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Vert.x MySQL / PostgreSQL client

The Async MySQL / PostgreSQL Client is responsible for providing an interface for Vert.x applications that need to interact with a MySQL or PostgreSQL database.

It uses Mauricio Linhares async driver to interact with the MySQL or PostgreSQL databases in a non blocking way.

Using the MySQL and PostgreSQL client

This section describes how to configure your project to be able to use the MySQL / PostgreSQL client in your application.

In a regular application

To use this client, you need to add the following jar to your CLASSPATH:

All these jars are downloadable from Maven Central.

In an application packaged in a fat jar

If you are building a Fat-jar using Maven or Gradle, just add the following dependencies:

  • Maven (in your pom.xml):

<dependency>
 <groupId>io.vertx</groupId>
 <artifactId>vertx-mysql-postgresql-client</artifactId>
 <version>3.8.2</version>
</dependency>

  • Gradle (in your build.gradle file):

compile 'io.vertx:vertx-mysql-postgresql-client:3.8.2'

In an application using a vert.x distributions

If you are using a vert.x distribution, add the jar files listed above to the $VERTX_HOME/lib directory.

Alternatively, you can edit the vertx-stack.json file located in $VERTX_HOME, and set "included": true for the vertx-mysql-postgresql-client dependency. Once done, launch: vertx resolve --dir=lib --stack= ./vertx-stack.json. It downloads the client and its dependencies.

Creating a client

There are several ways to create a client. Let’s go through them all.

Using default shared pool

In most cases you will want to share a pool between different client instances.

E.g. you scale your application by deploying multiple instances of your verticle and you want each verticle instance to share the same pool so you don’t end up with multiple pools

You do this as follows:

// To create a MySQL client:

var mySQLClientConfig = json {
  obj("host" to "mymysqldb.mycompany")
}
var mySQLClient = MySQLClient.createShared(vertx, mySQLClientConfig)

// To create a PostgreSQL client:

var postgreSQLClientConfig = json {
  obj("host" to "mypostgresqldb.mycompany")
}
var postgreSQLClient = PostgreSQLClient.createShared(vertx, postgreSQLClientConfig)

The first call to MySQLClient.createShared or PostgreSQLClient.createShared will actually create the data source, and the specified config will be used.

Subsequent calls will return a new client instance that uses the same data source, so the configuration won’t be used.

Specifying a pool name

You can create a client specifying a pool name as follows

// To create a MySQL client:

var mySQLClientConfig = json {
  obj("host" to "mymysqldb.mycompany")
}
var mySQLClient = MySQLClient.createShared(vertx, mySQLClientConfig, "MySQLPool1")

// To create a PostgreSQL client:

var postgreSQLClientConfig = json {
  obj("host" to "mypostgresqldb.mycompany")
}
var postgreSQLClient = PostgreSQLClient.createShared(vertx, postgreSQLClientConfig, "PostgreSQLPool1")

If different clients are created using the same Vert.x instance and specifying the same pool name, they will share the same data source.

The first call to MySQLClient.createShared or PostgreSQLClient.createShared will actually create the data source, and the specified config will be used.

Subsequent calls will return a new client instance that uses the same pool, so the configuration won’t be used.

Use this way of creating if you wish different groups of clients to have different pools, e.g. they’re interacting with different databases.

Creating a client with a non shared data source

In most cases you will want to share a pool between different client instances. However, it’s possible you want to create a client instance that doesn’t share its pool with any other client.

In that case you can use MySQLClient.createNonShared or PostgreSQLClient.createNonShared

// To create a MySQL client:

var mySQLClientConfig = json {
  obj("host" to "mymysqldb.mycompany")
}
var mySQLClient = MySQLClient.createNonShared(vertx, mySQLClientConfig)

// To create a PostgreSQL client:

var postgreSQLClientConfig = json {
  obj("host" to "mypostgresqldb.mycompany")
}
var postgreSQLClient = PostgreSQLClient.createNonShared(vertx, postgreSQLClientConfig)

This is equivalent to calling MySQLClient.createShared or PostgreSQLClient.createShared with a unique pool name each time.

Closing the client

You can hold on to the client for a long time (e.g. the life-time of your verticle), but once you have finished with it, you should close it using close or close

Getting a connection

Use getConnection to get a connection.

This will return the connection in the handler when one is ready from the pool.

// Now do stuff with it:

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

    var connection = res.result()

    // Got a connection

  } else {
    // Failed to get connection - deal with it
  }
})

Once you’ve finished with the connection make sure you close it afterwards.

The connection is an instance of SQLConnection which is a common interface used by other SQL clients.

You can learn how to use it in the common sql interface documentation.

Configuring reconnections

This service is able to recover from temporary database outages, such as those which occur during a database restart or brief loss of network connectivity. You can configure the expected behaviour when acquiring connections via the following properties:

  • maxConnectionRetries

  • connectionRetryDelay

When the internal connection pool attempts to acquire an open connection and fails, it will retry up to maxConnectionRetries times, with a delay of connectionRetryDelay milliseconds between each attempt. If all attempts fail, any clients waiting for connections from the pool will be notified with an Error, indicating that a Connection could not be acquired. Note that clients will not be notified with an Error until a full round of attempts fail, which may be some time after the initial connection attempt.

If maxConnectionRetries is set to 0, the internal connection pool will not perform any reconnection (default). If maxConnectionRetries is set to -1, the internal connection pool will attempt to acquire new connections indefinitely, so any call to getConnection may be indefinitely waiting for a successful acquisition.

Once a full round of acquisition attempts fails, the internal connection pool will remain active, and will try again to acquire connections in response to future requests for connections.

Note that if a database restart occurs, a pool may contain previously acquired but now stale Connections that will only be detected and purged lazily, when the pool attempts to reuse them.

Note about date and timestamps

Whenever you get dates back from the database, this service will implicitly convert them into ISO 8601 (yyyy-MM-ddTHH:mm:ss.SSS) formatted strings. MySQL usually discards milliseconds, so you will regularly see .000.

Note about last inserted ids

When inserting new rows into a table, you might want to retrieve auto-incremented ids from the database. The JDBC API usually lets you retrieve the last inserted id from a connection. If you use MySQL, it will work the way it does like the JDBC API. In PostgreSQL you can add the "RETURNING" clause to get the latest inserted ids. Use one of the query methods to get access to the returned columns.

Note about stored procedures

The call and callWithParams methods are not implemented currently.

Configuration

Both the PostgreSql and MySql clients take the same configuration:

{
 "host" : <your-host>,
 "port" : <your-port>,
 "maxPoolSize" : <maximum-number-of-open-connections>,
 "username" : <your-username>,
 "password" : <your-password>,
 "database" : <name-of-your-database>,
 "charset" : <name-of-the-character-set>,
 "connectTimeout" : <timeout-in-milliseconds>,
 "testTimeout" : <timeout-in-milliseconds>,
 "queryTimeout" : <timeout-in-milliseconds>,
 "maxConnectionRetries" : <maximum-number-of-connection-retries>,
 "connectionRetryDelay" : <delay-in-milliseconds>,
 "sslMode" : <"disable"|"prefer"|"require"|"verify-ca"|"verify-full">,
 "sslRootCert" : <path to file with certificate>
}
host

The host of the database. Defaults to localhost.

port

The port of the database. Defaults to 5432 for PostgreSQL and 3306 for MySQL.

maxPoolSize

The number of connections that may be kept open. Defaults to 10.

username

The username to connect to the database. Defaults to vertx.

password

The password to connect to the database. Defaults to password.

database

The name of the database you want to connect to. Defaults to testdb.

charset

The name of the character set you want to use for the connection. Defaults to UTF-8.

connectTimeout

The timeout to wait for connecting to the database. Defaults to 10000 (= 10 seconds).

testTimeout

The timeout for connection tests performed by pools. Defaults to 10000 (= 10 seconds).

queryTimeout

The timeout to wait for a query in milliseconds. Default is not set.

maxConnectionRetries

Maximum number of connection retries. Defaults to 0 (no retries).
Special values:

-1

Unlimited number of connection retries

0

No connection retries will be done

connectionRetryDelay

Delay in milliseconds between each retry attempt. Defaults to 5000 (= 5 seconds).

sslMode

If you want to enable SSL support you should enable this parameter. For example to connect Heroku you will need to use prefer.

"disable"

only try a non-SSL connection

"prefer"

first try an SSL connection; if that fails, try a non-SSL connection

"require"

only try an SSL connection, but don’t verify Certificate Authority

"verify-ca"

only try an SSL connection, and verify that the server certificate is issued by a trusted certificate authority (CA)

"verify-full"

only try an SSL connection, verify that the server certificate is issued by a trusted CA and that the server host name matches that in the certificate

sslRootCert

Path to SSL root certificate file. Is used if you want to verify privately issued certificate. Refer to postgresql-async documentation for more details.