Databases
API docs

Reactive PostgreSQL Client

The Reactive PostgreSQL Client is a client for PostgreSQL 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.

  • Event driven

  • Lightweight

  • Built-in connection pooling

  • Prepared queries caching

  • Publish / subscribe using PostgreSQL NOTIFY/LISTEN

  • Batch and cursor

  • Row streaming

  • Command pipelining

  • RxJava API

  • Direct memory to object without unnecessary copies

  • Java 8 Date and Time

  • SSL/TLS

  • Unix domain socket

  • HTTP/1.x CONNECT, SOCKS4a or SOCKS5 proxy support

  • Proxy (level 4 and 7) support

Usage

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

  • Maven (in your pom.xml):

<dependency>
 <groupId>io.vertx</groupId>
 <artifactId>vertx-pg-client</artifactId>
 <version>4.5.11</version>
</dependency>

  • Gradle (in your build.gradle file):

dependencies {
 compile 'io.vertx:vertx-pg-client:4.5.11'
}

Getting started

Here is the simplest way to connect, query and disconnect

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

// Pool options
PoolOptions poolOptions = new PoolOptions()
  .setMaxSize(5);

// Create the client pool
SqlClient client = PgBuilder
  .client()
  .with(poolOptions)
  .connectingTo(connectOptions)
  .build();

// A simple query
client
  .query("SELECT * FROM users WHERE id='julien'")
  .execute()
  .onComplete(ar -> {
    if (ar.succeeded()) {
      RowSet<Row> 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 PostgreSQL

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

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

// Pool options
PoolOptions poolOptions = new PoolOptions()
  .setMaxSize(5);

// Create the pooled client
SqlClient client = PgBuilder
  .client()
  .with(poolOptions)
  .connectingTo(connectOptions)
  .build();

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:

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

// Pool options
PoolOptions poolOptions = new PoolOptions()
  .setMaxSize(5);

// Create the pooled client
SqlClient client = PgBuilder
  .client()
  .with(poolOptions)
  .connectingTo(connectOptions)
  .using(vertx)
  .build();

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

client.close();

When you need to execute several operations on the same connection, you need to acquire a connection from a pool.

You can easily get one from the pool:

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

// Pool options
PoolOptions poolOptions = new PoolOptions()
  .setMaxSize(5);

// Create the pooled client
Pool pool = PgBuilder
  .pool()
  .with(poolOptions)
  .connectingTo(connectOptions)
  .using(vertx)
  .build();

// Get a connection from the pool
pool.getConnection().compose(conn -> {
  System.out.println("Got a connection from the pool");

  // All operations execute on the same connection
  return conn
    .query("SELECT * FROM users WHERE id='julien'")
    .execute()
    .compose(res -> conn
      .query("SELECT * FROM users WHERE id='emad'")
      .execute())
    .onComplete(ar -> {
      // Release the connection to the pool
      conn.close();
    });
}).onComplete(ar -> {
  if (ar.succeeded()) {
    System.out.println("Done");
  } else {
    System.out.println("Something went wrong " + ar.cause().getMessage());
  }
});

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

Command pipelining

In some use cases, command pipelining can improve database access performance.

You can configure the client to use pipelining

Pool pool = PgBuilder
  .pool()
  .connectingTo(connectOptions.setPipeliningLimit(16))
  .with(poolOptions)
  .using(vertx)
  .build();

The default pipelining limit is 256.

You can set this value to 1 to disable pipelining.

Pool versus pooled client

The PgBuilder allows you to create a pool or a pooled client

SqlClient client = PgBuilder
  .client()
  .with(poolOptions)
  .connectingTo(connectOptions)
  .using(vertx)
  .build();

// Pipelined
Future<RowSet<Row>> res1 = client.query(sql).execute();

// Connection pool
Pool pool = PgBuilder
  .pool()
  .connectingTo(connectOptions)
  .with(poolOptions)
  .using(vertx)
  .build();

// Not pipelined
Future<RowSet<Row>> res2 = pool.query(sql).execute();

  • pool operations are not pipelined, only connections acquired from the pool are pipelined

  • pooled client operations are pipelined, you cannot acquire a connection from a pooled client

Pool sharing

You can share an pool between multiple verticles or instances of the same verticle. Such pool should be created outside a verticle otherwise it will be closed when the verticle that created it is undeployed

Pool pool = Pool.pool(database, new PoolOptions().setMaxSize(maxSize));
vertx.deployVerticle(() -> new AbstractVerticle() {
  @Override
  public void start() throws Exception {
    // Use the pool
  }
}, new DeploymentOptions().setInstances(4));

You can also create a shared pool in each verticle:

vertx.deployVerticle(() -> new AbstractVerticle() {
  Pool pool;
  @Override
  public void start() {
    // Get or create a shared pool
    // this actually creates a lease to the pool
    // when the verticle is undeployed, the lease will be released automaticaly
    pool = PgBuilder.pool()
      .with(new PoolOptions()
        .setMaxSize(maxSize)
        .setShared(true)
        .setName("my-pool"))
      .connectingTo(database)
      .using(vertx)
      .build();
  }
}, new DeploymentOptions().setInstances(4));

The first time a shared pool is created it will create the resources for the pool. Subsequent calls will reuse this pool and create a lease to this pool. The resources are disposed after all leases have been closed.

By default, a pool reuses the current event-loop when it needs to create a TCP connection. The shared pool will therefore randomly use event-loops of verticles using it.

You can assign a number of event loop a pool will use independently of the context using it

Pool pool = PgBuilder.pool()
  .with(new PoolOptions()
    .setMaxSize(maxSize)
    .setShared(true)
    .setName("my-pool")
    .setEventLoopSize(4))
  .connectingTo(database)
  .using(vertx)
  .build();

Unix domain sockets

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.

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

// Pool options
PoolOptions poolOptions = new PoolOptions()
  .setMaxSize(5);

// Create the pooled client
Pool client = PgBuilder
  .pool()
  .connectingTo(connectOptions)
  .with(poolOptions)
  .build();

// Create the pooled client with a vertx instance
// Make sure the vertx instance has enabled native transports
Pool client2 = PgBuilder
  .pool()
  .connectingTo(connectOptions)
  .with(poolOptions)
  .using(vertx)
  .build();

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

Connect retries

You can configure the client to retry when a connection fails to be established.

options
  .setReconnectAttempts(2)
  .setReconnectInterval(1000);

Configuration

There are several alternatives for you to configure the client.

data object

A simple way to configure the client is to specify a PgConnectOptions data object.

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

// Pool Options
PoolOptions poolOptions = new PoolOptions().setMaxSize(5);

// Create the pool from the data object
Pool pool = PgBuilder.pool()
  .with(poolOptions)
  .connectingTo(connectOptions)
  .using(vertx)
  .build();

pool.getConnection()
  .onComplete(ar -> {
    // Handling your connection
  });

You can also configure the generic properties with the setProperties or addProperty methods. Note setProperties will override the default client properties.

When using this client with CockroachDB DBaaS, the cluster option needs to be included using addProperty("options", "--cluster=<cluster-id>") or in the URL …​&options=--cluster%3D<cluster-id>

For example, you can set a default schema for the connection with adding a search_path property.

PgConnectOptions connectOptions = new PgConnectOptions();

// Set the default schema
Map<String, String> props = new HashMap<>();
props.put("search_path", "myschema");
connectOptions.setProperties(props);

More information about the available properties can be found in the PostgreSQL Manuals.

Connection URI

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

String connectionUri = "postgresql://dbuser:[email protected]:5432/mydb";

// Create the pool from the connection URI
Pool pool = PgBuilder.pool()
  .connectingTo(connectionUri)
  .using(vertx)
  .build();

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

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

Currently, the client supports the following parameter keys:

  • host

  • hostaddr

  • port

  • user

  • password

  • dbname

  • sslmode

  • additional properties, including:

    • application_name

    • fallback_application_name

    • search_path

    • options

Configuring parameters in connection URI will override the default properties.

environment variables

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:

  • PGHOST

  • PGHOSTADDR

  • PGPORT

  • PGDATABASE

  • PGUSER

  • PGPASSWORD

  • PGSSLMODE

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
Pool pool = PgBuilder.pool()
  .using(vertx)
  .build();

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

SASL SCRAM-SHA-256 authentication mechanism.

To use the sasl SCRAM-SHA-256 authentication add the following dependency to the dependencies section of your build descriptor:

  • Maven (in your pom.xml):

<dependency>
 <groupId>com.ongres.scram</groupId>
 <artifactId>client</artifactId>
 <version>2.1</version>
</dependency>

  • Gradle (in your build.gradle file):

dependencies {
 compile 'com.ongres.scram:client:2.1'
}
SCRAM-SHA-256-PLUS (added in Postgresql 11) is not supported.

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'")
  .execute()
  .onComplete(ar -> {
  if (ar.succeeded()) {
    RowSet<Row> result = ar.result();
    System.out.println("Got " + result.size() + " rows ");
  } else {
    System.out.println("Failure: " + ar.cause().getMessage());
  }
});

Prepared queries

You can do the same with prepared queries.

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

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

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

client
  .preparedQuery("SELECT first_name, last_name FROM users")
  .execute()
  .onComplete(ar -> {
  if (ar.succeeded()) {
    RowSet<Row> 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)")
  .execute(Tuple.of("Julien", "Viet"))
  .onComplete(ar -> {
  if (ar.succeeded()) {
    RowSet<Row> 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));
Column indexes start at 0, not at 1.

Alternatively, data can be retrieved by name:

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

The client will not do any magic here and the column name is identified with the name in the table regardless of how your SQL text is.

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 use cached prepared statements to execute one-shot prepared queries:

connectOptions.setCachePreparedStatements(true);
client
  .preparedQuery("SELECT * FROM users WHERE id = $1")
  .execute(Tuple.of("julien"))
  .onComplete(ar -> {
    if (ar.succeeded()) {
      RowSet<Row> rows = ar.result();
      System.out.println("Got " + rows.size() + " rows ");
    } else {
      System.out.println("Failure: " + ar.cause().getMessage());
    }
  });

You can create a PreparedStatement and manage the lifecycle by yourself.

sqlConnection
  .prepare("SELECT * FROM users WHERE id = $1")
  .onComplete(ar -> {
    if (ar.succeeded()) {
      PreparedStatement preparedStatement = ar.result();
      preparedStatement.query()
        .execute(Tuple.of("julien"))
        .onComplete(ar2 -> {
          if (ar2.succeeded()) {
            RowSet<Row> rows = ar2.result();
            System.out.println("Got " + rows.size() + " rows ");
            preparedStatement.close();
          } else {
            System.out.println("Failure: " + ar2.cause().getMessage());
          }
        });
    } else {
      System.out.println("Failure: " + ar.cause().getMessage());
    }
  });

Batches

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
  .preparedQuery("INSERT INTO USERS (id, name) VALUES ($1, $2)")
  .executeBatch(batch)
  .onComplete(res -> {
  if (res.succeeded()) {

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

Returning clauses

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")
  .execute(Tuple.of("white", "red", "blue"))
  .onSuccess(rows -> {
    for (Row row : rows) {
      System.out.println("generated key: " + row.getInteger("color_id"));
    }
});

This works with any SQL as long as there is a RETURNING clause:

client
  .query("DELETE FROM color RETURNING color_name")
  .execute()
  .onSuccess(rows -> {
    for (Row row : rows) {
      System.out.println("deleted color: " + row.getString("color_name"));
    }
  });

A batch query with a RETURNING clause creates a RowSet containing a single for each element of the batch:

client
  .preparedQuery("INSERT INTO color (color_name) VALUES ($1) RETURNING color_id")
  .executeBatch(Arrays.asList(Tuple.of("white"), Tuple.of("red"), Tuple.of("blue")))
  .onSuccess(res -> {
    for (RowSet<Row> rows = res; rows != null; rows = rows.next()) {
      Integer colorId = rows.iterator().next().getInteger("color_id");
      System.out.println("generated key: " + colorId);
    }
  });

Using connections

Getting a connection

When you need to execute sequential queries (without a transaction), you can create a new connection or borrow one from the pool. Remember that between acquiring the connection from the pool and returning it to the pool, you should take care of the connection because it might be closed by the server for some reason such as an idle time out.

pool
  .getConnection()
  .compose(connection ->
    connection
      .preparedQuery("INSERT INTO Users (first_name,last_name) VALUES ($1, $2)")
      .executeBatch(Arrays.asList(
        Tuple.of("Julien", "Viet"),
        Tuple.of("Emad", "Alblueshi")
      ))
      .compose(res -> connection
        // Do something with rows
        .query("SELECT COUNT(*) FROM Users")
        .execute()
        .map(rows -> rows.iterator().next().getInteger(0)))
      // Return the connection to the pool
      .eventually(v -> connection.close())
  ).onSuccess(count -> {
  System.out.println("Insert users, now the number of users is " + count);
});

Prepared queries can be created:

connection
  .prepare("SELECT * FROM users WHERE first_name LIKE $1")
  .compose(pq ->
    pq.query()
      .execute(Tuple.of("Julien"))
      .eventually(v -> pq.close())
  ).onSuccess(rows -> {
  // All rows
});

Simplified connection API

When you use a pool, you can call withConnection to pass it a function executed within a connection.

It borrows a connection from the pool and calls the function with this connection.

The function must return a future of an arbitrary result.

After the future completes, the connection is returned to the pool and the overall result is provided.

pool.withConnection(connection ->
  connection
    .preparedQuery("INSERT INTO Users (first_name,last_name) VALUES ($1, $2)")
    .executeBatch(Arrays.asList(
      Tuple.of("Julien", "Viet"),
      Tuple.of("Emad", "Alblueshi")
    ))
    .compose(res -> connection
      // Do something with rows
      .query("SELECT COUNT(*) FROM Users")
      .execute()
      .map(rows -> rows.iterator().next().getInteger(0)))
).onSuccess(count -> {
  System.out.println("Insert users, now the number of users is " + count);
});

Using transactions

Transactions with connections

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

Or you can use the transaction API of SqlConnection:

pool.getConnection()
  // Transaction must use a connection
  .onSuccess(conn -> {
  // Begin the transaction
  conn.begin()
    .compose(tx -> conn
      // Various statements
      .query("INSERT INTO Users (first_name,last_name) VALUES ('Julien','Viet')")
      .execute()
      .compose(res2 -> conn
        .query("INSERT INTO Users (first_name,last_name) VALUES ('Emad','Alblueshi')")
        .execute())
      // Commit the transaction
      .compose(res3 -> tx.commit()))
    // Return the connection to the pool
    .eventually(v -> conn.close())
    .onSuccess(v -> System.out.println("Transaction succeeded"))
    .onFailure(err -> System.out.println("Transaction failed: " + err.getMessage()));
});

When the database server 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 completion future is failed with a TransactionRollbackException:

tx.completion()
  .onFailure(err -> {
  System.out.println("Transaction failed => rolled back");
});

Simplified transaction API

When you use a pool, you can call withTransaction to pass it a function executed within a transaction.

It borrows a connection from the pool, begins the transaction and calls the function with a client executing all operations in the scope of this transaction.

The function must return a future of an arbitrary result:

  • when the future succeeds the client will commit the transaction

  • when the future fails the client will rollback the transaction

After the transaction completes, the connection is returned to the pool and the overall result is provided.

pool.withTransaction(client -> client
  .query("INSERT INTO Users (first_name,last_name) VALUES ('Julien','Viet')")
  .execute()
  .flatMap(res -> client
    .query("INSERT INTO Users (first_name,last_name) VALUES ('Emad','Alblueshi')")
    .execute()
    // Map to a message result
    .map("Users inserted")))
  .onSuccess(v -> System.out.println("Transaction succeeded"))
  .onFailure(err -> System.out.println("Transaction failed: " + err.getMessage()));

Cursors and streaming

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

connection
  .prepare("SELECT * FROM users WHERE first_name LIKE $1")
  .onComplete(ar0 -> {
  if (ar0.succeeded()) {
    PreparedStatement pq = ar0.result();

    // Cursors require to run within a transaction
    connection
      .begin()
      .onComplete(ar1 -> {
      if (ar1.succeeded()) {
        Transaction tx = ar1.result();

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

        // Read 50 rows
        cursor.read(50).onComplete(ar2 -> {
          if (ar2.succeeded()) {
            RowSet<Row> rows = ar2.result();

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

Cursors shall be closed when they are released prematurely:

cursor
  .read(50)
  .onComplete(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")
  .onComplete(ar0 -> {
  if (ar0.succeeded()) {
    PreparedStatement pq = ar0.result();

    // Streams require to run within a transaction
    connection
      .begin()
      .onComplete(ar1 -> {
      if (ar1.succeeded()) {
        Transaction tx = ar1.result();

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

        // Use the stream
        stream.exceptionHandler(err -> {
          System.out.println("Error: " + err.getMessage());
        });
        stream.endHandler(v -> {
          // Close the stream to release the resources in the database
          stream
            .close()
            .onComplete(closed -> {
            tx.commit()
              .onComplete(committed -> {
              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.

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.

Tracing queries

The SQL client can trace query execution when Vert.x has tracing enabled.

The client reports the following client spans:

  • Query operation name

  • tags

  • db.system: the database management system product

  • db.user: the database username

  • db.instance: the database instance

  • db.statement: the SQL query

  • db.type: sql

The default tracing policy is PROPAGATE, the client will only create a span when involved in an active trace.

You can change the client policy with setTracingPolicy, e.g you can set ALWAYS to always report a span:

options.setTracingPolicy(TracingPolicy.ALWAYS);

PostgreSQL type mapping

Currently the client supports the following PostgreSQL types

  • BOOLEAN (java.lang.Boolean)

  • INT2 (java.lang.Short)

  • INT4 (java.lang.Integer)

  • INT8 (java.lang.Long)

  • FLOAT4 (java.lang.Float)

  • FLOAT8 (java.lang.Double)

  • CHAR (java.lang.String)

  • VARCHAR (java.lang.String)

  • TEXT (java.lang.String)

  • ENUM (java.lang.String)

  • NAME (java.lang.String)

  • SERIAL2 (java.lang.Short)

  • SERIAL4 (java.lang.Integer)

  • SERIAL8 (java.lang.Long)

  • NUMERIC (io.vertx.sqlclient.data.Numeric)

  • UUID (java.util.UUID)

  • DATE (java.time.LocalDate)

  • TIME (java.time.LocalTime)

  • TIMETZ (java.time.OffsetTime)

  • TIMESTAMP (java.time.LocalDateTime)

  • TIMESTAMPTZ (java.time.OffsetDateTime)

  • INTERVAL (io.vertx.pgclient.data.Interval)

  • BYTEA (io.vertx.core.buffer.Buffer)

  • JSON (io.vertx.core.json.JsonObject, io.vertx.core.json.JsonArray, Number, Boolean, String, io.vertx.sqlclient.Tuple#JSON_NULL)

  • JSONB (io.vertx.core.json.JsonObject, io.vertx.core.json.JsonArray, Number, Boolean, String, io.vertx.sqlclient.Tuple#JSON_NULL)

  • POINT (io.vertx.pgclient.data.Point)

  • LINE (io.vertx.pgclient.data.Line)

  • LSEG (io.vertx.pgclient.data.LineSegment)

  • BOX (io.vertx.pgclient.data.Box)

  • PATH (io.vertx.pgclient.data.Path)

  • POLYGON (io.vertx.pgclient.data.Polygon)

  • CIRCLE (io.vertx.pgclient.data.Circle)

  • TSVECTOR (java.lang.String)

  • TSQUERY (java.lang.String)

  • INET (io.vertx.pgclient.data.Inet)

  • MONEY (io.vertx.pgclient.data.Money)

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\"")
  .execute()
  .onComplete(ar -> {
    RowSet<Row> 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\"")
  .execute()
  .onComplete(ar -> {
    RowSet<Row> 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

PostgreSQL JSON and JSONB types are represented by the following Java types:

  • String

  • Number

  • Boolean

  • io.vertx.core.json.JsonObject

  • io.vertx.core.json.JsonArray

  • io.vertx.sqlclient.Tuple#JSON_NULL for representing the JSON null literal

Tuple tuple = Tuple.of(
  Tuple.JSON_NULL,
  new JsonObject().put("foo", "bar"),
  3);

// Retrieving json
Object value = tuple.getValue(0); // Expect JSON_NULL

//
value = tuple.get(JsonObject.class, 1); // Expect JSON object

//
value = tuple.get(Integer.class, 2); // Expect 3
value = tuple.getInteger(2); // Expect 3

Handling NUMERIC

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

Numeric numeric = row.get(Numeric.class, 0);
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.addArrayOfString(new String[]{"another", "array"});

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

Handling Date/Time infinity

PostgreSQL defines special values to represent infinity.

The max/min constants of the corresponding type represents special value.

  • OffsetDateTime.MAX/OffsetDateTime.MIN`

  • LocalDateTime.MAX/LocalDateTime.MIN`

  • LocalDate.MAX/LocalDate.MIN`

client
  .query("SELECT 'infinity'::DATE \"LocalDate\"")
  .execute()
  .onComplete(ar -> {
    if (ar.succeeded()) {
      Row row = ar.result().iterator().next();
      System.out.println(row.getLocalDate("LocalDate").equals(LocalDate.MAX));
    } else {
      System.out.println("Failure: " + ar.cause().getMessage());
    }
  });

Handling custom types

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

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

client
  .preparedQuery("SELECT address, (address).city FROM address_book WHERE id=$1")
  .execute(Tuple.of(3))
  .onComplete(ar -> {
  if (ar.succeeded()) {
    RowSet<Row> 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 PostgreSQL by providing a string

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

Handling text search

Text search is handling using java String

client
  .preparedQuery("SELECT to_tsvector( $1 ) @@ to_tsquery( $2 )")
  .execute(Tuple.of("fat cats ate fat rats", "fat & rat"))
  .onComplete(ar -> {
  if (ar.succeeded()) {
    RowSet<Row> rows = ar.result();
    for (Row row : rows) {
      System.out.println("Match : " + row.getBoolean(0));
    }
  } else {
    System.out.println("Failure: " + ar.cause().getMessage());
  }
});

tsvector and tsquery can be fetched from db using java String

client
  .preparedQuery("SELECT to_tsvector( $1 ), to_tsquery( $2 )")
  .execute(Tuple.of("fat cats ate fat rats", "fat & rat"))
  .onComplete(ar -> {
  if (ar.succeeded()) {
    RowSet<Row> rows = ar.result();
    for (Row row : rows) {
      System.out.println("Vector : " + row.getString(0) + ", query : "+row.getString(1));
    }
  } else {
    System.out.println("Failure: " + ar.cause().getMessage());
  }
});

Handling enumerated types

PostgreSQL enumerated types are mapped to java strings.

client
  .preparedQuery("INSERT INTO colors VALUES ($2)")
  .execute(Tuple.of("red"))
  .onComplete(res -> {
    // ...
  });

Using Java enum types

You can map Java enum types to these column types:

  • Strings (VARCHAR, TEXT)

  • PosgreSQL enumerated types

  • Numbers (INT2, INT4, INT8)

client
  .preparedQuery("INSERT INTO colors VALUES ($1)")
  .execute(Tuple.of(Color.red))
  .flatMap(res ->
    client
      .preparedQuery("SELECT color FROM colors")
      .execute()
  ).onComplete(res -> {
    if (res.succeeded()) {
      RowSet<Row> rows = res.result();
      for (Row row : rows) {
        System.out.println(row.get(Color.class, "color"));
      }
    }
});

String and PostgreSQL enumerated types are matched with the Java enum’s name returned by the name() method.

Numbers types are matched with the Java enum’s ordinal returned by the ordinal() method.

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")
  .collecting(collector)
  .execute()
  .onComplete(ar -> {
  if (ar.succeeded()) {
    SqlResult<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")
  .collecting(collector)
  .execute()
  .onComplete(ar -> {
    if (ar.succeeded()) {
      SqlResult<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());
    }
  });

Pub/sub

PostgreSQL supports pub/sub communication channels.

You can set a notificationHandler to receive PostgreSQL notifications:

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

connection
  .query("LISTEN some-channel")
  .execute()
  .onComplete(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()
  .onComplete(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 PostgreSQL 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()
  .onComplete(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'")
          .execute()
          .onComplete(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'")
          .execute()
          .onComplete(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:

  • when amountOfTime < 0: the subscriber is closed and there is no retry

  • when amountOfTime = 0: the subscriber retries to connect immediately

  • when amountOfTime > 0: the subscriber retries after amountOfTime milliseconds

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.

Notice messages

PostgreSQL can send notice message during the lifetime of a connection.

By default, such messages are logged on the console as warns.

You can set a handler on a connection to catch them and do something useful with them.

connection.noticeHandler(notice -> {
  System.out.println("Received notice " + notice.getSeverity() + "" + notice.getMessage());
});

Cancelling Request

PostgreSQL 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)")
  .execute()
  .onComplete(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()
  .onComplete(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"));

PgConnection
  .connect(vertx, options)
  .onComplete(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 level 4 proxy

You can configure the client to use an HTTP/1.x CONNECT, SOCKS4a or SOCKS5 level 4 proxy.

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

Using a level 7 proxy

Level 7 proxies can load balance queries on several connections to the actual database. When it happens, the client can be confused by the lack of session affinity and unwanted errors can happen like ERROR: unnamed prepared statement does not exist (26000).

Supported proxies:

  • PgBouncer configured with _pool_mode=transaction.

You can configure the client to interact differently to the proxy:

connectOptions.setUseLayer7Proxy(true);

When doing so, prepared statement cannot be cached and therefore

  • prepared statement caching must be disabled

  • explicit prepared statement can only live within the scope of a transaction, it means you can use cursors but the prepared statement for the cursor must be created and destroyed within the scope of a transaction

Advanced pool configuration

Server load balancing

You can configure the pool with a list of servers instead of a single server.

Pool pool = PgBuilder.pool()
  .with(options)
  .connectingTo(Arrays.asList(server1, server2, server3))
  .using(vertx)
  .build();

The pool uses a round-robin load balancing when a connection is created to select different servers.

this provides load balancing when the connection is created and not when the connection is borrowed from the pool.

Pool connection initialization

You can use the withConnectHandler to interact with a connection after it has been created and before it is inserted in a pool.

builder.withConnectHandler(conn -> {
  conn.query(sql).execute().onSuccess(res -> {
    // Release the connection to the pool, ready to be used by the application
    conn.close();
  });
});

Once you are done with the connection, you should simply close it to signal the pool to use it.

Dynamic connection configuration

You can configure the pool connection details using a Java supplier instead of an instance of SqlConnectOptions.

Since the supplier is asynchronous, it can be used to provide dynamic pool configuration (e.g. password rotation).

Pool pool = PgBuilder.pool()
  .with(poolOptions)
  .connectingTo(() -> {
    Future<SqlConnectOptions> connectOptions = retrieveOptions();
    return connectOptions;
  })
  .using(vertx)
  .build();

RxJava 3 API

The client provides an Rxified version of the original API. The following examples use RxJava 3.

Simple query

Single<RowSet<Row>> single = pool.query("SELECT * FROM users WHERE id='julien'").rxExecute();

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

Connection

The simplified connection API allows to easily use a connection, the withConnection method borrows a connection from the pool and return it for you:

Maybe<RowSet<Row>> maybe = pool.withConnection(conn ->
  conn
    .query("INSERT INTO Users (first_name,last_name) VALUES ('Julien','Viet')")
    .rxExecute()
    .flatMap(result -> conn
      .query("SELECT * FROM Users")
      .rxExecute())
    .toMaybe());

maybe.subscribe(rows -> {
  // Success
}, err -> {
  // Failed
});

Transaction

The simplified transaction API allows to easily write transactional asynchronous flows, The withTransaction method start and commit a transaction for you:

Completable completable = pool.withTransaction(conn ->
  conn
    .query("INSERT INTO Users (first_name,last_name) VALUES ('Julien','Viet')")
    .rxExecute()
    .flatMap(result -> conn
      .query("INSERT INTO Users (first_name,last_name) VALUES ('Emad','Alblueshi')")
      .rxExecute())
    .toMaybe())
  .ignoreElement();

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

Streaming

RxJava supports Observable and Flowable types, these are exposed using the RowStream that you can get from a PreparedQuery:

Observable<Row> observable = pool.rxGetConnection().flatMapObservable(conn -> conn
  .rxBegin()
  .flatMapObservable(tx ->
    conn
      .rxPrepare("SELECT * FROM users WHERE first_name LIKE $1")
      .flatMapObservable(preparedQuery -> {
        // Fetch 50 rows at a time
        RowStream<Row> stream = preparedQuery.createStream(50, Tuple.of("julien"));
        return stream.toObservable();
      })
      .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.rxGetConnection().flatMapPublisher(conn -> conn
  .rxBegin()
  .flatMapPublisher(tx ->
    conn
      .rxPrepare("SELECT * FROM users WHERE first_name LIKE $1")
      .flatMapPublisher(preparedQuery -> {
        // Fetch 50 rows at a time
        RowStream<Row> stream = preparedQuery.createStream(50, Tuple.of("julien"));
        return stream.toFlowable();
      })
      .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");
  }
});