如何从Python CouchDB使用Iterview函数

Question

I have been working with couchdb module in python to meet some projects needs. I was happily using view method from couchdb to retrieve result sets from my database until recently.

for row in db.view(mapping_function):
    print row.key

However lately I have been needing to work with databases a lot bigger in size than before (~ 15-20 Gb). This is when I ran into an unfortunate issue.

db.view() method loads all rows in memory before you can do anything with it. This is not an issue with small databases but a big problem with large databases.

That is when I came across iterview function. This looks promising but I couldn't find a example usage of it. Can someone share or point me to example usage of iteview function in python-couchdb

Thanks - A

Answer 1

Doing this is almost working for me:

import couchdb.client
server = couchdb.client.Server()
db = server['db_name']
for row in db.iterview('my_view', 10, group=True):
    print row.key + ': ' + row.value

I say it almost works because it does return all of the data and all the rows are printed. However, at the end of the batch, it throws a KeyError exception inside couchdb/client.py (line 884) in iterview

Answer 2

This worked for me. You need to add include_docs=True to the iterview call, and then you will get a doc attribute on each row which can be passed to the database delete method:

import couchdb
server = couchdb.Server("http://127.0.0.1:5984")
db = server['your_view']
for row in db.iterview('your_view/your_view', 10, include_docs=True):
    # print(type(row))
    # print(type(row.doc))
    # print(dir(row))
    # print(row.id)
    # print(row.keys())
    db.delete(row.doc)