Add support for custom_query_jumble as a node field attribute

michaelpq · michaelpq · commit 5ac462e2b7ac · 2025-03-25T14:18:00.000+09:00
This option gives the possibility for query jumble to define a custom routine for the field of a Node, extending support for custom_query_jumble as a node field attribute. When dealing with complex node structures, this can be simpler than having to enforce a custom function across a full node. Custom functions need to be defined in queryjumblefuncs.c, named as _jumble${node}_${field}(), and use in input the JumbleState, the node and its field. The field is not really required if we have the Node, but it makes custom implementations somewhat easier to think about. The code generated by gen_node_support.pl uses a macro called JUMBLE_CUSTOM(), hiding the internals of the logic inside queryjumblefuncs.c. This will be used by an upcoming patch manipulating adding a custom routine into a field of RangeTblEntry, but this facility can become useful in more cases. Reviewed-by: Christoph Berg <myon@debian.org> Discussion: https://postgr.es/m/Z9y43-dRvb4EtxQ0@paquier.xyz
diff --git a/src/backend/nodes/gen_node_support.pl b/src/backend/nodes/gen_node_support.pl
@@ -471,6 +471,7 @@ sub elem
 								&& $attr !~ /^read_as\(\w+\)$/
 								&& !elem $attr,
 								qw(copy_as_scalar
+								custom_query_jumble
 								equal_as_scalar
 								equal_ignore
 								equal_ignore_if_zero
@@ -1283,12 +1284,17 @@ sub elem
 		my $t = $node_type_info{$n}->{field_types}{$f};
 		my @a = @{ $node_type_info{$n}->{field_attrs}{$f} };
 		my $query_jumble_ignore = $struct_no_query_jumble;
+		my $query_jumble_custom = 0;
 		my $query_jumble_location = 0;
 		my $query_jumble_squash = 0;
 
 		# extract per-field attributes
 		foreach my $a (@a)
 		{
+			if ($a eq 'custom_query_jumble')
+			{
+				$query_jumble_custom = 1;
+			}
 			if ($a eq 'query_jumble_ignore')
 			{
 				$query_jumble_ignore = 1;
@@ -1304,7 +1310,12 @@ sub elem
 		}
 
 		# node type
-		if (($t =~ /^(\w+)\*$/ or $t =~ /^struct\s+(\w+)\*$/)
+		if ($query_jumble_custom)
+		{
+			# Custom function that applies to one field of a node.
+			print $jff "\tJUMBLE_CUSTOM($n, $f);\n";
+		}
+		elsif (($t =~ /^(\w+)\*$/ or $t =~ /^struct\s+(\w+)\*$/)
 			and elem $1, @node_types)
 		{
 			# Squash constants if requested.
diff --git a/src/backend/nodes/queryjumblefuncs.c b/src/backend/nodes/queryjumblefuncs.c
@@ -333,6 +333,9 @@ do { \
 	if (expr->str) \
 		AppendJumble(jstate, (const unsigned char *) (expr->str), strlen(expr->str) + 1); \
 } while(0)
+/* Function name used for the node field attribute custom_query_jumble. */
+#define JUMBLE_CUSTOM(nodetype, item) \
+	_jumble##nodetype##_##item(jstate, expr, expr->item)
 
 #include "queryjumblefuncs.funcs.c"
 
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
@@ -54,6 +54,7 @@ typedef enum NodeTag
  *   readfuncs.c.
  *
  * - custom_query_jumble: Has custom implementation in queryjumblefuncs.c.
+ *   Also available as a node field attribute.
  *
  * - no_copy: Does not support copyObject() at all.
  *
@@ -101,6 +102,9 @@ typedef enum NodeTag
  * - equal_ignore_if_zero: Ignore the field for equality if it is zero.
  *   (Otherwise, compare normally.)
  *
+ * - custom_query_jumble: Has custom implementation in queryjumblefuncs.c
+ *   for the field of a node.  Also available as a node attribute.
+ *
  * - query_jumble_ignore: Ignore the field for the query jumbling.  Note
  *   that typmod and collation information are usually irrelevant for the
  *   query jumbling.

Original file line number	Diff line number	Diff line change
`@@ -54,6 +54,7 @@ typedef enum NodeTag`
`54`	`54`	`* readfuncs.c.`
`55`	`55`	`*`
`56`	`56`	`* - custom_query_jumble: Has custom implementation in queryjumblefuncs.c.`
	`57`	`+ * Also available as a node field attribute.`
`57`	`58`	`*`
`58`	`59`	`* - no_copy: Does not support copyObject() at all.`
`59`	`60`	`*`
`@@ -101,6 +102,9 @@ typedef enum NodeTag`
`101`	`102`	`* - equal_ignore_if_zero: Ignore the field for equality if it is zero.`
`102`	`103`	`* (Otherwise, compare normally.)`
`103`	`104`	`*`
	`105`	`+ * - custom_query_jumble: Has custom implementation in queryjumblefuncs.c`
	`106`	`+ * for the field of a node. Also available as a node attribute.`
	`107`	`+ *`
`104`	`108`	`* - query_jumble_ignore: Ignore the field for the query jumbling. Note`
`105`	`109`	`* that typmod and collation information are usually irrelevant for the`
`106`	`110`	`* query jumbling.`