ExArrow.FlightSQL.Statement (ex_arrow v0.6.0)

An opaque handle to a server-side prepared statement.

A Statement is created by ExArrow.FlightSQL.Client.prepare/2 and represents a query that has been parsed and planned on the server. The same statement can be executed multiple times.

Usage

{:ok, stmt} = ExArrow.FlightSQL.Client.prepare(client, "SELECT * FROM t WHERE ts > '2024-01-01'")

# Execute as a streaming query
{:ok, stream} = ExArrow.FlightSQL.Statement.execute(stmt)
batches = Enum.to_list(stream)

# Execute again (reuses the server-side plan)
{:ok, stream2} = ExArrow.FlightSQL.Statement.execute(stmt)

Lifecycle

The underlying server-side handle is released when the Statement struct is garbage-collected. There is no explicit close/1 in v0.5.0; dropping the struct is sufficient.

Parameter binding

Parameter binding is not supported in v0.5.0. Statements are executed with no bound parameters. Parameterized queries (SELECT * FROM t WHERE id = ?) can be prepared and executed, but the parameter values cannot be set from Elixir in this release.

Compatibility

Prepared statement support is optional in the Arrow Flight SQL specification. Servers that do not implement CreatePreparedStatement will cause Client.prepare/2 to return {:error, %ExArrow.FlightSQL.Error{code: :unimplemented}}.

Summary

Types

t()

Functions

execute(statement)

Execute the prepared statement and return a lazy record-batch stream.

execute_update(statement)

Execute the prepared statement as a DML or DDL operation.

Types

t()

@opaque t()

Functions

execute(statement)

@spec execute(t()) ::
  {:ok, ExArrow.Stream.t()} | {:error, ExArrow.FlightSQL.Error.t()}

Execute the prepared statement and return a lazy record-batch stream.

Sends ExecutePreparedStatement to the server and opens a DoGet stream on the returned endpoint.

Returns {:ok, %ExArrow.Stream{}} or {:error, %ExArrow.FlightSQL.Error{}}.

Examples

{:ok, stream} = ExArrow.FlightSQL.Statement.execute(stmt)
batches = Enum.to_list(stream)

execute_update(statement)

@spec execute_update(t()) ::
  {:ok, non_neg_integer() | :unknown} | {:error, ExArrow.FlightSQL.Error.t()}

Execute the prepared statement as a DML or DDL operation.

Returns {:ok, n} where n is the number of affected rows, or {:ok, :unknown} when the server does not report a count.

Returns {:error, %ExArrow.FlightSQL.Error{}} on failure.

Examples

{:ok, stmt}    = ExArrow.FlightSQL.Client.prepare(client, "DELETE FROM t WHERE id = 42")
{:ok, 1}       = ExArrow.FlightSQL.Statement.execute_update(stmt)