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/*
* include/query/knn.h
*
* Copyright (C) 2023 Douglas B. Rumbaugh <drumbaugh@psu.edu>
*
* Distributed under the Modified BSD License.
*
* A query class for k-NN queries, designed for use with the VPTree
* shard.
*
* FIXME: no support for tombstone deletes just yet. This would require a
* query resumption mechanism, most likely.
*/
#pragma once
#include "framework/QueryRequirements.h"
#include "psu-ds/PriorityQueue.h"
namespace de {
namespace knn {
using psudb::PriorityQueue;
template <ShardInterface S> class Query {
typedef typename S::RECORD R;
public:
struct Parameters {
R point;
size_t k;
};
struct LocalQuery {
Parameters global_parms;
};
struct LocalQueryBuffer {
BufferView<R> *buffer;
Parameters global_parms;
};
typedef Wrapped<R> LocalResultType;
typedef R ResultType;
constexpr static bool EARLY_ABORT = false;
constexpr static bool SKIP_DELETE_FILTER = true;
static LocalQuery *local_preproc(S *shard, Parameters *parms) {
auto query = new LocalQuery();
query->global_parms = *parms;
return query;
}
static LocalQueryBuffer *local_preproc_buffer(BufferView<R> *buffer,
Parameters *parms) {
auto query = new LocalQueryBuffer();
query->global_parms = *parms;
query->buffer = buffer;
return query;
}
static void distribute_query(Parameters *parms,
std::vector<LocalQuery *> const &local_queries,
LocalQueryBuffer *buffer_query) {
return;
}
static std::vector<LocalResultType> local_query(S *shard, LocalQuery *query) {
std::vector<LocalResultType> results;
Wrapped<R> wrec;
wrec.rec = query->global_parms.point;
wrec.header = 0;
PriorityQueue<Wrapped<R>, DistCmpMax<Wrapped<R>>> pq(query->global_parms.k,
&wrec);
shard->search(query->global_parms.point, query->global_parms.k, pq);
while (pq.size() > 0) {
results.emplace_back(*pq.peek().data);
pq.pop();
}
return results;
}
static std::vector<LocalResultType>
local_query_buffer(LocalQueryBuffer *query) {
std::vector<LocalResultType> results;
Wrapped<R> wrec;
wrec.rec = query->global_parms.point;
wrec.header = 0;
PriorityQueue<Wrapped<R>, DistCmpMax<Wrapped<R>>> pq(query->global_parms.k,
&wrec);
for (size_t i = 0; i < query->buffer->get_record_count(); i++) {
// Skip over deleted records (under tagging)
if (query->buffer->get(i)->is_deleted()) {
continue;
}
if (pq.size() < query->global_parms.k) {
pq.push(query->buffer->get(i));
} else {
double head_dist = pq.peek().data->rec.calc_distance(wrec.rec);
double cur_dist = (query->buffer->get(i))->rec.calc_distance(wrec.rec);
if (cur_dist < head_dist) {
pq.pop();
pq.push(query->buffer->get(i));
}
}
}
while (pq.size() > 0) {
results.emplace_back(*(pq.peek().data));
pq.pop();
}
return std::move(results);
}
static void
combine(std::vector<std::vector<LocalResultType>> const &local_results,
Parameters *parms, std::vector<ResultType> &output) {
PriorityQueue<R, DistCmpMax<R>> pq(parms->k, &(parms->point));
for (size_t i = 0; i < local_results.size(); i++) {
for (size_t j = 0; j < local_results[i].size(); j++) {
if (pq.size() < parms->k) {
pq.push(&local_results[i][j].rec);
} else {
double head_dist = pq.peek().data->calc_distance(parms->point);
double cur_dist = local_results[i][j].rec.calc_distance(parms->point);
if (cur_dist < head_dist) {
pq.pop();
pq.push(&local_results[i][j].rec);
}
}
}
}
while (pq.size() > 0) {
output.emplace_back(*pq.peek().data);
pq.pop();
}
}
static bool repeat(Parameters *parms, std::vector<ResultType> &output,
std::vector<LocalQuery *> const &local_queries,
LocalQueryBuffer *buffer_query) {
return false;
}
};
} // namespace knn
} // namespace de
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