# mysqlnd_qc_get_normalized_query_trace_log

(PECL mysqlnd_qc >= 1.0.0)

mysqlnd_qc_get_normalized_query_trace_log — Returns a normalized query trace log for each query inspected by the query cache

### 说明

mysqlnd_qc_get_normalized_query_trace_log ( void ) : array

Returns a normalized query trace log for each query inspected by the query cache. The collection of the trace log is disabled by default. To collect the trace log you have to set the PHP configuration directive mysqlnd_qc.collect_normalized_query_trace to 1

Entries in the trace log are grouped by the normalized query statement. The normalized query statement is the query statement with all statement parameter values being replaced with a question mark. For example, the two statements SELECT id FROM test WHERE id = 1 and SELECT id FROM test WHERE id = 2 are normalized as SELECT id FROM test WHERE id = ?. Whenever a statement is inspected by the query cache which matches the normalized statement pattern, its statistics are grouped by the normalized statement string.

### 参数

此函数没有参数。

### 返回值

An array of query log. Every list entry contains the normalized query stringand further detail information.

Key | Description
--- | ---
query | Normalized statement string.
occurences | How many statements have matched the normalized statement string in addition to the one which has created the log entry. The value is zero if a statement has been normalized, its normalized representation has been added to the log but no further queries inspected by PECL/mysqlnd_qc have the same normalized statement string.
eligible_for_caching | Whether the statement could be cached. An statement eligible for caching has not necessarily been cached. It not possible to tell for sure if or how many cached statement have contributed to the aggregated normalized statement log entry. However, comparing the minimum and average run time one can make an educated guess.
avg_run_time | The average run time of all queries contributing to the query log entry. The run time is the time between sending the query statement to MySQL and receiving an answer from MySQL.
avg_store_time | The average store time of all queries contributing to the query log entry. The store time is the time needed to fetch a statements result set from the server to the client and, storing it on the client.
min_run_time | The minimum run time of all queries contributing to the query log entry.
min_store_time | The minimum store time of all queries contributing to the query log entry.
max_run_time | The maximum run time of all queries contributing to the query log entry.
max_store_time | The maximum store time of all queries contributing to the query log entry.

### 范例

Example #1 mysqlnd_qc_get_normalized_query_trace_log() example

    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());
    ?>

以上例程会输出：

    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)
      }
    }

### 参见

- Runtime configuration
- mysqlnd_qc.collect_normalized_query_trace
- mysqlnd_qc.time_statistics
- mysqlnd_qc_get_query_trace_log() - Returns a backtrace for each query inspected by the query cache