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path: root/src/backend/rewrite/rewriteManip.c
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Diffstat (limited to 'src/backend/rewrite/rewriteManip.c')
-rw-r--r--src/backend/rewrite/rewriteManip.c227
1 files changed, 222 insertions, 5 deletions
diff --git a/src/backend/rewrite/rewriteManip.c b/src/backend/rewrite/rewriteManip.c
index 980f5839150..6f51c7ee754 100644
--- a/src/backend/rewrite/rewriteManip.c
+++ b/src/backend/rewrite/rewriteManip.c
@@ -40,6 +40,20 @@ typedef struct
int win_location;
} locate_windowfunc_context;
+typedef struct
+{
+ const Bitmapset *target_relids;
+ const Bitmapset *added_relids;
+ int sublevels_up;
+} add_nulling_relids_context;
+
+typedef struct
+{
+ const Bitmapset *removable_relids;
+ const Bitmapset *except_relids;
+ int sublevels_up;
+} remove_nulling_relids_context;
+
static bool contain_aggs_of_level_walker(Node *node,
contain_aggs_of_level_context *context);
static bool locate_agg_of_level_walker(Node *node,
@@ -50,6 +64,10 @@ static bool locate_windowfunc_walker(Node *node,
static bool checkExprHasSubLink_walker(Node *node, void *context);
static Relids offset_relid_set(Relids relids, int offset);
static Relids adjust_relid_set(Relids relids, int oldrelid, int newrelid);
+static Node *add_nulling_relids_mutator(Node *node,
+ add_nulling_relids_context *context);
+static Node *remove_nulling_relids_mutator(Node *node,
+ remove_nulling_relids_context *context);
/*
@@ -381,6 +399,8 @@ OffsetVarNodes_walker(Node *node, OffsetVarNodes_context *context)
if (var->varlevelsup == context->sublevels_up)
{
var->varno += context->offset;
+ var->varnullingrels = offset_relid_set(var->varnullingrels,
+ context->offset);
if (var->varnosyn > 0)
var->varnosyn += context->offset;
}
@@ -419,6 +439,8 @@ OffsetVarNodes_walker(Node *node, OffsetVarNodes_context *context)
{
phv->phrels = offset_relid_set(phv->phrels,
context->offset);
+ phv->phnullingrels = offset_relid_set(phv->phnullingrels,
+ context->offset);
}
/* fall through to examine children */
}
@@ -543,11 +565,13 @@ ChangeVarNodes_walker(Node *node, ChangeVarNodes_context *context)
{
Var *var = (Var *) node;
- if (var->varlevelsup == context->sublevels_up &&
- var->varno == context->rt_index)
+ if (var->varlevelsup == context->sublevels_up)
{
- var->varno = context->new_index;
- /* If the syntactic referent is same RTE, fix it too */
+ if (var->varno == context->rt_index)
+ var->varno = context->new_index;
+ var->varnullingrels = adjust_relid_set(var->varnullingrels,
+ context->rt_index,
+ context->new_index);
if (var->varnosyn == context->rt_index)
var->varnosyn = context->new_index;
}
@@ -590,6 +614,9 @@ ChangeVarNodes_walker(Node *node, ChangeVarNodes_context *context)
phv->phrels = adjust_relid_set(phv->phrels,
context->rt_index,
context->new_index);
+ phv->phnullingrels = adjust_relid_set(phv->phnullingrels,
+ context->rt_index,
+ context->new_index);
}
/* fall through to examine children */
}
@@ -866,7 +893,8 @@ rangeTableEntry_used_walker(Node *node,
Var *var = (Var *) node;
if (var->varlevelsup == context->sublevels_up &&
- var->varno == context->rt_index)
+ (var->varno == context->rt_index ||
+ bms_is_member(context->rt_index, var->varnullingrels)))
return true;
return false;
}
@@ -1095,6 +1123,195 @@ AddInvertedQual(Query *parsetree, Node *qual)
/*
+ * add_nulling_relids() finds Vars and PlaceHolderVars that belong to any
+ * of the target_relids, and adds added_relids to their varnullingrels
+ * and phnullingrels fields.
+ */
+Node *
+add_nulling_relids(Node *node,
+ const Bitmapset *target_relids,
+ const Bitmapset *added_relids)
+{
+ add_nulling_relids_context context;
+
+ context.target_relids = target_relids;
+ context.added_relids = added_relids;
+ context.sublevels_up = 0;
+ return query_or_expression_tree_mutator(node,
+ add_nulling_relids_mutator,
+ &context,
+ 0);
+}
+
+static Node *
+add_nulling_relids_mutator(Node *node,
+ add_nulling_relids_context *context)
+{
+ if (node == NULL)
+ return NULL;
+ if (IsA(node, Var))
+ {
+ Var *var = (Var *) node;
+
+ if (var->varlevelsup == context->sublevels_up &&
+ bms_is_member(var->varno, context->target_relids))
+ {
+ Relids newnullingrels = bms_union(var->varnullingrels,
+ context->added_relids);
+
+ /* Copy the Var ... */
+ var = copyObject(var);
+ /* ... and replace the copy's varnullingrels field */
+ var->varnullingrels = newnullingrels;
+ return (Node *) var;
+ }
+ /* Otherwise fall through to copy the Var normally */
+ }
+ else if (IsA(node, PlaceHolderVar))
+ {
+ PlaceHolderVar *phv = (PlaceHolderVar *) node;
+
+ if (phv->phlevelsup == context->sublevels_up &&
+ bms_overlap(phv->phrels, context->target_relids))
+ {
+ Relids newnullingrels = bms_union(phv->phnullingrels,
+ context->added_relids);
+
+ /*
+ * We don't modify the contents of the PHV's expression, only add
+ * to phnullingrels. This corresponds to assuming that the PHV
+ * will be evaluated at the same level as before, then perhaps be
+ * nulled as it bubbles up. Hence, just flat-copy the node ...
+ */
+ phv = makeNode(PlaceHolderVar);
+ memcpy(phv, node, sizeof(PlaceHolderVar));
+ /* ... and replace the copy's phnullingrels field */
+ phv->phnullingrels = newnullingrels;
+ return (Node *) phv;
+ }
+ /* Otherwise fall through to copy the PlaceHolderVar normally */
+ }
+ else if (IsA(node, Query))
+ {
+ /* Recurse into RTE or sublink subquery */
+ Query *newnode;
+
+ context->sublevels_up++;
+ newnode = query_tree_mutator((Query *) node,
+ add_nulling_relids_mutator,
+ (void *) context,
+ 0);
+ context->sublevels_up--;
+ return (Node *) newnode;
+ }
+ return expression_tree_mutator(node, add_nulling_relids_mutator,
+ (void *) context);
+}
+
+/*
+ * remove_nulling_relids() removes mentions of the specified RT index(es)
+ * in Var.varnullingrels and PlaceHolderVar.phnullingrels fields within
+ * the given expression, except in nodes belonging to rels listed in
+ * except_relids.
+ */
+Node *
+remove_nulling_relids(Node *node,
+ const Bitmapset *removable_relids,
+ const Bitmapset *except_relids)
+{
+ remove_nulling_relids_context context;
+
+ context.removable_relids = removable_relids;
+ context.except_relids = except_relids;
+ context.sublevels_up = 0;
+ return query_or_expression_tree_mutator(node,
+ remove_nulling_relids_mutator,
+ &context,
+ 0);
+}
+
+static Node *
+remove_nulling_relids_mutator(Node *node,
+ remove_nulling_relids_context *context)
+{
+ if (node == NULL)
+ return NULL;
+ if (IsA(node, Var))
+ {
+ Var *var = (Var *) node;
+
+ if (var->varlevelsup == context->sublevels_up &&
+ !bms_is_member(var->varno, context->except_relids) &&
+ bms_overlap(var->varnullingrels, context->removable_relids))
+ {
+ Relids newnullingrels = bms_difference(var->varnullingrels,
+ context->removable_relids);
+
+ /* Micro-optimization: ensure nullingrels is NULL if empty */
+ if (bms_is_empty(newnullingrels))
+ newnullingrels = NULL;
+ /* Copy the Var ... */
+ var = copyObject(var);
+ /* ... and replace the copy's varnullingrels field */
+ var->varnullingrels = newnullingrels;
+ return (Node *) var;
+ }
+ /* Otherwise fall through to copy the Var normally */
+ }
+ else if (IsA(node, PlaceHolderVar))
+ {
+ PlaceHolderVar *phv = (PlaceHolderVar *) node;
+
+ if (phv->phlevelsup == context->sublevels_up &&
+ !bms_overlap(phv->phrels, context->except_relids))
+ {
+ Relids newnullingrels = bms_difference(phv->phnullingrels,
+ context->removable_relids);
+
+ /*
+ * Micro-optimization: ensure nullingrels is NULL if empty.
+ *
+ * Note: it might seem desirable to remove the PHV altogether if
+ * phnullingrels goes to empty. Currently we dare not do that
+ * because we use PHVs in some cases to enforce separate identity
+ * of subexpressions; see wrap_non_vars usages in prepjointree.c.
+ */
+ if (bms_is_empty(newnullingrels))
+ newnullingrels = NULL;
+ /* Copy the PlaceHolderVar and mutate what's below ... */
+ phv = (PlaceHolderVar *)
+ expression_tree_mutator(node,
+ remove_nulling_relids_mutator,
+ (void *) context);
+ /* ... and replace the copy's phnullingrels field */
+ phv->phnullingrels = newnullingrels;
+ /* We must also update phrels, if it contains a removable RTI */
+ phv->phrels = bms_difference(phv->phrels,
+ context->removable_relids);
+ Assert(!bms_is_empty(phv->phrels));
+ return (Node *) phv;
+ }
+ /* Otherwise fall through to copy the PlaceHolderVar normally */
+ }
+ else if (IsA(node, Query))
+ {
+ /* Recurse into RTE or sublink subquery */
+ Query *newnode;
+
+ context->sublevels_up++;
+ newnode = query_tree_mutator((Query *) node,
+ remove_nulling_relids_mutator,
+ (void *) context,
+ 0);
+ context->sublevels_up--;
+ return (Node *) newnode;
+ }
+ return expression_tree_mutator(node, remove_nulling_relids_mutator,
+ (void *) context);
+}
+
+
+/*
* replace_rte_variables() finds all Vars in an expression tree
* that reference a particular RTE, and replaces them with substitute
* expressions obtained from a caller-supplied callback function.
generated by cgit v1.2.3 (git 2.39.1) at 2025-06-15 07:29:57 +0000