From 1284b474a343132ffba117c9b5af5debd9c0c5e6 Mon Sep 17 00:00:00 2001
From: Robert Haas <rhaas@postgresql.org>
Date: Wed, 21 May 2025 16:17:31 -0400
Subject: [PATCH] debugging code that shows it doesn't work

this prints out unrolled joins in a fairly raw format, and the result
is we can see we're not unrolling anything
---
 contrib/pg_plan_advice/pg_plan_advice.c | 13 ++++
 contrib/pg_plan_advice/pgpa_join.c      | 95 +++++++++++++++++++++++++
 contrib/pg_plan_advice/pgpa_join.h      |  5 ++
 3 files changed, 113 insertions(+)

diff --git a/contrib/pg_plan_advice/pg_plan_advice.c b/contrib/pg_plan_advice/pg_plan_advice.c
index 4c867a1369..687211b17d 100644
--- a/contrib/pg_plan_advice/pg_plan_advice.c
+++ b/contrib/pg_plan_advice/pg_plan_advice.c
@@ -49,8 +49,21 @@ static void
 pgpa_check_plan(PlannedStmt *pstmt)
 {
 	pgpa_plan_walker_context context;
+	StringInfoData	buf;
+	ListCell   *lc;
 
 	memset(&context, 0, sizeof(pgpa_plan_walker_context));
 	context.pstmt = pstmt;
 	pgpa_plan_walker(&context, pstmt->planTree, NULL);
+
+	initStringInfo(&buf);
+	foreach(lc, context.unrolled_joins)
+	{
+		pgpa_unrolled_join *join = lfirst(lc);
+
+		appendStringInfoChar(&buf, ' ');
+		pgpa_debug_out_unrolled_join(&buf, join);
+	}
+
+	elog(WARNING, "unrolled joins:%s", buf.data);
 }
diff --git a/contrib/pg_plan_advice/pgpa_join.c b/contrib/pg_plan_advice/pgpa_join.c
index 03f3a2c9b3..ce136853f3 100644
--- a/contrib/pg_plan_advice/pgpa_join.c
+++ b/contrib/pg_plan_advice/pgpa_join.c
@@ -19,6 +19,11 @@ static pgpa_join_strategy pgpa_decompose_join(Plan *plan,
 											  Plan **realinner,
 											  Plan **realouter);
 
+static void pgpa_debug_out_join_member(StringInfo buf,
+									   pgpa_join_member *member);
+static char *pgpa_cstring_join_clump_strategy(pgpa_join_clump_strategy strategy);
+static char *pgpa_cstring_join_strategy(pgpa_join_strategy strategy);
+
 /*
  * Should a given plan node be represented by a pgpa_unrolled_join, a
  * pgpa_clumped_join, or neither?
@@ -281,3 +286,93 @@ pgpa_decompose_join(Plan *plan, Plan **realinner, Plan **realouter)
 	*realouter = outerplan;
 	return strategy;
 }
+
+void
+pgpa_debug_out_clumped_join(StringInfo buf, pgpa_clumped_join *clump)
+{
+	char   *cstrategy;
+	int		rti = -1;
+	bool	first = true;
+
+	cstrategy = pgpa_cstring_join_clump_strategy(clump->strategy);
+	appendStringInfo(buf, "%s(", cstrategy);
+	while ((rti = bms_next_member(clump->relids, rti)) >= 0)
+	{
+		if (first)
+		{
+			first = false;
+			appendStringInfo(buf, "%d", rti);
+		}
+		else
+			appendStringInfo(buf, " %d", rti);
+	}
+	appendStringInfoChar(buf, ')');
+}
+
+void
+pgpa_debug_out_unrolled_join(StringInfo buf, pgpa_unrolled_join *join)
+{
+	appendStringInfoChar(buf, '(');
+
+	pgpa_debug_out_join_member(buf, &join->outer);
+
+	for (int k = 0; k < join->ninner; ++k)
+	{
+		char   *cstrategy;
+
+		cstrategy = pgpa_cstring_join_strategy(join->strategy[k]);
+		appendStringInfo(buf, " %s ", cstrategy);
+		pgpa_debug_out_join_member(buf, &join->inner[k]);
+	}
+
+	appendStringInfoChar(buf, ')');
+}
+
+static void
+pgpa_debug_out_join_member(StringInfo buf, pgpa_join_member *member)
+{
+	if (member->clump_join != NULL)
+		pgpa_debug_out_clumped_join(buf, member->clump_join);
+	else if (member->unrolled_join != NULL)
+		pgpa_debug_out_unrolled_join(buf, member->unrolled_join);
+	else
+		appendStringInfo(buf, "%d", member->rti);
+}
+
+static char *
+pgpa_cstring_join_clump_strategy(pgpa_join_clump_strategy strategy)
+{
+	switch (strategy)
+	{
+		case JSTRAT_CLUMP_DEGENERATE:
+			return "DEGENERATE";
+		case JSTRAT_CLUMP_FOREIGN:
+			return "FOREIGN";
+		case JSTRAT_CLUMP_PARTITIONWISE:
+			return "PARTITIONWISE";
+	}
+
+	Assert(false);
+}
+
+static char *
+pgpa_cstring_join_strategy(pgpa_join_strategy strategy)
+{
+	switch (strategy)
+	{
+		case JSTRAT_MERGE_JOIN_PLAIN:
+			return "MERGE_JOIN_PLAIN";
+		case JSTRAT_MERGE_JOIN_MATERIALIZE:
+			return "MERGE_JOIN_MATERIALIZE";
+		case JSTRAT_NESTED_LOOP_PLAIN:
+			return "NESTED_LOOP_PLAIN";
+		case JSTRAT_NESTED_LOOP_MATERIALIZE:
+			return "NESTED_LOOP_MATERIALIZE";
+		case JSTRAT_NESTED_LOOP_MEMOIZE:
+			return "NESTED_LOOP_MEMOIZE";
+		case JSTRAT_HASH_JOIN:
+			return "HASH_JOIN";
+	}
+
+	Assert(false);
+}
diff --git a/contrib/pg_plan_advice/pgpa_join.h b/contrib/pg_plan_advice/pgpa_join.h
index 59336ee988..a8f82deb3a 100644
--- a/contrib/pg_plan_advice/pgpa_join.h
+++ b/contrib/pg_plan_advice/pgpa_join.h
@@ -143,4 +143,9 @@ extern pgpa_unrolled_join *pgpa_build_unrolled_join(PlannedStmt *pstmt,
 													pgpa_join_unroller *join_unroller);
 extern void pgpa_destroy_join_unroller(pgpa_join_unroller *join_unroller);
 
+extern void pgpa_debug_out_clumped_join(StringInfo buf,
+										pgpa_clumped_join *clump);
+extern void pgpa_debug_out_unrolled_join(StringInfo buf,
+										 pgpa_unrolled_join *join);
+
 #endif
-- 
2.39.5