Struct PageQuery 

pub struct PageQuery { /* private fields */ }

What a PageSource is asked for: its rows, in an order (an ORDER BY).

Implementations

impl PageQuery

pub fn new() -> Self

The source’s rows in its own order.

pub fn sorted_by(self, key: SortKey) -> Self

The query with its rows sorted by key too, after the keys it has.

pub fn sort(&self) -> &[SortKey]

The keys rows are sorted by, the first first; none for the source’s own order.

pub fn order_by_sql<S: AsRef<str>>(&self, keys: &[S]) -> String

The order as an SQL ORDER BY clause, for a source that pages a query with LIMIT and OFFSET: the sort keys, then the keys not among them, ascending. Give as keys the columns that tell rows apart (an id): rows that tie in every sort key then keep one order from page to page, so none shows twice or goes missing. Names are quoted as standard SQL quotes them ("time", and "a ""b""" for a column named a "b"), each once. Empty with no sort keys and no keys, which leaves the order to the engine: one that reads in parallel may change it from one page to the next.

use densa_arrow::{PageQuery, SortKey};
use densa_grid::SortOrder;

let query = PageQuery::new().sorted_by(SortKey::new("time", SortOrder::Descending));
let order = query.order_by_sql(&["id"]);
assert_eq!(order, r#"ORDER BY "time" DESC, "id""#);
let sql = format!("SELECT * FROM trips {order} LIMIT 256 OFFSET 512");

Trait Implementations

impl Clone for PageQuery

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for PageQuery

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

Formats the value using the given formatter.

impl Default for PageQuery

fn default() -> Self

Returns the “default value” for a type.

impl PartialEq for PageQuery

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for PageQuery