Flight SQL Driver#

The Flight SQL Driver provides access to any database implementing a Arrow Flight SQL compatible endpoint.

Installation#

The Flight SQL driver is shipped as a standalone library.

go get github.com/apache/arrow-adbc/go

pip install adbc_driver_sqlite

Usage#

To connect to a database, supply the “uri” parameter when constructing the AdbcDatabase.

#include "adbc.h"

// Ignoring error handling
struct AdbcDatabase database;
AdbcDatabaseNew(&database, nullptr);
AdbcDatabaseSetOption(&database, "driver", "adbc_driver_flightsql", nullptr);
AdbcDatabaseSetOption(&database, "uri", "grpc://localhost:8080", nullptr);
AdbcDatabaseInit(&database, nullptr);

import adbc_driver_flightsql.dbapi

with adbc_driver_flightsql.dbapi.connect("grpc://localhost:8080") as conn:
    pass

Supported Features#

The Flight SQL driver generally supports features defined in the ADBC API specification 1.0.0, as well as some additional, custom options.

Authentication#

The driver does no authentication by default. The driver implements a few optional authentication schemes:

  • Mutual TLS (mTLS): see “Client Options” below.

  • An HTTP-style scheme mimicking the Arrow Flight SQL JDBC driver.

    Set the options username and password on the AdbcDatabase. Alternatively, set the option adbc.flight.sql.authorization_header for full control.

    The client provides credentials sending an authorization from client to server. The server then responds with an authorization header on the first request. The value of this header will then be sent back as the authorization header on all future requests.

Bulk Ingestion#

Flight SQL does not have a dedicated API for bulk ingestion of Arrow data into a given table. The driver does not currently implement bulk ingestion as a result.

Client Options#

The options used for creating the Flight RPC client can be customized. These options map 1:1 with the options in FlightClientOptions:

adbc.flight.sql.client_option.mtls_cert_chain

The certificate chain to use for mTLS.

adbc.flight.sql.client_option.mtls_private_key

The private key to use for mTLS.

adbc.flight.sql.client_option.tls_override_hostname

Override the hostname used to verify the server’s TLS certificate.

adbc.flight.sql.client_option.tls_skip_verify

Disable verification of the server’s TLS certificate. Value should be true or false.

adbc.flight.sql.client_option.tls_root_certs

Override the root certificates used to validate the server’s TLS certificate.

adbc.flight.sql.client_option.with_block

Whether connections should wait until connections are established, or connect lazily when used. The latter is gRPC’s default behavior, but the driver defaults to eager connection to surface errors earlier. Value should be true or false.

adbc.flight.sql.client_option.with_max_msg_size

The maximum message size to accept from the server. The driver defaults to 16 MiB since Flight services tend to return larger reponse payloads. Should be a positive integer number of bytes.

Custom Call Headers#

Custom HTTP headers can be attached to requests via options that apply to AdbcDatabase, AdbcConnection, and AdbcStatement.

adbc.flight.sql.rpc.call_header.<HEADER NAME>

Add the header <HEADER NAME> to outgoing requests with the given value.

Warning

Header names must be in all lowercase.

Distributed Result Sets#

The driver will fetch all partitions (FlightEndpoints) returned by the server, in an unspecified order (note that Flight SQL itself does not define an ordering on these partitions). If an endpoint has no locations, the data will be fetched using the original server connection. Else, the driver will try each location given, in order, until a request succeeds. If the connection or request fails, it will try the next location.

The driver does not currently cache or pool these secondary connections. It also does not retry connections or requests.

All partitions are fetched in parallel. A limited number of batches are queued per partition. Data is returned to the client in the order of the partitions.

The queue size can be changed by setting an option on the AdbcStatement:

adbc.rpc.result_queue_size

The number of batches to queue per partition. Defaults to 5.

Metadata#

The driver currently will not populate column constraint info (foreign keys, primary keys, etc.) in AdbcConnectionGetObjects(). Also, catalog filters are evaluated as simple string matches, not LIKE-style patterns.

Partitioned Result Sets#

The Flight SQL driver supports ADBC’s partitioned result sets. When requested, each partition of a result set contains a serialized FlightInfo, containing one of the FlightEndpoints of the original response. Clients who may wish to introspect the partition can do so by deserializing the contained FlightInfo from the ADBC partitions. (For example, a client that wishes to distribute work across multiple workers or machines may want to try to take advantage of locality information that ADBC does not have.)

Timeouts#

By default, timeouts are not used for RPC calls. They can be set via special options on AdbcConnection. In general, it is best practice to set timeouts to avoid unexpectedly getting stuck. The options are as follows:

adbc.flight.sql.rpc.timeout_seconds.fetch

A timeout (in floating-point seconds) for any API calls that fetch data. This corresponds to Flight DoGet calls.

For example, this controls the timeout of the underlying Flight calls that fetch more data as a result set is consumed.

adbc.flight.sql.rpc.timeout_seconds.query

A timeout (in floating-point seconds) for any API calls that execute a query. This corresponds to Flight GetFlightInfo calls.

For example, this controls the timeout of the underlying Flight calls that implement AdbcStatementExecuteQuery().

adbc.flight.sql.rpc.timeout_seconds.update

A timeout (in floating-point seconds) for any API calls that upload data or perform other updates.

For example, this controls the timeout of the underlying Flight calls that implement bulk ingestion, or transaction support.

Transactions#

The driver supports transactions. It will first check the server’s SqlInfo to determine whether this is supported. Otherwise, transaction-related ADBC APIs will return ADBC_STATUS_NOT_IMPLEMENTED.