Struct odbc_api::buffers::ColumnarRowSet

pub struct ColumnarRowSet { /* fields omitted */ }

A columnar buffer intended to be bound with crate::Cursor::bind_buffer in order to obtain results from a cursor.

This buffer is designed to be versatile. It supports a wide variety of usage scenarios. It is efficient in retrieving data, but expensive to allocate, as columns are allocated separately. This is required in order to efficiently allow for rebinding columns, if this buffer is used to provide array input parameters those maximum size is not known in advance.

Most applications should find the overhead negligible, especially if instances are reused.

Implementations

impl ColumnarRowSet

pub fn new(
    max_rows: u32,
    description: impl Iterator<Item = BufferDescription>
) -> Self

Allocates for each buffer description a buffer large enough to hold max_rows.

pub fn with_column_indices(
    max_rows: u32,
    description: impl Iterator<Item = (u16, BufferDescription)>
) -> Self

Allows you to pass the buffer descriptions together with a one based column index referring the column, the buffer is supposed to bind to. This allows you also to ignore columns in a result set, by not binding them at all. There is no restriction on the order of column indices passed, but the function will panic, if the indices are not unique.

pub fn column(&self, buffer_index: usize) -> AnyColumnView<'_>

Use this method to gain access to the actual column data.

Parameters

• buffer_index: Please note that the buffer index is not identical to the ODBC column index. For once it is zero based. It also indexes the buffer bound, and not the columns of the output result set. This is important, because not every column needs to be bound. Some columns may simply be ignored. That being said, if every column of the output should is bound in the buffer, in the same order in which they are enumerated in the result set, the relationship between column index and buffer index is `buffer_index = column_index - 1'.

pub fn num_rows(&self) -> usize

Number of valid rows in the buffer.

Trait Implementations

impl RowSetBuffer for ColumnarRowSet

pub fn bind_type(&self) -> u32

Declares the bind type of the Row set buffer. 0 Means a columnar binding is used. Any non zero number is interpreted as the size of a single row in a row wise binding style.

pub fn row_array_size(&self) -> u32

The batch size for bulk cursors, if retrieving many rows at once.

pub fn mut_num_fetch_rows(&mut self) -> &mut usize

Mutable reference to the number of fetched rows.

pub unsafe fn bind_to_cursor(
    &mut self,
    cursor: &mut impl Cursor
) -> Result<(), Error>

Binds the buffer either column or row wise to the cursor.