Server

The optional [server] table configures the DataFusion query engine runtime.

[server]
memory-limit = "4GB"
flight-sql-server-port = 32010

Option	Type	Required	Default	Description
memory-limit	String	No	Unlimited	Caps the memory available to the query engine.
flight-sql-server-port	Integer	Required for --flight-sql-server	None	Port the Arrow Flight SQL server listens on.

The value is an integer with an optional, case-insensitive unit. With no unit, the value is treated as bytes.

Unit	Meaning
b	Bytes
k, kb	Kibibytes
m, mb	Mebibytes
g, gb	Gibibytes
t, tb	Tebibytes

Arrow Flight SQL server

Lakelet can run as an Arrow Flight SQL server instead of the interactive REPL:

lakelet --config config.toml --flight-sql-server

flight-sql-server-port must be configured under [server], otherwise startup fails. The server binds to 0.0.0.0 and accepts remote connections. Note that the server currently has no authentication, so only expose it on networks you trust.

Currently supported: statement execution (CommandStatementQuery) with streaming Arrow results. Prepared statements and catalog metadata commands (GetCatalogs, GetTables, ...) are not implemented yet. Each request runs in its own session, so USE statements do not carry over between queries — use fully qualified table names (<catalog>.<schema>.<table>) or set --default-catalog / --default-schema at startup.

Connect with dft

Example using the datafusion-dft CLI/TUI (installed with the flightsql feature):

# ~/.config/dft/config.toml
[flightsql_client]
connection_url = "http://127.0.0.1:32010"

dft -c "select 1" --flightsql            # CLI
dft                                      # TUI: switch to the FlightSQL tab