20 Kasım 2023 Pazartesi

JDBC Reactive

Giriş
Açıklaması şöyle
The JDBC Reactive Extensions are available in the Oracle JDBC Thin Driver 21c or later. The extensions expose standard Java Flow Subscriber and Publisher types and APIs that can interoperate with the R2DBC API and other Reactive Streams libraries.
Jar
Açıklaması şöyle
Interestingly, if you are using the Oracle JDBC Driver, you do not have to include another JAR as a dependency. The JDBC Reactive Extensions belong to the same dependency artefact (JAR file) as the Oracle JDBC Driver.
Tipler
Açıklaması şöyle. Yani JDBC Reactive ile diğer kütüphanelerin beklediği tipler uyuşmuyor
The JDBC Reactive Extensions APIs handle the low-level mechanics of the Flow API to the application using java.util.concurrent.Flow.Publisher and java.util.concurrent.Flow.Subscriber. Popular libraries such as Reactor, RxJava, and Akka-Streams interface with the org.reactivestreams.Publisher and org.reactivestreams.Subscriber types defined by the reactive-streams-jvm project as specified in the following link:
Açıklaması şöyle. Yani JDBC Reactive ile diğer kütüphanelerin beklediği tipler uyuşmuyor
You can convert between the Flow type and the org.reactivestreams type using the org.reactivestreams.FlowAdapters class 
...
Oracle recommends that you use the Reactive Streams libraries when interfacing with the Flow types exposed by the JDBC driver.
API
OraclePreparedStatement  metodları şöyle
Flow.Publisher<Boolean> executeAsyncOracle
Flow.Publisher<Long> executeUpdateAsyncOracle
Flow.Publisher<Long> executeBatchAsyncOracle
Flow.Publisher<OracleResultSet> executeQueryAsyncOracle
Açıklaması şöyle
JDBC Reactive Extensions have the following limitations:

- You must access the asynchronous methods through the java.sql.Wrapper.unwrap method, instead of accessing those through a typecast. This ensures correct behaviour of the asynchronous methods when you use them with proxy Oracle JDBC classes, for example, when you use asynchronous methods with connection pools.
- Reading large responses from the network may require blocking I/O bound operations. Blocking read operations can occur if the driver reads a response that is larger than the TCP Receive buffer size.
- Asynchronous SQL execution supports neither scrollable ResultSet types nor sensitive ResultSet types.

executeAsyncOracle metodu
Örnek - CREATE TABLE
Elimizde şöyle bir kod olsun
import java.sql.SQLException;
import java.util.concurrent.Flow;

import oracle.jdbc.OracleConnection;
import oracle.jdbc.OraclePreparedStatement;
import oracle.jdbc.pool.OracleDataSource;

private OracleDataSource ods = null;
private OracleConnection conn = null;

try {
  OracleDataSource ods = new OracleDataSource();
  // jdbc:oracle:thin@[hostname]:[port]/[DB service/name]
  ods.setURL("jdbc:oracle:thin@[hostname]:[port]/[DB service/name");
  ods.setUser("[Username]");
  ods.setPassword("[Password]");

  conn = (OracleConnection) ods.getConnection();
  // Execute a SQL DDL statement to create a database table asynchronously
  createTable(conn);
} catch (SQLException e) {
 ...
}
Şöyle yaparız
Flow.Publisher<Boolean> createTable(OracleConnection connection)throws SQLException {
  OraclePreparedStatement createTableStatement = (OraclePreparedStatement) 
  connection.prepareStatement("CREATE TABLE employee_names (id NUMBER PRIMARY KEY,"
      + "first_name VARCHAR(50), last_name VARCHAR2(50))");

  Flow.Publisher<Boolean> createTablePublisher = createTableStatement
    .unwrap(OraclePreparedStatement.class)
    .executeAsyncOracle();

  createTablePublisher.subscribe(
    // This subscriber will close the PreparedStatement
    new Flow.Subscriber<Boolean>() {
      @Override
      public void onSubscribe(Flow.Subscription subscription) {
	subscription.request(1L);
      }

      @Override
      public void onNext(Boolean item) {}

      @Override
      public void onError(Throwable throwable) {closeStatement();}

      @Override
      public void onComplete() {closeStatement();}

      void closeStatement() {
	try {
	  createTableStatement.close();
	} catch (SQLException closeException) {
	}
      }
  });
  return createTablePublisher;
}
executeUpdateAsyncOracle metodu
Örnek
Şöyle yaparız
class PipelineExample{
  void pipelineExample(OracleConnection connection) throws SQLException {
    PreparedStatement delete = connection.prepareStatement(
            "DELETE FROM example WHERE id = 0");
    PreparedStatement insert = connection.prepareStatement(
            "INSERT INTO example (id, value) VALUES (1, 'x')");
    PreparedStatement select = connection.prepareStatement(
            "SELECT id, value FROM example WHERE id = 2");

    Flow.Publisher<Long> deletePublisher =
            delete.unwrap(OraclePreparedStatement.class).executeUpdateAsyncOracle();
    Flow.Publisher<Long> insertPublisher =
            insert.unwrap(OraclePreparedStatement.class).executeUpdateAsyncOracle();
    Flow.Publisher<OracleResultSet> selectPublisher =
            select.unwrap(OraclePreparedStatement.class).executeQueryAsyncOracle();

    // Subscribe to publishers to get results back
    …
  }
}
Örnek
Şöyle yaparız. Burada org.reactivestreams.FlowAdapters.toPublisher() kullanılıyor
// Execute statements in a pipeline
Flow.Publisher<Long> deletePublisher =
  delete.unwrap(OraclePreparedStatement.class).executeUpdateAsyncOracle();
Flow.Publisher<Long> insertPublisher =
  insert.unwrap(OraclePreparedStatement.class).executeUpdateAsyncOracle();
Flow.Publisher<OracleResultSet> selectPublisher =
  select.unwrap(OraclePreparedStatement.class).executeQueryAsyncOracle();

// Consume statement results synchronously with Project Reactor
long deleteCount = Mono.from(toPublisher(deletePublisher)).block();
System.out.println(deleteCount + " rows deleted");

long insertCount = Mono.from(toPublisher(insertPublisher)).block();
System.out.println(insertCount + " rows inserted");

OracleResultSet resultSet = Mono.from(toPublisher(selectPublisher)).block();



9 Kasım 2023 Perşembe

DUAL Sistem Tablosu

Örnek
Şöyle yaparız
SELECT 'Hello World!' FROM dual;

Docker ve Oracle

Örnek - 23c
Şöyle yaparız
docker pull gvenzl/oracle-free

docker run -d \
  -p 1521:1521 \
  -e ORACLE_PASSWORD=<your password> \
  -v oracle-volume:/opt/oracle/oradata \
  gvenzl/oracle-free
XE ve Slim
Oracle Database Express Edition (Oracle Database XE) anlamına gelir. Oracle Application Express (APEX) araçlarını içermez

Örnek
Şöyle yaparız. Kullanıcı adı system şifre mypassword  olur
docker run -d -p 1521:1521 -e ORACLE_PASSWORD=mypassword gvenzl/oracle-xe:21-slim-faststart



22 Ağustos 2023 Salı

TestContainers

Maven
Şu satırı dahil ederiz
<dependency>
  <groupId>org.testcontainers</groupId>
  <artifactId>oracle-xe</artifactId>
  <version>${testcontainers.version}</version>
  <scope>test</scope>
</dependency>
Örnek
Şöyle yaparız
OracleContainer oracleContainer = new OracleContainer("gvenzl/oracle-xe:21-slim-faststart")
  .withDatabaseName("testDB")
  .withUsername("testUser")
  .withPassword("testPassword")


1 Haziran 2023 Perşembe

Transactional Event Queues

Oracle Advanced Queuing (or AQ) vs Transactional Event Queues
Açıklaması şöyle
Oracle Database has had queueing for many years (since Oracle 8). The older implementation was (and still is) called Oracle Advanced Queuing (or AQ). TxEventQ is a newer implementation that is optimized for much higher throughput and lower latency, and it provides transactional semantics (hence the name). There are clients in all common languages, and you can set up propagation between databases, even across long distances.
Kafka APIs for Transactional Event Queues
Oracle Database 23c Free ile geliyor. Açıklaması şöyle
It has three main parts:

1. The ability for Java applications written using the Kafka API for Java to use the Oracle Database as a Kafka broker,
2. The ability for the Oracle Database to provide Kafka REST APIs, and
3. Connectors that allow the propagation of events between Kafka and the Oracle Datbase, and vice versa.
Şeklen şöyle



Oracle Advanced Queuing

Giriş
Açıklaması şöyle.  Oracle Advanced Queuing yerine Transactional Event Queues kullanılabilir
Oracle Database has had queueing for many years (since Oracle 8). The older implementation was (and still is) called Oracle Advanced Queuing (or AQ).

23 Mayıs 2023 Salı

Oracle Cloud Infrastructure - OCI

SDK
Oracle Cloud Infrastructure altyapıya erişim için aynı AWS gibi SDK sağlıyor

Maven
Şu satırı dahil ederiz
<dependency>
  <groupId>com.oracle.oci.sdk</groupId>
  <artifactId>oci-java-sdk-common</artifactId>
  <version>3.2.0</version>
</dependency>
<dependency>
  <groupId>com.oracle.oci.sdk</groupId>
  <artifactId>oci-java-sdk-common-httpclient-jersey</artifactId>
  <version>3.2.0</version>
</dependency>
<dependency>
  <groupId>com.oracle.oci.sdk</groupId>
  <artifactId>oci-java-sdk-identity</artifactId>
  <version>3.2.0</version>
</dependency>
Burada bir örnek var

OCI GoldenGate
Açıklaması şöyle. Change Data Capture (CDC) içindir.
OCI offers a fully managed NoSQL Cloud Database, a robust alternative to Amazon DynamoDB, and a comprehensive Change Data Capture tool known as OCI GoldenGate. 

8 Mart 2023 Çarşamba

Kafka Connect OracleCdcSourceConnector

Bir yazı burada

Oracle LogMiner

Giriş
Hem Kafka Connect hem de Debezium bu arayüzü kullanııyor

Kafka Connect 
Kafka Connect için açıklaması şöyle
This connector uses the Oracle LogMiner interface to query online and archived redo log files. That’s an Oracle specific way to stream both the DML and DDL directly from the redo of the database. This is similar to how the Debezium project reads the Postgres write-ahead log or the MySQL binlog.

Debezium 
Debezium için açıklaması şöyle
Debezium ingests change events using Oracle’s native LogMiner database package. Oracle LogMiner is part of the Oracle Database utilities and provides a well-defined, easy-to-use, and comprehensive interface for querying online and archived redo log files.

The first time the Debezium Oracle connector starts, it performs an initial consistent snapshot of the database to see its entire history. You can change this behavior by setting the snapshot.mode. After the connector completes its initial snapshot, the Debezium connector continues streaming from the position it reads from the current system change number (SCN) position in the redo log. The initial snapshot ensures that the connector has a complete and consistent data set.

The Debezium connector for Oracle Databases supports the following database versions:
Oracle Database 12.2 EE
Oracle Database 19.3 EE
Oracle Database 21.3 EE

The Oracle connector used with Oracle Real Application Clusters (RAC) is in Technology Preview (TP) for this release.

26 Ocak 2023 Perşembe

Oracle Goldengate

Kafka'dan Oracle NoSQL Veri Tabanına
Açıklaması şöyle
Oracle’s GoldenGate seamlessly orchestrates data replication from source to sink through remote capture processes, known as Extract and Replicat. The Extract process captures the data and records it to trail files. These trail files are then leveraged to create a Replicat process, effectively applying the records to the sink.
Şeklen şöyle


PostgreSQL Veri Tabanından Oracle Veri Tabanına
Şeklen şöyle Burada iki tane ürün var
1. Goldengate 21c OCI Marketplace for PostgreSQL
2. OCI Goldengate for Oracle