From 26edadde9996f6fe266b7eaf77ad202162aea26f Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <peter@eisentraut.org>
Date: Wed, 10 Aug 2022 23:40:52 +0200
Subject: [PATCH v1 5/7] Implement WRITE_READ_PARSE_PLAN_TREES for raw parse
 trees

This requires a special node to print and restore the full precision
of float values.
---
 src/backend/nodes/outfuncs.c | 14 ++++++++++++++
 src/backend/tcop/postgres.c  | 26 +++++++++++++++++++++-----
 src/include/nodes/nodes.h    |  4 ++++
 3 files changed, 39 insertions(+), 5 deletions(-)

diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 24ea0487e7..acc4738581 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -15,6 +15,7 @@
 #include "postgres.h"
 
 #include <ctype.h>
+#include <float.h>
 
 #include "access/attnum.h"
 #include "lib/stringinfo.h"
@@ -26,6 +27,9 @@
 
 static void outChar(StringInfo str, char c);
 
+#ifdef WRITE_READ_PARSE_PLAN_TREES
+bool output_all_float_digits = false;
+#endif
 
 /*
  * Macros to simplify output of different kinds of fields.  Use these
@@ -70,8 +74,18 @@ static void outChar(StringInfo str, char c);
 					 (int) node->fldname)
 
 /* Write a float field --- caller must give format to define precision */
+#ifdef WRITE_READ_PARSE_PLAN_TREES
+#define WRITE_FLOAT_FIELD(fldname,format) \
+	do { \
+		if (output_all_float_digits) \
+			appendStringInfo(str, " :" CppAsString(fldname) " %.*f", DBL_DIG + 3, node->fldname); \
+		else \
+			appendStringInfo(str, " :" CppAsString(fldname) " " format, node->fldname); \
+	} while(0)
+#else
 #define WRITE_FLOAT_FIELD(fldname,format) \
 	appendStringInfo(str, " :" CppAsString(fldname) " " format, node->fldname)
+#endif
 
 /* Write a boolean field */
 #define WRITE_BOOL_FIELD(fldname) \
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 7bec4e4ff5..154e6dbeca 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -601,11 +601,27 @@ pg_parse_query(const char *query_string)
 	}
 #endif
 
-	/*
-	 * Currently, outfuncs/readfuncs support is missing for many raw parse
-	 * tree nodes, so we don't try to implement WRITE_READ_PARSE_PLAN_TREES
-	 * here.
-	 */
+#ifdef WRITE_READ_PARSE_PLAN_TREES
+	/* Optional debugging check: pass raw parsetrees through outfuncs/readfuncs */
+	{
+		char	   *str;
+		List	   *new_list;
+
+		output_all_float_digits = true;
+
+		str = nodeToString(raw_parsetree_list);
+		new_list = stringToNodeWithLocations(str);
+		pfree(str);
+
+		output_all_float_digits = false;
+
+		/* This checks both outfuncs/readfuncs and the equal() routines... */
+		if (!equal(new_list, raw_parsetree_list))
+			elog(WARNING, "outfuncs/readfuncs failed to produce an equal raw parse tree");
+		else
+			raw_parsetree_list = new_list;
+	}
+#endif
 
 	TRACE_POSTGRESQL_QUERY_PARSE_DONE(query_string);
 
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index cdd6debfa0..6d6478bcb4 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -192,6 +192,10 @@ castNodeImpl(NodeTag type, void *ptr)
 struct Bitmapset;				/* not to include bitmapset.h here */
 struct StringInfoData;			/* not to include stringinfo.h here */
 
+#ifdef WRITE_READ_PARSE_PLAN_TREES
+extern bool output_all_float_digits;
+#endif
+
 extern void outNode(struct StringInfoData *str, const void *obj);
 extern void outToken(struct StringInfoData *str, const char *s);
 extern void outBitmapset(struct StringInfoData *str,
-- 
2.37.1