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Add support for nearest-neighbor (KNN) searches to SP-GiST

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Currently, KNN searches were supported only by GiST.  SP-GiST also capable to
support them.  This commit implements that support.  SP-GiST scan stack is
replaced with queue, which serves as stack if no ordering is specified.  KNN
support is provided for three SP-GIST opclasses: quad_point_ops, kd_point_ops
and poly_ops (catversion is bumped).  Some common parts between GiST and SP-GiST
KNNs are extracted into separate functions.

Discussion: https://postgr.es/m/570825e8-47d0-4732-2bf6-88d67d2d51c8%40postgrespro.ru
Author: Nikita Glukhov, Alexander Korotkov based on GSoC work by Vlad Sterzhanov
Review: Andrey Borodin, Alexander Korotkov
This commit is contained in:
Alexander Korotkov
2018-09-19 01:54:10 +03:00
parent d0cfc3d6a4
commit 2a6368343f
29 changed files with 1681 additions and 428 deletions
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70
src/backend/access/index/indexam.c
View File

@@ -74,6 +74,7 @@
#include "access/transam.h"
#include "access/xlog.h"
#include "catalog/index.h"
#include "catalog/pg_type.h"
#include "pgstat.h"
#include "storage/bufmgr.h"
#include "storage/lmgr.h"
@@ -897,3 +898,72 @@ index_getprocinfo(Relation irel,
return locinfo;
}
/* ----------------
* index_store_float8_orderby_distances
*
* Convert AM distance function's results (that can be inexact)
* to ORDER BY types and save them into xs_orderbyvals/xs_orderbynulls
* for a possible recheck.
* ----------------
*/
void
index_store_float8_orderby_distances(IndexScanDesc scan, Oid *orderByTypes,
double *distances, bool recheckOrderBy)
{
int i;
scan->xs_recheckorderby = recheckOrderBy;
if (!distances)
{
Assert(!scan->xs_recheckorderby);
for (i = 0; i < scan->numberOfOrderBys; i++)
{
scan->xs_orderbyvals[i] = (Datum) 0;
scan->xs_orderbynulls[i] = true;
}
return;
}
for (i = 0; i < scan->numberOfOrderBys; i++)
{
if (orderByTypes[i] == FLOAT8OID)
{
#ifndef USE_FLOAT8_BYVAL
/* must free any old value to avoid memory leakage */
if (!scan->xs_orderbynulls[i])
pfree(DatumGetPointer(scan->xs_orderbyvals[i]));
#endif
scan->xs_orderbyvals[i] = Float8GetDatum(distances[i]);
scan->xs_orderbynulls[i] = false;
}
else if (orderByTypes[i] == FLOAT4OID)
{
/* convert distance function's result to ORDER BY type */
#ifndef USE_FLOAT4_BYVAL
/* must free any old value to avoid memory leakage */
if (!scan->xs_orderbynulls[i])
pfree(DatumGetPointer(scan->xs_orderbyvals[i]));
#endif
scan->xs_orderbyvals[i] = Float4GetDatum((float4) distances[i]);
scan->xs_orderbynulls[i] = false;
}
else
{
/*
* If the ordering operator's return value is anything else, we
* don't know how to convert the float8 bound calculated by the
* distance function to that. The executor won't actually need
* the order by values we return here, if there are no lossy
* results, so only insist on converting if the *recheck flag is
* set.
*/
if (scan->xs_recheckorderby)
elog(ERROR, "ORDER BY operator must return float8 or float4 if the distance function is lossy");
scan->xs_orderbynulls[i] = true;
}
}
}