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Added same cost adjustment to HNSW as IVFFlat since TOAST not included in seq scan cost - #682 [skip ci]

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Andrew Kane
2024-09-25 15:33:57 -07:00
parent 1370dd6e86
commit 242a12b7d5
1 changed files with 19 additions and 0 deletions
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19
src/hnsw.c
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@@ -12,6 +12,7 @@
#include "utils/float.h"
#include "utils/guc.h"
#include "utils/selfuncs.h"
#include "utils/spccache.h"
#if PG_VERSION_NUM < 150000
#define MarkGUCPrefixReserved(x) EmitWarningsOnPlaceholders(x)
@@ -103,6 +104,7 @@ hnswcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
int layer0TuplesMax;
double layer0Selectivity;
double scalingFactor = 0.55;
double spc_seq_page_cost;
Relation index;
/* Never use index without order */
@@ -159,6 +161,23 @@ hnswcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
genericcostestimate(root, path, loop_count, &costs);
get_tablespace_page_costs(path->indexinfo->reltablespace, NULL, &spc_seq_page_cost);
/* Adjust cost if needed since TOAST not included in seq scan cost */
if (costs.numIndexPages > path->indexinfo->rel->pages)
{
/* Change all page cost from random to sequential */
costs.indexTotalCost -= costs.numIndexPages * (costs.spc_random_page_cost - spc_seq_page_cost);
/* Remove cost of extra pages */
costs.indexTotalCost -= (costs.numIndexPages - path->indexinfo->rel->pages) * spc_seq_page_cost;
}
else
{
/* Change some page cost from random to sequential */
costs.indexTotalCost -= 0.5 * costs.numIndexPages * (costs.spc_random_page_cost - spc_seq_page_cost);
}
/* Use total cost since most work happens before first tuple is returned */
*indexStartupCost = costs.indexTotalCost;
*indexTotalCost = costs.indexTotalCost;