Struct BLob 

pub struct BLob(/* private fields */);

LOB implementation for binary values.

BLob is used within HdbValue::BLOB instances received from the database.

Bigger LOBs are not transferred completely in the first roundtrip, instead more data is fetched in subsequent roundtrips when needed.

BLob respects the Connection’s lob read length (see Connection::set_lob_read_length).

Implementations

impl BLob

pub async fn into_bytes(self) -> HdbResult<Vec<u8>>

Converts the BLob into a Vec.

All outstanding data (data that were not yet fetched from the server) are fetched into this BLob object, before the complete data, as far as they were not yet read from this BLob object, are returned.

Example

 let mut result_set = connection.query(query)?;
 let mut blob = result_set.into_single_row()?.into_single_value()?.try_into_blob()?;

 let b = blob.into_bytes()?; // Vec<u8>, can be huge

Alternative

For larger objects, a streaming approach using BLob::write_into might by more appropriate, to avoid total allocation of the large object.

Errors

Several variants of HdbError can occur.

pub async fn write_into<W: Unpin + AsyncWriteExt>( self, writer: &mut W, ) -> HdbResult<()>

Writes the content into the given writer.

Reads outstanding data in chunks of size Connection::lob_read_length from the database and writes them immediately into the writer, thus avoiding that all data are materialized within this BLob.

Errors

Various errors can occur.

pub async fn read_slice( &mut self, offset: u64, length: u32, ) -> HdbResult<Vec<u8>>

Reads from given offset and the given length, in bytes.

Errors

Several variants of HdbError can occur.

pub fn total_byte_length(&self) -> u64

Total length of data, in bytes.

pub fn is_empty(&self) -> bool

Returns true if the BLob does not contain data.

pub fn cur_buf_len(&self) -> usize

Current size of the internal buffer, in bytes.

pub fn server_usage(&self) -> ServerUsage

Provides information about the the server-side resource consumption that is related to this BLob object.

Trait Implementations

impl Clone for BLob

fn clone(&self) -> BLob

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for BLob

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

Formats the value using the given formatter.