问题描述:
上周有个需求，把mongodb中birthday (ISO日期格式) 转换成北京时间，并保存成string类型。
最初思路：
遍历查找出的结果，逐个加8小时，然后通过_id逐个去update_one。但是发现这种方式效率太低了，一分钟才能更新一千五百条数据。
# -*- coding: utf-8 -*-
from pymongo import MongoClient
import time
import datetime def init():
myclient = MongoClient(host='*.*.*.*', port=27117)
# admin为登陆校验库
auth_db = myclient.admin
auth_db.authenticate('admin', '')
# 连接库
mydb = myclient['SR_123']
mycol = mydb['Data_170724145755025001_0305_copy4']
print(time.time())
count = 0
# 只取有birthday的数据，且只返回_id和birthday
for x in mycol.find({'birthday':{'$exists': True}},{'_id','birthday'}):
count = count + 1
print(count)
_time = x.get('birthday')
_time += datetime.timedelta(hours=8)
timeStr = _time.strftime("%Y%m%d")
_id = x.get('_id')
query1 = {"_id": _id}
newvalues = {"$set": {"birthdayStr": timeStr}}
mycol.update_one(query1, newvalues)
print(time.time()) init()
新的思路：
通过birthday去重，然后通过birthday去update_many。
for x in mycol.find().distinct('birthday'):
_time1 = x + datetime.timedelta(hours=8)
timeStr = _time1.strftime("%Y%m%d")
query1 = {"birthday": x}
newvalues = {"$set": {"birthdayStr": timeStr}}
mycol.update_many(query1, newvalues)
最终思路:
利用mongodb 的批量操作bulk_write，并且控制每次批量的数量，避免拼接过长报错。最终发现这种方式，当数据多的时候，效率远比上面两种方式快。
# -*- coding: utf-8 -*-
from pymongo import MongoClient
from pymongo import UpdateOne
import time
import datetime def init():
myclient = MongoClient(host='*.*.*.*', port=27117)
# admin为登陆校验库
auth_db = myclient.admin
auth_db.authenticate('admin', '1234')
# 连接库
mydb = myclient['SR_123']
mycol = mydb['Data_170724145755025001_0305_copy4']
print(time.time())
testList = []
i = 0
aa=mycol.find({'birthday': {'$exists': True}},{'_id','birthday'})
for x in aa:
i = i + 1;
_time = x.get('birthday')
_time += datetime.timedelta(hours=8)
try:
timeStr = _time.strftime("%Y%m%d")
except:
print(x)
_id = x.get('_id')
query1 = {"_id": _id}
newvalues = {"$set": {"birthdayStr": r''+timeStr}}
op = UpdateOne(query1, newvalues, upsert=True)
testList.append(op)
if( i % 50 == 0):
print(i)
mycol.bulk_write(testList, ordered=False, bypass_document_validation=True)
testList.clear() init()