Struct scylla::transport::iterator::QueryPager

pub struct QueryPager { /* private fields */ }

An intermediate object that allows to construct a stream over a query that is asynchronously paged in the background.

Before the results can be processed in a convenient way, the QueryPager needs to be cast into a typed stream. This is done by use of rows_stream() method. As the method is generic over the target type, the turbofish syntax can come in handy there, e.g. query_pager.rows_stream::<(i32, String, Uuid)>().

A pre-0.15.0 interface is also available, although deprecated: into_legacy() method converts QueryPager to LegacyRowIterator, enabling Stream’ed operation on rows being eagerly deserialized to the middle-man Row type. This is inefficient, especially if Row is not the intended target type.

Implementations

impl QueryPager

pub fn type_check<'frame, 'metadata, RowT: DeserializeRow<'frame, 'metadata>>( &self, ) -> Result<(), TypeCheckError>

Type-checks the iterator against given type.

This is automatically called upon transforming QueryPager into TypedRowStream. Can be used with next() for manual deserialization. See next() for an example.

pub fn rows_stream<RowT: 'static + for<'frame, 'metadata> DeserializeRow<'frame, 'metadata>>( self, ) -> Result<TypedRowStream<RowT>, TypeCheckError>

Casts the iterator to a given row type, enabling Stream’ed operations on rows, which deserialize them on-the-fly to that given type. It only allows deserializing owned types, because Stream is not lending. Begins with performing type check.

pub fn into_legacy(self) -> LegacyRowIterator

👎Deprecated since 0.15.0: Legacy deserialization API is inefficient and is going to be removed soon

Converts this iterator into an iterator over rows parsed as given type, using the legacy deserialization framework. This is inefficient, because all rows are being eagerly deserialized to a middle-man Row type.

pub fn tracing_ids(&self) -> &[Uuid]

If tracing was enabled returns tracing ids of all finished page queries

pub fn column_specs(&self) -> ColumnSpecs<'_>

Returns specification of row columns