reactive-pg-client

High performance reactive PostgreSQL client written in Java

View the Project on GitHub vietj/reactive-pg-client

Reactive Postgres Client

The Reactive Postgres Client is a client for Postgres with a straightforward API focusing on scalability and low overhead.

The client is reactive and non blocking, allowing to handle many database connections with a single thread.

Usage

To use the Reactive Postgres Client add the following dependency to the dependencies section of your build descriptor:

<dependency>
 <groupId>io.reactiverse</groupId>
 <artifactId>reactive-pg-client</artifactId>
 <version>0.11.4</version>
</dependency>

dependencies {
 compile 'io.reactiverse:reactive-pg-client:0.11.4'
}

Getting started

Here is the simplest way to connect, query and disconnect

PgPoolOptions options = new PgPoolOptions()
  .setPort(5432)
  .setHost("the-host")
  .setDatabase("the-db")
  .setUser("user")
  .setPassword("secret")
  .setMaxSize(5);

// Create the client pool
PgPool client = PgClient.pool(options);

// A simple query
client.query("SELECT * FROM users WHERE id='julien'", ar -> {
  if (ar.succeeded()) {
    PgRowSet result = ar.result();
    System.out.println("Got " + result.size() + " rows ");
  } else {
    System.out.println("Failure: " + ar.cause().getMessage());
  }

  // Now close the pool
  client.close();
});

Connecting to Postgres

Most of the time you will use a pool to connect to Postgres:

PgPoolOptions options = new PgPoolOptions()
  .setPort(5432)
  .setHost("the-host")
  .setDatabase("the-db")
  .setUser("user")
  .setPassword("secret")
  .setMaxSize(5);

// Create the pooled client
PgPool client = PgClient.pool(options);

The pooled client uses a connection pool and any operation will borrow a connection from the pool to execute the operation and release it to the pool.

If you are running with Vert.x you can pass it your Vertx instance:

PgPoolOptions options = new PgPoolOptions()
  .setPort(5432)
  .setHost("the-host")
  .setDatabase("the-db")
  .setUser("user")
  .setPassword("secret")
  .setMaxSize(5);

// Create the pooled client
PgPool client = PgClient.pool(vertx, options);

You need to release the pool when you don’t need it anymore:

pool.close();

When you need to execute several operations on the same connection, you need to use a client connection.

You can easily get one from the pool:

PgPoolOptions options = new PgPoolOptions()
  .setPort(5432)
  .setHost("the-host")
  .setDatabase("the-db")
  .setUser("user")
  .setPassword("secret")
  .setMaxSize(5);

// Create the pooled client
PgPool client = PgClient.pool(vertx, options);

// Get a connection from the pool
client.getConnection(ar1 -> {

  if (ar1.succeeded()) {

    System.out.println("Connected");

    // Obtain our connection
    PgConnection conn = ar1.result();

    // All operations execute on the same connection
    conn.query("SELECT * FROM users WHERE id='julien'", ar2 -> {
      if (ar2.succeeded()) {
        conn.query("SELECT * FROM users WHERE id='emad'", ar3 -> {
          // Release the connection to the pool
          conn.close();
        });
      } else {
        // Release the connection to the pool
        conn.close();
      }
    });
  } else {
    System.out.println("Could not connect: " + ar1.cause().getMessage());
  }
});

Once you are done with the connection you must close it to release it to the pool, so it can be reused.

Sometimes you want to improve performance via Unix domain socket connection, we achieve this with Vert.x Native transports.

Make sure you have added the required netty-transport-native dependency in your classpath and enabled the Unix domain socket option.

PgPoolOptions options = new PgPoolOptions()
  .setHost("/var/run/postgresql")
  .setPort(5432)
  .setDatabase("the-db");

// Create the pooled client
PgPool client = PgClient.pool(options);

// Create the pooled client with a vertx instance
// Make sure the vertx instance has enabled native transports
PgPool client2 = PgClient.pool(vertx, options);

More information can be found in the Vert.x documentation.

Configuration

There are several options for you to configure the client.

Apart from configuring with a PgPoolOptions data object, We also provide you an alternative way to connect when you want to configure with a connection URI:

String connectionUri = "postgresql://dbuser:secretpassword@database.server.com:3211/mydb";

// Create the pool from the connection URI
PgPool pool = PgClient.pool(connectionUri);

// Create the connection from the connection URI
PgClient.connect(vertx, connectionUri, res -> {
  // Handling your connection
});

More information about connection string formats can be found in the PostgreSQL Manuals.

You can also use environment variables to set default connection setting values, this is useful when you want to avoid hard-coding database connection information. You can refer to the official documentation for more details. The following parameters are supported:

If you don’t specify a data object or a connection URI string to connect, environment variables will take precedence over them.

$ PGUSER=user \
 PGHOST=the-host \
 PGPASSWORD=secret \
 PGDATABASE=the-db \
 PGPORT=5432 \
 PGSSLMODE=DISABLE

PgPool pool = PgClient.pool();

// Create the connection from the environment variables
PgClient.connect(vertx, res -> {
  // Handling your connection
});

Running queries

When you don’t need a transaction or run single queries, you can run queries directly on the pool; the pool will use one of its connection to run the query and return the result to you.

Here is how to run simple queries:

client.query("SELECT * FROM users WHERE id='julien'", ar -> {
  if (ar.succeeded()) {
    PgRowSet result = ar.result();
    System.out.println("Got " + result.size() + " rows ");
  } else {
    System.out.println("Failure: " + ar.cause().getMessage());
  }
});

You can do the same with prepared queries.

The SQL string can refer to parameters by position, using $1, $2, etc…​

client.preparedQuery("SELECT * FROM users WHERE id=$1", Tuple.of("julien"),  ar -> {
  if (ar.succeeded()) {
    PgRowSet rows = ar.result();
    System.out.println("Got " + rows.size() + " rows ");
  } else {
    System.out.println("Failure: " + ar.cause().getMessage());
  }
});

Query methods provides an asynchronous PgRowSet instance that works for SELECT queries

client.preparedQuery("SELECT first_name, last_name FROM users", ar -> {
  if (ar.succeeded()) {
    PgRowSet rows = ar.result();
    for (Row row : rows) {
      System.out.println("User " + row.getString(0) + " " + row.getString(1));
    }
  } else {
    System.out.println("Failure: " + ar.cause().getMessage());
  }
});

or UPDATE/INSERT queries:

client.preparedQuery("INSERT INTO users (first_name, last_name) VALUES ($1, $2)", Tuple.of("Julien", "Viet"),  ar -> {
  if (ar.succeeded()) {
    PgRowSet rows = ar.result();
    System.out.println(rows.rowCount());
  } else {
    System.out.println("Failure: " + ar.cause().getMessage());
  }
});

The Row gives you access to your data by index

System.out.println("User " + row.getString(0) + " " + row.getString(1));

or by name

System.out.println("User " + row.getString("first_name") + " " + row.getString("last_name"));

You can access a wide variety of of types

String firstName = row.getString("first_name");
Boolean male = row.getBoolean("male");
Integer age = row.getInteger("age");

You can execute prepared batch

List<Tuple> batch = new ArrayList<>();
batch.add(Tuple.of("julien", "Julien Viet"));
batch.add(Tuple.of("emad", "Emad Alblueshi"));

// Execute the prepared batch
client.preparedBatch("INSERT INTO USERS (id, name) VALUES ($1, $2)", batch, res -> {
  if (res.succeeded()) {

    // Process rows
    PgRowSet rows = res.result();
  } else {
    System.out.println("Batch failed " + res.cause());
  }
});

You can cache prepared queries:

options.setCachePreparedStatements(true);

PgPool client = PgClient.pool(vertx, options);

You can fetch generated keys with a ‘RETURNING’ clause in your query:

client.preparedQuery("INSERT INTO color (color_name) VALUES ($1), ($2), ($3) RETURNING color_id", Tuple.of("white", "red", "blue"), ar -> {
  if (ar.succeeded()) {
    PgRowSet rows = ar.result();
    System.out.println(rows.rowCount());
    for (Row row : rows) {
      System.out.println("generated key: " + row.getInteger("color_id"));
    }
  } else {
    System.out.println("Failure: " + ar.cause().getMessage());
  }
});

Using connections

When you need to execute sequential queries (without a transaction), you can create a new connection or borrow one from the pool:

pool.getConnection(ar1 -> {
  if (ar1.succeeded()) {
    PgConnection connection = ar1.result();

    connection.query("SELECT * FROM users WHERE id='julien'", ar2 -> {
      if (ar1.succeeded()) {
        connection.query("SELECT * FROM users WHERE id='paulo'", ar3 -> {
          // Do something with rows and return the connection to the pool
          connection.close();
        });
      } else {
        // Return the connection to the pool
        connection.close();
      }
    });
  }
});

Prepared queries can be created:

connection.prepare("SELECT * FROM users WHERE first_name LIKE $1", ar1 -> {
  if (ar1.succeeded()) {
    PgPreparedQuery pq = ar1.result();
    pq.execute(Tuple.of("julien"), ar2 -> {
      if (ar2.succeeded()) {
        // All rows
        PgRowSet rows = ar2.result();
      }
    });
  }
});

NOTE: prepared query caching depends on the setCachePreparedStatements and does not depend on whether you are creating prepared queries or use direct prepared queries

PgPreparedQuerycan perform efficient batching:

connection.prepare("INSERT INTO USERS (id, name) VALUES ($1, $2)", ar1 -> {
  if (ar1.succeeded()) {
    PgPreparedQuery prepared = ar1.result();

    // Create a query : bind parameters
    List<Tuple> batch = new ArrayList();

    // Add commands to the createBatch
    batch.add(Tuple.of("julien", "Julien Viet"));
    batch.add(Tuple.of("emad", "Emad Alblueshi"));

    prepared.batch(batch, res -> {
      if (res.succeeded()) {

        // Process rows
        PgRowSet rows = res.result();
      } else {
        System.out.println("Batch failed " + res.cause());
      }
    });
  }
});

Using transactions

Transactions with connections

You can execute transaction using SQL BEGIN/COMMIT/ROLLBACK, if you do so you must use a PgConnection and manage it yourself.

Or you can use the transaction API of PgConnection:

pool.getConnection(res -> {
  if (res.succeeded()) {

    // Transaction must use a connection
    PgConnection conn = res.result();

    // Begin the transaction
    PgTransaction tx = conn.begin();

    // Various statements
    conn.query("INSERT INTO Users (first_name,last_name) VALUES ('Julien','Viet')", ar -> {});
    conn.query("INSERT INTO Users (first_name,last_name) VALUES ('Emad','Alblueshi')", ar -> {});

    // Commit the transaction
    tx.commit(ar -> {
      if (ar.succeeded()) {
        System.out.println("Transaction succeeded");
      } else {
        System.out.println("Transaction failed " + ar.cause().getMessage());
      }

      // Return the connection to the pool
      conn.close();
    });
  }
});

When Postgres reports the current transaction is failed (e.g the infamous current transaction is aborted, commands ignored until end of transaction block), the transaction is rollbacked and the abortHandler is called:

pool.getConnection(res -> {
  if (res.succeeded()) {

    // Transaction must use a connection
    PgConnection conn = res.result();

    // Begin the transaction
    PgTransaction tx = conn
      .begin()
      .abortHandler(v -> {
      System.out.println("Transaction failed => rollbacked");
    });

    conn.query("INSERT INTO Users (first_name,last_name) VALUES ('Julien','Viet')", ar -> {
      // Works fine of course
      if (ar.succeeded()) {

      } else {
        tx.rollback();
        conn.close();
      }
    });
    conn.query("INSERT INTO Users (first_name,last_name) VALUES ('Julien','Viet')", ar -> {
      // Fails and triggers transaction aborts
    });

    // Attempt to commit the transaction
    tx.commit(ar -> {
      // But transaction abortion fails it

      // Return the connection to the pool
      conn.close();
    });
  }
});

Simplified transaction API

When you use a pool, you can start a transaction directly on the pool.

It borrows a connection from the pool, begins the transaction and releases the connection to the pool when the transaction ends.

pool.begin(res -> {
  if (res.succeeded()) {

    // Get the transaction
    PgTransaction tx = res.result();

    // Various statements
    tx.query("INSERT INTO Users (first_name,last_name) VALUES ('Julien','Viet')", ar -> {});
    tx.query("INSERT INTO Users (first_name,last_name) VALUES ('Emad','Alblueshi')", ar -> {});

    // Commit the transaction and return the connection to the pool
    tx.commit(ar -> {
      if (ar.succeeded()) {
        System.out.println("Transaction succeeded");
      } else {
        System.out.println("Transaction failed " + ar.cause().getMessage());
      }
    });
  }
});

Cursors and streaming

By default prepared query execution fetches all rows, you can use a PgCursorto control the amount of rows you want to read:

connection.prepare("SELECT * FROM users WHERE first_name LIKE $1", ar1 -> {
  if (ar1.succeeded()) {
    PgPreparedQuery pq = ar1.result();

    // Cursors require to run within a transaction
    PgTransaction tx = connection.begin();

    // Create a cursor
    PgCursor cursor = pq.cursor(Tuple.of("julien"));

    // Read 50 rows
    cursor.read(50, ar2 -> {
      if (ar2.succeeded()) {
        PgRowSet rows = ar2.result();

        // Check for more ?
        if (cursor.hasMore()) {
          // Repeat the process...
        } else {
          // No more rows - commit the transaction
          tx.commit();
        }
      }
    });
  }
});

PostreSQL destroys cursors at the end of a transaction, so the cursor API shall be used within a transaction, otherwise you will likely get the 34000 PostgreSQL error.

Cursors shall be closed when they are released prematurely:

cursor.read(50, ar2 -> {
  if (ar2.succeeded()) {
    // Close the cursor
    cursor.close();
  }
});

A stream API is also available for cursors, which can be more convenient, specially with the Rxified version.

connection.prepare("SELECT * FROM users WHERE first_name LIKE $1", ar1 -> {
  if (ar1.succeeded()) {
    PgPreparedQuery pq = ar1.result();

    // Streams require to run within a transaction
    PgTransaction tx = connection.begin();

    // Fetch 50 rows at a time
    PgStream<Row> stream = pq.createStream(50, Tuple.of("julien"));

    // Use the stream
    stream.exceptionHandler(err -> {
      System.out.println("Error: " + err.getMessage());
    });
    stream.endHandler(v -> {
      tx.commit();
      System.out.println("End of stream");
    });
    stream.handler(row -> {
      System.out.println("User: " + row.getString("last_name"));
    });
  }
});

The stream read the rows by batch of 50 and stream them, when the rows have been passed to the handler, a new batch of 50 is read and so on.

The stream can be resumed or paused, the loaded rows will remain in memory until they are delivered and the cursor will stop iterating.

Postgres type mapping

Currently the client supports the following Postgres types

Tuple decoding uses the above types when storing values, it also performs on the flu conversion the actual value when possible:

pool.query("SELECT 1::BIGINT \"VAL\"", ar -> {
  PgRowSet rowSet = ar.result();
  Row row = rowSet.iterator().next();

  // Stored as java.lang.Long
  Object value = row.getValue(0);

  // Convert to java.lang.Integer
  Integer intValue = row.getInteger(0);
});

Tuple encoding uses the above type mapping for encoding, unless the type is numeric in which case java.lang.Number is used instead:

pool.query("SELECT 1::BIGINT \"VAL\"", ar -> {
  PgRowSet rowSet = ar.result();
  Row row = rowSet.iterator().next();

  // Stored as java.lang.Long
  Object value = row.getValue(0);

  // Convert to java.lang.Integer
  Integer intValue = row.getInteger(0);
});

Arrays of these types are supported.

Handling JSON

The Json Java type is used to represent the Postgres JSON and JSONB type.

The main reason of this type is handling null JSON values.

Tuple tuple = Tuple.of(
  Json.create(Json.create(null)),
  Json.create(Json.create(new JsonObject().put("foo", "bar"))),
  Json.create(Json.create(null)));

// Retrieving json
Object value = tuple.getJson(0).value(); // Expect null

//
value = tuple.getJson(1).value(); // Expect JSON object

//
value = tuple.getJson(3).value(); // Expect 3

Handling NUMERIC

The Numeric Java type is used to represent the Postgres NUMERIC type.

Numeric numeric = row.getNumeric("value");
if (numeric.isNaN()) {
  // Handle NaN
} else {
  BigDecimal value = numeric.bigDecimalValue();
}

Handling arrays

Arrays are available on Tuple and Row:

Tuple tuple = Tuple.of(new String[]{ "a", "tuple", "with", "arrays" });

// Add a string array to the tuple
tuple.addStringArray(new String[]{"another", "array"});

// Get the first array of string
String[] array = tuple.getStringArray(0);

Handling custom types

Strings are used to represent custom types, both sent to and returned from Postgres.

You can read from Postgres and get the custom type as a string

client.preparedQuery("SELECT address, (address).city FROM address_book WHERE id=$1", Tuple.of(3),  ar -> {
  if (ar.succeeded()) {
    PgRowSet rows = ar.result();
    for (Row row : rows) {
      System.out.println("Full Address " + row.getString(0) + ", City " + row.getString(1));
    }
  } else {
    System.out.println("Failure: " + ar.cause().getMessage());
  }
});

You can also write to Postgres by providing a string

client.preparedQuery("INSERT INTO address_book (id, address) VALUES ($1, $2)", Tuple.of(3, "('Anytown', 'Second Ave', false)"),  ar -> {
  if (ar.succeeded()) {
    PgRowSet rows = ar.result();
    System.out.println(rows.rowCount());
  } else {
    System.out.println("Failure: " + ar.cause().getMessage());
  }
});

Collector queries

You can use Java collectors with the query API:

Collector<Row, ?, Map<Long, String>> collector = Collectors.toMap(
  row -> row.getLong("id"),
  row -> row.getString("last_name"));

// Run the query with the collector
client.query("SELECT * FROM users",
  collector,
  ar -> {
  if (ar.succeeded()) {
    PgResult<Map<Long, String>> result = ar.result();

    // Get the map created by the collector
    Map<Long, String> map = result.value();
    System.out.println("Got " + map);
  } else {
    System.out.println("Failure: " + ar.cause().getMessage());
  }
});

The collector processing must not keep a reference on the Row as there is a single row used for processing the entire set.

The Java Collectors provides many interesting predefined collectors, for example you can create easily create a string directly from the row set:

Collector<Row, ?, String> collector = Collectors.mapping(
  row -> row.getString("last_name"),
  Collectors.joining(",", "(", ")")
);

// Run the query with the collector
client.query("SELECT * FROM users",
  collector,
  ar -> {
    if (ar.succeeded()) {
      PgResult<String> result = ar.result();

      // Get the string created by the collector
      String list = result.value();
      System.out.println("Got " + list);
    } else {
      System.out.println("Failure: " + ar.cause().getMessage());
    }
  });

RxJava support

The rxified API supports RxJava 1 and RxJava 2, the following examples use RxJava 2.

Most asynchronous constructs are available as methods prefixed by rx:

Single<PgRowSet> single = pool.rxQuery("SELECT * FROM users WHERE id='julien'");

// Execute the query
single.subscribe(result -> {
  System.out.println("Got " + result.size() + " rows ");
}, err -> {
  System.out.println("Failure: " + err.getMessage());
});

Streaming

RxJava 2 supports Observable and Flowable types, these are exposed using the PgStream that you can get from a PgPreparedQuery:

Observable<Row> observable = pool.rxBegin() // Cursors require a transaction
  .flatMapObservable(tx -> tx
    .rxPrepare("SELECT * FROM users WHERE first_name LIKE $1")
    .flatMapObservable(preparedQuery -> {
      // Fetch 50 rows at a time
      PgStream<Row> stream = preparedQuery.createStream(50, Tuple.of("julien"));
      return stream.toObservable();
    })
    // Commit the transaction after usage
    .doAfterTerminate(tx::commit));

// Then subscribe
observable.subscribe(row -> {
  System.out.println("User: " + row.getString("last_name"));
}, err -> {
  System.out.println("Error: " + err.getMessage());
}, () -> {
  System.out.println("End of stream");
});

The same example using Flowable:

  Flowable<Row> flowable = pool.rxBegin()  // Cursors require a transaction
  .flatMapPublisher(tx -> tx.rxPrepare("SELECT * FROM users WHERE first_name LIKE $1")
    .flatMapPublisher(preparedQuery -> {
      // Fetch 50 rows at a time
      PgStream<Row> stream = preparedQuery.createStream(50, Tuple.of("julien"));
      return stream.toFlowable();
    })
    // Commit the transaction after usage
    .doAfterTerminate(tx::commit));

// Then subscribe
flowable.subscribe(new Subscriber<Row>() {

  private Subscription sub;

  @Override
  public void onSubscribe(Subscription subscription) {
    sub = subscription;
    subscription.request(1);
  }

  @Override
  public void onNext(Row row) {
    sub.request(1);
    System.out.println("User: " + row.getString("last_name"));
  }

  @Override
  public void onError(Throwable err) {
    System.out.println("Error: " + err.getMessage());
  }

  @Override
  public void onComplete() {
    System.out.println("End of stream");
  }
});

Transaction

The simplified transaction API allows to easily write transactional asynchronous flows:

Completable completable = pool
  .rxBegin()
  .flatMapCompletable(tx -> tx
    .rxQuery("INSERT INTO Users (first_name,last_name) VALUES ('Julien','Viet')")
    .flatMap(result -> tx.rxQuery("INSERT INTO Users (first_name,last_name) VALUES ('Emad','Alblueshi')"))
    .flatMapCompletable(result -> tx.rxCommit()));

completable.subscribe(() -> {
  // Transaction succeeded
}, err -> {
  // Transaction failed
});

Pub/sub

Postgres supports pub/sub communication channels.

You can set a notificationHandler to receive Postgres notifications:

connection.notificationHandler(notification -> {
  System.out.println("Received " + notification.getPayload() + " on channel " + notification.getChannel());
});

connection.query("LISTEN some-channel", ar -> {
  System.out.println("Subscribed to channel");
});

The PgSubscriber is a channel manager managing a single connection that provides per channel subscription:

PgSubscriber subscriber = PgSubscriber.subscriber(vertx, new PgConnectOptions()
  .setPort(5432)
  .setHost("the-host")
  .setDatabase("the-db")
  .setUser("user")
  .setPassword("secret")
);

// You can set the channel before connect
subscriber.channel("channel1").handler(payload -> {
  System.out.println("Received " + payload);
});

subscriber.connect(ar -> {
  if (ar.succeeded()) {

    // Or you can set the channel after connect
    subscriber.channel("channel2").handler(payload -> {
      System.out.println("Received " + payload);
    });
  }
});

The channel name that is given to the channel method will be the exact name of the channel as held by Postgres for sending notifications. Note this is different than the representation of the channel name in SQL, and internally PgSubscriber will prepare the submitted channel name as a quoted identifier:

PgSubscriber subscriber = PgSubscriber.subscriber(vertx, new PgConnectOptions()
  .setPort(5432)
  .setHost("the-host")
  .setDatabase("the-db")
  .setUser("user")
  .setPassword("secret")
);

subscriber.connect(ar -> {
    if (ar.succeeded()) {
      // Complex channel name - name in PostgreSQL requires a quoted ID
      subscriber.channel("Complex.Channel.Name").handler(payload -> {
        System.out.println("Received " + payload);
      });
      subscriber.channel("Complex.Channel.Name").subscribeHandler(subscribed -> {
    	  subscriber.actualConnection().query(
    			  "NOTIFY \"Complex.Channel.Name\", 'msg'", notified -> {
    		  System.out.println("Notified \"Complex.Channel.Name\"");
    	  });
      });

      // PostgreSQL simple ID's are forced lower-case
      subscriber.channel("simple_channel").handler(payload -> {
          System.out.println("Received " + payload);
      });
      subscriber.channel("simple_channel").subscribeHandler(subscribed -> {
    	  // The following simple channel identifier is forced to lower case
          subscriber.actualConnection().query(
        		"NOTIFY Simple_CHANNEL, 'msg'", notified -> {
      		  System.out.println("Notified simple_channel");
      	  });
      });

      // The following channel name is longer than the current
      // (NAMEDATALEN = 64) - 1 == 63 character limit and will be truncated
      subscriber.channel(
    		  "aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaabbbbb"
    		  ).handler(payload -> {
          System.out.println("Received " + payload);
      });
    }
  });

You can provide a reconnect policy as a function that takes the number of retries as argument and returns an amountOfTime value:

PgSubscriber subscriber = PgSubscriber.subscriber(vertx, new PgConnectOptions()
  .setPort(5432)
  .setHost("the-host")
  .setDatabase("the-db")
  .setUser("user")
  .setPassword("secret")
);

// Reconnect at most 10 times after 100 ms each
subscriber.reconnectPolicy(retries -> {
  if (retries < 10) {
    return 100L;
  } else {
    return -1L;
  }
});

The default policy is to not reconnect.

Cancelling Request

Postgres supports cancellation of requests in progress. You can cancel inflight requests using cancelRequest. Cancelling a request opens a new connection to the server and cancels the request and then close the connection.

connection.query("SELECT pg_sleep(20)", ar -> {
  if (ar.succeeded()) {
    // imagine this is a long query and is still running
    System.out.println("Query success");
  } else {
    // the server will abort the current query after cancelling request
    System.out.println("Failed to query due to " + ar.cause().getMessage());
  }
});
connection.cancelRequest(ar -> {
  if (ar.succeeded()) {
    System.out.println("Cancelling request has been sent");
  } else {
    System.out.println("Failed to send cancelling request");
  }
});

The cancellation signal might or might not have any effect — for example, if it arrives after the backend has finished processing the query, then it will have no effect. If the cancellation is effective, it results in the current command being terminated early with an error message.

More information can be found in the official documentation.

Using SSL/TLS

To configure the client to use SSL connection, you can configure the PgConnectOptions like a Vert.x NetClient. All SSL modes are supported and you are able to configure sslmode. The client is in DISABLE SSL mode by default. ssl parameter is kept as a mere shortcut for setting sslmode. setSsl(true) is equivalent to setSslMode(VERIFY_CA) and setSsl(false) is equivalent to setSslMode(DISABLE).

PgConnectOptions options = new PgConnectOptions()
  .setPort(5432)
  .setHost("the-host")
  .setDatabase("the-db")
  .setUser("user")
  .setPassword("secret")
  .setSslMode(SslMode.VERIFY_CA)
  .setPemTrustOptions(new PemTrustOptions().addCertPath("/path/to/cert.pem"));

PgClient.connect(vertx, options, res -> {
  if (res.succeeded()) {
    // Connected with SSL
  } else {
    System.out.println("Could not connect " + res.cause());
  }
});

More information can be found in the Vert.x documentation.

Using a proxy

You can also configure the client to use an HTTP/1.x CONNECT, SOCKS4a or SOCKS5 proxy.

More information can be found in the Vert.x documentation.