[google-appengine] Re: sort on _key_ out of order
On Sun, Apr 19, 2009 at 2:39 AM, David Wilson david.wil...@entertainmentcloud.com wrote: I wasnt using a datetime just to save a bit of space, but i can see i need to know to guarantee ordering, or if i want to do ordered paging via key i would need to handle key creation myself to make sure they are in order. Unless you are storing a truly huge number of entities (at least millions), I don't think the extra space should be an issue. The datastore is really geared towards you adding properties as needed for exactly this sort of thing. Dave. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Google App Engine group. To post to this group, send email to google-appengine@googlegroups.com To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~--~~~~--~~--~--~---
[google-appengine] Re: sort on _key_ out of order
Key isn't automatic plus 1 when you put a entity.Sometimes it will add 1000 (or some other value), and then back to the ordinary value. You can check the document about entity's id. 2009/4/18 David Wilson david.wil...@entertainmentcloud.com Hi, Our myspace application is now running live with an app engine back end, but im seeing a few out of order comment and event lists. I've tracked the issue to the fact were using a sort on _key_ to order the data by date, But new data being put into the datastore does not seem to be given id values that are larger then the data that is already in there (same Model). ie: ID:6143 Date:2009-04-18 04:53:16.961484 ID:10009 Date:2009-04-18 00:29:37.483112 Is this expected behaviour? and thus do i need to always give a key_name to guarantee order? this creates scaling issues for order counter (which is probably why its not in order in the backend :) ) Thanks David. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Google App Engine group. To post to this group, send email to google-appengine@googlegroups.com To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~--~~~~--~~--~--~---
[google-appengine] Re: sort on _key_ out of order
On Sat, Apr 18, 2009 at 3:21 PM, David Wilson david.wil...@entertainmentcloud.com wrote: Is this expected behaviour? and thus do i need to always give a key_name to guarantee order? this creates scaling issues for order counter (which is probably why its not in order in the backend :) ) Keys are only guaranteed to be unique, not sequential or in order: http://code.google.com/appengine/docs/python/datastore/keysandentitygroups.html#Paths_and_Key_Uniqueness What is wrong with giving your models a timestamp property (with auto_now_add=True), and sorting by that? Dave. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Google App Engine group. To post to this group, send email to google-appengine@googlegroups.com To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~--~~~~--~~--~--~---
[google-appengine] Re: sort on _key_ out of order
thanks! i missed that in the docs :) I wasnt using a datetime just to save a bit of space, but i can see i need to know to guarantee ordering, or if i want to do ordered paging via key i would need to handle key creation myself to make sure they are in order. This becomes harder in one case for me as users can create designs that need to be paged through in creation order. There will be too much contention on a glodal counter for this, so i guess an offset page on date is the best i can do for now. Or just not worry when some 'new designs' are out of order. On Apr 18, 2:20 am, David Symonds dsymo...@gmail.com wrote: On Sat, Apr 18, 2009 at 3:21 PM, David Wilson david.wil...@entertainmentcloud.com wrote: Is this expected behaviour? and thus do i need to always give a key_name to guarantee order? this creates scaling issues for order counter (which is probably why its not in order in the backend :) ) Keys are only guaranteed to be unique, not sequential or in order: http://code.google.com/appengine/docs/python/datastore/keysandentityg... What is wrong with giving your models a timestamp property (with auto_now_add=True), and sorting by that? Dave. --~--~-~--~~~---~--~~ You received this message because you are subscribed to the Google Groups Google App Engine group. To post to this group, send email to google-appengine@googlegroups.com To unsubscribe from this group, send email to google-appengine+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/google-appengine?hl=en -~--~~~~--~~--~--~---
[google-appengine] Re: sort on _key_ out of order
I use this code to keep an id:
class M(db.Model):
id = db.IntegerProperty()
time = db.DateTimeProperty(auto_now_add=True)
@staticmethod
def max_id():
maxID = memcache.get('MaxID')
if maxID:
return maxID
messages = Message.all()
messages.order(-id)
message = messages.get()
if message:
return message.id
else:
return 0
entity = M()
entity.id = M.maxID + 1
entity.put()
2009/4/19 David Wilson david.wil...@entertainmentcloud.com
thanks! i missed that in the docs :)
I wasnt using a datetime just to save a bit of space, but i can see i
need to know to guarantee ordering, or if i want to do ordered paging
via key i would need to handle key creation myself to make sure they
are in order.
This becomes harder in one case for me as users can create designs
that need to be paged through in creation order. There will be too
much contention on a glodal counter for this, so i guess an offset
page on date is the best i can do for now. Or just not worry when some
'new designs' are out of order.
On Apr 18, 2:20 am, David Symonds dsymo...@gmail.com wrote:
On Sat, Apr 18, 2009 at 3:21 PM, David Wilson
david.wil...@entertainmentcloud.com wrote:
Is this expected behaviour? and thus do i need to always give a
key_name to guarantee order? this creates scaling issues for order
counter (which is probably why its not in order in the backend :) )
Keys are only guaranteed to be unique, not sequential or in order:
http://code.google.com/appengine/docs/python/datastore/keysandentityg.
..
What is wrong with giving your models a timestamp property (with
auto_now_add=True), and sorting by that?
Dave.
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[google-appengine] Re: sort on _key_ out of order
If two requests want to create an M() they will get the same ID.
You must use some kind of transaction to get unique IDs
2009/4/18 风笑雪 kea...@gmail.com:
I use this code to keep an id:
class M(db.Model):
id = db.IntegerProperty()
time = db.DateTimeProperty(auto_now_add=True)
@staticmethod
def max_id():
maxID = memcache.get('MaxID')
if maxID:
return maxID
messages = Message.all()
messages.order(-id)
message = messages.get()
if message:
return message.id
else:
return 0
entity = M()
entity.id = M.maxID + 1
entity.put()
2009/4/19 David Wilson david.wil...@entertainmentcloud.com
thanks! i missed that in the docs :)
I wasnt using a datetime just to save a bit of space, but i can see i
need to know to guarantee ordering, or if i want to do ordered paging
via key i would need to handle key creation myself to make sure they
are in order.
This becomes harder in one case for me as users can create designs
that need to be paged through in creation order. There will be too
much contention on a glodal counter for this, so i guess an offset
page on date is the best i can do for now. Or just not worry when some
'new designs' are out of order.
On Apr 18, 2:20 am, David Symonds dsymo...@gmail.com wrote:
On Sat, Apr 18, 2009 at 3:21 PM, David Wilson
david.wil...@entertainmentcloud.com wrote:
Is this expected behaviour? and thus do i need to always give a
key_name to guarantee order? this creates scaling issues for order
counter (which is probably why its not in order in the backend :) )
Keys are only guaranteed to be unique, not sequential or in order:
http://code.google.com/appengine/docs/python/datastore/keysandentityg...
What is wrong with giving your models a timestamp property (with
auto_now_add=True), and sorting by that?
Dave.
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[google-appengine] Re: sort on _key_ out of order
Well, but I don't care it, my application allows the same ID, I just need it
for sorting, and it's harder to sort by time when the browser do an AJAX
get. Some times I need handle the timezone difference between server
and browser.
If you want keep a unique ID, the best way is set its key_name, and try
again if put failed.
2009/4/19 djidjadji djidja...@gmail.com
If two requests want to create an M() they will get the same ID.
You must use some kind of transaction to get unique IDs
2009/4/18 风笑雪 kea...@gmail.com:
I use this code to keep an id:
class M(db.Model):
id = db.IntegerProperty()
time = db.DateTimeProperty(auto_now_add=True)
@staticmethod
def max_id():
maxID = memcache.get('MaxID')
if maxID:
return maxID
messages = Message.all()
messages.order(-id)
message = messages.get()
if message:
return message.id
else:
return 0
entity = M()
entity.id = M.maxID + 1
entity.put()
2009/4/19 David Wilson david.wil...@entertainmentcloud.com
thanks! i missed that in the docs :)
I wasnt using a datetime just to save a bit of space, but i can see i
need to know to guarantee ordering, or if i want to do ordered paging
via key i would need to handle key creation myself to make sure they
are in order.
This becomes harder in one case for me as users can create designs
that need to be paged through in creation order. There will be too
much contention on a glodal counter for this, so i guess an offset
page on date is the best i can do for now. Or just not worry when some
'new designs' are out of order.
On Apr 18, 2:20 am, David Symonds dsymo...@gmail.com wrote:
On Sat, Apr 18, 2009 at 3:21 PM, David Wilson
david.wil...@entertainmentcloud.com wrote:
Is this expected behaviour? and thus do i need to always give a
key_name to guarantee order? this creates scaling issues for order
counter (which is probably why its not in order in the backend :) )
Keys are only guaranteed to be unique, not sequential or in order:
http://code.google.com/appengine/docs/python/datastore/keysandentityg...
What is wrong with giving your models a timestamp property (with
auto_now_add=True), and sorting by that?
Dave.
--~--~-~--~~~---~--~~
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