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Only adjust cost if random_page_cost is higher than seq_page_cost

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This commit is contained in:
Andrew Kane
2023-06-10 01:06:05 -07:00
parent d6ab4892fe
commit 81cc04df61
1 changed files with 14 additions and 11 deletions
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25
src/ivfflat.c
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@@ -118,19 +118,22 @@ ivfflatcostestimate(PlannerInfo *root, IndexPath *path, double loop_count,
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 && ratio < 0.5)
if (costs.spc_random_page_cost > spc_seq_page_cost)
{
/* Change page cost from random to sequential */
startupCost -= 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 page cost from random to sequential */
startupCost -= costs.numIndexPages * (costs.spc_random_page_cost - spc_seq_page_cost);
/* Remove cost of extra pages */
startupCost -= (costs.numIndexPages - path->indexinfo->rel->pages) * spc_seq_page_cost;
}
else if (ratio < 0.5)
{
/* Change some page cost from random to sequential */
startupCost -= 0.5 * costs.numIndexPages * (costs.spc_random_page_cost - spc_seq_page_cost);
/* Remove cost of extra pages */
startupCost -= (costs.numIndexPages - path->indexinfo->rel->pages) * spc_seq_page_cost;
}
else if (ratio < 0.5)
{
/* Change some page cost from random to sequential */
startupCost -= 0.5 * costs.numIndexPages * (costs.spc_random_page_cost - spc_seq_page_cost);
}
}
/*