Datastore applied

[Phil McDonnell]

I'm in java on GWT app engine and I'm having some intermittent issues where it looks like datastore put() commands are not being reflected by subsequent get() calls.  From my reading I thought this was not possible.  Am I mistaken?

Here's what I'm doing...

// STATE A

Entity x = ...

datastore.put(x);

// STATE B

... 

x = ... some new values ... 

datastore.put(x);

// STATE C

... 

datastore.get(keyOfX);

The final get() sometimes returns an x of state C and sometimes it returns an x of state B.  Any idea why this happens?  I'm assuming it's some sort of concurrency thing within my app, but perhaps I've misunderstood the datastore guarantees?  Should the get() always get an x from state C?

Thanks,

Phil

[Jeff Schnitzer]

Are you executing in a transaction?  get()s in a transaction always show the entity "frozen in time" as of the start of the transaction.  Even if you put() a change, get() will show the old value until the transaction is committed.

Jeff

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[Phil McDonnell]

No, the puts/gets are executing normally.  I did try wrapping the puts() in a transaction, but it didn't help.  If I wrap just the get() in a transaction should that somehow trigger the puts() to apply?  Is there some way to wait?

Thanks so much,

Phil

[YuchTing]

check http://code.google.com/status/appengine for GAE current status.

Is GAE datastore abnomal?

[Phil McDonnell]

As it turns out, I was using a Query and not a get().  I believe Queries might not be guaranteed to return everything that has been put(), right?  That would explain the inconsistencies I've been seeing if this is the case.  Can someone confirm this?

Thanks,

Phil

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[Francois Masurel]

Try to use the same transaction for your gets, it will be ok then.

François

[Jeff Schnitzer]

Assuming you are on the HRD, that is correct.  Queries (without an ancestor() restriction) are always eventually consistent and may return stale data.

Jeff

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