zstan commented on code in PR #13114:
URL: https://github.com/apache/ignite/pull/13114#discussion_r3225832862
##########
docs/_docs/distributed-computing/distributed-computing.adoc:
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@@ -305,60 +305,27 @@ If you want to use the key and value objects inside
`IgniteCallable` and `Ignite
====
-////////////////////////////////////////////////////////////////////////////////
-
-
-
-In the cases where you do not need to colocate computations with data but
simply want to process all data remotely, you can run local cache queries
inside the `call()` method. Consider the following example.
-
-Let's say we have a cache that stores information about persons and we want to
calculate the average age of all persons. One way to accomplish this is to run
a link:key-value-api/using-cache-queries[scan query] that will fetch the ages
of all persons to the local node, where you can calculate the average age.
-
-A more efficient way, however, is to avoid network calls to other nodes by
running the query locally on each remote node and aggregating the result on the
local node.
-
-This task can be easily split
-
-[source, java]
--------------------------------------------------------------------------------
-private class AverageAgeJob implements IgniteCallable<Double> {
-
- @IgniteInstanceResource
- private Ignite ignite;
-
- @Override
- public Double call() throws Exception {
-
- IgniteCache<Long, Person> cache = ignite.cache("person");
-
- int localAvg = 0;
- try (QueryCursor<Cache.Entry<Long, Person>> cursor = cache
- .query(new ScanQuery<Long, Person>().setLocal(true))) {
- for (Cache.Entry<Long, Person> entry : cursor) {
- localAvg += (int) entry.getValue().getAge();
- }
- }
-
- return (localAvg / (double) cache.size());
- }
-}
-
--------------------------------------------------------------------------------
-Note that the scan query is executed in the local mode. It means that it will
only fetch objects from the Person cache that are stored localy and will not
request data from other nodes.
+=== Processing Cache Data Locally
-If you broadcast this task to all nodes, all person objecs will be processed
(each locally), and the results are sent to the node that initiated the task.
-
-[source, java]
--------------------------------------------------------------------------------
-Ignite ignite = Ignition.ignite();
-
-double average = ignite.compute().broadcast(new
AverageAgeTask()).stream().reduce(0D, (a, b) -> a + b);
--------------------------------------------------------------------------------
-
-
-The task is executed on every node, where it will query all persons stored
locally and calculate the local average. Then the result are sent to the node
that initiated the task and summed up. In this implementation, objects are not
transferred via network.
+If you need to process all cache data remotely, you can broadcast a task to
the data nodes and run a local cache query inside the task.
+In this mode, each node scans only the cache entries stored locally, processes
them there, and returns only the aggregated result to the caller.
+For example, assume that a cache stores `Person` objects and you need to
calculate the average age of all persons.
Review Comment:
nitpicking - seems it more clear to use 3-rd face form, like :
For example, assume that a cache stores Person objects and it is necessary
to calculate the average age of all persons.
Or
For example, assume that a cache stores Person objects and one needs to
calculate the average age of all persons.
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