From 36ed866e3d28a709fd1133a89ecdc7a2654a657f Mon Sep 17 00:00:00 2001 From: Ilia Evdokimov Date: Wed, 2 Apr 2025 10:49:27 +0300 Subject: [PATCH v6] Display estimated distinct keys and cache capacity in EXPLAIN ANALYZE for Memoize when cache misses occur --- src/backend/commands/explain.c | 13 +++++++++++++ src/backend/optimizer/path/costsize.c | 3 +++ src/backend/optimizer/plan/createplan.c | 10 +++++++--- src/backend/optimizer/util/pathnode.c | 3 +++ src/include/nodes/pathnodes.h | 2 ++ src/include/nodes/plannodes.h | 6 ++++++ 6 files changed, 34 insertions(+), 3 deletions(-) diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c index ef8aa489af8..f21de58e0a0 100644 --- a/src/backend/commands/explain.c +++ b/src/backend/commands/explain.c @@ -3635,6 +3635,19 @@ show_memoize_info(MemoizeState *mstate, List *ancestors, ExplainState *es) if (mstate->stats.cache_misses > 0) { + if (es->format == EXPLAIN_FORMAT_TEXT) + { + ExplainIndentText(es); + appendStringInfo(es->str, "Estimated Capacity: %u Estimated Distinct Lookup Keys: %0.0f\n", + ((Memoize *) plan)->est_entries, + ((Memoize *) plan)->est_unique_keys); + } + else + { + ExplainPropertyUInteger("Estimated Capacity", "", ((Memoize *) plan)->est_entries, es); + ExplainPropertyFloat("Estimated Distinct Lookup Keys", "", ((Memoize *) plan)->est_unique_keys, 0, es); + } + /* * mem_peak is only set when we freed memory, so we must use mem_used * when mem_peak is 0. diff --git a/src/backend/optimizer/path/costsize.c b/src/backend/optimizer/path/costsize.c index f6f77b8fe19..e3abf9ccc26 100644 --- a/src/backend/optimizer/path/costsize.c +++ b/src/backend/optimizer/path/costsize.c @@ -2604,6 +2604,9 @@ cost_memoize_rescan(PlannerInfo *root, MemoizePath *mpath, mpath->est_entries = Min(Min(ndistinct, est_cache_entries), PG_UINT32_MAX); + /* Remember ndistinct for a potential EXPLAIN later */ + mpath->est_unique_keys = ndistinct; + /* * When the number of distinct parameter values is above the amount we can * store in the cache, then we'll have to evict some entries from the diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c index 75e2b0b9036..38882501484 100644 --- a/src/backend/optimizer/plan/createplan.c +++ b/src/backend/optimizer/plan/createplan.c @@ -284,7 +284,8 @@ static Material *make_material(Plan *lefttree); static Memoize *make_memoize(Plan *lefttree, Oid *hashoperators, Oid *collations, List *param_exprs, bool singlerow, bool binary_mode, - uint32 est_entries, Bitmapset *keyparamids); + uint32 est_entries, double est_unique_keys, + Bitmapset *keyparamids); static WindowAgg *make_windowagg(List *tlist, WindowClause *wc, int partNumCols, AttrNumber *partColIdx, Oid *partOperators, Oid *partCollations, int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations, @@ -1703,7 +1704,8 @@ create_memoize_plan(PlannerInfo *root, MemoizePath *best_path, int flags) plan = make_memoize(subplan, operators, collations, param_exprs, best_path->singlerow, best_path->binary_mode, - best_path->est_entries, keyparamids); + best_path->est_entries, best_path->est_unique_keys, + keyparamids); copy_generic_path_info(&plan->plan, (Path *) best_path); @@ -6636,7 +6638,8 @@ materialize_finished_plan(Plan *subplan) static Memoize * make_memoize(Plan *lefttree, Oid *hashoperators, Oid *collations, List *param_exprs, bool singlerow, bool binary_mode, - uint32 est_entries, Bitmapset *keyparamids) + uint32 est_entries, double est_unique_keys, + Bitmapset *keyparamids) { Memoize *node = makeNode(Memoize); Plan *plan = &node->plan; @@ -6654,6 +6657,7 @@ make_memoize(Plan *lefttree, Oid *hashoperators, Oid *collations, node->binary_mode = binary_mode; node->est_entries = est_entries; node->keyparamids = keyparamids; + node->est_unique_keys = est_unique_keys; return node; } diff --git a/src/backend/optimizer/util/pathnode.c b/src/backend/optimizer/util/pathnode.c index 93e73cb44db..1fbcda99067 100644 --- a/src/backend/optimizer/util/pathnode.c +++ b/src/backend/optimizer/util/pathnode.c @@ -1701,6 +1701,9 @@ create_memoize_path(PlannerInfo *root, RelOptInfo *rel, Path *subpath, Assert(enable_memoize); pathnode->path.disabled_nodes = subpath->disabled_nodes; + /* Estimated number of distinct memoization keys, computed using estimate_num_groups() */ + pathnode->est_unique_keys = 0; + /* * Add a small additional charge for caching the first entry. All the * harder calculations for rescans are performed in cost_memoize_rescan(). diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h index c24a1fc8514..0946ccea994 100644 --- a/src/include/nodes/pathnodes.h +++ b/src/include/nodes/pathnodes.h @@ -2040,6 +2040,8 @@ typedef struct MemoizePath uint32 est_entries; /* The maximum number of entries that the * planner expects will fit in the cache, or 0 * if unknown */ + double est_unique_keys; /* Estimated number of distinct memoization keys, + * used for cache size evaluation. Kept for EXPLAIN */ } MemoizePath; /* diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h index 658d76225e4..3d9d3a1159d 100644 --- a/src/include/nodes/plannodes.h +++ b/src/include/nodes/plannodes.h @@ -1063,6 +1063,12 @@ typedef struct Memoize /* paramids from param_exprs */ Bitmapset *keyparamids; + + /* + * Estimated number of distinct memoization keys, + * used for cache size evaluation. Kept for EXPLAIN + */ + double est_unique_keys; } Memoize; /* ---------------- -- 2.34.1