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Use variable for sequential ratio [skip ci]

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This commit is contained in:
Andrew Kane
2024-09-28 19:29:53 -07:00
parent d423ac3230
commit 71f54cabf4
1 changed files with 3 additions and 2 deletions
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5
src/ivfflat.c
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@@ -69,6 +69,7 @@ ivfflatcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
GenericCosts costs;
int lists;
double ratio;
double sequentialRatio = 0.5;
double startupPages;
double spc_seq_page_cost;
Relation index;
@@ -100,7 +101,7 @@ 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 -= 0.5 * costs.numIndexPages * (costs.spc_random_page_cost - spc_seq_page_cost);
costs.indexTotalCost -= sequentialRatio * costs.numIndexPages * (costs.spc_random_page_cost - spc_seq_page_cost);
/* Startup cost is cost before returning the first row */
costs.indexStartupCost = costs.indexTotalCost * ratio;
@@ -110,7 +111,7 @@ ivfflatcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
if (startupPages > path->indexinfo->rel->pages && ratio < 0.5)
{
/* Change rest of page cost from random to sequential */
costs.indexStartupCost -= 0.5 * startupPages * (costs.spc_random_page_cost - spc_seq_page_cost);
costs.indexStartupCost -= (1 - sequentialRatio) * startupPages * (costs.spc_random_page_cost - spc_seq_page_cost);
/* Remove cost of extra pages */
costs.indexStartupCost -= (startupPages - path->indexinfo->rel->pages) * spc_seq_page_cost;