How to specify ID greater than in the where clause?

Question

Just recently tried something like the following in the appengine interactive console:

from google.appengine.ext import db
from django.utils import simplejson

class TestDb(db.Model):
    author = db.StringProperty()

def add(name):
    t = TestDb()
    t.author = name
    t.put()
#added some names...
lst = db.GqlQuery("Select * from TestDb")

print [(x.key().id(), x.author) for x in lst]

I know for fact that ID is not sequential, but I assume it will be ascending in order for every new record that comes in.

Now I want to put a condition whose SQL would look something like:

SELECT * FROM TestDb WHERE ID > 2

Is this possible via GqlQuery()?

Have you tried doing that? You should have no problem testing this. — pydsigner, Nov 06 '12 at 18:56
Well, I really haven't used GQL, but if you can't use the query, you could add an if statement to the list comprehension without much of a performance hit. — pydsigner, Nov 06 '12 at 19:06

score 2 · Accepted Answer · answered Nov 06 '12 at 19:11

2

Automatically assigned IDs are not guaranteed to be sequential, so if you want to rely on ordering your entities you should either assign IDs yourself (which I wouldn't recommend), or sort by another property (perhaps a creation timestamp?)

With that said, you can filter by ID using the special __key__ property. See Key Filters.

answered Nov 06 '12 at 19:11

Dan Holevoet

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can you write this in the where clause...? – deostroll Nov 06 '12 at 19:31
Yes, I believe so: https://developers.google.com/appengine/docs/python/datastore/gqlreference – Dan Holevoet Nov 06 '12 at 19:32
the id needn't be sequential, but will the last record I "put" have a value greater than its corresponding value in the penultimate record entry...? – deostroll Nov 07 '12 at 03:31
The only way that could be is if the record IDs are sequential, so no. – Dan Holevoet Nov 07 '12 at 04:37
No, entities with smaller IDs may be created after entities with larger ones. @DanHolevoet 1 2 10 11 50 101 – Nick Johnson Nov 07 '12 at 10:26
@NickJohnson I didn't say otherwise. – Dan Holevoet Nov 07 '12 at 21:16
@DanHolevoet "1, 2, 10" is not sequential - but it still meets the requirement of each ID being greater than the ones that come before it. – Nick Johnson Nov 07 '12 at 21:20
@NickJohnson I was defining "sequential" as increasing (possibly non-consecutively). However, I guess that's only one possible interpretation of sequence (even if a common one). But we're arguing over semantics, the answer's still "No" regardless. – Dan Holevoet Nov 07 '12 at 21:39

How to specify ID greater than in the where clause?

1 Answers1