IT. Expert System.

PHP

Installs a callback which decides whether a statement is cached


mysqlnd_qc_set_is_select

(PECL mysqlnd_qc >= 1.0.0)

mysqlnd_qc_set_is_selectInstalls a callback which decides whether a statement is cached

Description

mixed mysqlnd_qc_set_is_select ( string $callback )

Installs a callback which decides whether a statement is cached.

There are several ways of hinting PELC/mysqlnd_qc to cache a query. By default, PECL/mysqlnd_qc attempts to cache a if caching of all statements is enabled or the query string begins with a certain SQL hint. The plugin internally calls a function named is_select() to find out. This internal function can be replaced with a user-defined callback. Then, the user-defined callback is responsible to decide whether the plugin attempts to cache a statement. Because the internal function is replaced with the callback, the callback gains full control. The callback is free to ignore the configuration setting mysqlnd_qc.cache_by_default and SQL hints.

The callback is invoked for every statement inspected by the plugin. It is given the statements string as a parameter. The callback returns FALSE if the statement shall not be cached. It returns TRUE to make the plugin attempt to cache the statements result set, if any. A so-created cache entry is given the default TTL set with the PHP configuration directive mysqlnd_qc.ttl. If a different TTL shall be used, the callback returns a numeric value to be used as the TTL.

The internal is_select function is part of the internal cache storage handler interface. Thus, a user-defined storage handler offers the same capabilities.

Parameters

This function has no parameters.

Return Values

Returns TRUE on success or FALSE on failure.

Examples

Example #1 mysqlnd_qc_set_is_select() example

<?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 

See Also



Content

Android Reference

Java basics

Java Enterprise Edition (EE)

Java Standard Edition (SE)

SQL

HTML

PHP

CSS

Java Script

MYSQL

JQUERY

VBS

REGEX

C

C++

C#

Design patterns

RFC (standard status)

RFC (proposed standard status)

RFC (draft standard status)

RFC (informational status)

RFC (experimental status)

RFC (best current practice status)

RFC (historic status)

RFC (unknown status)

IT dictionary

License.
All information of this service is derived from the free sources and is provided solely in the form of quotations. This service provides information and interfaces solely for the familiarization (not ownership) and under the "as is" condition.
Copyright 2016 © ELTASK.COM. All rights reserved.
Site is optimized for mobile devices.
Downloads: 535 / . Delta: 0.01095 с