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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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82
src/backend/access/spgist/spgkdtreeproc.c
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@@ -16,9 +16,11 @@
#include "postgres.h"
#include "access/spgist.h"
#include "access/spgist_private.h"
#include "access/stratnum.h"
#include "catalog/pg_type.h"
#include "utils/builtins.h"
#include "utils/float.h"
#include "utils/geo_decls.h"
@@ -162,6 +164,7 @@ spg_kd_inner_consistent(PG_FUNCTION_ARGS)
double coord;
int which;
int i;
BOX bboxes[2];
Assert(in->hasPrefix);
coord = DatumGetFloat8(in->prefixDatum);
@@ -248,12 +251,87 @@ spg_kd_inner_consistent(PG_FUNCTION_ARGS)
}
/* We must descend into the children identified by which */
out->nodeNumbers = (int *) palloc(sizeof(int) * 2);
out->nNodes = 0;
/* Fast-path for no matching children */
if (!which)
PG_RETURN_VOID();
out->nodeNumbers = (int *) palloc(sizeof(int) * 2);
/*
* When ordering scan keys are specified, we've to calculate distance for
* them. In order to do that, we need calculate bounding boxes for both
* children nodes. Calculation of those bounding boxes on non-zero level
* require knowledge of bounding box of upper node. So, we save bounding
* boxes to traversalValues.
*/
if (in->norderbys > 0)
{
BOX infArea;
BOX *area;
out->distances = (double **) palloc(sizeof(double *) * in->nNodes);
out->traversalValues = (void **) palloc(sizeof(void *) * in->nNodes);
if (in->level == 0)
{
float8 inf = get_float8_infinity();
infArea.high.x = inf;
infArea.high.y = inf;
infArea.low.x = -inf;
infArea.low.y = -inf;
area = &infArea;
}
else
{
area = (BOX *) in->traversalValue;
Assert(area);
}
bboxes[0].low = area->low;
bboxes[1].high = area->high;
if (in->level % 2)
{
/* split box by x */
bboxes[0].high.x = bboxes[1].low.x = coord;
bboxes[0].high.y = area->high.y;
bboxes[1].low.y = area->low.y;
}
else
{
/* split box by y */
bboxes[0].high.y = bboxes[1].low.y = coord;
bboxes[0].high.x = area->high.x;
bboxes[1].low.x = area->low.x;
}
}
for (i = 1; i <= 2; i++)
{
if (which & (1 << i))
out->nodeNumbers[out->nNodes++] = i - 1;
{
out->nodeNumbers[out->nNodes] = i - 1;
if (in->norderbys > 0)
{
MemoryContext oldCtx = MemoryContextSwitchTo(
in->traversalMemoryContext);
BOX *box = box_copy(&bboxes[i - 1]);
MemoryContextSwitchTo(oldCtx);
out->traversalValues[out->nNodes] = box;
out->distances[out->nNodes] = spg_key_orderbys_distances(
BoxPGetDatum(box), false,
in->orderbys, in->norderbys);
}
out->nNodes++;
}
}
/* Set up level increments, too */