v8-0003-Show-estimated-lookups-in-EXPLAIN-ouput-for-Memoi.patch

From bbce295626e45d899e93a572d38074c40e8c9335 Mon Sep 17 00:00:00 2001
From: Evdokimov Ilia <ilya.evdokimov@tantorlabs.com>
Date: Wed, 16 Apr 2025 00:53:50 +0300
Subject: [PATCH v8 3/3] Show estimated lookups in EXPLAIN ouput for Memoize

Reviewed-by: David Rowley <dgrowleyml@gmail.com>
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Reviewed-by: Andrei Lepikhov <lepihov@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
---
 src/backend/commands/explain.c          |  4 +++-
 src/backend/optimizer/plan/createplan.c | 10 +++++++---
 src/include/nodes/plannodes.h           |  3 +++
 3 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/src/backend/commands/explain.c b/src/backend/commands/explain.c
index 85b22561aa6..6fcfa53a166 100644
--- a/src/backend/commands/explain.c
+++ b/src/backend/commands/explain.c
@@ -3633,15 +3633,17 @@ show_memoize_info(MemoizeState *mstate, List *ancestors, ExplainState *es)
 		if (es->format == EXPLAIN_FORMAT_TEXT)
 		{
 			ExplainIndentText(es);
-			appendStringInfo(es->str, "Estimates: capacity=%u distinct keys=%.0f hit ratio=%.2f%%\n",
+			appendStringInfo(es->str, "Estimates: capacity=%u distinct keys=%.0f lookups=%.0f hit ratio=%.2f%%\n",
 							((Memoize *) plan)->est_entries,
 							((Memoize *) plan)->est_unique_keys,
+							((Memoize *) plan)->lookups,
 							((Memoize *) plan)->hit_ratio * 100.0);
 		}
 		else
 		{
 			ExplainPropertyUInteger("Estimated Capacity", "", ((Memoize *) plan)->est_entries, es);
 			ExplainPropertyFloat("Estimated Distinct Lookup Keys", "", ((Memoize *) plan)->est_unique_keys, 0, es);
+			ExplainPropertyFloat("Estimated Lookups", "", ((Memoize *) plan)->lookups, 0, es);
 			ExplainPropertyFloat("Estimated Hit Ratio", "", ((Memoize *) plan)->hit_ratio * 100.0, 2, es);
 		}
 	}
diff --git a/src/backend/optimizer/plan/createplan.c b/src/backend/optimizer/plan/createplan.c
index ccb880158fe..47a092747d5 100644
--- a/src/backend/optimizer/plan/createplan.c
+++ b/src/backend/optimizer/plan/createplan.c
@@ -285,7 +285,8 @@ static Memoize *make_memoize(Plan *lefttree, Oid *hashoperators,
 							 Oid *collations, List *param_exprs,
 							 bool singlerow, bool binary_mode,
 							uint32 est_entries, Bitmapset *keyparamids,
-							double est_unique_keys, double hit_ratio);
+							double est_unique_keys, double hit_ratio,
+							double lookups);
 static WindowAgg *make_windowagg(List *tlist, WindowClause *wc,
 								 int partNumCols, AttrNumber *partColIdx, Oid *partOperators, Oid *partCollations,
 								 int ordNumCols, AttrNumber *ordColIdx, Oid *ordOperators, Oid *ordCollations,
@@ -1705,7 +1706,8 @@ 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_unique_keys, best_path->hit_ratio);
+						best_path->est_unique_keys, best_path->hit_ratio,
+						best_path->calls);
 
 	copy_generic_path_info(&plan->plan, (Path *) best_path);
 
@@ -6639,7 +6641,8 @@ static Memoize *
 make_memoize(Plan *lefttree, Oid *hashoperators, Oid *collations,
 			 List *param_exprs, bool singlerow, bool binary_mode,
 			uint32 est_entries, Bitmapset *keyparamids,
-			double est_unique_keys, double hit_ratio)
+			double est_unique_keys, double hit_ratio,
+			double lookups)
 {
 	Memoize    *node = makeNode(Memoize);
 	Plan	   *plan = &node->plan;
@@ -6659,6 +6662,7 @@ make_memoize(Plan *lefttree, Oid *hashoperators, Oid *collations,
 	node->keyparamids = keyparamids;
 	node->est_unique_keys = est_unique_keys;
 	node->hit_ratio = hit_ratio;
+	node->lookups = lookups;
 
 	return node;
 }
diff --git a/src/include/nodes/plannodes.h b/src/include/nodes/plannodes.h
index 4354d4f66d3..6eb08866304 100644
--- a/src/include/nodes/plannodes.h
+++ b/src/include/nodes/plannodes.h
@@ -1072,6 +1072,9 @@ typedef struct Memoize
 
 	/* Estimated cache hit ratio. Kept for EXPLAIN */
 	double		hit_ratio;
+
+	/* Estimated number of lookups. Kept for EXPLAIN */
+	double		lookups;
 } Memoize;
 
 /* ----------------
-- 
2.34.1