I can think of three ways:
1) Iterate over the query results and delete each without the transaction.
2) Make a separate transaction for every group of 5 keys.
3) Use the MapReduce library and a MapOnlyMapper to walk all the keys.
On Monday, February 15, 2016 at 10:23:50 AM UTC-6, Louise Elmose Hedegaard
wrote:
>
> I have a datastore with a kind "shop", a kind "order" and a kind
> "transaction".
> One shop has many orders, and one order has many transactions.
> The parent of a transaction is an order, the parent of an order is a shop.
>
> I want to delete all entries in the transactions table:
>
> public void cleanUp() {
> Query query = new
> Query(TransactionDBFields.TRANSACTION_TABLE_NAME);
> query.setKeysOnly();
> query.setFilter(
> new Query.FilterPredicate(
> TransactionDBFields.CREATED_AT,
> Query.FilterOperator.LESS_THAN_OR_EQUAL,
> new Date())
> );
>
> PreparedQuery preparedQuery = datastore.prepare(query);
> Iterable<Entity> entities =
> preparedQuery.asIterable(FetchOptions.Builder.withLimit(5));
>
> TransactionOptions options =
> TransactionOptions.Builder.withXG(true);
> Transaction txn = datastore.beginTransaction(options);
> for (Entity en : entities) {
> datastore.delete(txn, en.getKey());
> }
> txn.commit();
> }
>
> If I change the limit to anything larger than 5 I get the error:
>
> java.lang.IllegalArgumentException: operating on too many entity groups in
> a single transaction.
>
> - apparently as GAE does not allow operating on more than 5 entity groups
> in a single transaction.
>
> Is there a way to delete more than 5 entities at a time? executing the
> above code continuously to delete all transaction entities does not seem
> reasonable, nor when considering performance.
>
> -Louise
>
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