use std::{cmp::Ordering, collections::BinaryHeap};
use reifydb_core::{
error::diagnostic::query,
sort::{
SortDirection,
SortDirection::{Asc, Desc},
SortKey,
},
value::column::{buffer::ColumnBuffer, columns::Columns, headers::ColumnHeaders},
};
use reifydb_transaction::transaction::Transaction;
use reifydb_value::{error, reifydb_assertions, value::Value};
use tracing::instrument;
use crate::{
Result,
vm::volcano::query::{QueryContext, QueryNode, charge_query_memory},
};
struct HeapEntry {
row_idx: usize,
sort_values: Vec<Value>,
directions: Vec<SortDirection>,
}
impl HeapEntry {
fn new(row_idx: usize, sort_values: Vec<Value>, directions: Vec<SortDirection>) -> Self {
Self {
row_idx,
sort_values,
directions,
}
}
}
impl PartialEq for HeapEntry {
fn eq(&self, other: &Self) -> bool {
self.cmp(other) == Ordering::Equal
}
}
impl Eq for HeapEntry {}
impl PartialOrd for HeapEntry {
fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
Some(self.cmp(other))
}
}
impl Ord for HeapEntry {
fn cmp(&self, other: &Self) -> Ordering {
for i in 0..self.sort_values.len() {
let ord = self.sort_values[i].partial_cmp(&other.sort_values[i]).unwrap_or(Ordering::Equal);
let ord = match self.directions[i] {
Asc => ord,
Desc => ord.reverse(),
};
if ord != Ordering::Equal {
return ord;
}
}
Ordering::Equal
}
}
pub(crate) struct TopKNode {
input: Box<dyn QueryNode>,
by: Vec<SortKey>,
limit: usize,
initialized: Option<()>,
}
impl TopKNode {
pub(crate) fn new(input: Box<dyn QueryNode>, by: Vec<SortKey>, limit: usize) -> Self {
Self {
input,
by,
limit,
initialized: None,
}
}
}
impl QueryNode for TopKNode {
#[instrument(level = "trace", skip_all, name = "volcano::top_k::initialize")]
fn initialize<'a>(&mut self, rx: &mut Transaction<'a>, ctx: &QueryContext) -> Result<()> {
self.input.initialize(rx, ctx)?;
self.initialized = Some(());
Ok(())
}
#[instrument(level = "trace", skip_all, name = "volcano::top_k::next")]
fn next<'a>(&mut self, rx: &mut Transaction<'a>, ctx: &mut QueryContext) -> Result<Option<Columns>> {
reifydb_assertions! {
assert!(self.initialized.is_some(), "TopKNode::next() called before initialize()");
}
if self.limit == 0 {
return Ok(None);
}
let columns_opt = self.collect_input(rx, ctx)?;
let mut columns = match columns_opt {
Some(f) => f,
None => return Ok(None),
};
let row_count = columns.row_count();
if row_count <= self.limit {
return self.sort_all(&mut columns);
}
let key_cols: Vec<_> =
self.by.iter().map(|key| Self::resolve_key(&columns, key)).collect::<Result<Vec<_>>>()?;
let directions: Vec<_> = self.by.iter().map(|k| k.direction.clone()).collect();
let indices = self.select_top(&key_cols, &directions, row_count);
Self::permute(&mut columns, &indices);
Ok(Some(columns))
}
fn headers(&self) -> Option<ColumnHeaders> {
self.input.headers()
}
}
impl TopKNode {
fn resolve_key(columns: &Columns, key: &SortKey) -> Result<(ColumnBuffer, SortDirection)> {
let name = key.column.fragment();
if let Some(data) = columns.system_column(name) {
return Ok((data, key.direction.clone()));
}
let col = columns
.iter()
.find(|c| c.name() == name)
.ok_or_else(|| error!(query::column_not_found(key.column.clone())))?;
Ok((col.data().clone(), key.direction.clone()))
}
fn sort_all(&self, columns: &mut Columns) -> Result<Option<Columns>> {
let key_refs: Vec<_> =
self.by.iter().map(|key| Self::resolve_key(columns, key)).collect::<Result<Vec<_>>>()?;
let row_count = columns.row_count();
let mut indices: Vec<usize> = (0..row_count).collect();
indices.sort_unstable_by(|&l, &r| {
for (col, dir) in &key_refs {
let vl = col.get_value(l);
let vr = col.get_value(r);
let ord = vl.partial_cmp(&vr).unwrap_or(Ordering::Equal);
let ord = match dir {
Asc => ord,
Desc => ord.reverse(),
};
if ord != Ordering::Equal {
return ord;
}
}
Ordering::Equal
});
Self::permute(columns, &indices);
Ok(Some(columns.clone()))
}
#[instrument(level = "trace", skip_all, name = "volcano::top_k::collect")]
fn collect_input<'a>(&mut self, rx: &mut Transaction<'a>, ctx: &mut QueryContext) -> Result<Option<Columns>> {
let mut columns_opt: Option<Columns> = None;
let mut charged = 0usize;
while let Some(columns) = self.input.next(rx, ctx)? {
if let Some(existing_columns) = &mut columns_opt {
existing_columns.system.extend(&columns.system)?;
for (i, col) in columns.columns.iter().enumerate() {
existing_columns[i].extend(col.clone())?;
}
} else {
columns_opt = Some(columns);
}
if let Some(acc) = &columns_opt {
charge_query_memory(&ctx.memory, &mut charged, acc)?;
}
}
Ok(columns_opt)
}
#[instrument(level = "trace", skip_all, name = "volcano::top_k::heap")]
fn select_top(
&self,
key_cols: &[(ColumnBuffer, SortDirection)],
directions: &[SortDirection],
row_count: usize,
) -> Vec<usize> {
let mut heap: BinaryHeap<HeapEntry> = BinaryHeap::with_capacity(self.limit);
for row_idx in 0..row_count {
let sort_values: Vec<Value> = key_cols.iter().map(|(col, _)| col.get_value(row_idx)).collect();
let entry = HeapEntry::new(row_idx, sort_values, directions.to_vec());
if heap.len() < self.limit {
heap.push(entry);
} else if let Some(top) = heap.peek()
&& entry.cmp(top) == Ordering::Less
{
heap.pop();
heap.push(entry);
}
}
let mut indices: Vec<usize> = heap.into_iter().map(|e| e.row_idx).collect();
indices.sort_unstable_by(|&l, &r| {
for (col, dir) in key_cols {
let vl = col.get_value(l);
let vr = col.get_value(r);
let ord = vl.partial_cmp(&vr).unwrap_or(Ordering::Equal);
let ord = match dir {
Asc => ord,
Desc => ord.reverse(),
};
if ord != Ordering::Equal {
return ord;
}
}
Ordering::Equal
});
indices
}
#[instrument(level = "trace", skip_all, name = "volcano::top_k::permute")]
fn permute(columns: &mut Columns, indices: &[usize]) {
columns.system.permute_in_place(indices);
let cols = &mut columns.columns;
for col in cols.iter_mut() {
col.reorder(indices);
}
}
}