Hi Garrett,
Sorry, for the delay. Below you can find my comments ...
The count would be determined by executing the following query (would return
> 10 in the above example):
> data(doc("COUNTER")/COUNTER)
>
> The count would be incrementd by 5 with the following query:
> UPDATE REPLACE $x in doc("COUNTER")/COUNTER/COUNT with
> <COUNT>{$x+5}</COUNT>
>
> Then starting at 11 till 15, Elements would be added in with the following
> query (with x replaced by number)
> UPDATE insert(<ELENMENTx id='x'></ELEMENTx>) into doc("doc")//
>
> Is there a way to ensure that between the read of the COUNT value, and the
> UPDATE of the COUNT value, that no other client reads or writes to the COUNT
> value?
>
To prevent counter read between the first and second statements you just
need to swap them - first you update counter (and ensure exclusive locking
on doc('counter')), then you read the value (since delta is known it's easy
to get initial value):
(:begin transaction:)
UPDATE REPLACE $x in doc("COUNTER")/COUNTER/COUNT with <COUNT>{$x+5}</COUNT>
data(doc("COUNTER")/COUNTER) - 5
(:end transaction:)
Note, don't forget that at least first two statement must be within one
transaction.
BTW, try also to replace text() node instead of the whole <count>, something
like this should work (let me know if it doesn't :) ):
UPDATE REPLACE $x in doc("COUNTER")/COUNTER/COUNT/text() with string($x+5)
Ivan Shcheklein,
Sedna Team
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