diff options
Diffstat (limited to 'src/backend/optimizer/path/costsize.c')
-rw-r--r-- | src/backend/optimizer/path/costsize.c | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c index 1f04a2c182c..344a3188317 100644 --- a/src/backend/optimizer/path/costsize.c +++ b/src/backend/optimizer/path/costsize.c @@ -2572,13 +2572,13 @@ cost_memoize_rescan(PlannerInfo *root, MemoizePath *mpath, Cost input_startup_cost = mpath->subpath->startup_cost; Cost input_total_cost = mpath->subpath->total_cost; double tuples = mpath->subpath->rows; - double calls = mpath->calls; + Cardinality est_calls = mpath->est_calls; int width = mpath->subpath->pathtarget->width; double hash_mem_bytes; double est_entry_bytes; - double est_cache_entries; - double ndistinct; + Cardinality est_cache_entries; + Cardinality ndistinct; double evict_ratio; double hit_ratio; Cost startup_cost; @@ -2604,7 +2604,7 @@ cost_memoize_rescan(PlannerInfo *root, MemoizePath *mpath, est_cache_entries = floor(hash_mem_bytes / est_entry_bytes); /* estimate on the distinct number of parameter values */ - ndistinct = estimate_num_groups(root, mpath->param_exprs, calls, NULL, + ndistinct = estimate_num_groups(root, mpath->param_exprs, est_calls, NULL, &estinfo); /* @@ -2616,7 +2616,10 @@ cost_memoize_rescan(PlannerInfo *root, MemoizePath *mpath, * certainly mean a MemoizePath will never survive add_path(). */ if ((estinfo.flags & SELFLAG_USED_DEFAULT) != 0) - ndistinct = calls; + ndistinct = est_calls; + + /* Remember the ndistinct estimate for EXPLAIN */ + mpath->est_unique_keys = ndistinct; /* * Since we've already estimated the maximum number of entries we can @@ -2644,9 +2647,12 @@ cost_memoize_rescan(PlannerInfo *root, MemoizePath *mpath, * must look at how many scans are estimated in total for this node and * how many of those scans we expect to get a cache hit. */ - hit_ratio = ((calls - ndistinct) / calls) * + hit_ratio = ((est_calls - ndistinct) / est_calls) * (est_cache_entries / Max(ndistinct, est_cache_entries)); + /* Remember the hit ratio estimate for EXPLAIN */ + mpath->est_hit_ratio = hit_ratio; + Assert(hit_ratio >= 0 && hit_ratio <= 1.0); /* |