
      int(4)
    }
  }
}

Flushing cache, cache put/cache miss    clear_cache(0)
bool(true)
        query_is_select('SELECT id FROM test WHERE id = 1'): 5
        get_hash(5)
        find_query_in_cache(1)
        add_query_to_cache_if_not_exists(6)
NULL

<?php
var_dump(mysqlnd_qc_get_available_handlers());
?>

   

The above examples will output:

array(5) {
  ["default"]=>
  array(2) {
    ["version"]=>
    string(5) "1.0.0"
    ["version_number"]=>
    int(100000)
  }
  ["user"]=>
  array(2) {
    ["version"]=>
    string(5) "1.0.0"
    ["version_number"]=>
    int(100000)
  }
  ["APC"]=>
  array(2) {
    ["version"]=>
    string(5) "1.0.0"
    ["version_number"]=>
    int(100000)
  }
  ["MEMCACHE"]=>
  array(2) {
    ["version"]=>
    string(5) "1.0.0"
    ["version_number"]=>
    int(100000)
  }
  ["sqlite"]=>
  array(2) {
    ["version"]=>
    string(5) "1.0.0"
    ["version_number"]=>
    int(100000)
  }
}

The example shows the output from the built-in default storage handler. Other storage handler may report different data.

<?php
/* Populate the cache, e.g. using mysqli */
$mysqli = new mysqli("host", "user", "password", "schema");
$mysqli->query("/*" . MYSQLND_QC_ENABLE_SWITCH . "*/SELECT id FROM test");

/* Display cache information */
var_dump(mysqlnd_qc_get_cache_info());
?>

   

The above examples will output:

array(4) {
 ["num_entries"]=>
 int(1)
 ["handler"]=>
 string(7) "default"
 ["handler_version"]=>
 string(5) "1.0.0"
 ["data"]=>
 array(1) {
   ["Localhost via UNIX socket 3306 user schema|/*qc=on*/SELECT id FROM test"]=>
   array(2) {
     ["statistics"]=>
     array(11) {
       ["rows"]=>
       int(6)
       ["stored_size"]=>
       int(101)
       ["cache_hits"]=>
       int(0)
       ["run_time"]=>
       int(471)
       ["store_time"]=>
       int(27)
       ["min_run_time"]=>
       int(0)
       ["max_run_time"]=>
       int(0)
       ["min_store_time"]=>
       int(0)
       ["max_store_time"]=>
       int(0)
       ["avg_run_time"]=>
       int(0)
       ["avg_store_time"]=>
       int(0)
     }
     ["metadata"]=>
     array(1) {
       [0]=>
       array(8) {
         ["name"]=>
         string(2) "id"
         ["orig_name"]=>
         string(2) "id"
         ["table"]=>
         string(4) "test"
         ["orig_table"]=>
         string(4) "test"
         ["db"]=>
         string(4) "schema"
         ["max_length"]=>
         int(1)
         ["length"]=>
         int(11)
         ["type"]=>
         int(3)
       }
     }
   }
 }
}

<?php
/* Enable collection of statistics - default: disabled */
ini_set("mysqlnd_qc.collect_statistics", 1);

/* Enable collection of all timing related statistics -
default: enabled but overruled by mysqlnd_qc.collect_statistics = 0 */
ini_set("mysqlnd_qc.collect_time_statistics", 1);

/* Populate the cache, e.g. using mysqli */
$mysqli = new mysqli('host', 'user', 'password', 'schema');

/* Cache miss and cache put */
$mysqli->query("/*qc=on*/SELECT id FROM test");
/* Cache hit */
$mysqli->query("/*qc=on*/SELECT id FROM test");

/* Display core statistics */
var_dump(mysqlnd_qc_get_core_stats());
?>

   

The above examples will output:

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)
}

mysqlnd_qc.collect_normalized_query_trace=1

   

<?php
/* Connect, create and populate test table */
$mysqli = new mysqli("host", "user", "password", "schema", "port", "socket");
$mysqli->query("DROP TABLE IF EXISTS test");
$mysqli->query("CREATE TABLE test(id INT)");
$mysqli->query("INSERT INTO test(id) VALUES (1), (2)");

/* not cached */
$res = $mysqli->query("SELECT id FROM test WHERE id = 1");
var_dump($res->fetch_assoc());
$res->free();

/* cache put */
$res = $mysqli->query("/*" . MYSQLND_QC_ENABLE_SWITCH . "*/" . "SELECT id FROM test WHERE id = 2");
var_dump($res->fetch_assoc());
$res->free();

/* cache hit */
$res = $mysqli->query("/*" . MYSQLND_QC_ENABLE_SWITCH . "*/" . "SELECT id FROM test WHERE id = 2");
var_dump($res->fetch_assoc());
$res->free();

var_dump(mysqlnd_qc_get_normalized_query_trace_log());
?>

   

The above examples will output:

array(1) {
  ["id"]=>
  string(1) "1"
}
array(1) {
  ["id"]=>
  string(1) "2"
}
array(1) {
  ["id"]=>
  string(1) "2"
}
array(4) {
  [0]=>
  array(9) {
    ["query"]=>
    string(25) "DROP TABLE IF EXISTS test"
    ["occurences"]=>
    int(0)
    ["eligible_for_caching"]=>
    bool(false)
    ["avg_run_time"]=>
    int(0)
    ["min_run_time"]=>
    int(0)
    ["max_run_time"]=>
    int(0)
    ["avg_store_time"]=>
    int(0)
    ["min_store_time"]=>
    int(0)
    ["max_store_time"]=>
    int(0)
  }
  [1]=>
  array(9) {
    ["query"]=>
    string(27) "CREATE TABLE test (id INT )"
    ["occurences"]=>
    int(0)
    ["eligible_for_caching"]=>
    bool(false)
    ["avg_run_time"]=>
    int(0)
    ["min_run_time"]=>
    int(0)
    ["max_run_time"]=>
    int(0)
    ["avg_store_time"]=>
    int(0)
    ["min_store_time"]=>
    int(0)
    ["max_store_time"]=>
    int(0)
  }
  [2]=>
  array(9) {
    ["query"]=>
    string(40) "INSERT INTO test (id ) VALUES (? ), (? )"
    ["occurences"]=>
    int(0)
    ["eligible_for_caching"]=>
    bool(false)
    ["avg_run_time"]=>
    int(0)
    ["min_run_time"]=>
    int(0)
    ["max_run_time"]=>
    int(0)
    ["avg_store_time"]=>
    int(0)
    ["min_store_time"]=>
    int(0)
    ["max_store_time"]=>
    int(0)
  }
  [3]=>
  array(9) {
    ["query"]=>
    string(31) "SELECT id FROM test WHERE id =?"
    ["occurences"]=>
    int(2)
    ["eligible_for_caching"]=>
    bool(true)
    ["avg_run_time"]=>
    int(159)
    ["min_run_time"]=>
    int(12)
    ["max_run_time"]=>
    int(307)
    ["avg_store_time"]=>
    int(10)
    ["min_store_time"]=>
    int(8)
    ["max_store_time"]=>
    int(13)
  }
}

mysqlnd_qc.collect_query_trace=1

   

<?php
/* Connect, create and populate test table */
$mysqli = new mysqli("host", "user", "password", "schema", "port", "socket");
$mysqli->query("DROP TABLE IF EXISTS test");
$mysqli->query("CREATE TABLE test(id INT)");
$mysqli->query("INSERT INTO test(id) VALUES (1), (2)");

/* not cached */
$res = $mysqli->query("SELECT id FROM test WHERE id = 1");
var_dump($res->fetch_assoc());
$res->free();

/* cache put */
$res = $mysqli->query("/*" . MYSQLND_QC_ENABLE_SWITCH . "*/" . "SELECT id FROM test WHERE id = 2");
var_dump($res->fetch_assoc());
$res->free();

/* cache hit */
$res = $mysqli->query("/*" . MYSQLND_QC_ENABLE_SWITCH . "*/" . "SELECT id FROM test WHERE id = 2");
var_dump($res->fetch_assoc());
$res->free();

var_dump(mysqlnd_qc_get_query_trace_log());
?>

   

The above examples will output:

array(1) {
  ["id"]=>
  string(1) "1"
}
array(1) {
  ["id"]=>
  string(1) "2"
}
array(1) {
  ["id"]=>
  string(1) "2"
}
array(6) {
  [0]=>
  array(8) {
    ["query"]=>
    string(25) "DROP TABLE IF EXISTS test"
    ["origin"]=>
    string(102) "#0 qc.php(4): mysqli->query('DROP TABLE IF E...')
#1 {main}"
    ["run_time"]=>
    int(0)
    ["store_time"]=>
    int(0)
    ["eligible_for_caching"]=>
    bool(false)
    ["no_table"]=>
    bool(false)
    ["was_added"]=>
    bool(false)
    ["was_already_in_cache"]=>
    bool(false)
  }
  [1]=>
  array(8) {
    ["query"]=>
    string(25) "CREATE TABLE test(id INT)"
    ["origin"]=>
    string(102) "#0 qc.php(5): mysqli->query('CREATE TABLE te...')
#1 {main}"
    ["run_time"]=>
    int(0)
    ["store_time"]=>
    int(0)
    ["eligible_for_caching"]=>
    bool(false)
    ["no_table"]=>
    bool(false)
    ["was_added"]=>
    bool(false)
    ["was_already_in_cache"]=>
    bool(false)
  }
  [2]=>
  array(8) {
    ["query"]=>
    string(36) "INSERT INTO test(id) VALUES (1), (2)"
    ["origin"]=>
    string(102) "#0 qc.php(6): mysqli->query('INSERT INTO tes...')
#1 {main}"
    ["run_time"]=>
    int(0)
    ["store_time"]=>
    int(0)
    ["eligible_for_caching"]=>
    bool(false)
    ["no_table"]=>
    bool(false)
    ["was_added"]=>
    bool(false)
    ["was_already_in_cache"]=>
    bool(false)
  }
  [3]=>
  array(8) {
    ["query"]=>
    string(32) "SELECT id FROM test WHERE id = 1"
    ["origin"]=>
    string(102) "#0 qc.php(9): mysqli->query('SELECT id FROM ...')
#1 {main}"
    ["run_time"]=>
    int(0)
    ["store_time"]=>
    int(25)
    ["eligible_for_caching"]=>
    bool(false)
    ["no_table"]=>
    bool(false)
    ["was_added"]=>
    bool(false)
    ["was_already_in_cache"]=>
    bool(false)
  }
  [4]=>
  array(8) {
    ["query"]=>
    string(41) "/*qc=on*/SELECT id FROM test WHERE id = 2"
    ["origin"]=>
    string(103) "#0 qc.php(14): mysqli->query('/*qc=on*/SELECT...')
#1 {main}"
    ["run_time"]=>
    int(311)
    ["store_time"]=>
    int(13)
    ["eligible_for_caching"]=>
    bool(true)
    ["no_table"]=>
    bool(false)
    ["was_added"]=>
    bool(true)
    ["was_already_in_cache"]=>
    bool(false)
  }
  [5]=>
  array(8) {
    ["query"]=>
    string(41) "/*qc=on*/SELECT id FROM test WHERE id = 2"
    ["origin"]=>
    string(103) "#0 qc.php(19): mysqli->query('/*qc=on*/SELECT...')
#1 {main}"
    ["run_time"]=>
    int(13)
    ["store_time"]=>
    int(8)
    ["eligible_for_caching"]=>
    bool(true)
    ["no_table"]=>
    bool(false)
    ["was_added"]=>
    bool(false)
    ["was_already_in_cache"]=>
    bool(true)
  }
}

<?php
/* Cache all accesses to tables with the name "new%" in schema/database "db_example" for 1 second */
if (!mysqlnd_qc_set_cache_condition(MYSQLND_QC_CONDITION_META_SCHEMA_PATTERN, "db_example.new%", 1)) {
  die("Failed to set cache condition!");
}

$mysqli = new mysqli("host", "user", "password", "db_example", "port");
/* cached although no SQL hint given  */
$mysqli->query("SELECT id, title FROM news");

$pdo_mysql = new PDO("mysql:host=host;dbname=db_example;port=port", "user", "password");
/* not cached: no SQL hint, no pattern match */
$pdo_mysql->query("SELECT id, title FROM latest_news");
/* cached: TTL 1 second, pattern match */
$pdo_mysql->query("SELECT id, title FROM news");
?>

<?php
/* callback which decides if query is cached */
function is_select($query) {
  static $patterns = array(
   /* true - use default from mysqlnd_qc.ttl */
   "@SELECT\s+.*\s+FROM\s+test@ismU" => true,
   /* 3 - use TTL = 3 seconds */
   "@SELECT\s+.*\s+FROM\s+news@ismU" => 3
  );
  /* check if query does match pattern */
  foreach ($patterns as $pattern => $ttl) {
    if (preg_match($pattern, $query)) {
      printf("is_select(%45s): cache\n", $query);
      return $ttl;
    }
  }
  printf("is_select(%45s): do not cache\n", $query);
  return false;
}
mysqlnd_qc_set_is_select("is_select");

/* Connect, create and populate test table */
$mysqli = new mysqli("host", "user", "password", "schema");
$mysqli->query("DROP TABLE IF EXISTS test");
$mysqli->query("CREATE TABLE test(id INT)");
$mysqli->query("INSERT INTO test(id) VALUES (1), (2), (3)");

/* cache put */
$mysqli->query("SELECT id FROM test WHERE id = 1");
/* cache hit */
$mysqli->query("SELECT id FROM test WHERE id = 1");
/* cache put */
$mysqli->query("SELECT * FROM test");
?>

   

The above examples will output:

is_select(                    DROP TABLE IF EXISTS test): do not cache
is_select(                    CREATE TABLE test(id INT)): do not cache
is_select(    INSERT INTO test(id) VALUES (1), (2), (3)): do not cache
is_select(             SELECT id FROM test WHERE id = 1): cache
is_select(             SELECT id FROM test WHERE id = 1): cache
is_select(                           SELECT * FROM test): cache

The example shows the output from the built-in default storage handler. Other storage handler may report different data.

<?php
var_dump(mysqlnd_qc_set_storage_handler("memcache"));

if (true === mysqlnd_qc_set_storage_handler("default"))
  printf("Default storage handler activated");

/* Catchable fatal error */
var_dump(mysqlnd_qc_set_storage_handler("unknown"));
?>

   

The above examples will output:

bool(true)
Default storage handler activated
Catchable fatal error: mysqlnd_qc_set_storage_handler(): Unknown handler 'unknown' in (file) on line (line)