Oracle 5.0 Reference Manual page 2686

The default
TTL
appear immediately after the SQL hint which enables caching. It is recommended to use the PHP
constant
MYSQLND_QC_TTL_SWITCH
Example 20.310. Setting TTL with SQL hints
<?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_S
$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
array(1) {
["id"]=>
string(1) "1"
}
array(1) {
["id"]=>
string(1) "1"
}
NULL
Script runtime
20.7.7.4.5. Pattern based caching
Copyright 1997-2012 the PHP Documentation Group. [2230]
An application has three options for telling PECL/mysqlnd_qc whether a particular
statement shall be used. The most basic approach is to cache all statements by setting
mysqlnd_qc.cache_by_default =
Mysqlnd query result cache plugin (mysqlnd_qc)
can be overruled using the SQL hint /*qc_tt=seconds*/. The SQL hint must be
instead of using the string value.
: 30 seconds
: 3 seconds
1. This approach is often of little practical value. But it enables
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