Spring Data YugaByteDB Example

Sample Spring application using Spring Data YugabyteDB YSQL project and Smart JDBC Driver - YugabyteDB Spring-data module.

Usage:

1. Install YugabyteDB

See full instructions here. For instance on macOS:

sudo ifconfig lo0 alias 127.0.0.2
sudo ifconfig lo0 alias 127.0.0.3
sudo ifconfig lo0 alias 127.0.0.4
sudo ifconfig lo0 alias 127.0.0.5
sudo ifconfig lo0 alias 127.0.0.6
sudo ifconfig lo0 alias 127.0.0.7
curl -O https://downloads.yugabyte.com/yugabyte-2.7.2.0-darwin.tar.gz
tar xvfz yugabyte-2.7.2.0-darwin.tar.gz && cd yugabyte-2.7.2.0/
./bin/yb-ctl --rf 3 create --tserver_flags="cql_nodelist_refresh_interval_secs=10" --master_flags="tserver_unresponsive_timeout_ms=10000"

This will create a 3-node local cluster with replication factor 3. The additional tserver and master flags lower some default flags to expedite demo steps below

notify the drivers of node changes at least every 10 seconds.
assume a node (tserver) is dead after it is unresponsive for 10 seconds or more.

2. Download and start this sample app

In another shell run

git clone https://github.com/yugabyte/spring-data-yugabytedb-example.git
cd spring-data-yugabytedb-example
./mvnw spring-boot:run

Spring App will connect to all the available nodes in the cluster.

Spring Boot application will connect to all the available servers in the YugabyteDB Cluster.

[source, text]
2021-08-06 22:28:20.864  INFO 35913 --- [nnection thread] org.postgresql.Driver                    : Getting the list of servers
2021-08-06 22:28:20.884  INFO 35913 --- [nnection thread] org.postgresql.Driver                    : List of servers got [127.0.0.3, 127.0.0.2, 127.0.0.1]

=== 3. Load Data

The `loaddb` endpoint will auto-generate and load customers into the customers table.

==== Examples

- Add `10` new customers (default amount).

http://localhost:8080/loaddb

- Add `100` new customers.

http://localhost:8080/loaddb?amount=100

NOTE: To inspect or modify the database with direct `SQL` commands you can just run `./bin/ysqlsh` from the Yugabyte
download folder to connect to the cluster.


=== 4. Show data

The `showdb` endpoint will show a paginated (page size `20`) view of the customers table.

==== Examples
- To show the first `20` rows

http://localhost:8080/showdb

- To show rows `61-80`

http://localhost:8080/showdb?page=3

=== 5. Add a node

In the first shell (in YugaByte folder) run

[source,sh]

/bin/yb-ctl add_node

In the other shell (sample app folder) you should see the Yugabyte module reporting it found the new node and initialize a connection pool to it.

NOTE: This might take a few seconds based on the flags set above.

You can use the app (load or show entries) _during_ these operations.

=== 6. Remove a node

In the first shell (in YugaByte folder) run

[source,sh]

/bin/yb-ctl remove_node 3

In the other shell (sample app folder) you should see the Yugabyte module reporting it discovered that a node is down and shutting down the connection pool for it.

NOTE: This might take a few seconds based on the flags set above.
In the meantime, atempting to use any already-open connections to the killed node will naturally throw errors.
Generally to handle (avoid) that you can use app-level retries that get a new connection (from one of the live nodes).

=== 7. Clean up.

Stop the Spring app by doing `Ctrl-C` in the respective shell.
To stop and erase all data of the Yugabyte cluster run

[source,sh]

/bin/yb-ctl destroy

NOTE: To just stop the cluster but keep that data run `./bin/yb-ctl stop`.
You can then start and reuse the cluster with `./bin/yb-ctl start`