django mysqldb 启用mysql compress压缩,为数据库瘦身
可以明显的看到对于文本压缩还是有必要的,将近5倍的压缩！
mysql也提供了compress和uncompress函数,django已经有集成的数据库api,懒得自己写原声mysql了,就找到下面这个比较懒的办法,也并不是太完美,应为采用了cStringIO库，把内存作为中转 ,如果访问量低于每天一万的话,还凑合可以使用！
修改django models.py 添加如下代码：
from django.db import models
from django.utils.text import compress_string
from django.db.models.signals import post_init
def uncompress_string(s):
'''helper function to reverse django.utils.text.compress_string'''
import cStringIO, gzip
try:
zbuf = cStringIO.StringIO(s)
zfile = gzip.GzipFile(fileobj=zbuf)
ret = zfile.read()
zfile.close()
except:
ret = s
return ret
class CompressedTextField(models.TextField):
'''transparently compress data before hitting the db and uncompress after fetching'''
def get_db_prep_save(self, value):
if value is not None:
value = compress_string(value)
return models.TextField.get_db_prep_save(self, value)
def _get_val_from_obj(self, obj):
if obj:
return uncompress_string(getattr(obj, self.attname))
else:
return self.get_default()
def post_init(self, instance=None, **kwargs):
value = self._get_val_from_obj(instance)
if value:
setattr(instance, self.attname, value)
def contribute_to_class(self, cls, name):
super(CompressedTextField, self).contribute_to_class(cls, name)
post_init.connect(self.post_init, sender=cls)
def get_internal_type(self):
return "TextField"
def db_type(self):
from django.conf import settings
db_types = {'mysql':'longblob','sqlite3':'blob'}
try:
return db_types[settings.DATABASE_ENGINE]
except KeyError:
raise Exception, '%s currently works only with: %s'%(self.__class__.__name__,','.join(db_types.keys()))
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祝君好运！
