Question

Such as to obtain a post before an after a record time field created

Try to use the following statement to obtain articles

# Created is the time of the creation of the current article
# Before a
prev_post = db.Post.find ({'created': {'$ lt': created}}, sort = [('created', -1)], limit = 1)
# After a
next_post = db.Post.find ({'created': {'$ gt': created}}, sort = [('created', 1)], limit = 1)

The result turn to be discontinuous,sometimes skip several records.I don’t know why,maybe I misunderstand the FIND?
Help please.

Answer 1

It may seem a strange behaviour indeed, but MongoDB does not guarantee you the order of stored records, unless you’re querying an array (in which records are kept in the insertion order). I believe what MongoDB does – it reaches the first document that matches your query and returns it.
Bottomline: if the logic requires neighbour records, use arrays.