Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
650 views
in Technique[技术] by (71.8m points)

php - Support server side prepared statements with PDO?

Given something like

DB()->prepare("SELECT * FROM mysql.general_log WHERE user_host LIKE ?");

$statement->execute( array('%console%') );

foreach($statement as $record){
    var_dump($record);
}

Contents of general_log is

*************************** 1. row ***************************
event_time: 2011-04-20 14:27:59
user_host: REDACTED[REDACTED] @ REDACTED [192.168.56.101]
thread_id: 30
server_id: 0
command_type: Connect
argument: REDACTED@REDACTED on REDACTED
*************************** 2. row ***************************
event_time: 2011-04-20 14:27:59
user_host: REDACTED[REDACTED] @ REDACTED [192.168.56.101]
thread_id: 30
server_id: 0
command_type: Query
argument: SELECT * FROM mysql.general_log WHERE user_host LIKE '%console%'

I'm working inside of an abomination framework ( no unit-tests, no documentation, no ryhme or reason ) so is it possible that somewhere someone explicitly disabled MySQL prepared statements forcing PDO to use emulated mode... or is this expected behavior?

PHP is PHP Version 5.2.10-2ubuntu6 PDO Driver for MySQL, client library version 5.1.41

Update: PDO() is constructed with the the following attributes

PDO::ATTR_PERSISTENT => false
PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION
PDO::MYSQL_ATTR_USE_BUFFERED_QUERY => true

I went through the PDO documentation, but unfortunately there doesn't seem to be mention of a flag like the one written about in this similar question

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

Some PDO drivers don't support native prepared statements, so PDO performs emulation of the prepare. It also lets you manually enable this emulation.

Check the PDO::ATTR_EMULATE_PREPARES attribute. It's poorly documented in the current PDO manual. By poorly documented, I mean that it appears only in comments on the site, not in the manual itself.

Generally you want to use native prepared statements whenever possible. In the case of MySQL, if you are taking advantage of the query cache, you might actually want to disable native prepared statements in PDO! The MySQL manual has more information, but the short version is that versions prior to 5.1.17 don't run prepared statements through the query cache, and subsequent versions only use the query cache under certain specific (but common) conditions.

(Some people recommend turning off the query cache entirely. Using large cache sizes can actually be a major performance hit.)


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...