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Added cost estimation [skip ci]

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This commit is contained in:
Andrew Kane
2024-09-20 21:30:52 -07:00
parent 88889f5a4c
commit 689f9c4659
1 changed files with 34 additions and 0 deletions
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34
src/ivfflat.c
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@@ -62,6 +62,35 @@ ivfflatbuildphasename(int64 phasenum)
}
}
/*
* Estimate the number of probes for iterative scans
*/
static int
EstimateProbes(PlannerInfo *root, IndexPath *path, int lists)
{
double selectivity = 1;
ListCell *lc;
double tuplesPerList;
/* Cannot estimate without limit */
/* limit_tuples includes offset */
if (root->limit_tuples < 0)
return 0;
/* Get the selectivity of non-index conditions */
foreach(lc, path->indexinfo->indrestrictinfo)
{
RestrictInfo *rinfo = lfirst(lc);
/* Skip DEFAULT_INEQ_SEL since it may be distance filter */
if (rinfo->norm_selec >= 0 && rinfo->norm_selec <= 1 && rinfo->norm_selec != (Selectivity) DEFAULT_INEQ_SEL)
selectivity *= rinfo->norm_selec;
}
tuplesPerList = path->indexinfo->tuples / (double) lists;
return root->limit_tuples / (tuplesPerList * selectivity);
}
/*
* Estimate the cost of an index scan
*/
@@ -73,6 +102,7 @@ ivfflatcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
{
GenericCosts costs;
int lists;
int probes;
double ratio;
double spc_seq_page_cost;
Relation index;
@@ -94,6 +124,10 @@ ivfflatcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
IvfflatGetMetaPageInfo(index, &lists, NULL);
index_close(index, NoLock);
probes = ivfflat_probes;
if (ivfflat_streaming)
probes = Max(probes, EstimateProbes(root, path, lists));
/* Get the ratio of lists that we need to visit */
ratio = ((double) ivfflat_probes) / lists;
if (ratio > 1.0)