README.md

php-murmur-hash

This is essentially the Percona murmur hash function ported/wrapped in a PHP extension that you can find here https://github.com/percona/build-test/blob/master/plugin/percona-udf/murmur_udf.cc

Mainly this exists so that you can get the exact same output in PHP as you do in MySQL with murmur_hash.

Installation

Clone this repo somewhere with the following and enter the new folder

git clone https://github.com/StirlingMarketingGroup/php-murmur-hash.git
cd php-murmur-hash

Then run the following commands to build the extension and install it

sudo apt install -y libmysqlclient-dev
phpize
CPPFLAGS="-fPIC -Wall -I/usr/include/mysql" ./configure --enable-murmur-hash
make
sudo make install

This should place the module into your PHP extensions directory (which you can find by running php-config --extension-dir).

Lastly, add extension=murmur_hash to the end of your php.ini file, which will be /etc/php/7.2/apache2/php.ini for PHP 7.2.

Note that this plugin doesn't function exactly the same as the MySQL version from Percona, and only accepts a single input, unlike the MySQL version which accepts infinite inputs. Only single-argument use will be the same.

Example output

In MySQL, the Percona extension is used like

select`murmur_hash`('Yeet')
-- -7850704420789372250

And in PHP

php -r 'echo murmur_hash("Yeet");'
// -7850704420789372250

Note that those are getting treated as signed integers for both environments, which you can solve in MySQL by using cast(`murmur_hash`('Yeet')as unsigned), but PHP doesn't support unsigned integers.

In MySQL, you can convert this integer to a binary string (conv in MySQL already treats it as unsigned, unless you give the "to base" a negative sign, like "-16")

unhex(conv(`murmur_hash`('Yeet'),10,16))
-- 0x930CB1EC9242BAA6

In PHP, you can get to the same output by using the pack function. The "J" option sepcifies "unsigned long long (always 64 bit, big endian byte order)", which is what I needed to use to get the same output, but for some reason if I used Q, or "unsigned long long (always 64 bit, machine byte order)", I get something different than MySQL, even if I do these things on the same machine as the MySQL server. (Maybe MySQL forces big endian onwith conv?)

echo bin2hex(pack("J",murmur_hash("Yeet")));
// 930cb1ec9242baa6