API Reference

Open/Connect

duckdb_state duckdb_open(const char *path, duckdb_database *out_database);
duckdb_state duckdb_open_ext(const char *path, duckdb_database *out_database, duckdb_config config, char **out_error);
void duckdb_close(duckdb_database *database);
duckdb_state duckdb_connect(duckdb_database database, duckdb_connection *out_connection);
void duckdb_disconnect(duckdb_connection *connection);

Configuration

duckdb_state duckdb_create_config(duckdb_config *out_config);
size_t duckdb_config_count();
duckdb_state duckdb_get_config_flag(size_t index, const char **out_name, const char **out_description);
duckdb_state duckdb_set_config(duckdb_config config, const char *name, const char *option);
void duckdb_destroy_config(duckdb_config *config);

Query Execution

duckdb_state duckdb_query(duckdb_connection connection, const char *query, duckdb_result *out_result);
void duckdb_destroy_result(duckdb_result *result);
const char *duckdb_column_name(duckdb_result *result, idx_t col);
duckdb_type duckdb_column_type(duckdb_result *result, idx_t col);
idx_t duckdb_column_count(duckdb_result *result);
idx_t duckdb_row_count(duckdb_result *result);
idx_t duckdb_rows_changed(duckdb_result *result);
void *duckdb_column_data(duckdb_result *result, idx_t col);
bool *duckdb_nullmask_data(duckdb_result *result, idx_t col);
char *duckdb_result_error(duckdb_result *result);

Result Functions

bool duckdb_value_boolean(duckdb_result *result, idx_t col, idx_t row);
int8_t duckdb_value_int8(duckdb_result *result, idx_t col, idx_t row);
int16_t duckdb_value_int16(duckdb_result *result, idx_t col, idx_t row);
int32_t duckdb_value_int32(duckdb_result *result, idx_t col, idx_t row);
int64_t duckdb_value_int64(duckdb_result *result, idx_t col, idx_t row);
duckdb_hugeint duckdb_value_hugeint(duckdb_result *result, idx_t col, idx_t row);
uint8_t duckdb_value_uint8(duckdb_result *result, idx_t col, idx_t row);
uint16_t duckdb_value_uint16(duckdb_result *result, idx_t col, idx_t row);
uint32_t duckdb_value_uint32(duckdb_result *result, idx_t col, idx_t row);
uint64_t duckdb_value_uint64(duckdb_result *result, idx_t col, idx_t row);
float duckdb_value_float(duckdb_result *result, idx_t col, idx_t row);
double duckdb_value_double(duckdb_result *result, idx_t col, idx_t row);
duckdb_date duckdb_value_date(duckdb_result *result, idx_t col, idx_t row);
duckdb_time duckdb_value_time(duckdb_result *result, idx_t col, idx_t row);
duckdb_timestamp duckdb_value_timestamp(duckdb_result *result, idx_t col, idx_t row);
duckdb_interval duckdb_value_interval(duckdb_result *result, idx_t col, idx_t row);
char *duckdb_value_varchar(duckdb_result *result, idx_t col, idx_t row);
char *duckdb_value_varchar_internal(duckdb_result *result, idx_t col, idx_t row);
duckdb_blob duckdb_value_blob(duckdb_result *result, idx_t col, idx_t row);
bool duckdb_value_is_null(duckdb_result *result, idx_t col, idx_t row);

Helpers

void *duckdb_malloc(size_t size);
void duckdb_free(void *ptr);

Date/Time/Timestamp Helpers

duckdb_date_struct duckdb_from_date(duckdb_date date);
duckdb_date duckdb_to_date(duckdb_date_struct date);
duckdb_time_struct duckdb_from_time(duckdb_time time);
duckdb_time duckdb_to_time(duckdb_time_struct time);
duckdb_timestamp_struct duckdb_from_timestamp(duckdb_timestamp ts);
duckdb_timestamp duckdb_to_timestamp(duckdb_timestamp_struct ts);

Hugeint Helpers

double duckdb_hugeint_to_double(duckdb_hugeint val);
duckdb_hugeint duckdb_double_to_hugeint(double val);

Prepared Statements

duckdb_state duckdb_prepare(duckdb_connection connection, const char *query, duckdb_prepared_statement *out_prepared_statement);
void duckdb_destroy_prepare(duckdb_prepared_statement *prepared_statement);
const char *duckdb_prepare_error(duckdb_prepared_statement prepared_statement);
idx_t duckdb_nparams(duckdb_prepared_statement prepared_statement);
duckdb_type duckdb_param_type(duckdb_prepared_statement prepared_statement, idx_t param_idx);
duckdb_state duckdb_bind_boolean(duckdb_prepared_statement prepared_statement, idx_t param_idx, bool val);
duckdb_state duckdb_bind_int8(duckdb_prepared_statement prepared_statement, idx_t param_idx, int8_t val);
duckdb_state duckdb_bind_int16(duckdb_prepared_statement prepared_statement, idx_t param_idx, int16_t val);
duckdb_state duckdb_bind_int32(duckdb_prepared_statement prepared_statement, idx_t param_idx, int32_t val);
duckdb_state duckdb_bind_int64(duckdb_prepared_statement prepared_statement, idx_t param_idx, int64_t val);
duckdb_state duckdb_bind_hugeint(duckdb_prepared_statement prepared_statement, idx_t param_idx, duckdb_hugeint val);
duckdb_state duckdb_bind_uint8(duckdb_prepared_statement prepared_statement, idx_t param_idx, uint8_t val);
duckdb_state duckdb_bind_uint16(duckdb_prepared_statement prepared_statement, idx_t param_idx, uint16_t val);
duckdb_state duckdb_bind_uint32(duckdb_prepared_statement prepared_statement, idx_t param_idx, uint32_t val);
duckdb_state duckdb_bind_uint64(duckdb_prepared_statement prepared_statement, idx_t param_idx, uint64_t val);
duckdb_state duckdb_bind_float(duckdb_prepared_statement prepared_statement, idx_t param_idx, float val);
duckdb_state duckdb_bind_double(duckdb_prepared_statement prepared_statement, idx_t param_idx, double val);
duckdb_state duckdb_bind_date(duckdb_prepared_statement prepared_statement, idx_t param_idx, duckdb_date val);
duckdb_state duckdb_bind_time(duckdb_prepared_statement prepared_statement, idx_t param_idx, duckdb_time val);
duckdb_state duckdb_bind_timestamp(duckdb_prepared_statement prepared_statement, idx_t param_idx, duckdb_timestamp val);
duckdb_state duckdb_bind_interval(duckdb_prepared_statement prepared_statement, idx_t param_idx, duckdb_interval val);
duckdb_state duckdb_bind_varchar(duckdb_prepared_statement prepared_statement, idx_t param_idx, const char *val);
duckdb_state duckdb_bind_varchar_length(duckdb_prepared_statement prepared_statement, idx_t param_idx, const char *val, idx_t length);
duckdb_state duckdb_bind_blob(duckdb_prepared_statement prepared_statement, idx_t param_idx, const void *data, idx_t length);
duckdb_state duckdb_bind_null(duckdb_prepared_statement prepared_statement, idx_t param_idx);
duckdb_state duckdb_execute_prepared(duckdb_prepared_statement prepared_statement, duckdb_result *out_result);
duckdb_state duckdb_execute_prepared_arrow(duckdb_prepared_statement prepared_statement, duckdb_arrow *out_result);

Appender

duckdb_state duckdb_appender_create(duckdb_connection connection, const char *schema, const char *table, duckdb_appender *out_appender);
const char *duckdb_appender_error(duckdb_appender appender);
duckdb_state duckdb_appender_flush(duckdb_appender appender);
duckdb_state duckdb_appender_close(duckdb_appender appender);
duckdb_state duckdb_appender_destroy(duckdb_appender *appender);
duckdb_state duckdb_appender_begin_row(duckdb_appender appender);
duckdb_state duckdb_appender_end_row(duckdb_appender appender);
duckdb_state duckdb_append_bool(duckdb_appender appender, bool value);
duckdb_state duckdb_append_int8(duckdb_appender appender, int8_t value);
duckdb_state duckdb_append_int16(duckdb_appender appender, int16_t value);
duckdb_state duckdb_append_int32(duckdb_appender appender, int32_t value);
duckdb_state duckdb_append_int64(duckdb_appender appender, int64_t value);
duckdb_state duckdb_append_hugeint(duckdb_appender appender, duckdb_hugeint value);
duckdb_state duckdb_append_uint8(duckdb_appender appender, uint8_t value);
duckdb_state duckdb_append_uint16(duckdb_appender appender, uint16_t value);
duckdb_state duckdb_append_uint32(duckdb_appender appender, uint32_t value);
duckdb_state duckdb_append_uint64(duckdb_appender appender, uint64_t value);
duckdb_state duckdb_append_float(duckdb_appender appender, float value);
duckdb_state duckdb_append_double(duckdb_appender appender, double value);
duckdb_state duckdb_append_date(duckdb_appender appender, duckdb_date value);
duckdb_state duckdb_append_time(duckdb_appender appender, duckdb_time value);
duckdb_state duckdb_append_timestamp(duckdb_appender appender, duckdb_timestamp value);
duckdb_state duckdb_append_interval(duckdb_appender appender, duckdb_interval value);
duckdb_state duckdb_append_varchar(duckdb_appender appender, const char *val);
duckdb_state duckdb_append_varchar_length(duckdb_appender appender, const char *val, idx_t length);
duckdb_state duckdb_append_blob(duckdb_appender appender, const void *data, idx_t length);
duckdb_state duckdb_append_null(duckdb_appender appender);

Arrow Interface

duckdb_state duckdb_query_arrow(duckdb_connection connection, const char *query, duckdb_arrow *out_result);
duckdb_state duckdb_query_arrow_schema(duckdb_arrow result, duckdb_arrow_schema *out_schema);
duckdb_state duckdb_query_arrow_array(duckdb_arrow result, duckdb_arrow_array *out_array);
idx_t duckdb_arrow_column_count(duckdb_arrow result);
idx_t duckdb_arrow_row_count(duckdb_arrow result);
idx_t duckdb_arrow_rows_changed(duckdb_arrow result);
const char *duckdb_query_arrow_error(duckdb_arrow result);
void duckdb_destroy_arrow(duckdb_arrow *result);

duckdb_open

Creates a new database or opens an existing database file stored at the the given path. If no path is given a new in-memory database is created instead.

Syntax

duckdb_state duckdb_open(
  const char *path,
  duckdb_database *out_database
);

Parameters

• path

Path to the database file on disk, or nullptr or :memory: to open an in-memory database.

• out_database

The result database object.

• returns

DuckDBSuccess on success or DuckDBError on failure.

duckdb_open_ext

Extended version of duckdb_open. Creates a new database or opens an existing database file stored at the the given path.

Syntax

duckdb_state duckdb_open_ext(
  const char *path,
  duckdb_database *out_database,
  duckdb_config config,
  char **out_error
);

Parameters

• path

Path to the database file on disk, or nullptr or :memory: to open an in-memory database.

• out_database

The result database object.

• config

(Optional) configuration used to start up the database system.

• out_error

If set and the function returns DuckDBError, this will contain the reason why the start-up failed. Note that the error must be freed using duckdb_free.

• returns

DuckDBSuccess on success or DuckDBError on failure.

duckdb_close

Closes the specified database and de-allocates all memory allocated for that database. This should be called after you are done with any database allocated through duckdb_open. Note that failing to call duckdb_close (in case of e.g. a program crash) will not cause data corruption. Still it is recommended to always correctly close a database object after you are done with it.

Syntax

void duckdb_close(
  duckdb_database *database
);

Parameters

• database

The database object to shut down.

duckdb_connect

Opens a connection to a database. Connections are required to query the database, and store transactional state associated with the connection.

Syntax

duckdb_state duckdb_connect(
  duckdb_database database,
  duckdb_connection *out_connection
);

Parameters

• database

The database file to connect to.

• out_connection

The result connection object.

• returns

DuckDBSuccess on success or DuckDBError on failure.

duckdb_disconnect

Closes the specified connection and de-allocates all memory allocated for that connection.

Syntax

void duckdb_disconnect(
  duckdb_connection *connection
);

Parameters

• connection

The connection to close.

duckdb_create_config

Initializes an empty configuration object that can be used to provide start-up options for the DuckDB instance through duckdb_open_ext.

This will always succeed unless there is a malloc failure.

Syntax

duckdb_state duckdb_create_config(
  duckdb_config *out_config
);

Parameters

• out_config

The result configuration object.

• returns

DuckDBSuccess on success or DuckDBError on failure.

duckdb_config_count

This returns the total amount of configuration options available for usage with duckdb_get_config_flag.

This should not be called in a loop as it internally loops over all the options.

Syntax

size_t duckdb_config_count(
  
);

Parameters

• returns

The amount of config options available.

duckdb_get_config_flag

Obtains a human-readable name and description of a specific configuration option. This can be used to e.g. display configuration options. This will succeed unless index is out of range (i.e. >= duckdb_config_count).

The result name or description MUST NOT be freed.

Syntax

duckdb_state duckdb_get_config_flag(
  size_t index,
  const char **out_name,
  const char **out_description
);

Parameters

• index

The index of the configuration option (between 0 and duckdb_config_count)

• out_name

A name of the configuration flag.

• out_description

A description of the configuration flag.

• returns

DuckDBSuccess on success or DuckDBError on failure.

duckdb_set_config

Sets the specified option for the specified configuration. The configuration option is indicated by name. To obtain a list of config options, see duckdb_get_config_flag.

In the source code, configuration options are defined in config.cpp.

This can fail if either the name is invalid, or if the value provided for the option is invalid.

Syntax

duckdb_state duckdb_set_config(
  duckdb_config config,
  const char *name,
  const char *option
);

Parameters

• duckdb_config

The configuration object to set the option on.

• name

The name of the configuration flag to set.

• option

The value to set the configuration flag to.

• returns

DuckDBSuccess on success or DuckDBError on failure.

duckdb_destroy_config

Destroys the specified configuration option and de-allocates all memory allocated for the object.

Syntax

void duckdb_destroy_config(
  duckdb_config *config
);

Parameters

• config

The configuration object to destroy.

duckdb_query

Executes a SQL query within a connection and stores the full (materialized) result in the out_result pointer. If the query fails to execute, DuckDBError is returned and the error message can be retrieved by calling duckdb_result_error.

Note that after running duckdb_query, duckdb_destroy_result must be called on the result object even if the query fails, otherwise the error stored within the result will not be freed correctly.

Syntax

duckdb_state duckdb_query(
  duckdb_connection connection,
  const char *query,
  duckdb_result *out_result
);

Parameters

• connection

The connection to perform the query in.

• query

The SQL query to run.

• out_result

The query result.

• returns

DuckDBSuccess on success or DuckDBError on failure.

duckdb_destroy_result

Closes the result and de-allocates all memory allocated for that connection.

Syntax

void duckdb_destroy_result(
  duckdb_result *result
);

Parameters

• result

The result to destroy.

duckdb_column_name

Returns the column name of the specified column. The result should not need be freed; the column names will automatically be destroyed when the result is destroyed.

Returns NULL if the column is out of range.

Syntax

const char *duckdb_column_name(
  duckdb_result *result,
  idx_t col
);

Parameters

• result

The result object to fetch the column name from.

• col

The column index.

• returns

The column name of the specified column.

duckdb_column_type

Returns the column type of the specified column.

Returns DUCKDB_TYPE_INVALID if the column is out of range.

Syntax

duckdb_type duckdb_column_type(
  duckdb_result *result,
  idx_t col
);

Parameters

• result

The result object to fetch the column type from.

• col

The column index.

• returns

The column type of the specified column.

duckdb_column_count

Returns the number of columns present in a the result object.

Syntax

idx_t duckdb_column_count(
  duckdb_result *result
);

Parameters

• result

The result object.

• returns

The number of columns present in the result object.

duckdb_row_count

Returns the number of rows present in a the result object.

Syntax

idx_t duckdb_row_count(
  duckdb_result *result
);

Parameters

• result

The result object.

• returns

The number of rows present in the result object.

duckdb_rows_changed

Returns the number of rows changed by the query stored in the result. This is relevant only for INSERT/UPDATE/DELETE queries. For other queries the rows_changed will be 0.

Syntax

idx_t duckdb_rows_changed(
  duckdb_result *result
);

Parameters

• result

The result object.

• returns

The number of rows changed.

duckdb_column_data

Returns the data of a specific column of a result in columnar format. This is the fastest way of accessing data in a query result, as no conversion or type checking must be performed (outside of the original switch). If performance is a concern, it is recommended to use this API over the duckdb_value functions.

The function returns a dense array which contains the result data. The exact type stored in the array depends on the corresponding duckdb_type (as provided by duckdb_column_type). For the exact type by which the data should be accessed, see the comments in the types section or the DUCKDB_TYPE enum.

For example, for a column of type DUCKDB_TYPE_INTEGER, rows can be accessed in the following manner:

int32_t *data = (int32_t *) duckdb_column_data(&result, 0);
printf("Data for row %d: %d\n", row, data[row]);

Syntax

void *duckdb_column_data(
  duckdb_result *result,
  idx_t col
);

Parameters

• result

The result object to fetch the column data from.

• col

The column index.

• returns

The column data of the specified column.

duckdb_nullmask_data

Returns the nullmask of a specific column of a result in columnar format. The nullmask indicates for every row whether or not the corresponding row is NULL. If a row is NULL, the values present in the array provided by duckdb_column_data are undefined.

int32_t *data = (int32_t *) duckdb_column_data(&result, 0);
bool *nullmask = duckdb_nullmask_data(&result, 0);
if (nullmask[row]) {
printf("Data for row %d: NULL\n", row);
} else {
printf("Data for row %d: %d\n", row, data[row]);
}

Syntax

bool *duckdb_nullmask_data(
  duckdb_result *result,
  idx_t col
);

Parameters

• result

The result object to fetch the nullmask from.

• col

The column index.

• returns

The nullmask of the specified column.

duckdb_result_error

Returns the error message contained within the result. The error is only set if duckdb_query returns DuckDBError.

The result of this function must not be freed. It will be cleaned up when duckdb_destroy_result is called.

Syntax

char *duckdb_result_error(
  duckdb_result *result
);

Parameters

• result

The result object to fetch the nullmask from.

• returns

The error of the result.

duckdb_value_boolean

Syntax

bool duckdb_value_boolean(
  duckdb_result *result,
  idx_t col,
  idx_t row
);

Parameters

• returns

The boolean value at the specified location, or false if the value cannot be converted.

duckdb_value_int8

Syntax

int8_t duckdb_value_int8(
  duckdb_result *result,
  idx_t col,
  idx_t row
);

Parameters

• returns

The int8_t value at the specified location, or 0 if the value cannot be converted.

duckdb_value_int16

Syntax

int16_t duckdb_value_int16(
  duckdb_result *result,
  idx_t col,
  idx_t row
);

Parameters

• returns

The int16_t value at the specified location, or 0 if the value cannot be converted.

duckdb_value_int32

Syntax

int32_t duckdb_value_int32(
  duckdb_result *result,
  idx_t col,
  idx_t row
);

Parameters

• returns

The int32_t value at the specified location, or 0 if the value cannot be converted.

duckdb_value_int64

Syntax

int64_t duckdb_value_int64(
  duckdb_result *result,
  idx_t col,
  idx_t row
);

Parameters

• returns

The int64_t value at the specified location, or 0 if the value cannot be converted.

duckdb_value_hugeint

Syntax

duckdb_hugeint duckdb_value_hugeint(
  duckdb_result *result,
  idx_t col,
  idx_t row
);

Parameters

• returns

The duckdb_hugeint value at the specified location, or 0 if the value cannot be converted.

duckdb_value_uint8

Syntax

uint8_t duckdb_value_uint8(
  duckdb_result *result,
  idx_t col,
  idx_t row
);

Parameters

• returns

The uint8_t value at the specified location, or 0 if the value cannot be converted.

duckdb_value_uint16

Syntax

uint16_t duckdb_value_uint16(
  duckdb_result *result,
  idx_t col,
  idx_t row
);

Parameters

• returns

The uint16_t value at the specified location, or 0 if the value cannot be converted.

duckdb_value_uint32

Syntax

uint32_t duckdb_value_uint32(
  duckdb_result *result,
  idx_t col,
  idx_t row
);

Parameters

• returns

The uint32_t value at the specified location, or 0 if the value cannot be converted.

duckdb_value_uint64

Syntax

uint64_t duckdb_value_uint64(
  duckdb_result *result,
  idx_t col,
  idx_t row
);

Parameters

• returns

The uint64_t value at the specified location, or 0 if the value cannot be converted.

duckdb_value_float

Syntax

float duckdb_value_float(
  duckdb_result *result,
  idx_t col,
  idx_t row
);

Parameters

• returns

The float value at the specified location, or 0 if the value cannot be converted.

duckdb_value_double

Syntax

double duckdb_value_double(
  duckdb_result *result,
  idx_t col,
  idx_t row
);

Parameters

• returns

The double value at the specified location, or 0 if the value cannot be converted.

duckdb_value_date

Syntax

duckdb_date duckdb_value_date(
  duckdb_result *result,
  idx_t col,
  idx_t row
);

Parameters

• returns

The duckdb_date value at the specified location, or 0 if the value cannot be converted.

duckdb_value_time

Syntax

duckdb_time duckdb_value_time(
  duckdb_result *result,
  idx_t col,
  idx_t row
);

Parameters

• returns

The duckdb_time value at the specified location, or 0 if the value cannot be converted.

duckdb_value_timestamp

Syntax

duckdb_timestamp duckdb_value_timestamp(
  duckdb_result *result,
  idx_t col,
  idx_t row
);

Parameters

• returns

The duckdb_timestamp value at the specified location, or 0 if the value cannot be converted.

duckdb_value_interval

Syntax

duckdb_interval duckdb_value_interval(
  duckdb_result *result,
  idx_t col,
  idx_t row
);

Parameters

• returns

The duckdb_interval value at the specified location, or 0 if the value cannot be converted.

duckdb_value_varchar

Syntax

char *duckdb_value_varchar(
  duckdb_result *result,
  idx_t col,
  idx_t row
);

Parameters

• returns

The char* value at the specified location, or nullptr if the value cannot be converted. The result must be freed with duckdb_free.

duckdb_value_varchar_internal

Syntax

char *duckdb_value_varchar_internal(
  duckdb_result *result,
  idx_t col,
  idx_t row
);

Parameters

• returns

The char* value at the specified location. ONLY works on VARCHAR columns and does not auto-cast. If the column is NOT a VARCHAR column this function will return NULL.

The result must NOT be freed.

duckdb_value_blob

Syntax

duckdb_blob duckdb_value_blob(
  duckdb_result *result,
  idx_t col,
  idx_t row
);

Parameters

• returns

The duckdb_blob value at the specified location. Returns a blob with blob.data set to nullptr if the value cannot be converted. The resulting “blob.data” must be freed with duckdb_free.

duckdb_value_is_null

Syntax

bool duckdb_value_is_null(
  duckdb_result *result,
  idx_t col,
  idx_t row
);

Parameters

• returns

Returns true if the value at the specified index is NULL, and false otherwise.

duckdb_malloc

Allocate size bytes of memory using the duckdb internal malloc function. Any memory allocated in this manner should be freed using duckdb_free.

Syntax

void *duckdb_malloc(
  size_t size
);

Parameters

• size

The number of bytes to allocate.

• returns

A pointer to the allocated memory region.

duckdb_free

Free a value returned from duckdb_malloc, duckdb_value_varchar or duckdb_value_blob.

Syntax

void duckdb_free(
  void *ptr
);

Parameters

• ptr

The memory region to de-allocate.

duckdb_from_date

Decompose a duckdb_date object into year, month and date (stored as duckdb_date_struct).

Syntax

duckdb_date_struct duckdb_from_date(
  duckdb_date date
);

Parameters

• date

The date object, as obtained from a DUCKDB_TYPE_DATE column.

• returns

The duckdb_date_struct with the decomposed elements.

duckdb_to_date

Re-compose a duckdb_date from year, month and date (duckdb_date_struct).

Syntax

duckdb_date duckdb_to_date(
  duckdb_date_struct date
);

Parameters

• date

The year, month and date stored in a duckdb_date_struct.

• returns

The duckdb_date element.

duckdb_from_time

Decompose a duckdb_time object into hour, minute, second and microsecond (stored as duckdb_time_struct).

Syntax

duckdb_time_struct duckdb_from_time(
  duckdb_time time
);

Parameters

• time

The time object, as obtained from a DUCKDB_TYPE_TIME column.

• returns

The duckdb_time_struct with the decomposed elements.

duckdb_to_time

Re-compose a duckdb_time from hour, minute, second and microsecond (duckdb_time_struct).

Syntax

duckdb_time duckdb_to_time(
  duckdb_time_struct time
);

Parameters

• time

The hour, minute, second and microsecond in a duckdb_time_struct.

• returns

The duckdb_time element.

duckdb_from_timestamp

Decompose a duckdb_timestamp object into a duckdb_timestamp_struct.

Syntax

duckdb_timestamp_struct duckdb_from_timestamp(
  duckdb_timestamp ts
);

Parameters

• ts

The ts object, as obtained from a DUCKDB_TYPE_TIMESTAMP column.

• returns

The duckdb_timestamp_struct with the decomposed elements.

duckdb_to_timestamp

Re-compose a duckdb_timestamp from a duckdb_timestamp_struct.

Syntax

duckdb_timestamp duckdb_to_timestamp(
  duckdb_timestamp_struct ts
);

Parameters

• ts

The de-composed elements in a duckdb_timestamp_struct.

• returns

The duckdb_timestamp element.

duckdb_hugeint_to_double

Converts a duckdb_hugeint object (as obtained from a DUCKDB_TYPE_HUGEINT column) into a double.

Syntax

double duckdb_hugeint_to_double(
  duckdb_hugeint val
);

Parameters

• val

The hugeint value.

• returns

The converted double element.

duckdb_double_to_hugeint

Converts a double value to a duckdb_hugeint object.

If the conversion fails because the double value is too big the result will be 0.

Syntax

duckdb_hugeint duckdb_double_to_hugeint(
  double val
);

Parameters

• val

The double value.

• returns

The converted duckdb_hugeint element.

duckdb_prepare

Create a prepared statement object from a query.

Note that after calling duckdb_prepare, the prepared statement should always be destroyed using duckdb_destroy_prepare, even if the prepare fails.

If the prepare fails, duckdb_prepare_error can be called to obtain the reason why the prepare failed.

Syntax

duckdb_state duckdb_prepare(
  duckdb_connection connection,
  const char *query,
  duckdb_prepared_statement *out_prepared_statement
);

Parameters

• connection

The connection object

• query

The SQL query to prepare

• out_prepared_statement

The resulting prepared statement object

• returns

DuckDBSuccess on success or DuckDBError on failure.

duckdb_destroy_prepare

Closes the prepared statement and de-allocates all memory allocated for that connection.

Syntax

void duckdb_destroy_prepare(
  duckdb_prepared_statement *prepared_statement
);

Parameters

• prepared_statement

The prepared statement to destroy.

duckdb_prepare_error

Returns the error message associated with the given prepared statement. If the prepared statement has no error message, this returns nullptr instead.

The error message should not be freed. It will be de-allocated when duckdb_destroy_prepare is called.

Syntax

const char *duckdb_prepare_error(
  duckdb_prepared_statement prepared_statement
);

Parameters

• prepared_statement

The prepared statement to obtain the error from.

• returns

The error message, or nullptr if there is none.

duckdb_nparams

Returns the number of parameters that can be provided to the given prepared statement.

Returns 0 if the query was not successfully prepared.

Syntax

idx_t duckdb_nparams(
  duckdb_prepared_statement prepared_statement
);

Parameters

• prepared_statement

The prepared statement to obtain the number of parameters for.

duckdb_param_type

Returns the parameter type for the parameter at the given index.

Returns DUCKDB_TYPE_INVALID if the parameter index is out of range or the statement was not successfully prepared.

Syntax

duckdb_type duckdb_param_type(
  duckdb_prepared_statement prepared_statement,
  idx_t param_idx
);

Parameters

• prepared_statement

The prepared statement.

• param_idx

The parameter index.

• returns

The parameter type

duckdb_bind_boolean

Binds a bool value to the prepared statement at the specified index.

Syntax

duckdb_state duckdb_bind_boolean(
  duckdb_prepared_statement prepared_statement,
  idx_t param_idx,
  bool val
);

duckdb_bind_int8

Binds an int8_t value to the prepared statement at the specified index.

Syntax

duckdb_state duckdb_bind_int8(
  duckdb_prepared_statement prepared_statement,
  idx_t param_idx,
  int8_t val
);

duckdb_bind_int16

Binds an int16_t value to the prepared statement at the specified index.

Syntax

duckdb_state duckdb_bind_int16(
  duckdb_prepared_statement prepared_statement,
  idx_t param_idx,
  int16_t val
);

duckdb_bind_int32

Binds an int32_t value to the prepared statement at the specified index.

Syntax

duckdb_state duckdb_bind_int32(
  duckdb_prepared_statement prepared_statement,
  idx_t param_idx,
  int32_t val
);

duckdb_bind_int64

Binds an int64_t value to the prepared statement at the specified index.

Syntax

duckdb_state duckdb_bind_int64(
  duckdb_prepared_statement prepared_statement,
  idx_t param_idx,
  int64_t val
);

duckdb_bind_hugeint

Binds an duckdb_hugeint value to the prepared statement at the specified index.

Syntax

duckdb_state duckdb_bind_hugeint(
  duckdb_prepared_statement prepared_statement,
  idx_t param_idx,
  duckdb_hugeint val
);

duckdb_bind_uint8

Binds an uint8_t value to the prepared statement at the specified index.

Syntax

duckdb_state duckdb_bind_uint8(
  duckdb_prepared_statement prepared_statement,
  idx_t param_idx,
  uint8_t val
);

duckdb_bind_uint16

Binds an uint16_t value to the prepared statement at the specified index.

Syntax

duckdb_state duckdb_bind_uint16(
  duckdb_prepared_statement prepared_statement,
  idx_t param_idx,
  uint16_t val
);

duckdb_bind_uint32

Binds an uint32_t value to the prepared statement at the specified index.

Syntax

duckdb_state duckdb_bind_uint32(
  duckdb_prepared_statement prepared_statement,
  idx_t param_idx,
  uint32_t val
);

duckdb_bind_uint64

Binds an uint64_t value to the prepared statement at the specified index.

Syntax

duckdb_state duckdb_bind_uint64(
  duckdb_prepared_statement prepared_statement,
  idx_t param_idx,
  uint64_t val
);

duckdb_bind_float

Binds an float value to the prepared statement at the specified index.

Syntax

duckdb_state duckdb_bind_float(
  duckdb_prepared_statement prepared_statement,
  idx_t param_idx,
  float val
);

duckdb_bind_double

Binds an double value to the prepared statement at the specified index.

Syntax

duckdb_state duckdb_bind_double(
  duckdb_prepared_statement prepared_statement,
  idx_t param_idx,
  double val
);

duckdb_bind_date

Binds a duckdb_date value to the prepared statement at the specified index.

Syntax

duckdb_state duckdb_bind_date(
  duckdb_prepared_statement prepared_statement,
  idx_t param_idx,
  duckdb_date val
);

duckdb_bind_time

Binds a duckdb_time value to the prepared statement at the specified index.

Syntax

duckdb_state duckdb_bind_time(
  duckdb_prepared_statement prepared_statement,
  idx_t param_idx,
  duckdb_time val
);

duckdb_bind_timestamp

Binds a duckdb_timestamp value to the prepared statement at the specified index.

Syntax

duckdb_state duckdb_bind_timestamp(
  duckdb_prepared_statement prepared_statement,
  idx_t param_idx,
  duckdb_timestamp val
);

duckdb_bind_interval

Binds a duckdb_interval value to the prepared statement at the specified index.

Syntax

duckdb_state duckdb_bind_interval(
  duckdb_prepared_statement prepared_statement,
  idx_t param_idx,
  duckdb_interval val
);

duckdb_bind_varchar

Binds a null-terminated varchar value to the prepared statement at the specified index.

Syntax

duckdb_state duckdb_bind_varchar(
  duckdb_prepared_statement prepared_statement,
  idx_t param_idx,
  const char *val
);

duckdb_bind_varchar_length

Binds a varchar value to the prepared statement at the specified index.

Syntax

duckdb_state duckdb_bind_varchar_length(
  duckdb_prepared_statement prepared_statement,
  idx_t param_idx,
  const char *val,
  idx_t length
);

duckdb_bind_blob

Binds a blob value to the prepared statement at the specified index.

Syntax

duckdb_state duckdb_bind_blob(
  duckdb_prepared_statement prepared_statement,
  idx_t param_idx,
  const void *data,
  idx_t length
);

duckdb_bind_null

Binds a NULL value to the prepared statement at the specified index.

Syntax

duckdb_state duckdb_bind_null(
  duckdb_prepared_statement prepared_statement,
  idx_t param_idx
);

duckdb_execute_prepared

Executes the prepared statement with the given bound parameters, and returns a materialized query result.

This method can be called multiple times for each prepared statement, and the parameters can be modified between calls to this function.

Syntax

duckdb_state duckdb_execute_prepared(
  duckdb_prepared_statement prepared_statement,
  duckdb_result *out_result
);

Parameters

• prepared_statement

The prepared statement to execute.

• out_result

The query result.

• returns

DuckDBSuccess on success or DuckDBError on failure.

duckdb_execute_prepared_arrow

Executes the prepared statement with the given bound parameters, and returns an arrow query result.

Syntax

duckdb_state duckdb_execute_prepared_arrow(
  duckdb_prepared_statement prepared_statement,
  duckdb_arrow *out_result
);

Parameters

• prepared_statement

The prepared statement to execute.

• out_result

The query result.

• returns

DuckDBSuccess on success or DuckDBError on failure.

duckdb_appender_create

Creates an appender object.

Syntax

duckdb_state duckdb_appender_create(
  duckdb_connection connection,
  const char *schema,
  const char *table,
  duckdb_appender *out_appender
);

Parameters

• connection

The connection context to create the appender in.

• schema

The schema of the table to append to, or nullptr for the default schema.

• table

The table name to append to.

• out_appender

The resulting appender object.

• returns

DuckDBSuccess on success or DuckDBError on failure.

duckdb_appender_error

Returns the error message associated with the given appender. If the appender has no error message, this returns nullptr instead.

The error message should be freed using duckdb_free.

Syntax

const char *duckdb_appender_error(
  duckdb_appender appender
);

Parameters

• appender

The appender to get the error from.

• returns

The error message, or nullptr if there is none.

duckdb_appender_flush

Flush the appender to the table, forcing the cache of the appender to be cleared and the data to be appended to the base table.

This should generally not be used unless you know what you are doing. Instead, call duckdb_appender_destroy when you are done with the appender.

Syntax

duckdb_state duckdb_appender_flush(
  duckdb_appender appender
);

Parameters

• appender

The appender to flush.

• returns

DuckDBSuccess on success or DuckDBError on failure.

duckdb_appender_close

Close the appender, flushing all intermediate state in the appender to the table and closing it for further appends.

This is generally not necessary. Call duckdb_appender_destroy instead.

Syntax

duckdb_state duckdb_appender_close(
  duckdb_appender appender
);

Parameters

• appender

The appender to flush and close.

• returns

DuckDBSuccess on success or DuckDBError on failure.

duckdb_appender_destroy

Close the appender and destroy it. Flushing all intermediate state in the appender to the table, and de-allocating all memory associated with the appender.

Syntax

duckdb_state duckdb_appender_destroy(
  duckdb_appender *appender
);

Parameters

• appender

The appender to flush, close and destroy.

• returns

DuckDBSuccess on success or DuckDBError on failure.

duckdb_appender_begin_row

A nop function, provided for backwards compatibility reasons. Does nothing. Only duckdb_appender_end_row is required.

Syntax

duckdb_state duckdb_appender_begin_row(
  duckdb_appender appender
);

duckdb_appender_end_row

Finish the current row of appends. After end_row is called, the next row can be appended.

Syntax

duckdb_state duckdb_appender_end_row(
  duckdb_appender appender
);

Parameters

• appender

The appender.

• returns

DuckDBSuccess on success or DuckDBError on failure.

duckdb_append_bool

Append a bool value to the appender.

Syntax

duckdb_state duckdb_append_bool(
  duckdb_appender appender,
  bool value
);

duckdb_append_int8

Append an int8_t value to the appender.

Syntax

duckdb_state duckdb_append_int8(
  duckdb_appender appender,
  int8_t value
);

duckdb_append_int16

Append an int16_t value to the appender.

Syntax

duckdb_state duckdb_append_int16(
  duckdb_appender appender,
  int16_t value
);

duckdb_append_int32

Append an int32_t value to the appender.

Syntax

duckdb_state duckdb_append_int32(
  duckdb_appender appender,
  int32_t value
);

duckdb_append_int64

Append an int64_t value to the appender.

Syntax

duckdb_state duckdb_append_int64(
  duckdb_appender appender,
  int64_t value
);

duckdb_append_hugeint

Append a duckdb_hugeint value to the appender.

Syntax

duckdb_state duckdb_append_hugeint(
  duckdb_appender appender,
  duckdb_hugeint value
);

duckdb_append_uint8

Append a uint8_t value to the appender.

Syntax

duckdb_state duckdb_append_uint8(
  duckdb_appender appender,
  uint8_t value
);

duckdb_append_uint16

Append a uint16_t value to the appender.

Syntax

duckdb_state duckdb_append_uint16(
  duckdb_appender appender,
  uint16_t value
);

duckdb_append_uint32

Append a uint32_t value to the appender.

Syntax

duckdb_state duckdb_append_uint32(
  duckdb_appender appender,
  uint32_t value
);

duckdb_append_uint64

Append a uint64_t value to the appender.

Syntax

duckdb_state duckdb_append_uint64(
  duckdb_appender appender,
  uint64_t value
);

duckdb_append_float

Append a float value to the appender.

Syntax

duckdb_state duckdb_append_float(
  duckdb_appender appender,
  float value
);

duckdb_append_double

Append a double value to the appender.

Syntax

duckdb_state duckdb_append_double(
  duckdb_appender appender,
  double value
);

duckdb_append_date

Append a duckdb_date value to the appender.

Syntax

duckdb_state duckdb_append_date(
  duckdb_appender appender,
  duckdb_date value
);

duckdb_append_time

Append a duckdb_time value to the appender.

Syntax

duckdb_state duckdb_append_time(
  duckdb_appender appender,
  duckdb_time value
);

duckdb_append_timestamp

Append a duckdb_timestamp value to the appender.

Syntax

duckdb_state duckdb_append_timestamp(
  duckdb_appender appender,
  duckdb_timestamp value
);

duckdb_append_interval

Append a duckdb_interval value to the appender.

Syntax

duckdb_state duckdb_append_interval(
  duckdb_appender appender,
  duckdb_interval value
);

duckdb_append_varchar

Append a varchar value to the appender.

Syntax

duckdb_state duckdb_append_varchar(
  duckdb_appender appender,
  const char *val
);

duckdb_append_varchar_length

Append a varchar value to the appender.

Syntax

duckdb_state duckdb_append_varchar_length(
  duckdb_appender appender,
  const char *val,
  idx_t length
);

duckdb_append_blob

Append a blob value to the appender.

Syntax

duckdb_state duckdb_append_blob(
  duckdb_appender appender,
  const void *data,
  idx_t length
);

duckdb_append_null

Append a NULL value to the appender (of any type).

Syntax

duckdb_state duckdb_append_null(
  duckdb_appender appender
);

duckdb_query_arrow

Executes a SQL query within a connection and stores the full (materialized) result in an arrow structure. If the query fails to execute, DuckDBError is returned and the error message can be retrieved by calling duckdb_query_arrow_error.

Note that after running duckdb_query_arrow, duckdb_destroy_arrow must be called on the result object even if the query fails, otherwise the error stored within the result will not be freed correctly.

Syntax

duckdb_state duckdb_query_arrow(
  duckdb_connection connection,
  const char *query,
  duckdb_arrow *out_result
);

Parameters

• connection

The connection to perform the query in.

• query

The SQL query to run.

• out_result

The query result.

• returns

DuckDBSuccess on success or DuckDBError on failure.

duckdb_query_arrow_schema

Fetch the internal arrow schema from the arrow result.

Syntax

duckdb_state duckdb_query_arrow_schema(
  duckdb_arrow result,
  duckdb_arrow_schema *out_schema
);

Parameters

• result

The result to fetch the schema from.

• out_schema

The output schema.

• returns

DuckDBSuccess on success or DuckDBError on failure.

duckdb_query_arrow_array

Fetch an internal arrow array from the arrow result.

This function can be called multiple time to get next chunks, which will free the previous out_array. So consume the out_array before calling this function again.

Syntax

duckdb_state duckdb_query_arrow_array(
  duckdb_arrow result,
  duckdb_arrow_array *out_array
);

Parameters

• result

The result to fetch the array from.

• out_array

The output array.

• returns

DuckDBSuccess on success or DuckDBError on failure.

duckdb_arrow_column_count

Returns the number of columns present in a the arrow result object.

Syntax

idx_t duckdb_arrow_column_count(
  duckdb_arrow result
);

Parameters

• result

The result object.

• returns

The number of columns present in the result object.

duckdb_arrow_row_count

Returns the number of rows present in a the arrow result object.

Syntax

idx_t duckdb_arrow_row_count(
  duckdb_arrow result
);

Parameters

• result

The result object.

• returns

The number of rows present in the result object.

duckdb_arrow_rows_changed

Returns the number of rows changed by the query stored in the arrow result. This is relevant only for INSERT/UPDATE/DELETE queries. For other queries the rows_changed will be 0.

Syntax

idx_t duckdb_arrow_rows_changed(
  duckdb_arrow result
);

Parameters

• result

The result object.

• returns

The number of rows changed.

duckdb_query_arrow_error

Returns the error message contained within the result. The error is only set if duckdb_query_arrow returns DuckDBError.

The result should be freed using duckdb_free.

Syntax

const char *duckdb_query_arrow_error(
  duckdb_arrow result
);

Parameters

• result

The result object to fetch the nullmask from.

• returns

The error of the result.

duckdb_destroy_arrow

Closes the result and de-allocates all memory allocated for the arrow result.

Syntax

void duckdb_destroy_arrow(
  duckdb_arrow *result
);

Parameters

• result

The result to destroy.