QueryIterator()

Creates an iterator that retrieves query results in bounded batches.

pub async fn query_iterator(&self, request: QueryIteratorRequest) -> Result<QueryIterator>

Request Syntax

let request = QueryIteratorRequest::builder()
    .query(
        QueryRequest::builder()
            .collection_name("books")
            .filter("id > 0")
            .output_fields(["id", "title"])
            .build()?,
    )
    .batch_size(100)
    .build()?;
let mut iterator = client.query_iterator(request).await?;

REQUEST FIELDS:

• query: QueryRequest

  The QueryRequest that defines the collection, filter, and output fields. Query iterators do not accept primary-key IDs or order_by_fields. Required.

• batch_size: usize

  Number of rows returned per next() call. Defaults to 1000.

• reduce_stop_for_best: bool

  Whether the iterator stops fetching a page as soon as the best result is found. Defaults to true.

• cursor: Option<QueryCursor>

  A resumable primary-key cursor that pins the MVCC snapshot and resumes pagination from the captured position. Resume only with a cursor obtained from QueryIterator::cursor.

RETURN TYPE:

Result

RETURNS:

A QueryIterator used to page through the query results in batches. Returns an Error if the operation fails.

QueryIterator
    next() // -> Result<Option<response::dql::QueryResponse>>
    close() // -> Result<()>
    cursor() // -> Option<QueryCursor>

METHODS:

• next() (Result>) -

  Fetches the next batch of query results, or None when exhausted.

• close() (Result<()>) -

  Closes the iterator and releases server resources.

• cursor() (Option) -

  The current cursor position, when present.

  • get_session_ts() (u64) -

    The session timestamp of the cursor.

  • get_pk() (&QueryCursorPk) -

    The primary key of the last returned row.

  • get_last_element_offset() (Option) -

    The offset of the last returned element, when present.

Example

let request = QueryIteratorRequest::builder()
    .query(
        QueryRequest::builder()
            .collection_name("books")
            .filter("id > 0")
            .output_fields(["id", "title"])
            .build()?,
    )
    .batch_size(100)
    .build()?;
let mut iterator = client.query_iterator(request).await?;
while let Some(batch) = iterator.next().await? {
    println!("got {} rows", batch.results().get_row_count());
}