Tech Talk - Persistence with Spring Data

©2022 VMware, Inc.
Persistence with
Spring Data
what it is and what comes next
Christoph Strobl (he/him)
Staff Engineer
March 2022

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©2022 VMware, Inc. 2
MongoDB
Redis
Elasticsearch
Cassandra
MariaDB
DynamoDB
Neo4j
Couchbase
CouchDB
Greenplum
Hazelcast
H2
SQL Server
Oracle
Db2
Areospike
OrientDB
MySQL
PostgreSQL
©2022 VMware, Inc.

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SELECT e FROM employee e WHERE e.firstName = :name
JPA
create().select().from(EMPLOYEE)
.where(EMPLOYEE.FIRST_NAME).eq(name)
.fetch()
JOOQ
db.employee.find({ first_name : name })
NoSQL
SELECT * FROM employee WHERE first_name = %1
SQL
MATCH (n:Employee) WHERE n.firstName = ’...’
query: { match: { first_name: '...' } }

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List findByFirstName(String name)
Spring Data
JPA
JDBC
Redis
Neo4j
R2DBC
MongoDB
ArangoDB
Couchbase
Cosmos DB
yugabyteDB
Elasticsearch
Apache Geode
Apache Cassandra
...

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No Magic

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Anatomy
Entity Manager
Database Driver
Template API
Mapping
Conversion
Resource & Transaction
Management
native store format <> domain type
eg. enum -> string
Default Implementation
Repository Interface

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Template APIs
class MongoTemplate implements MongoOperations {
List find(Query query, Class entityClass)
List findAndRemove(Query query, Class entityClass)
T execute(Class> entityClass, CollectionCallback callback)
query(where(“firstName”).is(...))
template.execute(Employee.class, collection -> {
return collection.find(new Document("firstname", "..."))
.into(new ArrayList());
});
Access to native
driver commands

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Repositories
interface Repo extends ...{ Repository
CrudRepository
findAll();
findById(...)
count();
save(...);
delete(...);
...
PagingAndSorting
Repository
findAll(Page);
findAll(Sort);
Proxy
Default Implementation
Store Specific
List findAll();
long count();
Predefined methods
List findByFirstName(String name);
Derived Finder Method

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Derived Find Queries
List findEmployeeByFirstNameLikeOrderByAgeAsc(String name)
read
get
query
search
stream
Placeholder For Anything You Like
matches
contains
lessThan
startsWith
greaterThan
isEmpty
isNull
isNotNull
before
after
...
Match Operator
Sort Direction
Delimiter
Employee
Page
Slice
Stream

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Derived Count | Exists | Delete Queries
int countEmployeeByFirstNameLike(String name)
boolean existsEmployeeByFirstNameLike(String name)
Some Stores Need a Little Help
@Modifying
List deleteEmployeeByFirstNameLike(String name)
remove
void
long
Interested in the
Operation Result?

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Data Projections
Closed Interface Projection
interface View2 {
String getFirstName();
String getLastName();
}
class View1 {
String firstName;
String lastName;
}
DTO Projection
interface View3 {
@Value(“#{target....}”)
String getName();
}
Open Interface Projection
Flexible View On Your Data

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Reactive
Flux findByFirstName(String name)
a Reactive Stream of Data

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Not one API
to rule them all

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@Entity
class Employee {
@Id
@GeneratedValue(...)
Long id;
@Column(name="FIRST_N")
String firstName;
...
}
@Document
class Employee {
@Id
Long id;
@Field(name="first_n")
String firstName;
...
}
JPA MongoDB

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class Employee {
Long id;
String firstName;
String lastName;
Manager manager;
}
class Manager {
Long id;
String name;
List employees
}
ID Name
1000 Marvin
ID FIRST_N LAST_N MANAGER_ID
1 Ford Prefect 1000
table based
manager
employee
linking by default
{
_id : 1000,
name : Marvin,
employees : [
{
id : 1,
firstName : Ford,
lastName : Prefect
}
...
document
store
embedding by default

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Native Queries
@Query(“SELECT m, COUNT(e) FROM Manager m
JOIN m.employees e GROUP BY e.name”)
List listManagerWithEmployeeCount();
JPA
@Aggregation(“{ $project: { id : 1, name: 1, $size : employees } }”)
List listManagerWithEmployeeCount();
MongoDB

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Richer / Slimmer API
Read the Documentation
for store specific features
@Procedure(”Employee.increaseSalary”)
Integer increaseSalary(Integer raise);
JPA
Stored Procedure call
GeoResults findByOfficeLoactionNear(Point p, Distance max)
List
Stream
Geospatial Query
@Update(”{ ... }”)
Integer findAndIncreaseSalaryByName(String name, Integer raise);
MongoDB Update

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interface Repo extends Repository {
...
}
Custom Implementations
interface MyExtension {
Reward beKind(Person person);
}
class MyExtensionImpl implements MyExtension {
ExtensionImpl(EntityManager em) { ... }
public Reward beKind(Person person) {
...
}
}
, MyExtension {
repository fragment

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No Silver Bullet

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Trouble Shooting
Repository Metrics
Logfiles
Network Stats
Query Planners

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Spring Data provides a
Familiar & Consistent
Programming Model
that resprects
Store Specific Traits

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What’s next? Spring Data
2.x & 3.0
The following is intended to outline the general direction of VMware's
offerings. It is intended for information purposes only and may not be
incorporated into any contract. Any information regarding pre-release of
VMware offerings, future updates or other planned modifications is subject
to ongoing evaluation by VMware and is subject to change. This information
is provided without warranty or any kind, express or implied, and is not a
commitment to deliver any material, code, or functionality, and should not
be relied upon in making purchasing decisions regarding VMware's
offerings. These purchasing decisions should only be based on features
currently available. The development, release, and timing of any features
or functionality described for VMware's offerings in this presentation remain
at the sole discretion of VMware. VMware has no obligation to update
forward looking information in this presentation

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2.x – Property Converters
class Person {
Long id;
String name;
String ssn;
}
@WritingConverter
class PersonToDocumentConverter implements Converter {
public Document convert(Person source) { ... }
}
@ReadingConverter
class DocumentToPersonConverter implements Converter {
public Person convert(Document source) { ... }
}

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2.x – Property Converters
class Person {
Long id;
String name;
@ValueConverter(EncryptingValueConverter.class)
String ssn;
}
declarative
PropertyValueConverterRegistrar registrar = new ...
registrar.registerConverter(Person.class, Person::getSsn)
.writing(utils::encrypt)
.reading(utils::decrypt);
programmatic
new
in
2.x

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3.0 - Baseline & Upgrades
• Java 17
• Jakarta EE 9
• Hibernate 6
• Validation API
• CDI Extensions
• ...

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3.0 - API Refinements
Repository
CrudRepository
Iterable findAll();
Iterable saveAll(...);
T findById(...)
long count();
void delete(...);
...
PagingAndSorting
Repository
Page findAll(Page);
...
ListCrudRepository
List findAll();
List saveAll(...);
T findById(...)
long count();
void delete(...);
...

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3.0 - Observability
AppOptics, Azure Monitor, Netflix Atlas, CloudWatch, Datadog,
Dynatrace, Elastic, Ganglia, Graphite, Humio, Influx/Telegraf, JMX,
KairosDB, New Relic, Prometheus, SignalFx, Google Stackdriver,
StatsD, Wavefront

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3.0 - GraalVM native
• static type hints
• dynamic configuration
processors

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Tech Talk - Persistence with Spring Data

Tech Talk - Persistence with Spring Data

Christoph Strobl

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