I got confused about how we were managing EquivalenceClass pointers
in the copy/equal infrastructure, and it took me awhile to remember
that the reason it works is that gen_node_support.pl has hard-wired
knowledge about that. I think that's something we'd be best off
dropping in favor of explicit annotations on affected fields.
Hence, I propose the attached. This results in zero change in
the generated copy/equal code.
regards, tom lane
diff --git a/src/backend/nodes/gen_node_support.pl b/src/backend/nodes/gen_node_support.pl
index b6f086e262..9f7b4b833f 100644
--- a/src/backend/nodes/gen_node_support.pl
+++ b/src/backend/nodes/gen_node_support.pl
@@ -166,9 +166,6 @@ my @custom_read_write;
# Track node types with manually assigned NodeTag numbers.
my %manual_nodetag_number;
-# EquivalenceClasses are never moved, so just shallow-copy the pointer
-push @scalar_types, qw(EquivalenceClass* EquivalenceMember*);
-
# This is a struct, so we can copy it by assignment. Equal support is
# currently not required.
push @scalar_types, qw(QualCost);
@@ -458,9 +455,14 @@ foreach my $infile (@ARGV)
&& $attr !~ /^copy_as\(\w+\)$/
&& $attr !~ /^read_as\(\w+\)$/
&& !elem $attr,
- qw(equal_ignore equal_ignore_if_zero read_write_ignore
- write_only_relids write_only_nondefault_pathtarget write_only_req_outer)
- )
+ qw(copy_as_scalar
+ equal_as_scalar
+ equal_ignore
+ equal_ignore_if_zero
+ read_write_ignore
+ write_only_relids
+ write_only_nondefault_pathtarget
+ write_only_req_outer))
{
die
"$infile:$lineno: unrecognized attribute \"$attr\"\n";
@@ -692,6 +694,8 @@ _equal${n}(const $n *a, const $n *b)
# extract per-field attributes
my $array_size_field;
my $copy_as_field;
+ my $copy_as_scalar = 0;
+ my $equal_as_scalar = 0;
foreach my $a (@a)
{
if ($a =~ /^array_size\(([\w.]+)\)$/)
@@ -702,19 +706,41 @@ _equal${n}(const $n *a, const $n *b)
{
$copy_as_field = $1;
}
+ elsif ($a eq 'copy_as_scalar')
+ {
+ $copy_as_scalar = 1;
+ }
+ elsif ($a eq 'equal_as_scalar')
+ {
+ $equal_as_scalar = 1;
+ }
elsif ($a eq 'equal_ignore')
{
$equal_ignore = 1;
}
}
- # override type-specific copy method if copy_as is specified
+ # override type-specific copy method if requested
if (defined $copy_as_field)
{
print $cff "\tnewnode->$f = $copy_as_field;\n"
unless $copy_ignore;
$copy_ignore = 1;
}
+ elsif ($copy_as_scalar)
+ {
+ print $cff "\tCOPY_SCALAR_FIELD($f);\n"
+ unless $copy_ignore;
+ $copy_ignore = 1;
+ }
+
+ # override type-specific equal method if requested
+ if ($equal_as_scalar)
+ {
+ print $eff "\tCOMPARE_SCALAR_FIELD($f);\n"
+ unless $equal_ignore;
+ $equal_ignore = 1;
+ }
# select instructions by field type
if ($t eq 'char*')
diff --git a/src/include/nodes/nodes.h b/src/include/nodes/nodes.h
index a80f43e540..d98f2c91d9 100644
--- a/src/include/nodes/nodes.h
+++ b/src/include/nodes/nodes.h
@@ -86,6 +86,12 @@ typedef enum NodeTag
*
* - copy_as(VALUE): In copyObject(), replace the field's value with VALUE.
*
+ * - copy_as_scalar: In copyObject(), copy the field's pointer value
+ * even if it is a node-type pointer.
+ *
+ * - equal_as_scalar: In equal(), compare the field by pointer equality
+ * even if it is a node-type pointer.
+ *
* - equal_ignore: Ignore the field for equality.
*
* - equal_ignore_if_zero: Ignore the field for equality if it is zero.
diff --git a/src/include/nodes/pathnodes.h b/src/include/nodes/pathnodes.h
index a544b313d3..885ad42327 100644
--- a/src/include/nodes/pathnodes.h
+++ b/src/include/nodes/pathnodes.h
@@ -1273,7 +1273,9 @@ typedef struct StatisticExtInfo
*
* NB: EquivalenceClasses are never copied after creation. Therefore,
* copyObject() copies pointers to them as pointers, and equal() compares
- * pointers to EquivalenceClasses via pointer equality.
+ * pointers to EquivalenceClasses via pointer equality. This is implemented
+ * by putting copy_as_scalar and equal_as_scalar attributes on fields that
+ * are pointers to EquivalenceClasses. The same goes for EquivalenceMembers.
*/
typedef struct EquivalenceClass
{
@@ -1364,7 +1366,8 @@ typedef struct PathKey
NodeTag type;
- EquivalenceClass *pk_eclass; /* the value that is ordered */
+ /* the value that is ordered */
+ EquivalenceClass *pk_eclass pg_node_attr(copy_as_scalar, equal_as_scalar);
Oid pk_opfamily; /* btree opfamily defining the ordering */
int pk_strategy; /* sort direction (ASC or DESC) */
bool pk_nulls_first; /* do NULLs come before normal values? */
@@ -2472,7 +2475,7 @@ typedef struct RestrictInfo
* Generating EquivalenceClass. This field is NULL unless clause is
* potentially redundant.
*/
- EquivalenceClass *parent_ec pg_node_attr(equal_ignore, read_write_ignore);
+ EquivalenceClass *parent_ec pg_node_attr(copy_as_scalar, equal_ignore, read_write_ignore);
/*
* cache space for cost and selectivity
@@ -2500,13 +2503,13 @@ typedef struct RestrictInfo
*/
/* EquivalenceClass containing lefthand */
- EquivalenceClass *left_ec pg_node_attr(equal_ignore, read_write_ignore);
+ EquivalenceClass *left_ec pg_node_attr(copy_as_scalar, equal_ignore, read_write_ignore);
/* EquivalenceClass containing righthand */
- EquivalenceClass *right_ec pg_node_attr(equal_ignore, read_write_ignore);
+ EquivalenceClass *right_ec pg_node_attr(copy_as_scalar, equal_ignore, read_write_ignore);
/* EquivalenceMember for lefthand */
- EquivalenceMember *left_em pg_node_attr(equal_ignore);
+ EquivalenceMember *left_em pg_node_attr(copy_as_scalar, equal_ignore);
/* EquivalenceMember for righthand */
- EquivalenceMember *right_em pg_node_attr(equal_ignore);
+ EquivalenceMember *right_em pg_node_attr(copy_as_scalar, equal_ignore);
/*
* List of MergeScanSelCache structs. Those aren't Nodes, so hard to
