Maybe you need to re-think your database models. This message may
help:
http://groups.google.com/group/google-appengine/browse_thread/thread/52d44bde94f2e8b8?pli=1
On 9 ene, 17:57, nischalshetty wrote:
> Say a user selects 5000 unread messages (each message is an entity)
> and wants to mark all
That is a good link Ernesto.
nischalshetty - I think the best answer is probably an "it depends"
kind of thing. What do you want to do with unread status? Of course
the key here is that unread is a per user deal. You might be able to
keep some kind of bit-map or other compressed data structure to
@Ernesto Thanks for the link, that's a good starting point.
@Jay Thanks for some more pointers.
Simply put here's what I want to do (a twitter app):
1. Pull all the tweets of a user
2. The user can selectively read tweets (which would be marked as 'Read')
3. Unread tweets would be well 'Unread
One option is to use a date time stamp when they mark all as read. If
you allow people to mark items as unread then you in addition need
have a way to detect that on old items. For example if you were to
use '0' for unread and '1' for read you could use '2' to override the
the all read after time.
You guys are all awesome. My friend and I are soon going to finalize a
way and I'll post it here. Your feedback would be greatly appreciated.
-N
On Jan 10, 10:20 pm, master outside wrote:
> One option is to use a date time stamp when they mark all as read. If
> you allow people to mark items as
You can save a date for the user on when the last mark all read date
was set. Then consider anything before that date as read by that
user. That way you only have to update a single entity.
On Jan 9, 8:57 am, nischalshetty wrote:
> Say a user selects 5000 unread messages (each message is an ent
@David
That sounds good but it would probably fail if the user marks one of the
messages in between as 'unread' :(
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This one year old thread discusses the same problem I think:
http://groups.google.com/group/google-appengine/browse_thread/thread/b35a0387dfdf918b/55563f57306defbc?lnk=gst&q=mark+as+read#55563f57306defbc
A possible solution:
class Message(db.Model):
sender=db.StringProperty()
body=db.TextProp
@Jay
As you have mentioned in the post about "bit-map or other compressed data
structure to hold read/unread info". Can you give an example for it or else
any link which provides implementation for bit-map thing.
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"Goo
@Sameer
A bit-map for holding the "list" of read/unread is a pretty common and
widely used pattern.
http://en.wikipedia.org/wiki/Bit_array
Also see data structure and algorithm books.
You can think of the bitmap as a compact list of all read/unread
assuming that the entries can be encoded with a k
@Jay
Thanks for your reply. This is really helpful to me to solve my problem. I
was quite aware of how the bit map works and all. But not able to co-relate
my problem to this. Thanks again.
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Here are some quick statistics I did using the idea that you have a entity
which consists solely of a key and no other properties. I called this entity
kind 'READ'. If a tweet has a matching key in this entity then the tweet has
been read. If it doesn't exist then the tweet is unread. I did a batch
@Stephen Wow! I'm grateful to you for taking time out to make things so
clear. From what I see, you're suggesting to have a different key that when
present indicates a tweet as 'Read'.
You're right, there would be pagination so I'll be displaying say 50 tweets
per page. Now, I would fetch 50 tw
It sholdn't be cumbersome at all. Use the same key identifier for the tweets
as for the Read entity, then do a batch get with those keys. Based on my
numbers I'd say latency for 50 keys will be from 10ms to 20ms. You'll get
back a Map (if using Java - not sure for Python). If they key is in the map
My bad. I forgot to mention, there would be an option where I show just the
'unread' tweets to the user or just the 'read' tweets. When I show all
tweets, your example would work perfectly fine. But what about the other two
scenarios? Any pointers would help. I use GAE/J.
-N
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You received t
I don't know if the requirement are the same but here's something I came up
with that might be of use to you as well.
If I need to mark a group of entities as having some common trait (the trait
could be read or unread in your case) in response to an action the user has
taken upon a group of entie
Ok. A trick I use is to use the key field to hold more than one piece of
data so that I can get around some of the limitations of queries as well as
get back info doing keys only queries and keeping down the number of the
custom keys I have, so you could do something like the following: I suppose
e
Nick Johnson's newsgroup e-mail explains pretty much what you need.. except
he leaves out some details (don't know, maybe he was busy building out the
Appengine subsystem at the time or something) explaining exactly how to set
it up underneath.
You should probably try something like this (which I
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