pgvector.git / summary / log / commit / refs

commit    629fa6f0cdc9f0e618b1383f7d69bd40317c878b
Author:   Andrew Kane <andrew@ankane.org>
Date:     Sat Jun 10 17:52:29 2023 +0000

    Updated cost estimation code (same logic)


 src/ivfflat.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/ivfflat.c b/src/ivfflat.c
index 196b763b..ef926a87 100644
--- a/src/ivfflat.c
+++ b/src/ivfflat.c
@@ -71,7 +71,6 @@ ivfflatcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 	int			lists;
 	double		ratio;
 	double		spc_seq_page_cost;
-	double		seqPageRatio = 0.5;
 	Relation	indexRel;
 #if PG_VERSION_NUM < 120000
 	List	   *qinfos;
@@ -115,18 +114,20 @@ ivfflatcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
 
 	get_tablespace_page_costs(path->indexinfo->reltablespace, NULL, &spc_seq_page_cost);
 
-	/* Change some page cost from random to sequential */
-	costs.indexTotalCost -= seqPageRatio * costs.numIndexPages * (costs.spc_random_page_cost - spc_seq_page_cost);
-
 	/* Adjust cost if needed since TOAST not included in seq scan cost */
 	if (costs.numIndexPages > path->indexinfo->rel->pages && ratio < 0.5)
 	{
-		/* Change rest of page cost from random to sequential */
-		costs.indexTotalCost -= (1 - seqPageRatio) * costs.numIndexPages * (costs.spc_random_page_cost - spc_seq_page_cost);
+		/* 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);
+	}
 
 	/*
 	 * If the list selectivity is lower than what is returned from the generic


[parent: a33e72d58e51]