The table function API can be used to define a table function that can then be called from within DuckDB in the FROM clause of a query.
API Reference
duckdb_table_function duckdb_create_table_function();
void duckdb_destroy_table_function(duckdb_table_function *table_function);
void duckdb_table_function_set_name(duckdb_table_function table_function, const char *name);
void duckdb_table_function_add_parameter(duckdb_table_function table_function, duckdb_logical_type type);
void duckdb_table_function_set_extra_info(duckdb_table_function table_function, void *extra_info, duckdb_delete_callback_t destroy);
void duckdb_table_function_set_bind(duckdb_table_function table_function, duckdb_table_function_bind_t bind);
void duckdb_table_function_set_init(duckdb_table_function table_function, duckdb_table_function_init_t init);
void duckdb_table_function_set_function(duckdb_table_function table_function, duckdb_table_function_t function);
duckdb_state duckdb_register_table_function(duckdb_connection con, duckdb_table_function function);
Table Function Bind
void *duckdb_bind_get_extra_info(duckdb_bind_info info);
void duckdb_bind_add_result_column(duckdb_bind_info info, const char *name, duckdb_logical_type type);
idx_t duckdb_bind_get_parameter_count(duckdb_bind_info info);
duckdb_value duckdb_bind_get_parameter(duckdb_bind_info info, idx_t index);
void duckdb_bind_set_bind_data(duckdb_bind_info info, void *bind_data, duckdb_delete_callback_t destroy);
void duckdb_bind_set_error(duckdb_bind_info info, const char *error);
Table Function Init
void *duckdb_init_get_extra_info(duckdb_init_info info);
void *duckdb_init_get_bind_data(duckdb_init_info info);
void duckdb_init_set_init_data(duckdb_init_info info, void *init_data, duckdb_delete_callback_t destroy);
void duckdb_init_set_error(duckdb_init_info info, const char *error);
Table Function
void *duckdb_function_get_extra_info(duckdb_function_info info);
void *duckdb_function_get_bind_data(duckdb_function_info info);
void *duckdb_function_get_init_data(duckdb_function_info info);
void duckdb_function_set_error(duckdb_function_info info, const char *error);
duckdb_create_table_function
Creates a new empty table function.
The return value should be destroyed with duckdb_destroy_table_function.
Syntax
duckdb_table_function duckdb_create_table_function(
);
Parameters
returns
The table function object.
duckdb_destroy_table_function
Destroys the given table function object.
Syntax
void duckdb_destroy_table_function(
duckdb_table_function *table_function
);
Parameters
table_function
The table function to destroy
duckdb_table_function_set_name
Sets the name of the given table function.
Syntax
void duckdb_table_function_set_name(
duckdb_table_function table_function,
const char *name
);
Parameters
table_function
The table function
name
The name of the table function
duckdb_table_function_add_parameter
Adds a parameter to the table function.
Syntax
void duckdb_table_function_add_parameter(
duckdb_table_function table_function,
duckdb_logical_type type
);
Parameters
table_function
The table function
type
The type of the parameter to add.
duckdb_table_function_set_extra_info
Assigns extra information to the table function that can be fetched during binding, etc.
Syntax
void duckdb_table_function_set_extra_info(
duckdb_table_function table_function,
void *extra_info,
duckdb_delete_callback_t destroy
);
Parameters
table_function
The table function
extra_info
The extra information
destroy
The callback that will be called to destroy the bind data (if any)
duckdb_table_function_set_bind
Sets the bind function of the table function
Syntax
void duckdb_table_function_set_bind(
duckdb_table_function table_function,
duckdb_table_function_bind_t bind
);
Parameters
table_function
The table function
bind
The bind function
duckdb_table_function_set_init
Sets the init function of the table function
Syntax
void duckdb_table_function_set_init(
duckdb_table_function table_function,
duckdb_table_function_init_t init
);
Parameters
table_function
The table function
init
The init function
duckdb_table_function_set_function
Sets the main function of the table function
Syntax
void duckdb_table_function_set_function(
duckdb_table_function table_function,
duckdb_table_function_t function
);
Parameters
table_function
The table function
function
The function
duckdb_register_table_function
Register the table function object within the given connection.
The function requires at least a name, a bind function, an init function and a main function.
If the function is incomplete or a function with this name already exists DuckDBError is returned.
Syntax
duckdb_state duckdb_register_table_function(
duckdb_connection con,
duckdb_table_function function
);
Parameters
con
The connection to register it in.
function
The function pointer
returns
Whether or not the registration was successful.
duckdb_bind_get_extra_info
Retrieves the extra info of the function as set in duckdb_table_function_set_extra_info
Syntax
void *duckdb_bind_get_extra_info(
duckdb_bind_info info
);
Parameters
info
The info object
returns
The extra info
duckdb_bind_add_result_column
Adds a result column to the output of the table function.
Syntax
void duckdb_bind_add_result_column(
duckdb_bind_info info,
const char *name,
duckdb_logical_type type
);
Parameters
info
The info object
name
The name of the column
type
The logical type of the column
duckdb_bind_get_parameter_count
Retrieves the number of regular (non-named) parameters to the function.
Syntax
idx_t duckdb_bind_get_parameter_count(
duckdb_bind_info info
);
Parameters
info
The info object
returns
The number of parameters
duckdb_bind_get_parameter
Retrieves the parameter at the given index.
The result must be destroyed with duckdb_destroy_value.
Syntax
duckdb_value duckdb_bind_get_parameter(
duckdb_bind_info info,
idx_t index
);
Parameters
info
The info object
index
The index of the parameter to get
returns
The value of the parameter. Must be destroyed with duckdb_destroy_value.
duckdb_bind_set_bind_data
Sets the user-provided bind data in the bind object. This object can be retrieved again during execution.
Syntax
void duckdb_bind_set_bind_data(
duckdb_bind_info info,
void *bind_data,
duckdb_delete_callback_t destroy
);
Parameters
info
The info object
extra_data
The bind data object.
destroy
The callback that will be called to destroy the bind data (if any)
duckdb_bind_set_error
Report that an error has occurred while calling bind.
Syntax
void duckdb_bind_set_error(
duckdb_bind_info info,
const char *error
);
Parameters
info
The info object
error
The error message
duckdb_init_get_extra_info
Retrieves the extra info of the function as set in duckdb_table_function_set_extra_info
Syntax
void *duckdb_init_get_extra_info(
duckdb_init_info info
);
Parameters
info
The info object
returns
The extra info
duckdb_init_get_bind_data
Gets the bind data set by duckdb_bind_set_bind_data during the bind.
Note that the bind data should be considered as read-only. For tracking state, use the init data instead.
Syntax
void *duckdb_init_get_bind_data(
duckdb_init_info info
);
Parameters
info
The info object
returns
The bind data object
duckdb_init_set_init_data
Sets the user-provided init data in the init object. This object can be retrieved again during execution.
Syntax
void duckdb_init_set_init_data(
duckdb_init_info info,
void *init_data,
duckdb_delete_callback_t destroy
);
Parameters
info
The info object
extra_data
The init data object.
destroy
The callback that will be called to destroy the init data (if any)
duckdb_init_set_error
Report that an error has occurred while calling init.
Syntax
void duckdb_init_set_error(
duckdb_init_info info,
const char *error
);
Parameters
info
The info object
error
The error message
duckdb_function_get_extra_info
Retrieves the extra info of the function as set in duckdb_table_function_set_extra_info
Syntax
void *duckdb_function_get_extra_info(
duckdb_function_info info
);
Parameters
info
The info object
returns
The extra info
duckdb_function_get_bind_data
Gets the bind data set by duckdb_bind_set_bind_data during the bind.
Note that the bind data should be considered as read-only. For tracking state, use the init data instead.
Syntax
void *duckdb_function_get_bind_data(
duckdb_function_info info
);
Parameters
info
The info object
returns
The bind data object
duckdb_function_get_init_data
Gets the init data set by duckdb_bind_set_init_data during the bind.
Syntax
void *duckdb_function_get_init_data(
duckdb_function_info info
);
Parameters
info
The info object
returns
The init data object
duckdb_function_set_error
Report that an error has occurred while executing the function.
Syntax
void duckdb_function_set_error(
duckdb_function_info info,
const char *error
);
Parameters
info
The info object
error
The error message