Actually, even just fetching one entity by key will frequently cause a
Timeout. My logs are full of these...
On Apr 30, 2:59 pm, Sylvain <sylvain.viv...@gmail.com> wrote:
> For my app, I never fetch more than 250 entities because I've seen
> that if this values is bigger you raise too many datastore timeouts.
> But even with 250 entities (with a very basic Kind) something I get atimeout.
>
> One "funny" thing is that you can fetch up to 1000 entities (whatever
> kind, number of attributes,...) but in the fact it doesn't work ->timeout.
>
> On 30 avr, 17:45, barabaka <oleg.g...@gmail.com> wrote:
>
> > Well, I've read a lot of posts about google datastore and the problems
> > with batch operations, relational approach to arrange data in bigtable
> > etc. but I always thought the problem wasn't in datastore itself but
> > in the way people use it. Now I can see with my experience that it
> > acts just in an unpredictable way. I deployed a test java app that
> > tries to clear 500 (guaranteed amount!) entries per request. All
> > entries are in the same entity group and delete is executed in batch
> > in single transaction. All operations are executed with low level API
> > so no possible overhead is involved. Here is a sample code and logs:
>
> > Code (cut):
> > =============
> > Query q = new Query(World.class.getSimpleName()); // create query
> > Iterator<Entity> i = datastoreService.prepare(q).asIterator();
> > idx = 0;
> > while (i.hasNext() && idx<500) {
> > keys.add(i.next().getKey());
> > idx++;
>
> > }
>
> > // delete keys in batch
> > Transaction t = datastoreService.beginTransaction();
> > datastoreService.delete(keys);
> > t.commit();
> > ==============
>
> > 1st request (all goes well, 500 entries removed)
> > -------------------------------------------------
> > 1.
> > I 04-30 07:52AM 02.091 org.itvn.controller.TvnController
> > clearDbBySize: Reading 500 entity keys...
> > See details
> > 2.
> > I 04-30 07:52AM 03.832 org.itvn.controller.TvnController
> > clearDbBySize: Removing keys by groups, total groups: 1
> > 3.
> > I 04-30 07:52AM 03.832 org.itvn.controller.TvnController
> > clearDbBySize: Trying to remove 500 entities...
> > 4.
> > I 04-30 07:52AM 07.873 org.itvn.controller.TvnController
> > clearDbBySize: Removed 500 entities.
>
> > 2nd request -timeoutexception, on READ operation (i.hasNext())
> > -------------------------------------------------
> > 1.
> > I 04-30 07:52AM 22.719 org.itvn.controller.TvnController
> > clearDbBySize: Reading 500 entity keys...
> > See details
> > 2.
> > W 04-30 07:52AM 26.551 Nested in
> > org.springframework.web.util.NestedServletException: Request
> > processing failed; nested exception is
> > com.google.appengine.api.datastore.Datas
> > 3.
> > W 04-30 07:52AM 26.552 /clear_db/500
> > com.google.appengine.api.datastore.DatastoreTimeoutException:
> > datastoretimeout: operation took too long. at
> > com.google.appengine.api.d
> > 4.
> > C 04-30 07:52AM 26.555 Uncaught exception from servlet
> > com.google.appengine.api.datastore.DatastoreTimeoutException:
> > datastoretimeout: operation took too long. at com.goog
>
> > Here we go, first request executes well, and the next (only a few
> > seconds later) fails! Note that this is only a test application, with
> > no load at all. Am I doing something wrong? What's the RELIABLE way to
> > read/remove 500 entities? Is it a problem with quantity (500)? If so
> > how much entities could be read withouttimeout? Can someone give the
> > reasonable answer to this? If you need more details about app, I can
> > share this test case in public.
>
> > Oleg
>
>
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