Github user jhuynh1 commented on a diff in the pull request:

    https://github.com/apache/geode-examples/pull/3#discussion_r108541629
  
    --- Diff: partitioned/README.md ---
    @@ -0,0 +1,156 @@
    +<!--
    +Licensed to the Apache Software Foundation (ASF) under one or more
    +contributor license agreements.  See the NOTICE file distributed with
    +this work for additional information regarding copyright ownership.
    +The ASF licenses this file to You under the Apache License, Version 2.0
    +(the "License"); you may not use this file except in compliance with
    +the License.  You may obtain a copy of the License at
    +
    +     http://www.apache.org/licenses/LICENSE-2.0
    +
    +Unless required by applicable law or agreed to in writing, software
    +distributed under the License is distributed on an "AS IS" BASIS,
    +WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    +See the License for the specific language governing permissions and
    +limitations under the License.
    +-->
    +
    +# Geode partitioned region example
    +
    +This example demonstrates the basic property of partitioning.
    +The basic property of partitioning is that data entries are distributed 
    +across all servers that host a region.
    +The distribution is like database sharding, except that the distribution
    +occurs automatically. It is also similar to data striping on disks,
    +except that the distribution is not based on hardware.
    +
    +In this example,
    +two servers host a single partitioned region. 
    +There is no redundancy, so that the basic property of partitioning
    +may be observed.
    +The Producer code puts the 10 entries into the region.
    +The Consumer gets and prints the entries from the region.
    +Because the region is partitioned,
    +its entries are distributed among the two servers hosting the region.
    +Since there is no redundancy of the data within the region,
    +when one of the servers goes away,
    +the entries hosted within that server are also gone.
    +
    +## Demonstration of Partitioning
    +1. Set directory ```geode-examples/partitioned``` to be the
    +current working directory.
    +Each step in this example specifies paths relative to that directory.
    +
    +1. Build the jar (with the ```EmployeeKey``` and ```EmployeeData``` 
classes):
    +
    +    ```
    +    $   ../gradlew build
    +    ```
    +1. Run a script that starts a locator and two servers.
    +The built JAR will be placed onto the classpath when the script 
    +starts the servers:
    +
    +    ```
    +    $ scripts/startAll.sh
    +    ```
    +    Each of the servers hosts the partitioned region.
    +    
    +1. Run the producer to put 10 entries into the ```EmployeeRegion```.
    +
    +    ```
    +    $ ../gradlew run -Pmain=Producer
    +    ...
    +    ... 
    +    INFO: Inserted 10 entries in EmployeeRegion.
    +    ```
    +
    +1. There are several ways to see the contents of the region.
    +Run the consumer to get and print all 10 entries in the `EmployeeRegion`.
    +
    +    ```
    +    $ ../gradlew run -Pmain=Consumer
    +    ...
    +    INFO: 10 entries in EmployeeRegion on the server(s).
    +    ...
    +    ```
    +
    +    If desired, use a ```gfsh``` query to see contents of the region keys:
    +
    +    ```
    +    $ $GEODE_HOME/bin/gfsh
    +    ...
    +    gfsh>connect
    +    gfsh>query --query="select e.key from /EmployeeRegion.entries e"
    +    ...
    +    ```
    +
    +    Note that the quantity of entries may also be observed with `gfsh`:
    + 
    +    ```
    +    gfsh>describe region --name=EmployeeRegion
    +    ..........................................................
    +    Name            : EmployeeRegion
    +    Data Policy     : partition
    +    Hosting Members : server2
    +                      server1
    +
    +    Non-Default Attributes Shared By Hosting Members  
    +
    +     Type  |    Name     | Value
    +    ------ | ----------- | ---------
    +    Region | size        | 10
    +           | data-policy | PARTITION
    +    ```
    +
    +    As an alternative, `gfsh` maybe used to identify how many entries
    +    are in the region on each server by looking at statistics.
    +
    +    ```
    +    gfsh>show metrics --categories=partition --region=/EmployeeRegion 
--member=server1
    +    ```
    +
    +    Within the output, the result for `totalBucketSize` identifies
    +    the number of entries hosted on the specified server.
    +    Vary the command to see statistics for both `server1` and `server2`.
    +
    +1. The region entries are distributed across both servers.
    +Kill one of the servers:
    +
    +    ```
    +    $ $GEODE_HOME/bin/gfsh
    +    ...
    +    gfsh>connect
    +    gfsh>stop server --name=server1
    +    gfsh>quit
    +    ```
    +
    +1. Run the consumer a second time, and notice that approximately half of
    +the entries of the ```EmployeeRegion``` are still available on the 
    +remaining server.
    +Those hosted by the server that was stopped were lost.
    --- End diff --
    
    As someone who might not know Geode that well, it may alarm a user that 
their entries were "lost."  Do we really need to show them/explain this step?  
The next step is shutting down the entire cluster anyways?


---
If your project is set up for it, you can reply to this email and have your
reply appear on GitHub as well. If your project does not have this feature
enabled and wishes so, or if the feature is enabled but not working, please
contact infrastructure at infrastruct...@apache.org or file a JIRA ticket
with INFRA.
---

Reply via email to