MongoDB地图/减少升高例外:失败:DB断言失败
题
我创建了映射/减少对组件的函数结果,结果一个结果对象。我在Python上写了Pymongo库:
m = Code("""function() {
data = {};
res = ''
if(this.result_id) {
res={'objectid':this.result_id.toString()};
} else {
res=this.result;
}
emit(this.data, res);
}""")
r = Code("""function(k,values) {
data={};
for(var i=0; i<values.length; i++ ) {
for(attr in values[i])
data[attr]=values[i][attr];
}
return data
}""")
我需要该结果对象的顺序与输入任务查询相同。但是,当我在请求中使用sort param时:
res = db.tasks.map_reduce(m, r, query={'job_id':job_id},sort={'position':pymongo.ASCENDING})
但这在MongoDB中提高了例外:
Traceback (most recent call last):
File "/usr/local/lib/python2.6/dist-packages/gevent/greenlet.py", line 403, in run
result = self._run(*self.args, **self.kwargs)
File "/data/www/public/app/seotools/daemon/scripts/mainconverter.py", line 129, in work
res = autoreconnect(self.db.tasks.map_reduce,m, r, query={'job_id':job_id},sort={'position':1})
File "/data/www/public/app/seotools/daemon/lib/db/mongo.py", line 95, in autoreconnect
result = func(*args,**kwargs)
File "/usr/local/lib/python2.6/dist-packages/pymongo-1.8.1-py2.6-linux-x86_64.egg/pymongo/collection.py", line 945, in map_reduce
map=map, reduce=reduce, **kwargs)
File "/usr/local/lib/python2.6/dist-packages/pymongo-1.8.1-py2.6-linux-x86_64.egg/pymongo/database.py", line 294, in command
(command, result["errmsg"]))
OperationFailure: command SON([('mapreduce', u'tasks'), ('sort', {'position': 1}), ('query', {'job_id': ObjectId('4d0b30909c7684b60e000000')}), ('reduce', Code('function(k,values) {
data={};
for(var i=0; i<values.length; i++ ) {
for(attr in values[i])
data[attr]=values[i][attr];
}
return data
}', {})), ('map', Code("function() {
data = {};
res = ''
if(this.result_id) {
res={'objectid':this.result_id.toString()};
} else {
res=this.result;
}
emit(this.data, res);
}", {}))]) failed: db assertion failure
当我使用相同的查询而无需排序参数时:
res = db.tasks.map_reduce(m, r, query={'job_id':job_id})
工作很好。
在哪里有问题?
解决方案
我发现我的问题。正如一位开发人员所说,没有索引,我们将无法使用分类。因此,如果使用排序,首先必须为该排序创建索引。
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