Struct arrow_odbc::BufferAllocationOptions

pub struct BufferAllocationOptions {
    pub max_text_size: Option<usize>,
    pub max_binary_size: Option<usize>,
    pub fallibale_allocations: bool,
}

Allows setting limits for buffers bound to the ODBC data source. Check this out if you find that you get memory allocation, or zero sized column errors. Used than constructing a reader using [crate::OdbcReader::with].

Fields

max_text_size: Option<usize>

An upper limit for the size of buffers bound to variadic text columns of the data source. This limit does not (directly) apply to the size of the created arrow buffers, but rather applies to the buffers used for the data in transit. Use this option if you have e.g. VARCHAR(MAX) fields in your database schema. In such a case without an upper limit, the ODBC driver of your data source is asked for the maximum size of an element, and is likely to answer with either 0 or a value which is way larger than any actual entry in the column If you can not adapt your database schema, this limit might be what you are looking for. On windows systems the size is double words (16Bit), as windows utilizes an UTF-16 encoding. So this translates to roughly the size in letters. On non windows systems this is the size in bytes and the datasource is assumed to utilize an UTF-8 encoding. None means no upper limit is set and the maximum element size, reported by ODBC is used to determine buffer sizes.

max_binary_size: Option<usize>

An upper limit for the size of buffers bound to variadic binary columns of the data source. This limit does not (directly) apply to the size of the created arrow buffers, but rather applies to the buffers used for the data in transit. Use this option if you have e.g. VARBINARY(MAX) fields in your database schema. In such a case without an upper limit, the ODBC driver of your data source is asked for the maximum size of an element, and is likely to answer with either 0 or a value which is way larger than any actual entry in the column. If you can not adapt your database schema, this limit might be what you are looking for. This is the maximum size in bytes of the binary column.

fallibale_allocations: bool

Set to true in order to trigger an ColumnFailure::TooLarge instead of a panic in case the buffers can not be allocated due to their size. This might have a performance cost for constructing the reader. false by default.

Trait Implementations

impl Clone for BufferAllocationOptions

fn clone(&self) -> BufferAllocationOptions

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for BufferAllocationOptions

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for BufferAllocationOptions

fn default() -> BufferAllocationOptions

Returns the “default value” for a type.

impl Copy for BufferAllocationOptions