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;
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;
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);
}
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);
}
/*
* The list may also contain PlaceHolderVars. These don't necessarily
* have a single owning relation; we keep their attr_needed info in
* root->placeholder_list instead. If create_new_ph is true, it's OK
- * to create new PlaceHolderInfos, and we also have to update ph_may_need;
- * otherwise, the PlaceHolderInfos must already exist, and we should only
- * update their ph_needed. (It should be true before deconstruct_jointree
- * begins, and false after that.)
+ * to create new PlaceHolderInfos; otherwise, the PlaceHolderInfos must
+ * already exist, and we should only update their ph_needed. (This should
+ * be true before deconstruct_jointree begins, and false after that.)
*/
void
add_vars_to_targetlist(PlannerInfo *root, List *vars,
PlaceHolderInfo *phinfo = find_placeholder_info(root, phv,
create_new_ph);
- /* Always adjust ph_needed */
phinfo->ph_needed = bms_add_members(phinfo->ph_needed,
where_needed);
-
- /*
- * If we are creating PlaceHolderInfos, mark them with the correct
- * maybe-needed locations. Otherwise, it's too late to change
- * that, so we'd better not have set ph_needed to more than
- * ph_may_need.
- */
- if (create_new_ph)
- mark_placeholder_maybe_needed(root, phinfo, where_needed);
- else
- Assert(bms_is_subset(phinfo->ph_needed, phinfo->ph_may_need));
}
else
elog(ERROR, "unrecognized node type: %d", (int) nodeTag(node));
* means setting suitable where_needed values for them.
*
* This has to run before deconstruct_jointree, since it might result in
- * creation of PlaceHolderInfos or extension of their ph_may_need sets.
+ * creation of PlaceHolderInfos.
*/
void
find_lateral_references(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.
+ * this join's nullable side, 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)
{
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);
}
#include "utils/lsyscache.h"
/* Local functions */
-static Relids find_placeholders_recurse(PlannerInfo *root, Node *jtnode);
-static void mark_placeholders_in_expr(PlannerInfo *root, Node *expr,
- Relids relids);
+static void find_placeholders_recurse(PlannerInfo *root, Node *jtnode);
+static void find_placeholders_in_expr(PlannerInfo *root, Node *expr);
/*
phinfo->phid = phv->phid;
phinfo->ph_var = copyObject(phv);
+ /* initialize ph_eval_at as the set of contained relids */
phinfo->ph_eval_at = pull_varnos((Node *) phv);
/* 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));
root->placeholder_list = lappend(root->placeholder_list, phinfo);
+ /*
+ * The PHV's contained expression may contain other, lower-level PHVs. We
+ * now know we need to get those into the PlaceHolderInfo list, too, so we
+ * may as well do that immediately.
+ */
+ find_placeholders_in_expr(root, (Node *) phinfo->ph_var->phexpr);
+
return phinfo;
}
/* 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(root, (Node *) root->parse->jointree);
}
}
* 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
+static void
find_placeholders_recurse(PlannerInfo *root, Node *jtnode)
{
- Relids jtrelids;
-
if (jtnode == NULL)
- return NULL;
+ return;
if (IsA(jtnode, RangeTblRef))
{
- int varno = ((RangeTblRef *) jtnode)->rtindex;
-
- /* No quals to deal with, just return correct result */
- jtrelids = bms_make_singleton(varno);
+ /* No quals to deal with here */
}
else if (IsA(jtnode, FromExpr))
{
ListCell *l;
/*
- * First, recurse to handle child joins, and form their relid set.
+ * First, recurse to handle child joins.
*/
- jtrelids = NULL;
foreach(l, f->fromlist)
{
- Relids sub_relids;
-
- sub_relids = find_placeholders_recurse(root, lfirst(l));
- jtrelids = bms_join(jtrelids, sub_relids);
+ find_placeholders_recurse(root, lfirst(l));
}
/*
* Now process the top-level quals.
*/
- mark_placeholders_in_expr(root, f->quals, jtrelids);
+ find_placeholders_in_expr(root, f->quals);
}
else if (IsA(jtnode, JoinExpr))
{
JoinExpr *j = (JoinExpr *) jtnode;
- Relids leftids,
- rightids;
/*
- * First, recurse to handle child joins, and form their relid set.
+ * First, recurse to handle child joins.
*/
- leftids = find_placeholders_recurse(root, j->larg);
- rightids = find_placeholders_recurse(root, j->rarg);
- jtrelids = bms_join(leftids, rightids);
+ find_placeholders_recurse(root, j->larg);
+ find_placeholders_recurse(root, j->rarg);
/* Process the qual clauses */
- mark_placeholders_in_expr(root, j->quals, jtrelids);
+ find_placeholders_in_expr(root, j->quals);
}
else
- {
elog(ERROR, "unrecognized node type: %d",
(int) nodeTag(jtnode));
- jtrelids = NULL; /* keep compiler quiet */
- }
- return jtrelids;
}
/*
- * mark_placeholders_in_expr
- * Find all PlaceHolderVars in the given expression, and mark them
- * as possibly needed at the specified join level.
- *
- * relids is the syntactic join level to mark as the "maybe needed" level
- * for each PlaceHolderVar found in the expression.
+ * find_placeholders_in_expr
+ * Find all PlaceHolderVars in the given expression, and create
+ * PlaceHolderInfo entries for them.
*/
static void
-mark_placeholders_in_expr(PlannerInfo *root, Node *expr, Relids relids)
+find_placeholders_in_expr(PlannerInfo *root, Node *expr)
{
List *vars;
ListCell *vl;
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, true);
-
- /* Mark it, and recursively process any contained placeholders */
- mark_placeholder_maybe_needed(root, phinfo, relids);
+ (void) find_placeholder_info(root, phv, true);
}
list_free(vars);
}
-/*
- * mark_placeholder_maybe_needed
- * Mark a placeholder as possibly needed at the specified join level.
- *
- * relids is the syntactic join level to mark as the "maybe needed" level
- * for the placeholder.
- *
- * This is called during an initial scan of the query's targetlist and quals
- * before we begin deconstruct_jointree. Once we begin deconstruct_jointree,
- * all active placeholders must be present in root->placeholder_list with
- * their correct ph_may_need values, because make_outerjoininfo and
- * update_placeholder_eval_levels require this info to be available while
- * we crawl up the join tree.
- */
-void
-mark_placeholder_maybe_needed(PlannerInfo *root, PlaceHolderInfo *phinfo,
- Relids relids)
-{
- Relids est_eval_level;
-
- /* Mark the PHV as possibly needed at the given 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, but not less than the level of any Vars it contains.
- * (Normally the Vars would come from below the syntactic location anyway,
- * but this might not be true if the PHV contains any LATERAL references.)
- */
- est_eval_level = bms_union(phinfo->ph_var->phrels, phinfo->ph_eval_at);
-
- /* Now recurse to take care of any such PHVs */
- mark_placeholders_in_expr(root, (Node *) phinfo->ph_var->phexpr,
- est_eval_level);
-
- bms_free(est_eval_level);
-}
-
/*
* update_placeholder_eval_levels
* Adjust the target evaluation levels for placeholders
* 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.
+ * Notice that when ph_eval_at is a join rather than a single baserel, the
+ * PlaceHolderInfo may create constraints on join order: the ph_eval_at join
+ * has to be formed below any outer joins that should null the PlaceHolderVar.
*
* We create a PlaceHolderInfo only after determining that the PlaceHolderVar
* is actually referenced in the plan tree, so that unreferenced placeholders
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;
extern PlaceHolderInfo *find_placeholder_info(PlannerInfo *root,
PlaceHolderVar *phv, bool create_new_ph);
extern void find_placeholders_in_jointree(PlannerInfo *root);
-extern void mark_placeholder_maybe_needed(PlannerInfo *root,
- PlaceHolderInfo *phinfo, Relids relids);
extern void update_placeholder_eval_levels(PlannerInfo *root,
SpecialJoinInfo *new_sjinfo);
extern void fix_placeholder_input_needed_levels(PlannerInfo *root);
Output: (COALESCE((COALESCE(b.q2, 42::bigint)), d.q2))
(26 rows)
+-- case that breaks the old ph_may_need optimization
+explain (verbose, costs off)
+select c.*,a.*,ss1.q1,ss2.q1,ss3.* from
+ int8_tbl c left join (
+ int8_tbl a left join
+ (select q1, coalesce(q2,f1) as x from int8_tbl b, int4_tbl b2
+ where q1 < f1) ss1
+ on a.q2 = ss1.q1
+ cross join
+ lateral (select q1, coalesce(ss1.x,q2) as y from int8_tbl d) ss2
+ ) on c.q2 = ss2.q1,
+ lateral (select * from int4_tbl i where ss2.y > f1) ss3;
+ QUERY PLAN
+-------------------------------------------------------------------------------------------
+ Hash Right Join
+ Output: c.q1, c.q2, a.q1, a.q2, b.q1, d.q1, i.f1
+ Hash Cond: (d.q1 = c.q2)
+ Filter: ((COALESCE((COALESCE(b.q2, (b2.f1)::bigint)), d.q2)) > i.f1)
+ -> Nested Loop
+ Output: a.q1, a.q2, b.q1, d.q1, COALESCE((COALESCE(b.q2, (b2.f1)::bigint)), d.q2)
+ -> Hash Right Join
+ Output: a.q1, a.q2, b.q1, (COALESCE(b.q2, (b2.f1)::bigint))
+ Hash Cond: (b.q1 = a.q2)
+ -> Nested Loop
+ Output: b.q1, COALESCE(b.q2, (b2.f1)::bigint)
+ Join Filter: (b.q1 < b2.f1)
+ -> Seq Scan on public.int8_tbl b
+ Output: b.q1, b.q2
+ -> Materialize
+ Output: b2.f1
+ -> Seq Scan on public.int4_tbl b2
+ Output: b2.f1
+ -> Hash
+ Output: a.q1, a.q2
+ -> Seq Scan on public.int8_tbl a
+ Output: a.q1, a.q2
+ -> Materialize
+ Output: d.q1, d.q2
+ -> Seq Scan on public.int8_tbl d
+ Output: d.q1, d.q2
+ -> Hash
+ Output: c.q1, c.q2, i.f1
+ -> Nested Loop
+ Output: c.q1, c.q2, i.f1
+ -> Seq Scan on public.int8_tbl c
+ Output: c.q1, c.q2
+ -> Materialize
+ Output: i.f1
+ -> Seq Scan on public.int4_tbl i
+ Output: i.f1
+(36 rows)
+
-- test some error cases where LATERAL should have been used but wasn't
select f1,g from int4_tbl a, (select f1 as g) ss;
ERROR: column "f1" does not exist
) on c.q2 = ss2.q1,
lateral (select ss2.y) ss3;
+-- case that breaks the old ph_may_need optimization
+explain (verbose, costs off)
+select c.*,a.*,ss1.q1,ss2.q1,ss3.* from
+ int8_tbl c left join (
+ int8_tbl a left join
+ (select q1, coalesce(q2,f1) as x from int8_tbl b, int4_tbl b2
+ where q1 < f1) ss1
+ on a.q2 = ss1.q1
+ cross join
+ lateral (select q1, coalesce(ss1.x,q2) as y from int8_tbl d) ss2
+ ) on c.q2 = ss2.q1,
+ lateral (select * from int4_tbl i where ss2.y > f1) ss3;
+
-- test some error cases where LATERAL should have been used but wasn't
select f1,g from int4_tbl a, (select f1 as g) ss;
select f1,g from int4_tbl a, (select a.f1 as g) ss;
projects / postgresql / commitdiff