This project contains the PostgreSQL implementation of the R2DBC SPI. This implementation is not intended to be used directly, but rather to be used as the backing implementation for a humane client library to delegate to.
This driver provides the following features:
- Implements R2DBC 0.9
- Login with username/password (MD5, SASL/SCRAM) or implicit trust
- SCRAM authentication
- Unix Domain Socket transport
- TLS
- Explicit transactions
- Notifications
- Logical Decode
- Binary data transfer
- Execution of prepared statements with bindings
- Execution of batch statements without bindings
- Read and write support for all data types except LOB types (e.g.
BLOB,CLOB) - Fetching of
REFCURSORusingio.r2dbc.postgresql.api.RefCursor - Extension points to register
Codecs to handle additional PostgreSQL data types
Next steps:
- Multi-dimensional arrays
This project is governed by the Code of Conduct. By participating, you are expected to uphold this code of conduct. Please report unacceptable behavior to r2dbc@googlegroups.com.
Here is a quick teaser of how to use R2DBC PostgreSQL in Java:
URL Connection Factory Discovery
ConnectionFactory connectionFactory = ConnectionFactories.get("r2dbc:postgresql://<host>:5432/<database>");
Publisher<? extends Connection> connectionPublisher = connectionFactory.create();Programmatic Connection Factory Discovery
Map<String, String> options = new HashMap<>();
options.put("lock_timeout", "10s");
options.put("statement_timeout", "5m");
ConnectionFactory connectionFactory = ConnectionFactories.get(ConnectionFactoryOptions.builder()
.option(DRIVER, "postgresql")
.option(HOST, "...")
.option(PORT, 5432) // optional, defaults to 5432
.option(USER, "...")
.option(PASSWORD, "...")
.option(DATABASE, "...") // optional
.option(OPTIONS, options) // optional
.build());
Publisher<? extends Connection> connectionPublisher = connectionFactory.create();
// Alternative: Creating a Mono using Project Reactor
Mono<Connection> connectionMono = Mono.from(connectionFactory.create());Supported ConnectionFactory Discovery Options
| Option | Description |
|---|---|
ssl |
Enables SSL usage (SSLMode.VERIFY_FULL). |
driver |
Must be postgresql. |
host |
Server hostname to connect to. |
port |
Server port to connect to. Defaults to 5432. (Optional) |
socket |
Unix Domain Socket path to connect to as alternative to TCP. (Optional) |
username |
Login username. |
password |
Login password. (Optional when using TLS Certificate authentication) |
database |
Database to select. (Optional) |
applicationName |
The name of the application connecting to the database. Defaults to r2dbc-postgresql. (Optional) |
autodetectExtensions |
Whether to auto-detect and register Extensions from the class path. Defaults to true. (Optional) |
compatibilityMode |
Enable compatibility mode for cursored fetching. Required when using newer pgpool versions. Defaults to false. (Optional) |
errorResponseLogLevel |
Log level for error responses. Any of OFF, DEBUG, INFO, WARN or ERROR Defaults to DEBUG. (Optional) |
fetchSize |
The default number of rows to return when fetching results. Defaults to 0 for unlimited. (Optional) |
forceBinary |
Whether to force binary transfer. Defaults to false. (Optional) |
loopResources |
TCP/Socket LoopResources (depends on the endpoint connection type). (Optional) |
noticeLogLevel |
Log level for error responses. Any of OFF, DEBUG, INFO, WARN or ERROR Defaults to DEBUG. (Optional) |
preferAttachedBuffers |
Configure whether codecs should prefer attached data buffers. The default is false, meaning that codecs will copy data from the input buffer into a byte array. Enabling attached buffers requires consumption of values such as Json to avoid memory leaks. |
preparedStatementCacheQueries |
Determine the number of queries that are cached in each connection. The default is -1, meaning there's no limit. The value of 0 disables the cache. Any other value specifies the cache size. |
options |
A Map<String, String> of connection parameters. These are applied to each database connection created by the ConnectionFactory. Useful for setting generic PostgreSQL connection parameters. _( |
| Optional)_ | |
schema |
The search path to set. (Optional) |
sslMode |
SSL mode to use, see SSLMode enum. Supported values: DISABLE, ALLOW, PREFER, REQUIRE, VERIFY_CA, VERIFY_FULL, TUNNEL. (Optional) |
sslRootCert |
Path to SSL CA certificate in PEM format. Can be also a resource path. (Optional) |
sslKey |
Path to SSL key for TLS authentication in PEM format. Can be also a resource path. (Optional) |
sslCert |
Path to SSL certificate for TLS authentication in PEM format. Can be also a resource path. (Optional) |
sslPassword |
Key password to decrypt SSL key. (Optional) |
sslHostnameVerifier |
javax.net.ssl.HostnameVerifier implementation. (Optional) |
tcpNoDelay |
Enable/disable TCP NoDelay. Enabled by default. (Optional) |
tcpKeepAlive |
Enable/disable TCP KeepAlive. Disabled by default. (Optional) |
Programmatic Configuration
Map<String, String> options = new HashMap<>();
options.put("lock_timeout", "10s");
PostgresqlConnectionFactory connectionFactory = new PostgresqlConnectionFactory(PostgresqlConnectionConfiguration.builder()
.host("...")
.port(5432) // optional, defaults to 5432
.username("...")
.password("...")
.database("...") // optional
.options(options) // optional
.build());
Mono<Connection> mono = connectionFactory.create();PostgreSQL uses index parameters that are prefixed with $. The following SQL statement makes use of parameters:
INSERT INTO person (id, first_name, last_name) VALUES ($1, $2, $3)Parameters are referenced using the same identifiers when binding these:
mono.flatMapMany(connection -> connection
.createStatement("INSERT INTO person (id, first_name, last_name) VALUES ($1, $2, $3)")
.bind("$1", 1)
.bind("$2", "Walter")
.bind("$3", "White")
.execute());Binding also allowed positional index (zero-based) references. The parameter index is derived from the parameter discovery order when parsing the query.
Artifacts can be found on Maven Central.
<dependency>
<groupId>org.postgresql</groupId>
<artifactId>r2dbc-postgresql</artifactId>
<version>${version}</version>
</dependency>If you'd rather like the latest snapshots of the upcoming major version, use our Maven snapshot repository and declare the appropriate dependency version.
<dependency>
<groupId>org.postgresql</groupId>
<artifactId>r2dbc-postgresql</artifactId>
<version>${version}.BUILD-SNAPSHOT</version>
</dependency>
<repository>
<id>sonatype-nexus-snapshots</id>
<name>Sonatype OSS Snapshot Repository</name>
<url>https://oss.sonatype.org/content/repositories/snapshots</url>
</repository>R2DBC Postgres supports both, the simple and extended message flow.
Cursored fetching is activated by configuring a fetchSize. Postgres cursors are valid for the duration of a transaction. R2DBC can use cursors in auto-commit mode (Execute and Flush) to not
require an explicit transaction (BEGIN…COMMIT/ROLLBACK). Newer pgpool versions don't support this feature. To work around this limitation, either use explicit transactions when configuring a fetch
size or enable compatibility mode. Compatibility mode avoids cursors in auto-commit mode (Execute with no limit + Sync). Cursors in a transaction use Execute (with fetch size as limit) + Sync
as message flow.
Listen and Notify provide a simple form of signal or inter-process communication mechanism for processes accessing the same PostgreSQL database. For Listen/Notify, two actors are involved: The sender (notify) and the receiver (listen). The following example uses two connections to illustrate how they work together:
PostgresqlConnection sender= …;
PostgresqlConnection receiver= …;
Flux<Notification> listen = receiver.createStatement("LISTEN mymessage")
.execute()
.flatMap(PostgresqlResult::getRowsUpdated)
.thenMany(receiver.getNotifications());
Mono<Void> notify=sender.createStatement("NOTIFY mymessage, 'Hello World'")
.execute()
.flatMap(PostgresqlResult::getRowsUpdated)
.then();Upon subscription, the first connection enters listen mode and publishes incoming Notifications as Flux. The second connection broadcasts a notification to the mymessage channel upon
subscription.
Postgres supports additional options when starting a transaction. In particular, the following options can be specified:
- Isolation Level (
isolationLevel) (reset after the transaction to previous value) - Transaction Mutability (
readOnly) - Deferrable Mode (
deferrable)
These options can be specified upon transaction begin to start the transaction and apply options in a single command roundtrip:
PostgresqlConnection connection= …;
connection.beginTransaction(PostgresTransactionDefinition.from(IsolationLevel.SERIALIZABLE).readOnly().notDeferrable());See also: https://www.postgresql.org/docs/current/sql-begin.html
PostgreSQL supports JSON by storing values in JSON/JSONB columns. These values can be consumed and written using the regular R2DBC SPI and by using driver-specific extensions with
the io.r2dbc.postgresql.codec.Json type.
You can choose from two approaches:
- Native JSONB encoding using the
Jsonwrapper type. - Using scalar types.
The difference between the Json type and scalar types is that Json values are written encoded as JSONB to the database.
byte[] and String types are represented as BYTEA respective VARCHAR and require casting ($1::JSON) when used with parameterized statements.
The following code shows INSERT and SELECT cases for JSON interaction:
CREATE TABLE my_table (my_json JSON);Write JSON
connection.createStatement("INSERT INTO my_table (my_json) VALUES($1)")
.bind("$1", Json.of("{\"hello\": \"world\"}")).execute();Consume JSON
connection.createStatement("SELECT my_json FROM my_table")
.execute()
.flatMap(it -> it.map((row, rowMetadata) -> row.get("my_json", Json.class)))
.map(Json::asString);Write JSON using casting
connection.createStatement("INSERT INTO my_table (my_json) VALUES($1::JSON)")
.bind("$1", "{\"hello\": \"world\"}").execute();Consume JSON as scalar type
connection.createStatement("SELECT my_json FROM my_table")
.execute()
.flatMap(it -> it.map((row, rowMetadata) -> row.get("my_json", String.class)));The following types are supported for JSON exchange:
io.r2dbc.postgresql.codec.JsonByteBuf(must be released after usage to avoid memory leaks)ByteBufferbyte[]StringInputStream(must be closed after usage to avoid memory leaks)
The driver can consume cursors that were created by PL/pgSQL as refcursor.
Cursors are represented as RefCursor objects. Cursors obtained from Result can be used to fetch the cursor directly.
Since cursors are stateful, they must be closed once they are no longer in use.
connection.createStatement("SELECT show_cities_multiple()").execute()
.flatMap(result -> result.map((row, rowMetadata) -> row.get(0, RefCursor.class)))
.flatMap(cursor -> {
Mono<PostgresResult> data = cursor.fetch()
.flatMap(…)
.then(rc.close());
return data;
});PostgreSQL allows replication streaming and decoding persistent changes to a database's tables into useful chunks of data. In PostgreSQL, logical decoding is implemented by decoding the contents of the write-ahead log, which describe changes on a storage level, into an application-specific form such as a stream of tuples or SQL statements.
Consuming the replication stream is a four-step process:
- Obtain a replication connection via
PostgresqlConnectionFactory.replication(). - Create a replication slot (physical/logical).
- Initiate replication using the replication slot.
- Once the replication stream is set up, you can consume and map the binary data using
ReplicationStream.map(…).
On application shutdown, close() the ReplicationStream.
Note that a connection is busy once the replication is active and a connection can have at most one active replication stream.
Mono<PostgresqlReplicationConnection> replicationMono = connectionFactory.replication();
// later:
ReplicationSlotRequest request = ReplicationSlotRequest.logical()
.slotName("my_slot")
.outputPlugin("test_decoding")
.temporary()
.build();
Mono<ReplicationSlot> createSlot = replicationConnection.createSlot(request);
ReplicationRequest replicationRequest = ReplicationRequest.logical()
.slotName("my_slot")
.startPosition(LogSequenceNumber.valueOf(0))
.slotOption("skip-empty-xacts", true)
.slotOption("include-xids", false)
.build();
Flux<T> replicationStream = replicationConnection.startReplication(replicationRequest).flatMapMany(it -> {
return it.map(byteBuf -> {…})
.doOnError(t -> it.close().subscribe());
});Applications may make use of Postgres enumerated types by using EnumCodec to map custom types to Java enum types.
EnumCodec requires the Postgres OID and the Java to map enum values to the Postgres protocol and to materialize Enum instances from Postgres results.
You can configure a CodecRegistrar through EnumCodec.builder() for one or more enumeration type mappings. Make sure to use different Java enum types otherwise the driver is not able to distinguish between Postgres OIDs.
Example:
SQL:
CREATE TYPE my_enum AS ENUM ('FIRST', 'SECOND');Java Model:
enum MyEnumType {
FIRST, SECOND;
}Codec Registration:
PostgresqlConnectionConfiguration.builder()
.codecRegistrar(EnumCodec.builder().withEnum("my_enum",MyEnumType.class).build());When available, the driver registers also an array variant of the codec.
This reference table shows the type mapping between PostgreSQL and Java data types:
Types in bold indicate the native (default) Java type.
Support for the following single-dimensional arrays (read and write):
This driver accepts the following extensions:
CodecRegistrarto contributeCodecs for PostgreSQL ObjectIDs.
Extensions can be registered programmatically using PostgresConnectionConfiguration or discovered using Java's ServiceLoader mechanism (from META-INF/services/io.r2dbc.postgresql.extension.Extension).
The driver ships with built-in dynamic codecs (e.g. hstore) that are registered during the connection handshake depending on their availability while connecting. Note that Postgres extensions registered after a connection was established require a reconnect to initialize the codec.
If SL4J is on the classpath, it will be used. Otherwise, there are two possible fallbacks: Console or java.util.logging.Logger). By default, the Console fallback is used. To use the JDK loggers, set the reactor.logging.fallback System property to JDK.
Logging facilities:
- Driver Logging (
io.r2dbc.postgresql) - Query Logging (
io.r2dbc.postgresql.QUERYonDEBUGlevel) - Parameters' values Logging (
io.r2dbc.postgresql.PARAMonDEBUGlevel) - Transport Logging (
io.r2dbc.postgresql.client)DEBUGenablesMessageexchange loggingTRACEenables traffic logging
Logging that is associated with a connection reports the logical connection id (cid) which is a driver-local connection counter and the Postgres Process Id (pid) once the connection handshake finishes.
Having trouble with R2DBC? We'd love to help!
- Check the spec documentation, and Javadoc.
- If you are upgrading, check out the changelog for "new and noteworthy" features.
- Ask a question - we monitor stackoverflow.com for questions
tagged with
r2dbc. You can also chat with the community on Gitter. - Report bugs with R2DBC PostgreSQL at github.com/pgjdbc/r2dbc-postgresql/issues.
R2DBC uses GitHub as issue tracking system to record bugs and feature requests. If you want to raise an issue, please follow the recommendations below:
- Before you log a bug, please search the issue tracker to see if someone has already reported the problem.
- If the issue doesn't already exist, create a new issue.
- Please provide as much information as possible with the issue report, we like to know the version of R2DBC PostgreSQL that you are using and JVM version.
- If you need to paste code, or include a stack trace use Markdown ``` escapes before and after your text.
- If possible try to create a test-case or project that replicates the issue. Attach a link to your code or a compressed file containing your code.
You don't need to build from source to use R2DBC PostgreSQL (binaries in Maven Central), but if you want to try out the latest and greatest, R2DBC PostgreSQL can be easily built with the maven wrapper. You also need JDK 1.8 and Docker to run integration tests.
$ ./mvnw clean installIf you want to build with the regular mvn command, you will need Maven v3.5.0 or above.
Also see CONTRIBUTING.adoc if you wish to submit pull requests.
Running the JMH benchmarks builds and runs the benchmarks without running tests.
$ ./mvnw clean install -PjmhThis project is released under version 2.0 of the Apache License.