* reduce_outer_joins
*
*
- * Portions Copyright (c) 1996-2011, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1996-2016, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
#include "optimizer/prep.h"
#include "optimizer/subselect.h"
#include "optimizer/tlist.h"
-#include "optimizer/var.h"
#include "parser/parse_relation.h"
#include "parser/parsetree.h"
#include "rewrite/rewriteManip.h"
PlannerInfo *root;
List *targetlist; /* tlist of subquery being pulled up */
RangeTblEntry *target_rte; /* RTE of subquery */
+ Relids relids; /* relids within subquery, as numbered after
+ * pullup (set only if target_rte->lateral) */
bool *outer_hasSubLinks; /* -> outer query's hasSubLinks */
int varno; /* varno of subquery */
bool need_phvs; /* do we need PlaceHolderVars? */
static Node *pull_up_sublinks_jointree_recurse(PlannerInfo *root, Node *jtnode,
Relids *relids);
static Node *pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node,
- Relids available_rels, Node **jtlink);
+ Node **jtlink1, Relids available_rels1,
+ Node **jtlink2, Relids available_rels2);
+static Node *pull_up_subqueries_recurse(PlannerInfo *root, Node *jtnode,
+ JoinExpr *lowest_outer_join,
+ JoinExpr *lowest_nulling_outer_join,
+ AppendRelInfo *containing_appendrel,
+ bool deletion_ok);
static Node *pull_up_simple_subquery(PlannerInfo *root, Node *jtnode,
RangeTblEntry *rte,
JoinExpr *lowest_outer_join,
- AppendRelInfo *containing_appendrel);
+ JoinExpr *lowest_nulling_outer_join,
+ AppendRelInfo *containing_appendrel,
+ bool deletion_ok);
static Node *pull_up_simple_union_all(PlannerInfo *root, Node *jtnode,
RangeTblEntry *rte);
static void pull_up_union_leaf_queries(Node *setOp, PlannerInfo *root,
int childRToffset);
static void make_setop_translation_list(Query *query, Index newvarno,
List **translated_vars);
-static bool is_simple_subquery(Query *subquery);
+static bool is_simple_subquery(Query *subquery, RangeTblEntry *rte,
+ JoinExpr *lowest_outer_join,
+ bool deletion_ok);
+static Node *pull_up_simple_values(PlannerInfo *root, Node *jtnode,
+ RangeTblEntry *rte);
+static bool is_simple_values(PlannerInfo *root, RangeTblEntry *rte,
+ bool deletion_ok);
static bool is_simple_union_all(Query *subquery);
static bool is_simple_union_all_recurse(Node *setOp, Query *setOpQuery,
List *colTypes);
static bool is_safe_append_member(Query *subquery);
+static bool jointree_contains_lateral_outer_refs(Node *jtnode, bool restricted,
+ Relids safe_upper_varnos);
static void replace_vars_in_jointree(Node *jtnode,
pullup_replace_vars_context *context,
- JoinExpr *lowest_outer_join);
+ JoinExpr *lowest_nulling_outer_join);
static Node *pullup_replace_vars(Node *expr,
pullup_replace_vars_context *context);
static Node *pullup_replace_vars_callback(Var *var,
replace_rte_variables_context *context);
+static Query *pullup_replace_vars_subquery(Query *query,
+ pullup_replace_vars_context *context);
+static Node *pull_up_subqueries_cleanup(Node *jtnode);
static reduce_outer_joins_state *reduce_outer_joins_pass1(Node *jtnode);
static void reduce_outer_joins_pass2(Node *jtnode,
reduce_outer_joins_state *state,
*
* A clause "foo op ANY (sub-SELECT)" can be processed by pulling the
* sub-SELECT up to become a rangetable entry and treating the implied
- * comparisons as quals of a semijoin. However, this optimization *only*
+ * comparisons as quals of a semijoin. However, this optimization *only*
* works at the top level of WHERE or a JOIN/ON clause, because we cannot
* distinguish whether the ANY ought to return FALSE or NULL in cases
* involving NULL inputs. Also, in an outer join's ON clause we can only
* transformations if any are found.
*
* This routine has to run before preprocess_expression(), so the quals
- * clauses are not yet reduced to implicit-AND format. That means we need
- * to recursively search through explicit AND clauses, which are
- * probably only binary ANDs. We stop as soon as we hit a non-AND item.
+ * clauses are not yet reduced to implicit-AND format, and are not guaranteed
+ * to be AND/OR-flat either. That means we need to recursively search through
+ * explicit AND clauses. We stop as soon as we hit a non-AND item.
*/
void
pull_up_sublinks(PlannerInfo *root)
/* Set up a link representing the rebuilt jointree */
jtlink = (Node *) newf;
/* Now process qual --- all children are available for use */
- newf->quals = pull_up_sublinks_qual_recurse(root, f->quals, frelids,
- &jtlink);
+ newf->quals = pull_up_sublinks_qual_recurse(root, f->quals,
+ &jtlink, frelids,
+ NULL, NULL);
/*
* Note that the result will be either newf, or a stack of JoinExprs
* point of the available_rels machinations is to ensure that we only
* pull up quals for which that's okay.
*
- * XXX for the moment, we refrain from pulling up IN/EXISTS clauses
- * appearing in LEFT or RIGHT join conditions. Although it is
- * semantically valid to do so under the above conditions, we end up
- * with a query in which the semijoin or antijoin must be evaluated
- * below the outer join, which could perform far worse than leaving it
- * as a sublink that is executed only for row pairs that meet the
- * other join conditions. Fixing this seems to require considerable
- * restructuring of the executor, but maybe someday it can happen.
- *
* We don't expect to see any pre-existing JOIN_SEMI or JOIN_ANTI
* nodes here.
*/
{
case JOIN_INNER:
j->quals = pull_up_sublinks_qual_recurse(root, j->quals,
+ &jtlink,
bms_union(leftrelids,
rightrelids),
- &jtlink);
+ NULL, NULL);
break;
case JOIN_LEFT:
-#ifdef NOT_USED /* see XXX comment above */
j->quals = pull_up_sublinks_qual_recurse(root, j->quals,
+ &j->rarg,
rightrelids,
- &j->rarg);
-#endif
+ NULL, NULL);
break;
case JOIN_FULL:
/* can't do anything with full-join quals */
break;
case JOIN_RIGHT:
-#ifdef NOT_USED /* see XXX comment above */
j->quals = pull_up_sublinks_qual_recurse(root, j->quals,
+ &j->larg,
leftrelids,
- &j->larg);
-#endif
+ NULL, NULL);
break;
default:
elog(ERROR, "unrecognized join type: %d",
/*
* Although we could include the pulled-up subqueries in the returned
* relids, there's no need since upper quals couldn't refer to their
- * outputs anyway. But we *do* need to include the join's own rtindex
+ * outputs anyway. But we *do* need to include the join's own rtindex
* because we haven't yet collapsed join alias variables, so upper
* levels would mistakenly think they couldn't use references to this
* join.
/*
* Recurse through top-level qual nodes for pull_up_sublinks()
*
- * jtlink points to the link in the jointree where any new JoinExprs should be
- * inserted. If we find multiple pull-up-able SubLinks, they'll get stacked
- * there in the order we encounter them. We rely on subsequent optimization
- * to rearrange the stack if appropriate.
+ * jtlink1 points to the link in the jointree where any new JoinExprs should
+ * be inserted if they reference available_rels1 (i.e., available_rels1
+ * denotes the relations present underneath jtlink1). Optionally, jtlink2 can
+ * point to a second link where new JoinExprs should be inserted if they
+ * reference available_rels2 (pass NULL for both those arguments if not used).
+ * Note that SubLinks referencing both sets of variables cannot be optimized.
+ * If we find multiple pull-up-able SubLinks, they'll get stacked onto jtlink1
+ * and/or jtlink2 in the order we encounter them. We rely on subsequent
+ * optimization to rearrange the stack if appropriate.
+ *
+ * Returns the replacement qual node, or NULL if the qual should be removed.
*/
static Node *
pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node,
- Relids available_rels, Node **jtlink)
+ Node **jtlink1, Relids available_rels1,
+ Node **jtlink2, Relids available_rels2)
{
if (node == NULL)
return NULL;
{
SubLink *sublink = (SubLink *) node;
JoinExpr *j;
+ Relids child_rels;
/* Is it a convertible ANY or EXISTS clause? */
if (sublink->subLinkType == ANY_SUBLINK)
{
- j = convert_ANY_sublink_to_join(root, sublink,
- available_rels);
- if (j)
+ if ((j = convert_ANY_sublink_to_join(root, sublink,
+ available_rels1)) != NULL)
{
- /* Yes, insert the new join node into the join tree */
- j->larg = *jtlink;
- *jtlink = (Node *) j;
- /* and return NULL representing constant TRUE */
+ /* Yes; insert the new join node into the join tree */
+ j->larg = *jtlink1;
+ *jtlink1 = (Node *) j;
+ /* Recursively process pulled-up jointree nodes */
+ j->rarg = pull_up_sublinks_jointree_recurse(root,
+ j->rarg,
+ &child_rels);
+
+ /*
+ * Now recursively process the pulled-up quals. Any inserted
+ * joins can get stacked onto either j->larg or j->rarg,
+ * depending on which rels they reference.
+ */
+ j->quals = pull_up_sublinks_qual_recurse(root,
+ j->quals,
+ &j->larg,
+ available_rels1,
+ &j->rarg,
+ child_rels);
+ /* Return NULL representing constant TRUE */
+ return NULL;
+ }
+ if (available_rels2 != NULL &&
+ (j = convert_ANY_sublink_to_join(root, sublink,
+ available_rels2)) != NULL)
+ {
+ /* Yes; insert the new join node into the join tree */
+ j->larg = *jtlink2;
+ *jtlink2 = (Node *) j;
+ /* Recursively process pulled-up jointree nodes */
+ j->rarg = pull_up_sublinks_jointree_recurse(root,
+ j->rarg,
+ &child_rels);
+
+ /*
+ * Now recursively process the pulled-up quals. Any inserted
+ * joins can get stacked onto either j->larg or j->rarg,
+ * depending on which rels they reference.
+ */
+ j->quals = pull_up_sublinks_qual_recurse(root,
+ j->quals,
+ &j->larg,
+ available_rels2,
+ &j->rarg,
+ child_rels);
+ /* Return NULL representing constant TRUE */
return NULL;
}
}
else if (sublink->subLinkType == EXISTS_SUBLINK)
{
- j = convert_EXISTS_sublink_to_join(root, sublink, false,
- available_rels);
- if (j)
+ if ((j = convert_EXISTS_sublink_to_join(root, sublink, false,
+ available_rels1)) != NULL)
{
- /* Yes, insert the new join node into the join tree */
- j->larg = *jtlink;
- *jtlink = (Node *) j;
- /* and return NULL representing constant TRUE */
+ /* Yes; insert the new join node into the join tree */
+ j->larg = *jtlink1;
+ *jtlink1 = (Node *) j;
+ /* Recursively process pulled-up jointree nodes */
+ j->rarg = pull_up_sublinks_jointree_recurse(root,
+ j->rarg,
+ &child_rels);
+
+ /*
+ * Now recursively process the pulled-up quals. Any inserted
+ * joins can get stacked onto either j->larg or j->rarg,
+ * depending on which rels they reference.
+ */
+ j->quals = pull_up_sublinks_qual_recurse(root,
+ j->quals,
+ &j->larg,
+ available_rels1,
+ &j->rarg,
+ child_rels);
+ /* Return NULL representing constant TRUE */
+ return NULL;
+ }
+ if (available_rels2 != NULL &&
+ (j = convert_EXISTS_sublink_to_join(root, sublink, false,
+ available_rels2)) != NULL)
+ {
+ /* Yes; insert the new join node into the join tree */
+ j->larg = *jtlink2;
+ *jtlink2 = (Node *) j;
+ /* Recursively process pulled-up jointree nodes */
+ j->rarg = pull_up_sublinks_jointree_recurse(root,
+ j->rarg,
+ &child_rels);
+
+ /*
+ * Now recursively process the pulled-up quals. Any inserted
+ * joins can get stacked onto either j->larg or j->rarg,
+ * depending on which rels they reference.
+ */
+ j->quals = pull_up_sublinks_qual_recurse(root,
+ j->quals,
+ &j->larg,
+ available_rels2,
+ &j->rarg,
+ child_rels);
+ /* Return NULL representing constant TRUE */
return NULL;
}
}
/* If the immediate argument of NOT is EXISTS, try to convert */
SubLink *sublink = (SubLink *) get_notclausearg((Expr *) node);
JoinExpr *j;
+ Relids child_rels;
if (sublink && IsA(sublink, SubLink))
{
if (sublink->subLinkType == EXISTS_SUBLINK)
{
- j = convert_EXISTS_sublink_to_join(root, sublink, true,
- available_rels);
- if (j)
+ if ((j = convert_EXISTS_sublink_to_join(root, sublink, true,
+ available_rels1)) != NULL)
+ {
+ /* Yes; insert the new join node into the join tree */
+ j->larg = *jtlink1;
+ *jtlink1 = (Node *) j;
+ /* Recursively process pulled-up jointree nodes */
+ j->rarg = pull_up_sublinks_jointree_recurse(root,
+ j->rarg,
+ &child_rels);
+
+ /*
+ * Now recursively process the pulled-up quals. Because
+ * we are underneath a NOT, we can't pull up sublinks that
+ * reference the left-hand stuff, but it's still okay to
+ * pull up sublinks referencing j->rarg.
+ */
+ j->quals = pull_up_sublinks_qual_recurse(root,
+ j->quals,
+ &j->rarg,
+ child_rels,
+ NULL, NULL);
+ /* Return NULL representing constant TRUE */
+ return NULL;
+ }
+ if (available_rels2 != NULL &&
+ (j = convert_EXISTS_sublink_to_join(root, sublink, true,
+ available_rels2)) != NULL)
{
- /* Yes, insert the new join node into the join tree */
- j->larg = *jtlink;
- *jtlink = (Node *) j;
- /* and return NULL representing constant TRUE */
+ /* Yes; insert the new join node into the join tree */
+ j->larg = *jtlink2;
+ *jtlink2 = (Node *) j;
+ /* Recursively process pulled-up jointree nodes */
+ j->rarg = pull_up_sublinks_jointree_recurse(root,
+ j->rarg,
+ &child_rels);
+
+ /*
+ * Now recursively process the pulled-up quals. Because
+ * we are underneath a NOT, we can't pull up sublinks that
+ * reference the left-hand stuff, but it's still okay to
+ * pull up sublinks referencing j->rarg.
+ */
+ j->quals = pull_up_sublinks_qual_recurse(root,
+ j->quals,
+ &j->rarg,
+ child_rels,
+ NULL, NULL);
+ /* Return NULL representing constant TRUE */
return NULL;
}
}
newclause = pull_up_sublinks_qual_recurse(root,
oldclause,
- available_rels,
- jtlink);
+ jtlink1,
+ available_rels1,
+ jtlink2,
+ available_rels2);
if (newclause)
newclauses = lappend(newclauses, newclause);
}
/* Successful expansion, replace the rtable entry */
rte->rtekind = RTE_SUBQUERY;
rte->subquery = funcquery;
- rte->funcexpr = NULL;
- rte->funccoltypes = NIL;
- rte->funccoltypmods = NIL;
+ rte->functions = NIL;
}
}
}
* grouping/aggregation then we can merge it into the parent's jointree.
* Also, subqueries that are simple UNION ALL structures can be
* converted into "append relations".
+ */
+void
+pull_up_subqueries(PlannerInfo *root)
+{
+ /* Top level of jointree must always be a FromExpr */
+ Assert(IsA(root->parse->jointree, FromExpr));
+ /* Reset flag saying we need a deletion cleanup pass */
+ root->hasDeletedRTEs = false;
+ /* Recursion starts with no containing join nor appendrel */
+ root->parse->jointree = (FromExpr *)
+ pull_up_subqueries_recurse(root, (Node *) root->parse->jointree,
+ NULL, NULL, NULL, false);
+ /* Apply cleanup phase if necessary */
+ if (root->hasDeletedRTEs)
+ root->parse->jointree = (FromExpr *)
+ pull_up_subqueries_cleanup((Node *) root->parse->jointree);
+ Assert(IsA(root->parse->jointree, FromExpr));
+}
+
+/*
+ * pull_up_subqueries_recurse
+ * Recursive guts of pull_up_subqueries.
+ *
+ * This recursively processes the jointree and returns a modified jointree.
+ * Or, if it's valid to drop the current node from the jointree completely,
+ * it returns NULL.
+ *
+ * If this jointree node is within either side of an outer join, then
+ * lowest_outer_join references the lowest such JoinExpr node; otherwise
+ * it is NULL. We use this to constrain the effects of LATERAL subqueries.
*
* If this jointree node is within the nullable side of an outer join, then
- * lowest_outer_join references the lowest such JoinExpr node; otherwise it
- * is NULL. This forces use of the PlaceHolderVar mechanism for references
- * to non-nullable targetlist items, but only for references above that join.
+ * lowest_nulling_outer_join references the lowest such JoinExpr node;
+ * otherwise it is NULL. This forces use of the PlaceHolderVar mechanism for
+ * references to non-nullable targetlist items, but only for references above
+ * that join.
*
* If we are looking at a member subquery of an append relation,
* containing_appendrel describes that relation; else it is NULL.
* This forces use of the PlaceHolderVar mechanism for all non-Var targetlist
* items, and puts some additional restrictions on what can be pulled up.
*
+ * deletion_ok is TRUE if the caller can cope with us returning NULL for a
+ * deletable leaf node (for example, a VALUES RTE that could be pulled up).
+ * If it's FALSE, we'll avoid pullup in such cases.
+ *
* A tricky aspect of this code is that if we pull up a subquery we have
* to replace Vars that reference the subquery's outputs throughout the
* parent query, including quals attached to jointree nodes above the one
* we are currently processing! We handle this by being careful not to
- * change the jointree structure while recursing: no nodes other than
- * subquery RangeTblRef entries will be replaced. Also, we can't turn
- * pullup_replace_vars loose on the whole jointree, because it'll return a
- * mutated copy of the tree; we have to invoke it just on the quals, instead.
- * This behavior is what makes it reasonable to pass lowest_outer_join as a
- * pointer rather than some more-indirect way of identifying the lowest OJ.
- * Likewise, we don't replace append_rel_list members but only their
+ * change the jointree structure while recursing: no nodes other than leaf
+ * RangeTblRef entries and entirely-empty FromExprs will be replaced or
+ * deleted. Also, we can't turn pullup_replace_vars loose on the whole
+ * jointree, because it'll return a mutated copy of the tree; we have to
+ * invoke it just on the quals, instead. This behavior is what makes it
+ * reasonable to pass lowest_outer_join and lowest_nulling_outer_join as
+ * pointers rather than some more-indirect way of identifying the lowest
+ * OJs. Likewise, we don't replace append_rel_list members but only their
* substructure, so the containing_appendrel reference is safe to use.
+ *
+ * Because of the rule that no jointree nodes with substructure can be
+ * replaced, we cannot fully handle the case of deleting nodes from the tree:
+ * when we delete one child of a JoinExpr, we need to replace the JoinExpr
+ * with a FromExpr, and that can't happen here. Instead, we set the
+ * root->hasDeletedRTEs flag, which tells pull_up_subqueries() that an
+ * additional pass over the tree is needed to clean up.
*/
-Node *
-pull_up_subqueries(PlannerInfo *root, Node *jtnode,
- JoinExpr *lowest_outer_join,
- AppendRelInfo *containing_appendrel)
+static Node *
+pull_up_subqueries_recurse(PlannerInfo *root, Node *jtnode,
+ JoinExpr *lowest_outer_join,
+ JoinExpr *lowest_nulling_outer_join,
+ AppendRelInfo *containing_appendrel,
+ bool deletion_ok)
{
- if (jtnode == NULL)
- return NULL;
+ Assert(jtnode != NULL);
if (IsA(jtnode, RangeTblRef))
{
int varno = ((RangeTblRef *) jtnode)->rtindex;
* unless is_safe_append_member says so.
*/
if (rte->rtekind == RTE_SUBQUERY &&
- is_simple_subquery(rte->subquery) &&
+ is_simple_subquery(rte->subquery, rte,
+ lowest_outer_join, deletion_ok) &&
(containing_appendrel == NULL ||
is_safe_append_member(rte->subquery)))
return pull_up_simple_subquery(root, jtnode, rte,
lowest_outer_join,
- containing_appendrel);
+ lowest_nulling_outer_join,
+ containing_appendrel,
+ deletion_ok);
/*
* Alternatively, is it a simple UNION ALL subquery? If so, flatten
is_simple_union_all(rte->subquery))
return pull_up_simple_union_all(root, jtnode, rte);
+ /*
+ * Or perhaps it's a simple VALUES RTE?
+ *
+ * We don't allow VALUES pullup below an outer join nor into an
+ * appendrel (such cases are impossible anyway at the moment).
+ */
+ if (rte->rtekind == RTE_VALUES &&
+ lowest_outer_join == NULL &&
+ containing_appendrel == NULL &&
+ is_simple_values(root, rte, deletion_ok))
+ return pull_up_simple_values(root, jtnode, rte);
+
/* Otherwise, do nothing at this node. */
}
else if (IsA(jtnode, FromExpr))
{
FromExpr *f = (FromExpr *) jtnode;
+ bool have_undeleted_child = false;
ListCell *l;
Assert(containing_appendrel == NULL);
+
+ /*
+ * If the FromExpr has quals, it's not deletable even if its parent
+ * would allow deletion.
+ */
+ if (f->quals)
+ deletion_ok = false;
+
foreach(l, f->fromlist)
- lfirst(l) = pull_up_subqueries(root, lfirst(l),
- lowest_outer_join, NULL);
+ {
+ /*
+ * In a non-deletable FromExpr, we can allow deletion of child
+ * nodes so long as at least one child remains; so it's okay
+ * either if any previous child survives, or if there's more to
+ * come. If all children are deletable in themselves, we'll force
+ * the last one to remain unflattened.
+ *
+ * As a separate matter, we can allow deletion of all children of
+ * the top-level FromExpr in a query, since that's a special case
+ * anyway.
+ */
+ bool sub_deletion_ok = (deletion_ok ||
+ have_undeleted_child ||
+ lnext(l) != NULL ||
+ f == root->parse->jointree);
+
+ lfirst(l) = pull_up_subqueries_recurse(root, lfirst(l),
+ lowest_outer_join,
+ lowest_nulling_outer_join,
+ NULL,
+ sub_deletion_ok);
+ if (lfirst(l) != NULL)
+ have_undeleted_child = true;
+ }
+
+ if (deletion_ok && !have_undeleted_child)
+ {
+ /* OK to delete this FromExpr entirely */
+ root->hasDeletedRTEs = true; /* probably is set already */
+ return NULL;
+ }
}
else if (IsA(jtnode, JoinExpr))
{
switch (j->jointype)
{
case JOIN_INNER:
- j->larg = pull_up_subqueries(root, j->larg,
- lowest_outer_join, NULL);
- j->rarg = pull_up_subqueries(root, j->rarg,
- lowest_outer_join, NULL);
+
+ /*
+ * INNER JOIN can allow deletion of either child node, but not
+ * both. So right child gets permission to delete only if
+ * left child didn't get removed.
+ */
+ j->larg = pull_up_subqueries_recurse(root, j->larg,
+ lowest_outer_join,
+ lowest_nulling_outer_join,
+ NULL,
+ true);
+ j->rarg = pull_up_subqueries_recurse(root, j->rarg,
+ lowest_outer_join,
+ lowest_nulling_outer_join,
+ NULL,
+ j->larg != NULL);
break;
case JOIN_LEFT:
case JOIN_SEMI:
case JOIN_ANTI:
- j->larg = pull_up_subqueries(root, j->larg,
- lowest_outer_join, NULL);
- j->rarg = pull_up_subqueries(root, j->rarg,
- j, NULL);
+ j->larg = pull_up_subqueries_recurse(root, j->larg,
+ j,
+ lowest_nulling_outer_join,
+ NULL,
+ false);
+ j->rarg = pull_up_subqueries_recurse(root, j->rarg,
+ j,
+ j,
+ NULL,
+ false);
break;
case JOIN_FULL:
- j->larg = pull_up_subqueries(root, j->larg,
- j, NULL);
- j->rarg = pull_up_subqueries(root, j->rarg,
- j, NULL);
+ j->larg = pull_up_subqueries_recurse(root, j->larg,
+ j,
+ j,
+ NULL,
+ false);
+ j->rarg = pull_up_subqueries_recurse(root, j->rarg,
+ j,
+ j,
+ NULL,
+ false);
break;
case JOIN_RIGHT:
- j->larg = pull_up_subqueries(root, j->larg,
- j, NULL);
- j->rarg = pull_up_subqueries(root, j->rarg,
- lowest_outer_join, NULL);
+ j->larg = pull_up_subqueries_recurse(root, j->larg,
+ j,
+ j,
+ NULL,
+ false);
+ j->rarg = pull_up_subqueries_recurse(root, j->rarg,
+ j,
+ lowest_nulling_outer_join,
+ NULL,
+ false);
break;
default:
elog(ERROR, "unrecognized join type: %d",
* Attempt to pull up a single simple subquery.
*
* jtnode is a RangeTblRef that has been tentatively identified as a simple
- * subquery by pull_up_subqueries. We return the replacement jointree node,
- * or jtnode itself if we determine that the subquery can't be pulled up after
- * all.
+ * subquery by pull_up_subqueries. We return the replacement jointree node,
+ * or NULL if the subquery can be deleted entirely, or jtnode itself if we
+ * determine that the subquery can't be pulled up after all.
*
* rte is the RangeTblEntry referenced by jtnode. Remaining parameters are
- * as for pull_up_subqueries.
+ * as for pull_up_subqueries_recurse.
*/
static Node *
pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte,
JoinExpr *lowest_outer_join,
- AppendRelInfo *containing_appendrel)
+ JoinExpr *lowest_nulling_outer_join,
+ AppendRelInfo *containing_appendrel,
+ bool deletion_ok)
{
Query *parse = root->parse;
int varno = ((RangeTblRef *) jtnode)->rtindex;
* Create a PlannerInfo data structure for this subquery.
*
* NOTE: the next few steps should match the first processing in
- * subquery_planner(). Can we refactor to avoid code duplication, or
+ * subquery_planner(). Can we refactor to avoid code duplication, or
* would that just make things uglier?
*/
subroot = makeNode(PlannerInfo);
subroot->glob = root->glob;
subroot->query_level = root->query_level;
subroot->parent_root = root->parent_root;
+ subroot->plan_params = NIL;
+ subroot->outer_params = NULL;
subroot->planner_cxt = CurrentMemoryContext;
subroot->init_plans = NIL;
subroot->cte_plan_ids = NIL;
+ subroot->multiexpr_params = NIL;
subroot->eq_classes = NIL;
subroot->append_rel_list = NIL;
subroot->rowMarks = NIL;
* pull_up_subqueries' processing is complete for its jointree and
* rangetable.
*
- * Note: we should pass NULL for containing-join info even if we are
- * within an outer join in the upper query; the lower query starts with a
- * clean slate for outer-join semantics. Likewise, we say we aren't
- * handling an appendrel member.
+ * Note: it's okay that the subquery's recursion starts with NULL for
+ * containing-join info, even if we are within an outer join in the upper
+ * query; the lower query starts with a clean slate for outer-join
+ * semantics. Likewise, we needn't pass down appendrel state.
*/
- subquery->jointree = (FromExpr *)
- pull_up_subqueries(subroot, (Node *) subquery->jointree, NULL, NULL);
+ pull_up_subqueries(subroot);
/*
* Now we must recheck whether the subquery is still simple enough to pull
- * up. If not, abandon processing it.
+ * up. If not, abandon processing it.
*
* We don't really need to recheck all the conditions involved, but it's
* easier just to keep this "if" looking the same as the one in
- * pull_up_subqueries.
+ * pull_up_subqueries_recurse.
*/
- if (is_simple_subquery(subquery) &&
+ if (is_simple_subquery(subquery, rte,
+ lowest_outer_join, deletion_ok) &&
(containing_appendrel == NULL || is_safe_append_member(subquery)))
{
/* good to go */
* Give up, return unmodified RangeTblRef.
*
* Note: The work we just did will be redone when the subquery gets
- * planned on its own. Perhaps we could avoid that by storing the
+ * planned on its own. Perhaps we could avoid that by storing the
* modified subquery back into the rangetable, but I'm not gonna risk
* it now.
*/
return jtnode;
}
+ /*
+ * We must flatten any join alias Vars in the subquery's targetlist,
+ * because pulling up the subquery's subqueries might have changed their
+ * expansions into arbitrary expressions, which could affect
+ * pullup_replace_vars' decisions about whether PlaceHolderVar wrappers
+ * are needed for tlist entries. (Likely it'd be better to do
+ * flatten_join_alias_vars on the whole query tree at some earlier stage,
+ * maybe even in the rewriter; but for now let's just fix this case here.)
+ */
+ subquery->targetList = (List *)
+ flatten_join_alias_vars(subroot, (Node *) subquery->targetList);
+
/*
* Adjust level-0 varnos in subquery so that we can append its rangetable
* to upper query's. We have to fix the subquery's append_rel_list as
/*
* The subquery's targetlist items are now in the appropriate form to
* insert into the top query, but if we are under an outer join then
- * non-nullable items may have to be turned into PlaceHolderVars. If we
- * are dealing with an appendrel member then anything that's not a simple
- * Var has to be turned into a PlaceHolderVar. Set up appropriate context
- * data for pullup_replace_vars.
+ * non-nullable items and lateral references may have to be turned into
+ * PlaceHolderVars. If we are dealing with an appendrel member then
+ * anything that's not a simple Var has to be turned into a
+ * PlaceHolderVar. Set up required context data for pullup_replace_vars.
*/
rvcontext.root = root;
rvcontext.targetlist = subquery->targetList;
rvcontext.target_rte = rte;
+ if (rte->lateral)
+ rvcontext.relids = get_relids_in_jointree((Node *) subquery->jointree,
+ true);
+ else /* won't need relids */
+ rvcontext.relids = NULL;
rvcontext.outer_hasSubLinks = &parse->hasSubLinks;
rvcontext.varno = varno;
- rvcontext.need_phvs = (lowest_outer_join != NULL ||
+ rvcontext.need_phvs = (lowest_nulling_outer_join != NULL ||
containing_appendrel != NULL);
rvcontext.wrap_non_vars = (containing_appendrel != NULL);
/* initialize cache array with indexes 0 .. length(tlist) */
* replace any of the jointree structure. (This'd be a lot cleaner if we
* could use query_tree_mutator.) We have to use PHVs in the targetList,
* returningList, and havingQual, since those are certainly above any
- * outer join. replace_vars_in_jointree tracks its location in the
+ * outer join. replace_vars_in_jointree tracks its location in the
* jointree and uses PHVs or not appropriately.
*/
parse->targetList = (List *)
pullup_replace_vars((Node *) parse->targetList, &rvcontext);
parse->returningList = (List *)
pullup_replace_vars((Node *) parse->returningList, &rvcontext);
+ if (parse->onConflict)
+ parse->onConflict->onConflictSet = (List *)
+ pullup_replace_vars((Node *) parse->onConflict->onConflictSet, &rvcontext);
replace_vars_in_jointree((Node *) parse->jointree, &rvcontext,
- lowest_outer_join);
+ lowest_nulling_outer_join);
Assert(parse->setOperations == NULL);
parse->havingQual = pullup_replace_vars(parse->havingQual, &rvcontext);
* Replace references in the joinaliasvars lists of join RTEs.
*
* You might think that we could avoid using PHVs for alias vars of joins
- * below lowest_outer_join, but that doesn't work because the alias vars
- * could be referenced above that join; we need the PHVs to be present in
- * such references after the alias vars get flattened. (It might be worth
- * trying to be smarter here, someday.)
+ * below lowest_nulling_outer_join, but that doesn't work because the
+ * alias vars could be referenced above that join; we need the PHVs to be
+ * present in such references after the alias vars get flattened. (It
+ * might be worth trying to be smarter here, someday.)
*/
foreach(lc, parse->rtable)
{
&rvcontext);
}
+ /*
+ * If the subquery had a LATERAL marker, propagate that to any of its
+ * child RTEs that could possibly now contain lateral cross-references.
+ * The children might or might not contain any actual lateral
+ * cross-references, but we have to mark the pulled-up child RTEs so that
+ * later planner stages will check for such.
+ */
+ if (rte->lateral)
+ {
+ foreach(lc, subquery->rtable)
+ {
+ RangeTblEntry *child_rte = (RangeTblEntry *) lfirst(lc);
+
+ switch (child_rte->rtekind)
+ {
+ case RTE_RELATION:
+ if (child_rte->tablesample)
+ child_rte->lateral = true;
+ break;
+ case RTE_SUBQUERY:
+ case RTE_FUNCTION:
+ case RTE_VALUES:
+ child_rte->lateral = true;
+ break;
+ case RTE_JOIN:
+ case RTE_CTE:
+ /* these can't contain any lateral references */
+ break;
+ }
+ }
+ }
+
/*
* Now append the adjusted rtable entries to upper query. (We hold off
* until after fixing the upper rtable entries; no point in running that
/*
* Return the adjusted subquery jointree to replace the RangeTblRef entry
- * in parent's jointree.
+ * in parent's jointree; or, if we're flattening a subquery with empty
+ * FROM list, return NULL to signal deletion of the subquery from the
+ * parent jointree (and set hasDeletedRTEs to ensure cleanup later).
*/
+ if (subquery->jointree->fromlist == NIL)
+ {
+ Assert(deletion_ok);
+ Assert(subquery->jointree->quals == NULL);
+ root->hasDeletedRTEs = true;
+ return NULL;
+ }
+
return (Node *) subquery->jointree;
}
* Pull up a single simple UNION ALL subquery.
*
* jtnode is a RangeTblRef that has been identified as a simple UNION ALL
- * subquery by pull_up_subqueries. We pull up the leaf subqueries and
+ * subquery by pull_up_subqueries. We pull up the leaf subqueries and
* build an "append relation" for the union set. The result value is just
* jtnode, since we don't actually need to change the query jointree.
*/
{
int varno = ((RangeTblRef *) jtnode)->rtindex;
Query *subquery = rte->subquery;
- int rtoffset;
+ int rtoffset = list_length(root->parse->rtable);
List *rtable;
/*
- * Append child RTEs to parent rtable.
- *
+ * Make a modifiable copy of the subquery's rtable, so we can adjust
+ * upper-level Vars in it. There are no such Vars in the setOperations
+ * tree proper, so fixing the rtable should be sufficient.
+ */
+ rtable = copyObject(subquery->rtable);
+
+ /*
* Upper-level vars in subquery are now one level closer to their parent
* than before. We don't have to worry about offsetting varnos, though,
- * because any such vars must refer to stuff above the level of the query
- * we are pulling into.
+ * because the UNION leaf queries can't cross-reference each other.
*/
- rtoffset = list_length(root->parse->rtable);
- rtable = copyObject(subquery->rtable);
IncrementVarSublevelsUp_rtable(rtable, -1, 1);
+
+ /*
+ * If the UNION ALL subquery had a LATERAL marker, propagate that to all
+ * its children. The individual children might or might not contain any
+ * actual lateral cross-references, but we have to mark the pulled-up
+ * child RTEs so that later planner stages will check for such.
+ */
+ if (rte->lateral)
+ {
+ ListCell *rt;
+
+ foreach(rt, rtable)
+ {
+ RangeTblEntry *child_rte = (RangeTblEntry *) lfirst(rt);
+
+ Assert(child_rte->rtekind == RTE_SUBQUERY);
+ child_rte->lateral = true;
+ }
+ }
+
+ /*
+ * Append child RTEs to parent rtable.
+ */
root->parse->rtable = list_concat(root->parse->rtable, rtable);
/*
* must build the AppendRelInfo first, because this will modify it.)
* Note that we can pass NULL for containing-join info even if we're
* actually under an outer join, because the child's expressions
- * aren't going to propagate up above the join.
+ * aren't going to propagate up to the join. Also, we ignore the
+ * possibility that pull_up_subqueries_recurse() returns a different
+ * jointree node than what we pass it; if it does, the important thing
+ * is that it replaced the child relid in the AppendRelInfo node.
*/
rtr = makeNode(RangeTblRef);
rtr->rtindex = childRTindex;
- (void) pull_up_subqueries(root, (Node *) rtr, NULL, appinfo);
+ (void) pull_up_subqueries_recurse(root, (Node *) rtr,
+ NULL, NULL, appinfo, false);
}
else if (IsA(setOp, SetOperationStmt))
{
* is_simple_subquery
* Check a subquery in the range table to see if it's simple enough
* to pull up into the parent query.
+ *
+ * rte is the RTE_SUBQUERY RangeTblEntry that contained the subquery.
+ * (Note subquery is not necessarily equal to rte->subquery; it could be a
+ * processed copy of that.)
+ * lowest_outer_join is the lowest outer join above the subquery, or NULL.
+ * deletion_ok is TRUE if it'd be okay to delete the subquery entirely.
*/
static bool
-is_simple_subquery(Query *subquery)
+is_simple_subquery(Query *subquery, RangeTblEntry *rte,
+ JoinExpr *lowest_outer_join,
+ bool deletion_ok)
{
/*
* Let's just make sure it's a valid subselect ...
*/
if (!IsA(subquery, Query) ||
subquery->commandType != CMD_SELECT ||
- subquery->utilityStmt != NULL ||
- subquery->intoClause != NULL)
+ subquery->utilityStmt != NULL)
elog(ERROR, "subquery is bogus");
/*
if (subquery->hasAggs ||
subquery->hasWindowFuncs ||
subquery->groupClause ||
+ subquery->groupingSets ||
subquery->havingQual ||
subquery->sortClause ||
subquery->distinctClause ||
subquery->cteList)
return false;
+ /*
+ * Don't pull up if the RTE represents a security-barrier view; we
+ * couldn't prevent information leakage once the RTE's Vars are scattered
+ * about in the upper query.
+ */
+ if (rte->security_barrier)
+ return false;
+
+ /*
+ * Don't pull up a subquery with an empty jointree, unless it has no quals
+ * and deletion_ok is TRUE and we're not underneath an outer join.
+ *
+ * query_planner() will correctly generate a Result plan for a jointree
+ * that's totally empty, but we can't cope with an empty FromExpr
+ * appearing lower down in a jointree: we identify join rels via baserelid
+ * sets, so we couldn't distinguish a join containing such a FromExpr from
+ * one without it. We can only handle such cases if the place where the
+ * subquery is linked is a FromExpr or inner JOIN that would still be
+ * nonempty after removal of the subquery, so that it's still identifiable
+ * via its contained baserelids. Safe contexts are signaled by
+ * deletion_ok.
+ *
+ * But even in a safe context, we must keep the subquery if it has any
+ * quals, because it's unclear where to put them in the upper query.
+ *
+ * Also, we must forbid pullup if such a subquery is underneath an outer
+ * join, because then we might need to wrap its output columns with
+ * PlaceHolderVars, and the PHVs would then have empty relid sets meaning
+ * we couldn't tell where to evaluate them. (This test is separate from
+ * the deletion_ok flag for possible future expansion: deletion_ok tells
+ * whether the immediate parent site in the jointree could cope, not
+ * whether we'd have PHV issues. It's possible this restriction could be
+ * fixed by letting the PHVs use the relids of the parent jointree item,
+ * but that complication is for another day.)
+ *
+ * Note that deletion of a subquery is also dependent on the check below
+ * that its targetlist contains no set-returning functions. Deletion from
+ * a FROM list or inner JOIN is okay only if the subquery must return
+ * exactly one row.
+ */
+ if (subquery->jointree->fromlist == NIL &&
+ (subquery->jointree->quals != NULL ||
+ !deletion_ok ||
+ lowest_outer_join != NULL))
+ return false;
+
+ /*
+ * If the subquery is LATERAL, check for pullup restrictions from that.
+ */
+ if (rte->lateral)
+ {
+ bool restricted;
+ Relids safe_upper_varnos;
+
+ /*
+ * The subquery's WHERE and JOIN/ON quals mustn't contain any lateral
+ * references to rels outside a higher outer join (including the case
+ * where the outer join is within the subquery itself). In such a
+ * case, pulling up would result in a situation where we need to
+ * postpone quals from below an outer join to above it, which is
+ * probably completely wrong and in any case is a complication that
+ * doesn't seem worth addressing at the moment.
+ */
+ if (lowest_outer_join != NULL)
+ {
+ restricted = true;
+ safe_upper_varnos = get_relids_in_jointree((Node *) lowest_outer_join,
+ true);
+ }
+ else
+ {
+ restricted = false;
+ safe_upper_varnos = NULL; /* doesn't matter */
+ }
+
+ if (jointree_contains_lateral_outer_refs((Node *) subquery->jointree,
+ restricted, safe_upper_varnos))
+ return false;
+
+ /*
+ * If there's an outer join above the LATERAL subquery, also disallow
+ * pullup if the subquery's targetlist has any references to rels
+ * outside the outer join, since these might get pulled into quals
+ * above the subquery (but in or below the outer join) and then lead
+ * to qual-postponement issues similar to the case checked for above.
+ * (We wouldn't need to prevent pullup if no such references appear in
+ * outer-query quals, but we don't have enough info here to check
+ * that. Also, maybe this restriction could be removed if we forced
+ * such refs to be wrapped in PlaceHolderVars, even when they're below
+ * the nearest outer join? But it's a pretty hokey usage, so not
+ * clear this is worth sweating over.)
+ */
+ if (lowest_outer_join != NULL)
+ {
+ Relids lvarnos = pull_varnos_of_level((Node *) subquery->targetList, 1);
+
+ if (!bms_is_subset(lvarnos, safe_upper_varnos))
+ return false;
+ }
+ }
+
/*
* Don't pull up a subquery that has any set-returning functions in its
- * targetlist. Otherwise we might well wind up inserting set-returning
+ * targetlist. Otherwise we might well wind up inserting set-returning
* functions into places where they mustn't go, such as quals of higher
- * queries.
+ * queries. This also ensures deletion of an empty jointree is valid.
*/
if (expression_returns_set((Node *) subquery->targetList))
return false;
/*
* Don't pull up a subquery that has any volatile functions in its
- * targetlist. Otherwise we might introduce multiple evaluations of these
+ * targetlist. Otherwise we might introduce multiple evaluations of these
* functions, if they get copied to multiple places in the upper query,
* leading to surprising results. (Note: the PlaceHolderVar mechanism
* doesn't quite guarantee single evaluation; else we could pull up anyway
if (contain_volatile_functions((Node *) subquery->targetList))
return false;
+ return true;
+}
+
+/*
+ * pull_up_simple_values
+ * Pull up a single simple VALUES RTE.
+ *
+ * jtnode is a RangeTblRef that has been identified as a simple VALUES RTE
+ * by pull_up_subqueries. We always return NULL indicating that the RTE
+ * can be deleted entirely (all failure cases should have been detected by
+ * is_simple_values()).
+ *
+ * rte is the RangeTblEntry referenced by jtnode. Because of the limited
+ * possible usage of VALUES RTEs, we do not need the remaining parameters
+ * of pull_up_subqueries_recurse.
+ */
+static Node *
+pull_up_simple_values(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte)
+{
+ Query *parse = root->parse;
+ int varno = ((RangeTblRef *) jtnode)->rtindex;
+ List *values_list;
+ List *tlist;
+ AttrNumber attrno;
+ pullup_replace_vars_context rvcontext;
+ ListCell *lc;
+
+ Assert(rte->rtekind == RTE_VALUES);
+ Assert(list_length(rte->values_lists) == 1);
+
/*
- * Hack: don't try to pull up a subquery with an empty jointree.
- * query_planner() will correctly generate a Result plan for a jointree
- * that's totally empty, but I don't think the right things happen if an
- * empty FromExpr appears lower down in a jointree. It would pose a
- * problem for the PlaceHolderVar mechanism too, since we'd have no way to
- * identify where to evaluate a PHV coming out of the subquery. Not worth
- * working hard on this, just to collapse SubqueryScan/Result into Result;
- * especially since the SubqueryScan can often be optimized away by
- * setrefs.c anyway.
+ * Need a modifiable copy of the VALUES list to hack on, just in case it's
+ * multiply referenced.
*/
- if (subquery->jointree->fromlist == NIL)
+ values_list = (List *) copyObject(linitial(rte->values_lists));
+
+ /*
+ * The VALUES RTE can't contain any Vars of level zero, let alone any that
+ * are join aliases, so no need to flatten join alias Vars.
+ */
+ Assert(!contain_vars_of_level((Node *) values_list, 0));
+
+ /*
+ * Set up required context data for pullup_replace_vars. In particular,
+ * we have to make the VALUES list look like a subquery targetlist.
+ */
+ tlist = NIL;
+ attrno = 1;
+ foreach(lc, values_list)
+ {
+ tlist = lappend(tlist,
+ makeTargetEntry((Expr *) lfirst(lc),
+ attrno,
+ NULL,
+ false));
+ attrno++;
+ }
+ rvcontext.root = root;
+ rvcontext.targetlist = tlist;
+ rvcontext.target_rte = rte;
+ rvcontext.relids = NULL;
+ rvcontext.outer_hasSubLinks = &parse->hasSubLinks;
+ rvcontext.varno = varno;
+ rvcontext.need_phvs = false;
+ rvcontext.wrap_non_vars = false;
+ /* initialize cache array with indexes 0 .. length(tlist) */
+ rvcontext.rv_cache = palloc0((list_length(tlist) + 1) *
+ sizeof(Node *));
+
+ /*
+ * Replace all of the top query's references to the RTE's outputs with
+ * copies of the adjusted VALUES expressions, being careful not to replace
+ * any of the jointree structure. (This'd be a lot cleaner if we could use
+ * query_tree_mutator.) Much of this should be no-ops in the dummy Query
+ * that surrounds a VALUES RTE, but it's not enough code to be worth
+ * removing.
+ */
+ parse->targetList = (List *)
+ pullup_replace_vars((Node *) parse->targetList, &rvcontext);
+ parse->returningList = (List *)
+ pullup_replace_vars((Node *) parse->returningList, &rvcontext);
+ if (parse->onConflict)
+ parse->onConflict->onConflictSet = (List *)
+ pullup_replace_vars((Node *) parse->onConflict->onConflictSet, &rvcontext);
+ replace_vars_in_jointree((Node *) parse->jointree, &rvcontext, NULL);
+ Assert(parse->setOperations == NULL);
+ parse->havingQual = pullup_replace_vars(parse->havingQual, &rvcontext);
+
+ /*
+ * There should be no appendrels to fix, nor any join alias Vars, nor any
+ * outer joins and hence no PlaceHolderVars.
+ */
+ Assert(root->append_rel_list == NIL);
+ Assert(list_length(parse->rtable) == 1);
+ Assert(root->join_info_list == NIL);
+ Assert(root->placeholder_list == NIL);
+
+ /*
+ * Return NULL to signal deletion of the VALUES RTE from the parent
+ * jointree (and set hasDeletedRTEs to ensure cleanup later).
+ */
+ root->hasDeletedRTEs = true;
+ return NULL;
+}
+
+/*
+ * is_simple_values
+ * Check a VALUES RTE in the range table to see if it's simple enough
+ * to pull up into the parent query.
+ *
+ * rte is the RTE_VALUES RangeTblEntry to check.
+ * deletion_ok is TRUE if it'd be okay to delete the VALUES RTE entirely.
+ */
+static bool
+is_simple_values(PlannerInfo *root, RangeTblEntry *rte, bool deletion_ok)
+{
+ Assert(rte->rtekind == RTE_VALUES);
+
+ /*
+ * We can only pull up a VALUES RTE if deletion_ok is TRUE. It's
+ * basically the same case as a sub-select with empty FROM list; see
+ * comments in is_simple_subquery().
+ */
+ if (!deletion_ok)
+ return false;
+
+ /*
+ * Also, there must be exactly one VALUES list, else it's not semantically
+ * correct to delete the VALUES RTE.
+ */
+ if (list_length(rte->values_lists) != 1)
+ return false;
+
+ /*
+ * Because VALUES can't appear under an outer join (or at least, we won't
+ * try to pull it up if it does), we need not worry about LATERAL, nor
+ * about validity of PHVs for the VALUES' outputs.
+ */
+
+ /*
+ * Don't pull up a VALUES that contains any set-returning or volatile
+ * functions. Again, the considerations here are basically identical to
+ * restrictions on a subquery's targetlist.
+ */
+ if (expression_returns_set((Node *) rte->values_lists) ||
+ contain_volatile_functions((Node *) rte->values_lists))
+ return false;
+
+ /*
+ * Do not pull up a VALUES that's not the only RTE in its parent query.
+ * This is actually the only case that the parser will generate at the
+ * moment, and assuming this is true greatly simplifies
+ * pull_up_simple_values().
+ */
+ if (list_length(root->parse->rtable) != 1 ||
+ rte != (RangeTblEntry *) linitial(root->parse->rtable))
return false;
return true;
/* Let's just make sure it's a valid subselect ... */
if (!IsA(subquery, Query) ||
subquery->commandType != CMD_SELECT ||
- subquery->utilityStmt != NULL ||
- subquery->intoClause != NULL)
+ subquery->utilityStmt != NULL)
elog(ERROR, "subquery is bogus");
/* Is it a set-operation query at all? */
Assert(subquery != NULL);
/* Leaf nodes are OK if they match the toplevel column types */
- /* We don't have to compare typmods here */
+ /* We don't have to compare typmods or collations here */
return tlist_same_datatypes(subquery->targetList, colTypes, true);
}
else if (IsA(setOp, SetOperationStmt))
return true;
}
+/*
+ * jointree_contains_lateral_outer_refs
+ * Check for disallowed lateral references in a jointree's quals
+ *
+ * If restricted is false, all level-1 Vars are allowed (but we still must
+ * search the jointree, since it might contain outer joins below which there
+ * will be restrictions). If restricted is true, return TRUE when any qual
+ * in the jointree contains level-1 Vars coming from outside the rels listed
+ * in safe_upper_varnos.
+ */
+static bool
+jointree_contains_lateral_outer_refs(Node *jtnode, bool restricted,
+ Relids safe_upper_varnos)
+{
+ if (jtnode == NULL)
+ return false;
+ if (IsA(jtnode, RangeTblRef))
+ return false;
+ else if (IsA(jtnode, FromExpr))
+ {
+ FromExpr *f = (FromExpr *) jtnode;
+ ListCell *l;
+
+ /* First, recurse to check child joins */
+ foreach(l, f->fromlist)
+ {
+ if (jointree_contains_lateral_outer_refs(lfirst(l),
+ restricted,
+ safe_upper_varnos))
+ return true;
+ }
+
+ /* Then check the top-level quals */
+ if (restricted &&
+ !bms_is_subset(pull_varnos_of_level(f->quals, 1),
+ safe_upper_varnos))
+ return true;
+ }
+ else if (IsA(jtnode, JoinExpr))
+ {
+ JoinExpr *j = (JoinExpr *) jtnode;
+
+ /*
+ * If this is an outer join, we mustn't allow any upper lateral
+ * references in or below it.
+ */
+ if (j->jointype != JOIN_INNER)
+ {
+ restricted = true;
+ safe_upper_varnos = NULL;
+ }
+
+ /* Check the child joins */
+ if (jointree_contains_lateral_outer_refs(j->larg,
+ restricted,
+ safe_upper_varnos))
+ return true;
+ if (jointree_contains_lateral_outer_refs(j->rarg,
+ restricted,
+ safe_upper_varnos))
+ return true;
+
+ /* Check the JOIN's qual clauses */
+ if (restricted &&
+ !bms_is_subset(pull_varnos_of_level(j->quals, 1),
+ safe_upper_varnos))
+ return true;
+ }
+ else
+ elog(ERROR, "unrecognized node type: %d",
+ (int) nodeTag(jtnode));
+ return false;
+}
+
/*
* Helper routine for pull_up_subqueries: do pullup_replace_vars on every
* expression in the jointree, without changing the jointree structure itself.
* Ugly, but there's no other way...
*
- * If we are at or below lowest_outer_join, we can suppress use of
+ * If we are at or below lowest_nulling_outer_join, we can suppress use of
* PlaceHolderVars wrapped around the replacement expressions.
*/
static void
replace_vars_in_jointree(Node *jtnode,
pullup_replace_vars_context *context,
- JoinExpr *lowest_outer_join)
+ JoinExpr *lowest_nulling_outer_join)
{
if (jtnode == NULL)
return;
if (IsA(jtnode, RangeTblRef))
{
- /* nothing to do here */
+ /*
+ * If the RangeTblRef refers to a LATERAL subquery (that isn't the
+ * same subquery we're pulling up), it might contain references to the
+ * target subquery, which we must replace. We drive this from the
+ * jointree scan, rather than a scan of the rtable, for a couple of
+ * reasons: we can avoid processing no-longer-referenced RTEs, and we
+ * can use the appropriate setting of need_phvs depending on whether
+ * the RTE is above possibly-nulling outer joins or not.
+ */
+ int varno = ((RangeTblRef *) jtnode)->rtindex;
+
+ if (varno != context->varno) /* ignore target subquery itself */
+ {
+ RangeTblEntry *rte = rt_fetch(varno, context->root->parse->rtable);
+
+ Assert(rte != context->target_rte);
+ if (rte->lateral)
+ {
+ switch (rte->rtekind)
+ {
+ case RTE_RELATION:
+ /* shouldn't be marked LATERAL unless tablesample */
+ Assert(rte->tablesample);
+ rte->tablesample = (TableSampleClause *)
+ pullup_replace_vars((Node *) rte->tablesample,
+ context);
+ break;
+ case RTE_SUBQUERY:
+ rte->subquery =
+ pullup_replace_vars_subquery(rte->subquery,
+ context);
+ break;
+ case RTE_FUNCTION:
+ rte->functions = (List *)
+ pullup_replace_vars((Node *) rte->functions,
+ context);
+ break;
+ case RTE_VALUES:
+ rte->values_lists = (List *)
+ pullup_replace_vars((Node *) rte->values_lists,
+ context);
+ break;
+ case RTE_JOIN:
+ case RTE_CTE:
+ /* these shouldn't be marked LATERAL */
+ Assert(false);
+ break;
+ }
+ }
+ }
}
else if (IsA(jtnode, FromExpr))
{
ListCell *l;
foreach(l, f->fromlist)
- replace_vars_in_jointree(lfirst(l), context, lowest_outer_join);
+ replace_vars_in_jointree(lfirst(l), context,
+ lowest_nulling_outer_join);
f->quals = pullup_replace_vars(f->quals, context);
}
else if (IsA(jtnode, JoinExpr))
JoinExpr *j = (JoinExpr *) jtnode;
bool save_need_phvs = context->need_phvs;
- if (j == lowest_outer_join)
+ if (j == lowest_nulling_outer_join)
{
/* no more PHVs in or below this join */
context->need_phvs = false;
- lowest_outer_join = NULL;
+ lowest_nulling_outer_join = NULL;
}
- replace_vars_in_jointree(j->larg, context, lowest_outer_join);
- replace_vars_in_jointree(j->rarg, context, lowest_outer_join);
+ replace_vars_in_jointree(j->larg, context, lowest_nulling_outer_join);
+ replace_vars_in_jointree(j->rarg, context, lowest_nulling_outer_join);
j->quals = pullup_replace_vars(j->quals, context);
/*
/*
* Insert PlaceHolderVar if needed. Notice that we are wrapping one
* PlaceHolderVar around the whole RowExpr, rather than putting one
- * around each element of the row. This is because we need the
+ * around each element of the row. This is because we need the
* expression to yield NULL, not ROW(NULL,NULL,...) when it is forced
* to null by an outer join.
*/
if (newnode && IsA(newnode, Var) &&
((Var *) newnode)->varlevelsup == 0)
{
- /* Simple Vars always escape being wrapped */
+ /*
+ * Simple Vars always escape being wrapped, unless they are
+ * lateral references to something outside the subquery being
+ * pulled up. (Even then, we could omit the PlaceHolderVar if
+ * the referenced rel is under the same lowest outer join, but
+ * it doesn't seem worth the trouble to check that.)
+ */
+ if (rcon->target_rte->lateral &&
+ !bms_is_member(((Var *) newnode)->varno, rcon->relids))
+ wrap = true;
+ else
+ wrap = false;
+ }
+ else if (newnode && IsA(newnode, PlaceHolderVar) &&
+ ((PlaceHolderVar *) newnode)->phlevelsup == 0)
+ {
+ /* No need to wrap a PlaceHolderVar with another one, either */
wrap = false;
}
else if (rcon->wrap_non_vars)
else
{
/*
- * If it contains a Var of current level, and does not contain
- * any non-strict constructs, then it's certainly nullable and
- * we don't need to insert a PlaceHolderVar. (Note: in future
- * maybe we should insert PlaceHolderVars anyway, when a tlist
- * item is expensive to evaluate?
+ * If it contains a Var of the subquery being pulled up, and
+ * does not contain any non-strict constructs, then it's
+ * certainly nullable so we don't need to insert a
+ * PlaceHolderVar.
+ *
+ * This analysis could be tighter: in particular, a non-strict
+ * construct hidden within a lower-level PlaceHolderVar is not
+ * reason to add another PHV. But for now it doesn't seem
+ * worth the code to be more exact.
+ *
+ * Note: in future maybe we should insert a PlaceHolderVar
+ * anyway, if the tlist item is expensive to evaluate?
+ *
+ * For a LATERAL subquery, we have to check the actual var
+ * membership of the node, but if it's non-lateral then any
+ * level-zero var must belong to the subquery.
*/
- if (contain_vars_of_level((Node *) newnode, 0) &&
+ if ((rcon->target_rte->lateral ?
+ bms_overlap(pull_varnos((Node *) newnode), rcon->relids) :
+ contain_vars_of_level((Node *) newnode, 0)) &&
!contain_nonstrict_functions((Node *) newnode))
{
/* No wrap needed */
/*
* Cache it if possible (ie, if the attno is in range, which it
- * probably always should be). We can cache the value even if we
+ * probably always should be). We can cache the value even if we
* decided we didn't need a PHV, since this result will be
* suitable for any request that has need_phvs.
*/
return newnode;
}
+/*
+ * Apply pullup variable replacement to a subquery
+ *
+ * This needs to be different from pullup_replace_vars() because
+ * replace_rte_variables will think that it shouldn't increment sublevels_up
+ * before entering the Query; so we need to call it with sublevels_up == 1.
+ */
+static Query *
+pullup_replace_vars_subquery(Query *query,
+ pullup_replace_vars_context *context)
+{
+ Assert(IsA(query, Query));
+ return (Query *) replace_rte_variables((Node *) query,
+ context->varno, 1,
+ pullup_replace_vars_callback,
+ (void *) context,
+ NULL);
+}
+
+/*
+ * pull_up_subqueries_cleanup
+ * Recursively fix up jointree after deletion of some subqueries.
+ *
+ * The jointree now contains some NULL subtrees, which we need to get rid of.
+ * In a FromExpr, just rebuild the child-node list with null entries deleted.
+ * In an inner JOIN, replace the JoinExpr node with a one-child FromExpr.
+ */
+static Node *
+pull_up_subqueries_cleanup(Node *jtnode)
+{
+ Assert(jtnode != NULL);
+ if (IsA(jtnode, RangeTblRef))
+ {
+ /* Nothing to do at leaf nodes. */
+ }
+ else if (IsA(jtnode, FromExpr))
+ {
+ FromExpr *f = (FromExpr *) jtnode;
+ List *newfrom = NIL;
+ ListCell *l;
+
+ foreach(l, f->fromlist)
+ {
+ Node *child = (Node *) lfirst(l);
+
+ if (child == NULL)
+ continue;
+ child = pull_up_subqueries_cleanup(child);
+ newfrom = lappend(newfrom, child);
+ }
+ f->fromlist = newfrom;
+ }
+ else if (IsA(jtnode, JoinExpr))
+ {
+ JoinExpr *j = (JoinExpr *) jtnode;
+
+ if (j->larg)
+ j->larg = pull_up_subqueries_cleanup(j->larg);
+ if (j->rarg)
+ j->rarg = pull_up_subqueries_cleanup(j->rarg);
+ if (j->larg == NULL)
+ {
+ Assert(j->jointype == JOIN_INNER);
+ Assert(j->rarg != NULL);
+ return (Node *) makeFromExpr(list_make1(j->rarg), j->quals);
+ }
+ else if (j->rarg == NULL)
+ {
+ Assert(j->jointype == JOIN_INNER);
+ return (Node *) makeFromExpr(list_make1(j->larg), j->quals);
+ }
+ }
+ else
+ elog(ERROR, "unrecognized node type: %d",
+ (int) nodeTag(jtnode));
+ return jtnode;
+}
+
/*
* flatten_simple_union_all
/*
* Make a copy of the leftmost RTE and add it to the rtable. This copy
- * will represent the leftmost leaf query in its capacity as a member
- * of the appendrel. The original will represent the appendrel as a
- * whole. (We must do things this way because the upper query's Vars
- * have to be seen as referring to the whole appendrel.)
+ * will represent the leftmost leaf query in its capacity as a member of
+ * the appendrel. The original will represent the appendrel as a whole.
+ * (We must do things this way because the upper query's Vars have to be
+ * seen as referring to the whole appendrel.)
*/
childRTE = copyObject(leftmostRTE);
parse->rtable = lappend(parse->rtable, childRTE);
parse->jointree->fromlist = list_make1(rtr);
/*
- * Now pretend the query has no setops. We must do this before trying
- * to do subquery pullup, because of Assert in pull_up_simple_subquery.
+ * Now pretend the query has no setops. We must do this before trying to
+ * do subquery pullup, because of Assert in pull_up_simple_subquery.
*/
parse->setOperations = NULL;
* SELECT ... FROM a LEFT JOIN b ON (a.x = b.y) WHERE b.y IS NULL;
* If the join clause is strict for b.y, then only null-extended rows could
* pass the upper WHERE, and we can conclude that what the query is really
- * specifying is an anti-semijoin. We change the join type from JOIN_LEFT
+ * specifying is an anti-semijoin. We change the join type from JOIN_LEFT
* to JOIN_ANTI. The IS NULL clause then becomes redundant, and must be
* removed to prevent bogus selectivity calculations, but we leave it to
* distribute_qual_to_rels to get rid of such clauses.
/*
* See if we can reduce JOIN_LEFT to JOIN_ANTI. This is the case if
* the join's own quals are strict for any var that was forced null by
- * higher qual levels. NOTE: there are other ways that we could
+ * higher qual levels. NOTE: there are other ways that we could
* detect an anti-join, in particular if we were to check whether Vars
* coming from the RHS must be non-null because of table constraints.
* That seems complicated and expensive though (in particular, one
* is that we pass either the local or the upper constraints,
* never both, to the children of an outer join.
*
+ * Note that a SEMI join works like an inner join here: it's okay
+ * to pass down both local and upper constraints. (There can't be
+ * any upper constraints affecting its inner side, but it's not
+ * worth having a separate code path to avoid passing them.)
+ *
* At a FULL join we just punt and pass nothing down --- is it
* possible to be smarter?
*/
if (!computed_local_nonnullable_vars)
local_nonnullable_vars = find_nonnullable_vars(j->quals);
local_forced_null_vars = find_forced_null_vars(j->quals);
- if (jointype == JOIN_INNER)
+ if (jointype == JOIN_INNER || jointype == JOIN_SEMI)
{
/* OK to merge upper and local constraints */
local_nonnullable_rels = bms_add_members(local_nonnullable_rels,
if (left_state->contains_outer)
{
- if (jointype == JOIN_INNER)
+ if (jointype == JOIN_INNER || jointype == JOIN_SEMI)
{
/* pass union of local and upper constraints */
pass_nonnullable_rels = local_nonnullable_rels;
pass_nonnullable_vars = local_nonnullable_vars;
pass_forced_null_vars = local_forced_null_vars;
}
- else if (jointype != JOIN_FULL) /* ie, LEFT/SEMI/ANTI */
+ else if (jointype != JOIN_FULL) /* ie, LEFT or ANTI */
{
/* can't pass local constraints to non-nullable side */
pass_nonnullable_rels = nonnullable_rels;
*
* Find any PlaceHolderVar nodes in the given tree that reference the
* pulled-up relid, and change them to reference the replacement relid(s).
- * We do not need to recurse into subqueries, since no subquery of the current
- * top query could (yet) contain such a reference.
*
* NOTE: although this has the form of a walker, we cheat and modify the
- * nodes in-place. This should be OK since the tree was copied by
+ * nodes in-place. This should be OK since the tree was copied by
* pullup_replace_vars earlier. Avoid scribbling on the original values of
* the bitmapsets, though, because expression_tree_mutator doesn't copy those.
*/
typedef struct
{
int varno;
+ int sublevels_up;
Relids subrelids;
} substitute_multiple_relids_context;
{
PlaceHolderVar *phv = (PlaceHolderVar *) node;
- if (bms_is_member(context->varno, phv->phrels))
+ if (phv->phlevelsup == context->sublevels_up &&
+ bms_is_member(context->varno, phv->phrels))
{
phv->phrels = bms_union(phv->phrels,
context->subrelids);
}
/* fall through to examine children */
}
+ if (IsA(node, Query))
+ {
+ /* Recurse into subselects */
+ bool result;
+
+ context->sublevels_up++;
+ result = query_tree_walker((Query *) node,
+ substitute_multiple_relids_walker,
+ (void *) context, 0);
+ context->sublevels_up--;
+ return result;
+ }
/* Shouldn't need to handle planner auxiliary nodes here */
Assert(!IsA(node, SpecialJoinInfo));
Assert(!IsA(node, AppendRelInfo));
substitute_multiple_relids_context context;
context.varno = varno;
+ context.sublevels_up = 0;
context.subrelids = subrelids;
/*
projects / postgresql / blobdiff