From f4abd0241de20d5d6a79b84992b9e88603d44134 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Wed, 11 Mar 2015 23:18:03 -0400
Subject: [PATCH] Support flattening of empty-FROM subqueries and one-row
VALUES tables.
We can't handle this in the general case due to limitations of the
planner's data representations; but we can allow it in many useful cases,
by being careful to flatten only when we are pulling a single-row subquery
up into a FROM (or, equivalently, inner JOIN) node that will still have at
least one remaining relation child. Per discussion of an example from
Kyotaro Horiguchi.
---
src/backend/nodes/outfuncs.c | 1 +
src/backend/optimizer/plan/planner.c | 3 +-
src/backend/optimizer/prep/prepjointree.c | 452 +++++++++++++++++++---
src/include/nodes/relation.h | 1 +
src/include/optimizer/prep.h | 2 +-
src/test/regress/expected/join.out | 28 +-
src/test/regress/expected/rangefuncs.out | 24 +-
src/test/regress/sql/join.sql | 13 +-
src/test/regress/sql/rangefuncs.sql | 13 +-
9 files changed, 466 insertions(+), 71 deletions(-)
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index ca596efb5b..fc418fcf9d 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -1762,6 +1762,7 @@ _outPlannerInfo(StringInfo str, const PlannerInfo *node)
WRITE_BOOL_FIELD(hasInheritedTarget);
WRITE_BOOL_FIELD(hasJoinRTEs);
WRITE_BOOL_FIELD(hasLateralRTEs);
+ WRITE_BOOL_FIELD(hasDeletedRTEs);
WRITE_BOOL_FIELD(hasHavingQual);
WRITE_BOOL_FIELD(hasPseudoConstantQuals);
WRITE_BOOL_FIELD(hasRecursion);
diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index b02a1079ae..88b91f1b20 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -352,8 +352,7 @@ subquery_planner(PlannerGlobal *glob, Query *parse,
* Check to see if any subqueries in the jointree can be merged into this
* query.
*/
- parse->jointree = (FromExpr *)
- pull_up_subqueries(root, (Node *) parse->jointree);
+ pull_up_subqueries(root);
/*
* If this is a simple UNION ALL query, flatten it into an appendrel. We
diff --git a/src/backend/optimizer/prep/prepjointree.c b/src/backend/optimizer/prep/prepjointree.c
index 8a0199ba93..50acfe40e9 100644
--- a/src/backend/optimizer/prep/prepjointree.c
+++ b/src/backend/optimizer/prep/prepjointree.c
@@ -65,12 +65,14 @@ static Node *pull_up_sublinks_qual_recurse(PlannerInfo *root, Node *node,
static Node *pull_up_subqueries_recurse(PlannerInfo *root, Node *jtnode,
JoinExpr *lowest_outer_join,
JoinExpr *lowest_nulling_outer_join,
- AppendRelInfo *containing_appendrel);
+ AppendRelInfo *containing_appendrel,
+ bool deletion_ok);
static Node *pull_up_simple_subquery(PlannerInfo *root, Node *jtnode,
RangeTblEntry *rte,
JoinExpr *lowest_outer_join,
JoinExpr *lowest_nulling_outer_join,
- AppendRelInfo *containing_appendrel);
+ 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,
@@ -79,7 +81,12 @@ static void pull_up_union_leaf_queries(Node *setOp, PlannerInfo *root,
static void make_setop_translation_list(Query *query, Index newvarno,
List **translated_vars);
static bool is_simple_subquery(Query *subquery, RangeTblEntry *rte,
- JoinExpr *lowest_outer_join);
+ 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);
@@ -95,6 +102,7 @@ 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,
@@ -593,20 +601,33 @@ inline_set_returning_functions(PlannerInfo *root)
* 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".
- *
- * This recursively processes the jointree and returns a modified jointree.
*/
-Node *
-pull_up_subqueries(PlannerInfo *root, Node *jtnode)
+void
+pull_up_subqueries(PlannerInfo *root)
{
- /* Start off with no containing join nor appendrel */
- return pull_up_subqueries_recurse(root, jtnode, NULL, NULL, NULL);
+ /* 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.
@@ -622,28 +643,39 @@ pull_up_subqueries(PlannerInfo *root, Node *jtnode)
* 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 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.
+ * 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.
*/
static Node *
pull_up_subqueries_recurse(PlannerInfo *root, Node *jtnode,
JoinExpr *lowest_outer_join,
JoinExpr *lowest_nulling_outer_join,
- AppendRelInfo *containing_appendrel)
+ AppendRelInfo *containing_appendrel,
+ bool deletion_ok)
{
- if (jtnode == NULL)
- return NULL;
+ Assert(jtnode != NULL);
if (IsA(jtnode, RangeTblRef))
{
int varno = ((RangeTblRef *) jtnode)->rtindex;
@@ -657,13 +689,15 @@ pull_up_subqueries_recurse(PlannerInfo *root, Node *jtnode,
* unless is_safe_append_member says so.
*/
if (rte->rtekind == RTE_SUBQUERY &&
- is_simple_subquery(rte->subquery, rte, lowest_outer_join) &&
+ 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,
lowest_nulling_outer_join,
- containing_appendrel);
+ containing_appendrel,
+ deletion_ok);
/*
* Alternatively, is it a simple UNION ALL subquery? If so, flatten
@@ -678,19 +712,68 @@ pull_up_subqueries_recurse(PlannerInfo *root, Node *jtnode,
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)
+ {
+ /*
+ * 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);
+ 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))
{
@@ -701,14 +784,22 @@ pull_up_subqueries_recurse(PlannerInfo *root, Node *jtnode,
switch (j->jointype)
{
case JOIN_INNER:
+
+ /*
+ * 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);
+ NULL,
+ true);
j->rarg = pull_up_subqueries_recurse(root, j->rarg,
lowest_outer_join,
lowest_nulling_outer_join,
- NULL);
+ NULL,
+ j->larg != NULL);
break;
case JOIN_LEFT:
case JOIN_SEMI:
@@ -716,31 +807,37 @@ pull_up_subqueries_recurse(PlannerInfo *root, Node *jtnode,
j->larg = pull_up_subqueries_recurse(root, j->larg,
j,
lowest_nulling_outer_join,
- NULL);
+ NULL,
+ false);
j->rarg = pull_up_subqueries_recurse(root, j->rarg,
j,
j,
- NULL);
+ NULL,
+ false);
break;
case JOIN_FULL:
j->larg = pull_up_subqueries_recurse(root, j->larg,
j,
j,
- NULL);
+ NULL,
+ false);
j->rarg = pull_up_subqueries_recurse(root, j->rarg,
j,
j,
- NULL);
+ NULL,
+ false);
break;
case JOIN_RIGHT:
j->larg = pull_up_subqueries_recurse(root, j->larg,
j,
j,
- NULL);
+ NULL,
+ false);
j->rarg = pull_up_subqueries_recurse(root, j->rarg,
j,
lowest_nulling_outer_join,
- NULL);
+ NULL,
+ false);
break;
default:
elog(ERROR, "unrecognized join type: %d",
@@ -760,8 +857,8 @@ pull_up_subqueries_recurse(PlannerInfo *root, Node *jtnode,
*
* 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.
+ * 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_recurse.
@@ -770,7 +867,8 @@ static Node *
pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte,
JoinExpr *lowest_outer_join,
JoinExpr *lowest_nulling_outer_join,
- AppendRelInfo *containing_appendrel)
+ AppendRelInfo *containing_appendrel,
+ bool deletion_ok)
{
Query *parse = root->parse;
int varno = ((RangeTblRef *) jtnode)->rtindex;
@@ -832,14 +930,12 @@ pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte,
* 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_recurse(subroot, (Node *) subquery->jointree,
- NULL, NULL, NULL);
+ pull_up_subqueries(subroot);
/*
* Now we must recheck whether the subquery is still simple enough to pull
@@ -849,7 +945,8 @@ pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte,
* easier just to keep this "if" looking the same as the one in
* pull_up_subqueries_recurse.
*/
- if (is_simple_subquery(subquery, rte, lowest_outer_join) &&
+ if (is_simple_subquery(subquery, rte,
+ lowest_outer_join, deletion_ok) &&
(containing_appendrel == NULL || is_safe_append_member(subquery)))
{
/* good to go */
@@ -1075,8 +1172,18 @@ pull_up_simple_subquery(PlannerInfo *root, Node *jtnode, RangeTblEntry *rte,
/*
* 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;
}
@@ -1203,12 +1310,15 @@ pull_up_union_leaf_queries(Node *setOp, PlannerInfo *root, int parentRTindex,
* 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 to 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_recurse(root, (Node *) rtr,
- NULL, NULL, appinfo);
+ NULL, NULL, appinfo, false);
}
else if (IsA(setOp, SetOperationStmt))
{
@@ -1263,10 +1373,12 @@ make_setop_translation_list(Query *query, Index newvarno,
* (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, RangeTblEntry *rte,
- JoinExpr *lowest_outer_join)
+ JoinExpr *lowest_outer_join,
+ bool deletion_ok)
{
/*
* Let's just make sure it's a valid subselect ...
@@ -1314,6 +1426,29 @@ is_simple_subquery(Query *subquery, RangeTblEntry *rte,
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. 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. This would for example break the
+ * PlaceHolderVar mechanism, since we'd have no way to identify where to
+ * evaluate a PHV coming out of the subquery. 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. (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 || !deletion_ok))
+ return false;
+
/*
* If the subquery is LATERAL, check for pullup restrictions from that.
*/
@@ -1373,7 +1508,7 @@ is_simple_subquery(Query *subquery, RangeTblEntry *rte,
* Don't pull up a subquery that has any set-returning functions in its
* 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;
@@ -1389,19 +1524,159 @@ is_simple_subquery(Query *subquery, RangeTblEntry *rte,
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);
+
/*
- * Don't pull up a subquery with an empty jointree. 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. This
- * would for example break the PlaceHolderVar mechanism, 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);
+ 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->lateral_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.
+ */
+
+ /*
+ * 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;
@@ -1909,6 +2184,65 @@ pullup_replace_vars_subquery(Query *query,
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
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index e6dd4e8515..334cf51976 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -244,6 +244,7 @@ typedef struct PlannerInfo
* inheritance child rel */
bool hasJoinRTEs; /* true if any RTEs are RTE_JOIN kind */
bool hasLateralRTEs; /* true if any RTEs are marked LATERAL */
+ bool hasDeletedRTEs; /* true if any RTE was deleted from jointree */
bool hasHavingQual; /* true if havingQual was non-null */
bool hasPseudoConstantQuals; /* true if any RestrictInfo has
* pseudoconstant = true */
diff --git a/src/include/optimizer/prep.h b/src/include/optimizer/prep.h
index 385f4a866a..05e46c5b78 100644
--- a/src/include/optimizer/prep.h
+++ b/src/include/optimizer/prep.h
@@ -23,7 +23,7 @@
*/
extern void pull_up_sublinks(PlannerInfo *root);
extern void inline_set_returning_functions(PlannerInfo *root);
-extern Node *pull_up_subqueries(PlannerInfo *root, Node *jtnode);
+extern void pull_up_subqueries(PlannerInfo *root);
extern void flatten_simple_union_all(PlannerInfo *root);
extern void reduce_outer_joins(PlannerInfo *root);
extern Relids get_relids_in_jointree(Node *jtnode, bool include_joins);
diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out
index 8c17ef41b9..57fc910133 100644
--- a/src/test/regress/expected/join.out
+++ b/src/test/regress/expected/join.out
@@ -3633,6 +3633,26 @@ select * from generate_series(100,200) g,
explain (costs off)
select count(*) from tenk1 a,
tenk1 b join lateral (values(a.unique1)) ss(x) on b.unique2 = ss.x;
+ QUERY PLAN
+------------------------------------------------------------
+ Aggregate
+ -> Merge Join
+ Merge Cond: (a.unique1 = b.unique2)
+ -> Index Only Scan using tenk1_unique1 on tenk1 a
+ -> Index Only Scan using tenk1_unique2 on tenk1 b
+(5 rows)
+
+select count(*) from tenk1 a,
+ tenk1 b join lateral (values(a.unique1)) ss(x) on b.unique2 = ss.x;
+ count
+-------
+ 10000
+(1 row)
+
+-- lateral with VALUES, no flattening possible
+explain (costs off)
+ select count(*) from tenk1 a,
+ tenk1 b join lateral (values(a.unique1),(-1)) ss(x) on b.unique2 = ss.x;
QUERY PLAN
------------------------------------------------------------------
Aggregate
@@ -3646,7 +3666,7 @@ explain (costs off)
(8 rows)
select count(*) from tenk1 a,
- tenk1 b join lateral (values(a.unique1)) ss(x) on b.unique2 = ss.x;
+ tenk1 b join lateral (values(a.unique1),(-1)) ss(x) on b.unique2 = ss.x;
count
-------
10000
@@ -4214,7 +4234,7 @@ select * from
cross join
lateral (select q1, coalesce(ss1.x,q2) as y from int8_tbl d) ss2
) on c.q2 = ss2.q1,
- lateral (select ss2.y) ss3;
+ lateral (select ss2.y offset 0) ss3;
QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Nested Loop
@@ -4296,9 +4316,9 @@ select c.*,a.*,ss1.q1,ss2.q1,ss3.* from
-- check processing of postponed quals (bug #9041)
explain (verbose, costs off)
select * from
- (select 1 as x) x cross join (select 2 as y) y
+ (select 1 as x offset 0) x cross join (select 2 as y offset 0) y
left join lateral (
- select * from (select 3 as z) z where z.z = x.x
+ select * from (select 3 as z offset 0) z where z.z = x.x
) zz on zz.z = y.y;
QUERY PLAN
----------------------------------------------
diff --git a/src/test/regress/expected/rangefuncs.out b/src/test/regress/expected/rangefuncs.out
index 7991e993f1..6dabe503cc 100644
--- a/src/test/regress/expected/rangefuncs.out
+++ b/src/test/regress/expected/rangefuncs.out
@@ -2034,7 +2034,7 @@ select x from int8_tbl, extractq2(int8_tbl) f(x);
(5 rows)
create function extractq2_2(t int8_tbl) returns table(ret1 int8) as $$
- select extractq2(t)
+ select extractq2(t) offset 0
$$ language sql immutable;
explain (verbose, costs off)
select x from int8_tbl, extractq2_2(int8_tbl) f(x);
@@ -2058,3 +2058,25 @@ select x from int8_tbl, extractq2_2(int8_tbl) f(x);
-4567890123456789
(5 rows)
+-- without the "offset 0", this function gets optimized quite differently
+create function extractq2_2_opt(t int8_tbl) returns table(ret1 int8) as $$
+ select extractq2(t)
+$$ language sql immutable;
+explain (verbose, costs off)
+select x from int8_tbl, extractq2_2_opt(int8_tbl) f(x);
+ QUERY PLAN
+-----------------------------
+ Seq Scan on public.int8_tbl
+ Output: int8_tbl.q2
+(2 rows)
+
+select x from int8_tbl, extractq2_2_opt(int8_tbl) f(x);
+ x
+-------------------
+ 456
+ 4567890123456789
+ 123
+ 4567890123456789
+ -4567890123456789
+(5 rows)
+
diff --git a/src/test/regress/sql/join.sql b/src/test/regress/sql/join.sql
index db7aefee28..06a27ea151 100644
--- a/src/test/regress/sql/join.sql
+++ b/src/test/regress/sql/join.sql
@@ -1137,6 +1137,13 @@ explain (costs off)
select count(*) from tenk1 a,
tenk1 b join lateral (values(a.unique1)) ss(x) on b.unique2 = ss.x;
+-- lateral with VALUES, no flattening possible
+explain (costs off)
+ select count(*) from tenk1 a,
+ tenk1 b join lateral (values(a.unique1),(-1)) ss(x) on b.unique2 = ss.x;
+select count(*) from tenk1 a,
+ tenk1 b join lateral (values(a.unique1),(-1)) ss(x) on b.unique2 = ss.x;
+
-- lateral injecting a strange outer join condition
explain (costs off)
select * from int8_tbl a,
@@ -1247,7 +1254,7 @@ select * from
cross join
lateral (select q1, coalesce(ss1.x,q2) as y from int8_tbl d) ss2
) on c.q2 = ss2.q1,
- lateral (select ss2.y) ss3;
+ lateral (select ss2.y offset 0) ss3;
-- case that breaks the old ph_may_need optimization
explain (verbose, costs off)
@@ -1265,9 +1272,9 @@ select c.*,a.*,ss1.q1,ss2.q1,ss3.* from
-- check processing of postponed quals (bug #9041)
explain (verbose, costs off)
select * from
- (select 1 as x) x cross join (select 2 as y) y
+ (select 1 as x offset 0) x cross join (select 2 as y offset 0) y
left join lateral (
- select * from (select 3 as z) z where z.z = x.x
+ select * from (select 3 as z offset 0) z where z.z = x.x
) zz on zz.z = y.y;
-- test some error cases where LATERAL should have been used but wasn't
diff --git a/src/test/regress/sql/rangefuncs.sql b/src/test/regress/sql/rangefuncs.sql
index 470571b0fb..9484023f97 100644
--- a/src/test/regress/sql/rangefuncs.sql
+++ b/src/test/regress/sql/rangefuncs.sql
@@ -621,10 +621,21 @@ select x from int8_tbl, extractq2(int8_tbl) f(x);
select x from int8_tbl, extractq2(int8_tbl) f(x);
create function extractq2_2(t int8_tbl) returns table(ret1 int8) as $$
- select extractq2(t)
+ select extractq2(t) offset 0
$$ language sql immutable;
explain (verbose, costs off)
select x from int8_tbl, extractq2_2(int8_tbl) f(x);
select x from int8_tbl, extractq2_2(int8_tbl) f(x);
+
+-- without the "offset 0", this function gets optimized quite differently
+
+create function extractq2_2_opt(t int8_tbl) returns table(ret1 int8) as $$
+ select extractq2(t)
+$$ language sql immutable;
+
+explain (verbose, costs off)
+select x from int8_tbl, extractq2_2_opt(int8_tbl) f(x);
+
+select x from int8_tbl, extractq2_2_opt(int8_tbl) f(x);
--
2.40.0