diff --git a/src/backend/nodes/copyfuncs.c b/src/backend/nodes/copyfuncs.c
index e07aa3ead232dfe2ef8f543d98a058aeebada323..5bd0ef07502fca76d8ac18f43cda1c7241a2aabb 100644
--- a/src/backend/nodes/copyfuncs.c
+++ b/src/backend/nodes/copyfuncs.c
@@ -1806,6 +1806,7 @@ _copyPlaceHolderInfo(PlaceHolderInfo *from)
COPY_NODE_FIELD(ph_var);
COPY_BITMAPSET_FIELD(ph_eval_at);
COPY_BITMAPSET_FIELD(ph_needed);
+ COPY_BITMAPSET_FIELD(ph_may_need);
COPY_SCALAR_FIELD(ph_width);
return newnode;
diff --git a/src/backend/nodes/equalfuncs.c b/src/backend/nodes/equalfuncs.c
index 8d083c8796d9ce6bb3f629b0b186e082c07987c0..c7dd42d13453d1531b1cd173339a2b6b2b7ffaba 100644
--- a/src/backend/nodes/equalfuncs.c
+++ b/src/backend/nodes/equalfuncs.c
@@ -838,6 +838,7 @@ _equalPlaceHolderInfo(PlaceHolderInfo *a, PlaceHolderInfo *b)
COMPARE_NODE_FIELD(ph_var);
COMPARE_BITMAPSET_FIELD(ph_eval_at);
COMPARE_BITMAPSET_FIELD(ph_needed);
+ COMPARE_BITMAPSET_FIELD(ph_may_need);
COMPARE_SCALAR_FIELD(ph_width);
return true;
diff --git a/src/backend/nodes/outfuncs.c b/src/backend/nodes/outfuncs.c
index 3b30d4f81c02b5c882ffd6facb5b693b50a95364..55665ca20e5f3e8bfb678a4b09acb7bae5ddd2d9 100644
--- a/src/backend/nodes/outfuncs.c
+++ b/src/backend/nodes/outfuncs.c
@@ -1768,6 +1768,7 @@ _outPlaceHolderInfo(StringInfo str, PlaceHolderInfo *node)
WRITE_NODE_FIELD(ph_var);
WRITE_BITMAPSET_FIELD(ph_eval_at);
WRITE_BITMAPSET_FIELD(ph_needed);
+ WRITE_BITMAPSET_FIELD(ph_may_need);
WRITE_INT_FIELD(ph_width);
}
diff --git a/src/backend/optimizer/plan/analyzejoins.c b/src/backend/optimizer/plan/analyzejoins.c
index 2a913578eba442e95952b79c0a29276012da34f2..89805c36b0664a3c44ab66e71177084f8aad5220 100644
--- a/src/backend/optimizer/plan/analyzejoins.c
+++ b/src/backend/optimizer/plan/analyzejoins.c
@@ -396,6 +396,8 @@ remove_rel_from_query(PlannerInfo *root, int relid, Relids joinrelids)
phinfo->ph_eval_at = bms_add_member(phinfo->ph_eval_at, relid);
phinfo->ph_needed = bms_del_member(phinfo->ph_needed, relid);
+ /* ph_may_need probably isn't used after this, but fix it anyway */
+ phinfo->ph_may_need = bms_del_member(phinfo->ph_may_need, relid);
}
/*
diff --git a/src/backend/optimizer/plan/initsplan.c b/src/backend/optimizer/plan/initsplan.c
index 2c61795ff271899892db8d94ff052eb02f30be4f..a2ff314679daa30003d59d04ec01066049e1cb13 100644
--- a/src/backend/optimizer/plan/initsplan.c
+++ b/src/backend/optimizer/plan/initsplan.c
@@ -187,6 +187,13 @@ add_vars_to_targetlist(PlannerInfo *root, List *vars, Relids where_needed)
phinfo->ph_needed = bms_add_members(phinfo->ph_needed,
where_needed);
+ /*
+ * Update ph_may_need too. This is currently only necessary
+ * when being called from build_base_rel_tlists, but we may as
+ * well do it always.
+ */
+ phinfo->ph_may_need = bms_add_members(phinfo->ph_may_need,
+ where_needed);
}
else
elog(ERROR, "unrecognized node type: %d", (int) nodeTag(node));
@@ -465,7 +472,11 @@ deconstruct_recurse(PlannerInfo *root, Node *jtnode, bool below_outer_join,
/* Now we can add the SpecialJoinInfo to join_info_list */
if (sjinfo)
+ {
root->join_info_list = lappend(root->join_info_list, sjinfo);
+ /* Each time we do that, recheck placeholder eval levels */
+ update_placeholder_eval_levels(root, sjinfo);
+ }
/*
* Finally, compute the output joinlist. We fold subproblems together
@@ -687,6 +698,32 @@ make_outerjoininfo(PlannerInfo *root,
}
}
+ /*
+ * Examine PlaceHolderVars. If a PHV is supposed to be evaluated within
+ * this join's nullable side, and it may get used above this join, then
+ * ensure that min_righthand contains the full eval_at set of the PHV.
+ * This ensures that the PHV actually can be evaluated within the RHS.
+ * Note that this works only because we should already have determined
+ * the final eval_at level for any PHV syntactically within this join.
+ */
+ foreach(l, root->placeholder_list)
+ {
+ PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(l);
+ Relids ph_syn_level = phinfo->ph_var->phrels;
+
+ /* Ignore placeholder if it didn't syntactically come from RHS */
+ if (!bms_is_subset(ph_syn_level, right_rels))
+ continue;
+
+ /* We can also ignore it if it's certainly not used above this join */
+ /* XXX this test is probably overly conservative */
+ if (bms_is_subset(phinfo->ph_may_need, min_righthand))
+ continue;
+
+ /* Else, prevent join from being formed before we eval the PHV */
+ min_righthand = bms_add_members(min_righthand, phinfo->ph_eval_at);
+ }
+
/*
* If we found nothing to put in min_lefthand, punt and make it the full
* LHS, to avoid having an empty min_lefthand which will confuse later
diff --git a/src/backend/optimizer/plan/planmain.c b/src/backend/optimizer/plan/planmain.c
index e82c3404b537568ab0043317d273b510c0d95fc9..9e884cbb3cb5e94014e627e669ff974b8fb393b1 100644
--- a/src/backend/optimizer/plan/planmain.c
+++ b/src/backend/optimizer/plan/planmain.c
@@ -180,14 +180,19 @@ query_planner(PlannerInfo *root, List *tlist,
add_base_rels_to_query(root, (Node *) parse->jointree);
/*
- * Examine the targetlist and qualifications, adding entries to baserel
- * targetlists for all referenced Vars. Restrict and join clauses are
- * added to appropriate lists belonging to the mentioned relations. We
- * also build EquivalenceClasses for provably equivalent expressions, and
- * form a target joinlist for make_one_rel() to work from.
+ * Examine the targetlist and join tree, adding entries to baserel
+ * targetlists for all referenced Vars, and generating PlaceHolderInfo
+ * entries for all referenced PlaceHolderVars. Restrict and join clauses
+ * are added to appropriate lists belonging to the mentioned relations.
+ * We also build EquivalenceClasses for provably equivalent expressions.
+ * The SpecialJoinInfo list is also built to hold information about join
+ * order restrictions. Finally, we form a target joinlist for
+ * make_one_rel() to work from.
*/
build_base_rel_tlists(root, tlist);
+ find_placeholders_in_jointree(root);
+
joinlist = deconstruct_jointree(root);
/*
@@ -218,10 +223,12 @@ query_planner(PlannerInfo *root, List *tlist,
/*
* Examine any "placeholder" expressions generated during subquery pullup.
- * Make sure that we know what level to evaluate them at, and that the
- * Vars they need are marked as needed.
+ * Make sure that the Vars they need are marked as needed at the relevant
+ * join level. This must be done before join removal because it might
+ * cause Vars or placeholders to be needed above a join when they weren't
+ * so marked before.
*/
- fix_placeholder_eval_levels(root);
+ fix_placeholder_input_needed_levels(root);
/*
* Remove any useless outer joins. Ideally this would be done during
diff --git a/src/backend/optimizer/util/placeholder.c b/src/backend/optimizer/util/placeholder.c
index 06bd6f2d011f61638dc18a761c2481b0e4a930c6..c9da718bd1f921257467ad6fea1d3cc6ff4b86a1 100644
--- a/src/backend/optimizer/util/placeholder.c
+++ b/src/backend/optimizer/util/placeholder.c
@@ -22,6 +22,11 @@
#include "optimizer/var.h"
#include "utils/lsyscache.h"
+/* Local functions */
+static Relids find_placeholders_recurse(PlannerInfo *root, Node *jtnode);
+static void find_placeholders_in_qual(PlannerInfo *root, Node *qual,
+ Relids relids);
+
/*
* make_placeholder_expr
@@ -47,6 +52,12 @@ make_placeholder_expr(PlannerInfo *root, Expr *expr, Relids phrels)
* find_placeholder_info
* Fetch the PlaceHolderInfo for the given PHV; create it if not found
*
+ * This is separate from make_placeholder_expr because subquery pullup has
+ * to make PlaceHolderVars for expressions that might not be used at all in
+ * the upper query, or might not remain after const-expression simplification.
+ * We build PlaceHolderInfos only for PHVs that are still present in the
+ * simplified query passed to query_planner().
+ *
* Note: this should only be called after query_planner() has started.
*/
PlaceHolderInfo *
@@ -71,8 +82,9 @@ find_placeholder_info(PlannerInfo *root, PlaceHolderVar *phv)
phinfo->phid = phv->phid;
phinfo->ph_var = copyObject(phv);
phinfo->ph_eval_at = pull_varnos((Node *) phv);
- /* ph_eval_at may change later, see fix_placeholder_eval_levels */
+ /* ph_eval_at may change later, see update_placeholder_eval_levels */
phinfo->ph_needed = NULL; /* initially it's unused */
+ phinfo->ph_may_need = NULL;
/* for the moment, estimate width using just the datatype info */
phinfo->ph_width = get_typavgwidth(exprType((Node *) phv->phexpr),
exprTypmod((Node *) phv->phexpr));
@@ -83,21 +95,168 @@ find_placeholder_info(PlannerInfo *root, PlaceHolderVar *phv)
}
/*
- * fix_placeholder_eval_levels
+ * find_placeholders_in_jointree
+ * Search the jointree for PlaceHolderVars, and build PlaceHolderInfos
+ *
+ * We don't need to look at the targetlist because build_base_rel_tlists()
+ * will already have made entries for any PHVs in the tlist.
+ */
+void
+find_placeholders_in_jointree(PlannerInfo *root)
+{
+ /* We need do nothing if the query contains no PlaceHolderVars */
+ if (root->glob->lastPHId != 0)
+ {
+ /* Start recursion at top of jointree */
+ Assert(root->parse->jointree != NULL &&
+ IsA(root->parse->jointree, FromExpr));
+ (void) find_placeholders_recurse(root, (Node *) root->parse->jointree);
+ }
+}
+
+/*
+ * find_placeholders_recurse
+ * One recursion level of find_placeholders_in_jointree.
+ *
+ * jtnode is the current jointree node to examine.
+ *
+ * The result is the set of base Relids contained in or below jtnode.
+ * This is just an internal convenience, it's not used at the top level.
+ */
+static Relids
+find_placeholders_recurse(PlannerInfo *root, Node *jtnode)
+{
+ Relids jtrelids;
+
+ if (jtnode == NULL)
+ return NULL;
+ if (IsA(jtnode, RangeTblRef))
+ {
+ int varno = ((RangeTblRef *) jtnode)->rtindex;
+
+ /* No quals to deal with, just return correct result */
+ jtrelids = bms_make_singleton(varno);
+ }
+ else if (IsA(jtnode, FromExpr))
+ {
+ FromExpr *f = (FromExpr *) jtnode;
+ ListCell *l;
+
+ /*
+ * First, recurse to handle child joins, and form their relid set.
+ */
+ jtrelids = NULL;
+ foreach(l, f->fromlist)
+ {
+ Relids sub_relids;
+
+ sub_relids = find_placeholders_recurse(root, lfirst(l));
+ jtrelids = bms_join(jtrelids, sub_relids);
+ }
+
+ /*
+ * Now process the top-level quals.
+ */
+ find_placeholders_in_qual(root, f->quals, jtrelids);
+ }
+ else if (IsA(jtnode, JoinExpr))
+ {
+ JoinExpr *j = (JoinExpr *) jtnode;
+ Relids leftids,
+ rightids;
+
+ /*
+ * First, recurse to handle child joins, and form their relid set.
+ */
+ leftids = find_placeholders_recurse(root, j->larg);
+ rightids = find_placeholders_recurse(root, j->rarg);
+ jtrelids = bms_join(leftids, rightids);
+
+ /* Process the qual clauses */
+ find_placeholders_in_qual(root, j->quals, jtrelids);
+ }
+ else
+ {
+ elog(ERROR, "unrecognized node type: %d",
+ (int) nodeTag(jtnode));
+ jtrelids = NULL; /* keep compiler quiet */
+ }
+ return jtrelids;
+}
+
+/*
+ * find_placeholders_in_qual
+ * Process a qual clause for find_placeholders_in_jointree.
+ *
+ * relids is the syntactic join level to mark as the "maybe needed" level
+ * for each PlaceHolderVar found in the qual clause.
+ */
+static void
+find_placeholders_in_qual(PlannerInfo *root, Node *qual, Relids relids)
+{
+ List *vars;
+ ListCell *vl;
+
+ /*
+ * pull_var_clause does more than we need here, but it'll do and it's
+ * convenient to use.
+ */
+ vars = pull_var_clause(qual, PVC_INCLUDE_PLACEHOLDERS);
+ foreach(vl, vars)
+ {
+ PlaceHolderVar *phv = (PlaceHolderVar *) lfirst(vl);
+ PlaceHolderInfo *phinfo;
+
+ /* Ignore any plain Vars */
+ if (!IsA(phv, PlaceHolderVar))
+ continue;
+
+ /* Create a PlaceHolderInfo entry if there's not one already */
+ phinfo = find_placeholder_info(root, phv);
+
+ /* Mark the PHV as possibly needed at the qual's syntactic level */
+ phinfo->ph_may_need = bms_add_members(phinfo->ph_may_need, relids);
+
+ /*
+ * This is a bit tricky: the PHV's contained expression may contain
+ * other, lower-level PHVs. We need to get those into the
+ * PlaceHolderInfo list, but they aren't going to be needed where the
+ * outer PHV is referenced. Rather, they'll be needed where the outer
+ * PHV is evaluated. We can estimate that (conservatively) as the
+ * syntactic location of the PHV's expression. Recurse to take care
+ * of any such PHVs.
+ */
+ find_placeholders_in_qual(root, (Node *) phv->phexpr, phv->phrels);
+ }
+ list_free(vars);
+}
+
+/*
+ * update_placeholder_eval_levels
* Adjust the target evaluation levels for placeholders
*
* The initial eval_at level set by find_placeholder_info was the set of
- * rels used in the placeholder's expression (or the whole subselect if
- * the expr is variable-free). If the subselect contains any outer joins
- * that can null any of those rels, we must delay evaluation to above those
- * joins.
+ * rels used in the placeholder's expression (or the whole subselect below
+ * the placeholder's syntactic location, if the expr is variable-free).
+ * If the subselect contains any outer joins that can null any of those rels,
+ * we must delay evaluation to above those joins.
+ *
+ * We repeat this operation each time we add another outer join to
+ * root->join_info_list. It's somewhat annoying to have to do that, but
+ * since we don't have very much information on the placeholders' locations,
+ * it's hard to avoid. Each placeholder's eval_at level must be correct
+ * by the time it starts to figure in outer-join delay decisions for higher
+ * outer joins.
*
* In future we might want to put additional policy/heuristics here to
* try to determine an optimal evaluation level. The current rules will
- * result in evaluation at the lowest possible level.
+ * result in evaluation at the lowest possible level. However, pushing a
+ * placeholder eval up the tree is likely to further constrain evaluation
+ * order for outer joins, so it could easily be counterproductive; and we
+ * don't have enough information at this point to make an intelligent choice.
*/
void
-fix_placeholder_eval_levels(PlannerInfo *root)
+update_placeholder_eval_levels(PlannerInfo *root, SpecialJoinInfo *new_sjinfo)
{
ListCell *lc1;
@@ -105,16 +264,27 @@ fix_placeholder_eval_levels(PlannerInfo *root)
{
PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(lc1);
Relids syn_level = phinfo->ph_var->phrels;
- Relids eval_at = phinfo->ph_eval_at;
+ Relids eval_at;
bool found_some;
ListCell *lc2;
+ /*
+ * We don't need to do any work on this placeholder unless the
+ * newly-added outer join is syntactically beneath its location.
+ */
+ if (!bms_is_subset(new_sjinfo->syn_lefthand, syn_level) ||
+ !bms_is_subset(new_sjinfo->syn_righthand, syn_level))
+ continue;
+
/*
* Check for delays due to lower outer joins. This is the same logic
* as in check_outerjoin_delay in initsplan.c, except that we don't
- * want to modify the delay_upper_joins flags; that was all handled
- * already during distribute_qual_to_rels.
+ * have anything to do with the delay_upper_joins flags; delay of
+ * upper outer joins will be handled later, based on the eval_at
+ * values we compute now.
*/
+ eval_at = phinfo->ph_eval_at;
+
do
{
found_some = false;
@@ -122,7 +292,7 @@ fix_placeholder_eval_levels(PlannerInfo *root)
{
SpecialJoinInfo *sjinfo = (SpecialJoinInfo *) lfirst(lc2);
- /* disregard joins not within the expr's sub-select */
+ /* disregard joins not within the PHV's sub-select */
if (!bms_is_subset(sjinfo->syn_lefthand, syn_level) ||
!bms_is_subset(sjinfo->syn_righthand, syn_level))
continue;
@@ -149,16 +319,32 @@ fix_placeholder_eval_levels(PlannerInfo *root)
} while (found_some);
phinfo->ph_eval_at = eval_at;
+ }
+}
- /*
- * Now that we know where to evaluate the placeholder, make sure that
- * any vars or placeholders it uses will be available at that join
- * level. NOTE: this could cause more PlaceHolderInfos to be added to
- * placeholder_list. That is okay because we'll process them before
- * falling out of the foreach loop. Also, it could cause the
- * ph_needed sets of existing list entries to expand, which is also
- * okay because this loop doesn't examine those.
- */
+/*
+ * fix_placeholder_input_needed_levels
+ * Adjust the "needed at" levels for placeholder inputs
+ *
+ * This is called after we've finished determining the eval_at levels for
+ * all placeholders. We need to make sure that all vars and placeholders
+ * needed to evaluate each placeholder will be available at the join level
+ * where the evaluation will be done. Note that this loop can have
+ * side-effects on the ph_needed sets of other PlaceHolderInfos; that's okay
+ * because we don't examine ph_needed here, so there are no ordering issues
+ * to worry about.
+ */
+void
+fix_placeholder_input_needed_levels(PlannerInfo *root)
+{
+ ListCell *lc;
+
+ foreach(lc, root->placeholder_list)
+ {
+ PlaceHolderInfo *phinfo = (PlaceHolderInfo *) lfirst(lc);
+ Relids eval_at = phinfo->ph_eval_at;
+
+ /* No work unless it'll be evaluated above baserel level */
if (bms_membership(eval_at) == BMS_MULTIPLE)
{
List *vars = pull_var_clause((Node *) phinfo->ph_var->phexpr,
@@ -175,11 +361,11 @@ fix_placeholder_eval_levels(PlannerInfo *root)
* Add any required PlaceHolderVars to base rels' targetlists.
*
* If any placeholder can be computed at a base rel and is needed above it,
- * add it to that rel's targetlist. We have to do this separately from
- * fix_placeholder_eval_levels() because join removal happens in between,
- * and can change the ph_eval_at sets. There is essentially the same logic
- * in add_placeholders_to_joinrel, but we can't do that part until joinrels
- * are formed.
+ * add it to that rel's targetlist. This might look like it could be merged
+ * with fix_placeholder_input_needed_levels, but it must be separate because
+ * join removal happens in between, and can change the ph_eval_at sets. There
+ * is essentially the same logic in add_placeholders_to_joinrel, but we can't
+ * do that part until joinrels are formed.
*/
void
add_placeholders_to_base_rels(PlannerInfo *root)
diff --git a/src/include/nodes/relation.h b/src/include/nodes/relation.h
index 6e3af0eae20c77ae71fc8c97487e9e20b59d582c..91f4c5c1c43716786e0f6382491ce7115535c13b 100644
--- a/src/include/nodes/relation.h
+++ b/src/include/nodes/relation.h
@@ -1316,8 +1316,22 @@ typedef struct AppendRelInfo
* then allow it to bubble up like a Var until the ph_needed join level.
* ph_needed has the same definition as attr_needed for a regular Var.
*
+ * ph_may_need is an initial estimate of ph_needed, formed using the
+ * syntactic locations of references to the PHV. We need this in order to
+ * determine whether the PHV reference forces a join ordering constraint:
+ * if the PHV has to be evaluated below the nullable side of an outer join,
+ * and then used above that outer join, we must constrain join order to ensure
+ * there's a valid place to evaluate the PHV below the join. The final
+ * actual ph_needed level might be lower than ph_may_need, but we can't
+ * determine that until later on. Fortunately this doesn't matter for what
+ * we need ph_may_need for: if there's a PHV reference syntactically
+ * above the outer join, it's not going to be allowed to drop below the outer
+ * join, so we would come to the same conclusions about join order even if
+ * we had the final ph_needed value to compare to.
+ *
* We create a PlaceHolderInfo only after determining that the PlaceHolderVar
- * is actually referenced in the plan tree.
+ * is actually referenced in the plan tree, so that unreferenced placeholders
+ * don't result in unnecessary constraints on join order.
*/
typedef struct PlaceHolderInfo
@@ -1328,6 +1342,7 @@ typedef struct PlaceHolderInfo
PlaceHolderVar *ph_var; /* copy of PlaceHolderVar tree */
Relids ph_eval_at; /* lowest level we can evaluate value at */
Relids ph_needed; /* highest level the value is needed at */
+ Relids ph_may_need; /* highest level it might be needed at */
int32 ph_width; /* estimated attribute width */
} PlaceHolderInfo;
diff --git a/src/include/optimizer/placeholder.h b/src/include/optimizer/placeholder.h
index 3f921a983a4d869ed156b80896ff0c63f380f74f..22d52411c2a3b25bef9a089449cdb26a80136385 100644
--- a/src/include/optimizer/placeholder.h
+++ b/src/include/optimizer/placeholder.h
@@ -21,7 +21,10 @@ extern PlaceHolderVar *make_placeholder_expr(PlannerInfo *root, Expr *expr,
Relids phrels);
extern PlaceHolderInfo *find_placeholder_info(PlannerInfo *root,
PlaceHolderVar *phv);
-extern void fix_placeholder_eval_levels(PlannerInfo *root);
+extern void find_placeholders_in_jointree(PlannerInfo *root);
+extern void update_placeholder_eval_levels(PlannerInfo *root,
+ SpecialJoinInfo *new_sjinfo);
+extern void fix_placeholder_input_needed_levels(PlannerInfo *root);
extern void add_placeholders_to_base_rels(PlannerInfo *root);
extern void add_placeholders_to_joinrel(PlannerInfo *root,
RelOptInfo *joinrel);
diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out
index 795495b14d1bd3449835121d9e1519b22c0d7263..178214b4b9d3258e934c775e07784a21a11eb3e0 100644
--- a/src/test/regress/expected/join.out
+++ b/src/test/regress/expected/join.out
@@ -2443,6 +2443,51 @@ group by t1.q2 order by 1;
4567890123456789 | 6
(4 rows)
+--
+-- test incorrect failure to NULL pulled-up subexpressions
+--
+begin;
+create temp table a (
+ code char not null,
+ constraint a_pk primary key (code)
+);
+NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "a_pk" for table "a"
+create temp table b (
+ a char not null,
+ num integer not null,
+ constraint b_pk primary key (a, num)
+);
+NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "b_pk" for table "b"
+create temp table c (
+ name char not null,
+ a char,
+ constraint c_pk primary key (name)
+);
+NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "c_pk" for table "c"
+insert into a (code) values ('p');
+insert into a (code) values ('q');
+insert into b (a, num) values ('p', 1);
+insert into b (a, num) values ('p', 2);
+insert into c (name, a) values ('A', 'p');
+insert into c (name, a) values ('B', 'q');
+insert into c (name, a) values ('C', null);
+select c.name, ss.code, ss.b_cnt, ss.const
+from c left join
+ (select a.code, coalesce(b_grp.cnt, 0) as b_cnt, -1 as const
+ from a left join
+ (select count(1) as cnt, b.a from b group by b.a) as b_grp
+ on a.code = b_grp.a
+ ) as ss
+ on (c.a = ss.code)
+order by c.name;
+ name | code | b_cnt | const
+------+------+-------+-------
+ A | p | 2 | -1
+ B | q | 0 | -1
+ C | | |
+(3 rows)
+
+rollback;
--
-- test the corner cases FULL JOIN ON TRUE and FULL JOIN ON FALSE
--
diff --git a/src/test/regress/sql/join.sql b/src/test/regress/sql/join.sql
index b5971b604482f7ea2659bb4925b680fa145eed4e..3012031fce3209cb6b36f57786d53801a7e5611d 100644
--- a/src/test/regress/sql/join.sql
+++ b/src/test/regress/sql/join.sql
@@ -562,6 +562,46 @@ from int8_tbl t1 left join
on (t1.q2 = t2.q1)
group by t1.q2 order by 1;
+--
+-- test incorrect failure to NULL pulled-up subexpressions
+--
+begin;
+
+create temp table a (
+ code char not null,
+ constraint a_pk primary key (code)
+);
+create temp table b (
+ a char not null,
+ num integer not null,
+ constraint b_pk primary key (a, num)
+);
+create temp table c (
+ name char not null,
+ a char,
+ constraint c_pk primary key (name)
+);
+
+insert into a (code) values ('p');
+insert into a (code) values ('q');
+insert into b (a, num) values ('p', 1);
+insert into b (a, num) values ('p', 2);
+insert into c (name, a) values ('A', 'p');
+insert into c (name, a) values ('B', 'q');
+insert into c (name, a) values ('C', null);
+
+select c.name, ss.code, ss.b_cnt, ss.const
+from c left join
+ (select a.code, coalesce(b_grp.cnt, 0) as b_cnt, -1 as const
+ from a left join
+ (select count(1) as cnt, b.a from b group by b.a) as b_grp
+ on a.code = b_grp.a
+ ) as ss
+ on (c.a = ss.code)
+order by c.name;
+
+rollback;
+
--
-- test the corner cases FULL JOIN ON TRUE and FULL JOIN ON FALSE
--