PHP performance 101: so you need to use a database
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The document provides insights into PHP database performance, highlighting the importance of efficient database connections and minimizing query overhead. It discusses common issues like the N+1 query problem, emphasizing the benefits of using efficient SQL queries and writable common table expressions (CTEs). The author recommends learning SQL to optimize performance and suggests various strategies to improve database interactions.
![n+1
// get a list of items
$sth = $dbh->prepare("select item_id from items
where active = true");
$sth->execute();
$items = $sth->fetchAll();
// get properties for each items
foreach ($items as $i) {
$sth_prop = $dbh->prepare("select * from
item_properties where item_id = ?");
$sth_prop->execute($item);
$item_list[$i[‘item_id’]][‘props’] = $sth_prop->fetchAll();
$item_list[$i[‘item_id’]][‘id’] = $i[‘id’];
}](https://image.slidesharecdn.com/phpdatabaseperformance-141114101718-conversion-gate02/85/PHP-performance-101-so-you-need-to-use-a-database-18-320.jpg)
![n+1 you don’t know about
// get a list of items
$items = get_active_item_ids();
// get properties for each items
foreach ($items as $i) {
$item = Item->new($i[‘item_id’])
$item_list[$i[‘item_id’][‘id’] = $item->item_id;
$item_list[$i[‘item_id’]][‘props’] = $item->properties();
}](https://image.slidesharecdn.com/phpdatabaseperformance-141114101718-conversion-gate02/85/PHP-performance-101-so-you-need-to-use-a-database-19-320.jpg)
![easy solution
// get a list of items with properties
$sth = $dbh->prepare("select i. item_id, p.* from items i,
item_properties p
where i.item_id = p.item_id
and active = true");
$sth->execute();
$items = $sth->fetchAll();
// arrange object to your liking
foreach ($items as $i) {
$item_list[$i[‘item_id’]][‘props’] = $i;
$item_list[$i[‘item_id’]][‘id’] = $i[‘id’];
}](https://image.slidesharecdn.com/phpdatabaseperformance-141114101718-conversion-gate02/85/PHP-performance-101-so-you-need-to-use-a-database-20-320.jpg)
![illustrating wrong
// get all orders
$sth = $dbh->prepare("select order_id, price from orders");
$sth->execute();
$orders= $sth->fetchAll();
//order by order_id
usort($orders, function ($a, $b) { if ($a['order_id'] == $b['order_id']) { return 0; }
return $a['order_id'] < $b['order_id'] ? -1 : 1; });
// get average $ for last 10 orders
$count = 1;
$total = 0;
$avg = 0;
foreach ($orders as $order) {
$total += $order[‘price’];
if ($count == 10) {
$avg = $total/$count;
break 1;
}
$count++;
}](https://image.slidesharecdn.com/phpdatabaseperformance-141114101718-conversion-gate02/85/PHP-performance-101-so-you-need-to-use-a-database-37-320.jpg)
![vs right
// get average $ for last 10 orders
$sth = $dbh->prepare("select avg(price) as avg_price
from (select price from orders
order by order_id desc limit 10) ");
$sth->execute();
$orders= $sth->fetchAll();
$avg = $orders[‘avg_price’];](https://image.slidesharecdn.com/phpdatabaseperformance-141114101718-conversion-gate02/85/PHP-performance-101-so-you-need-to-use-a-database-38-320.jpg)
PHP performance 101: so you need to use a database
- 1. PHP Performance 101: so you need to use a database Leon Fayer @papa_fire
- 2. Who am I ? • 20+ years development and operations of web applications • currently Vice President at OmniTI • can be found online: • @papa_fire • github:lfayer • http://fayerplay.com • https://joind.in/talk/view/11914
- 3. what it is about databases & performance
- 4. what it’s not about NoSQL MySQL
- 5. how database connection works ① establish connection ② send query ③ process query ④ send result ⑤ close connection
- 6. common database connection $dbh = new DB(…); $sth = $dbh->prepare($query); $sth->execute(); $result = $sth->fetchAll(); $dbh = null;
- 7. common database connection ① var $dbh = new DB(…); ② var $sth = $dbh->prepare($query); ① $sth->execute(); ② var $result = $sth->fetchAll(); ③ $dbh = null;
- 9. ① establish connection ⑤ close connection and
- 13. short and helpful answer persistent connections avoid multiple connections
- 14. how it works (high level) ① ① ① ⑤ ⑤ ⑤ ① ⑤
- 15. conclusion reduce # of connections
- 16. ② send query
- 18. n+1 // get a list of items $sth = $dbh->prepare("select item_id from items where active = true"); $sth->execute(); $items = $sth->fetchAll(); // get properties for each items foreach ($items as $i) { $sth_prop = $dbh->prepare("select * from item_properties where item_id = ?"); $sth_prop->execute($item); $item_list[$i[‘item_id’]][‘props’] = $sth_prop->fetchAll(); $item_list[$i[‘item_id’]][‘id’] = $i[‘id’]; }
- 19. n+1 you don’t know about // get a list of items $items = get_active_item_ids(); // get properties for each items foreach ($items as $i) { $item = Item->new($i[‘item_id’]) $item_list[$i[‘item_id’][‘id’] = $item->item_id; $item_list[$i[‘item_id’]][‘props’] = $item->properties(); }
- 20. easy solution // get a list of items with properties $sth = $dbh->prepare("select i. item_id, p.* from items i, item_properties p where i.item_id = p.item_id and active = true"); $sth->execute(); $items = $sth->fetchAll(); // arrange object to your liking foreach ($items as $i) { $item_list[$i[‘item_id’]][‘props’] = $i; $item_list[$i[‘item_id’]][‘id’] = $i[‘id’]; }
- 21. conclusion limit number of queries
- 22. cool stuff :BONUS: Common Table Expressions (CTEs) * MySQL does not support CTEs
- 23. // create temp table naughty_users // and get data from it with naughty_users as ( select * from users where banned = 1 ) select userid, email from naughty_users;
- 24. even more cool Writeable Common Table Expressions * Postgres 9.1+ only
- 25. multiple queries are required // create user record insert into users (name, email) values (?,?) returning userid // create address record insert into addresses (userid, address, city, state, zip) values (?,?,?,?,?) returning addressid // track changes to user information insert into user_history (userid, addressid, action) values (?,?,?) returning historyid
- 26. or are they? with userdata as ( insert into users (name, email) values (?,?) returning userid ), addressdata as ( insert into addresses (userid, address, city, state, zip) select userid,?,?,?,? from userdata returning addressid ), historydata as ( insert into user_history (userid, addressid, action) select userid, addressid,? from userdata, addressdata returning historyid ) select userid, addressid, historyid from userdata, addressdata, historydata;
- 27. why not use transactions? • no complicated transaction code • no complicated error handling code • reduced query overhead • better performance
- 28. find out more For more details: http://omniti.com/seeds/writable-ctes-improve-performance
- 29. ③ process query
- 30. unpopular opinion ORMs are evil
- 31. why? 1. machine-generated 2. object construction overhead 3. false sense of control
- 32. in one sentence you have no idea how it works
- 33. timely tweet
- 35. ④ send results
- 36. may be shocking, but … databases can do math
- 37. illustrating wrong // get all orders $sth = $dbh->prepare("select order_id, price from orders"); $sth->execute(); $orders= $sth->fetchAll(); //order by order_id usort($orders, function ($a, $b) { if ($a['order_id'] == $b['order_id']) { return 0; } return $a['order_id'] < $b['order_id'] ? -1 : 1; }); // get average $ for last 10 orders $count = 1; $total = 0; $avg = 0; foreach ($orders as $order) { $total += $order[‘price’]; if ($count == 10) { $avg = $total/$count; break 1; } $count++; }
- 38. vs right // get average $ for last 10 orders $sth = $dbh->prepare("select avg(price) as avg_price from (select price from orders order by order_id desc limit 10) "); $sth->execute(); $orders= $sth->fetchAll(); $avg = $orders[‘avg_price’];
- 40. other things to consider 1. cache is a wonderful thing 2. * is not your friend 3. EXPLAIN/ANALYZE are
- 41. Questions?