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Commitc1774d2

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More fixes for planner's handling of LATERAL.
Re-allow subquery pullup for LATERAL subqueries, except when the subqueryis below an outer join and contains lateral references to relations outsidethat outer join. If we pull up in such a case, we risk introducing lateralcross-references into outer joins' ON quals, which is something the code isentirely unprepared to cope with right now; and I'm not sure it'll ever beworth coping with.Support lateral refs in VALUES (this seems to be the only additional pathtype that needs such support as a consequence of re-allowing subquerypullup).Put in a slightly hacky fix for joinpath.c's refusal to considerparameterized join paths even when there cannot be any unparameterizedones. This was causing "could not devise a query plan for the given query"failures in queries involving more than two FROM items.Put in an even more hacky fix for distribute_qual_to_rels() being unhappywith join quals that contain references to rels outside their syntacticscope; which is to say, disable that test altogether. Need to think abouthow to preserve some sort of debugging cross-check here, while notexpending more cycles than befits a debugging cross-check.
1 parente76af54 commitc1774d2

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13 files changed

+390
-89
lines changed

13 files changed

+390
-89
lines changed

‎src/backend/optimizer/path/allpaths.c‎

Lines changed: 22 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -1210,15 +1210,33 @@ set_function_pathlist(PlannerInfo *root, RelOptInfo *rel, RangeTblEntry *rte)
12101210
* set_values_pathlist
12111211
*Build the (single) access path for a VALUES RTE
12121212
*
1213-
*There can be no need for a parameterized path here.(Although the SQL
1214-
*spec does allow LATERAL (VALUES (x)), theparser will transform that
1215-
*into asubquery, so it doesn't end up here.)
1213+
*As with subqueries, a VALUES RTE's path might be parameterized due to
1214+
*LATERAL references, but that's inherent in thevalues expressions and
1215+
*not aresult of pushing down join quals.
12161216
*/
12171217
staticvoid
12181218
set_values_pathlist(PlannerInfo*root,RelOptInfo*rel,RangeTblEntry*rte)
12191219
{
1220+
Relidsrequired_outer;
1221+
1222+
/*
1223+
* If it's a LATERAL RTE, it might contain some Vars of the current query
1224+
* level, requiring it to be treated as parameterized. (NB: even though
1225+
* the parser never marks VALUES RTEs as LATERAL, they could be so marked
1226+
* by now, as a result of subquery pullup.)
1227+
*/
1228+
if (rte->lateral)
1229+
{
1230+
required_outer=pull_varnos_of_level((Node*)rte->values_lists,0);
1231+
/* Enforce convention that empty required_outer is exactly NULL */
1232+
if (bms_is_empty(required_outer))
1233+
required_outer=NULL;
1234+
}
1235+
else
1236+
required_outer=NULL;
1237+
12201238
/* Generate appropriate path */
1221-
add_path(rel,create_valuesscan_path(root,rel));
1239+
add_path(rel,create_valuesscan_path(root,rel,required_outer));
12221240

12231241
/* Select cheapest path (pretty easy in this case...) */
12241242
set_cheapest(rel);

‎src/backend/optimizer/path/costsize.c‎

Lines changed: 15 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -1046,20 +1046,28 @@ cost_functionscan(Path *path, PlannerInfo *root,
10461046
/*
10471047
* cost_valuesscan
10481048
* Determines and returns the cost of scanning a VALUES RTE.
1049+
*
1050+
* 'baserel' is the relation to be scanned
1051+
* 'param_info' is the ParamPathInfo if this is a parameterized path, else NULL
10491052
*/
10501053
void
1051-
cost_valuesscan(Path*path,PlannerInfo*root,RelOptInfo*baserel)
1054+
cost_valuesscan(Path*path,PlannerInfo*root,
1055+
RelOptInfo*baserel,ParamPathInfo*param_info)
10521056
{
10531057
Coststartup_cost=0;
10541058
Costrun_cost=0;
1059+
QualCostqpqual_cost;
10551060
Costcpu_per_tuple;
10561061

10571062
/* Should only be applied to base relations that are values lists */
10581063
Assert(baserel->relid>0);
10591064
Assert(baserel->rtekind==RTE_VALUES);
10601065

1061-
/* valuesscans are never parameterized */
1062-
path->rows=baserel->rows;
1066+
/* Mark the path with the correct row estimate */
1067+
if (param_info)
1068+
path->rows=param_info->ppi_rows;
1069+
else
1070+
path->rows=baserel->rows;
10631071

10641072
/*
10651073
* For now, estimate list evaluation cost at one operator eval per list
@@ -1068,8 +1076,10 @@ cost_valuesscan(Path *path, PlannerInfo *root, RelOptInfo *baserel)
10681076
cpu_per_tuple=cpu_operator_cost;
10691077

10701078
/* Add scanning CPU costs */
1071-
startup_cost+=baserel->baserestrictcost.startup;
1072-
cpu_per_tuple+=cpu_tuple_cost+baserel->baserestrictcost.per_tuple;
1079+
get_restriction_qual_cost(root,baserel,param_info,&qpqual_cost);
1080+
1081+
startup_cost+=qpqual_cost.startup;
1082+
cpu_per_tuple+=cpu_tuple_cost+qpqual_cost.per_tuple;
10731083
run_cost+=cpu_per_tuple*baserel->tuples;
10741084

10751085
path->startup_cost=startup_cost;

‎src/backend/optimizer/path/joinpath.c‎

Lines changed: 26 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -147,6 +147,32 @@ add_paths_to_joinrel(PlannerInfo *root,
147147
sjinfo->min_lefthand));
148148
}
149149

150+
/*
151+
* However, when a LATERAL subquery is involved, we have to be a bit
152+
* laxer, because there may simply not be any paths for the joinrel that
153+
* aren't parameterized by whatever the subquery is parameterized by.
154+
* Hence, add to param_source_rels anything that is in the minimum
155+
* parameterization of either input (and not in the other input).
156+
*
157+
* XXX need a more principled way of determining minimum parameterization.
158+
*/
159+
if (outerrel->cheapest_total_path==NULL)
160+
{
161+
Path*cheapest= (Path*)linitial(outerrel->cheapest_parameterized_paths);
162+
163+
param_source_rels=bms_join(param_source_rels,
164+
bms_difference(PATH_REQ_OUTER(cheapest),
165+
innerrel->relids));
166+
}
167+
if (innerrel->cheapest_total_path==NULL)
168+
{
169+
Path*cheapest= (Path*)linitial(innerrel->cheapest_parameterized_paths);
170+
171+
param_source_rels=bms_join(param_source_rels,
172+
bms_difference(PATH_REQ_OUTER(cheapest),
173+
outerrel->relids));
174+
}
175+
150176
/*
151177
* 1. Consider mergejoin paths where both relations must be explicitly
152178
* sorted.Skip this if we can't mergejoin.

‎src/backend/optimizer/plan/createplan.c‎

Lines changed: 13 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -1713,20 +1713,32 @@ create_valuesscan_plan(PlannerInfo *root, Path *best_path,
17131713
ValuesScan*scan_plan;
17141714
Indexscan_relid=best_path->parent->relid;
17151715
RangeTblEntry*rte;
1716+
List*values_lists;
17161717

17171718
/* it should be a values base rel... */
17181719
Assert(scan_relid>0);
17191720
rte=planner_rt_fetch(scan_relid,root);
17201721
Assert(rte->rtekind==RTE_VALUES);
1722+
values_lists=rte->values_lists;
17211723

17221724
/* Sort clauses into best execution order */
17231725
scan_clauses=order_qual_clauses(root,scan_clauses);
17241726

17251727
/* Reduce RestrictInfo list to bare expressions; ignore pseudoconstants */
17261728
scan_clauses=extract_actual_clauses(scan_clauses, false);
17271729

1730+
/* Replace any outer-relation variables with nestloop params */
1731+
if (best_path->param_info)
1732+
{
1733+
scan_clauses= (List*)
1734+
replace_nestloop_params(root, (Node*)scan_clauses);
1735+
/* The values lists could contain nestloop params, too */
1736+
values_lists= (List*)
1737+
replace_nestloop_params(root, (Node*)values_lists);
1738+
}
1739+
17281740
scan_plan=make_valuesscan(tlist,scan_clauses,scan_relid,
1729-
rte->values_lists);
1741+
values_lists);
17301742

17311743
copy_path_costsize(&scan_plan->scan.plan,best_path);
17321744

‎src/backend/optimizer/plan/initsplan.c‎

Lines changed: 14 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -232,6 +232,8 @@ extract_lateral_references(PlannerInfo *root, int rtindex)
232232
vars=pull_vars_of_level((Node*)rte->subquery,1);
233233
elseif (rte->rtekind==RTE_FUNCTION)
234234
vars=pull_vars_of_level(rte->funcexpr,0);
235+
elseif (rte->rtekind==RTE_VALUES)
236+
vars=pull_vars_of_level((Node*)rte->values_lists,0);
235237
else
236238
return;
237239

@@ -874,9 +876,19 @@ distribute_qual_to_rels(PlannerInfo *root, Node *clause,
874876
/*
875877
* Cross-check: clause should contain no relids not within its scope.
876878
* Otherwise the parser messed up.
879+
*
880+
* XXX temporarily disable the qualscope cross-check, which tends to
881+
* reject quals pulled up from LATERAL subqueries. This is only in the
882+
* nature of a debugging crosscheck anyway. I'm loath to remove it
883+
* permanently, but need to think a bit harder about how to replace it.
884+
* See also disabled Assert below. (The ojscope test is still okay
885+
* because we prevent pullup of LATERAL subqueries that might cause it to
886+
* be violated.)
877887
*/
888+
#ifdefNOT_USED
878889
if (!bms_is_subset(relids,qualscope))
879890
elog(ERROR,"JOIN qualification cannot refer to other relations");
891+
#endif
880892
if (ojscope&& !bms_is_subset(relids,ojscope))
881893
elog(ERROR,"JOIN qualification cannot refer to other relations");
882894

@@ -1031,7 +1043,9 @@ distribute_qual_to_rels(PlannerInfo *root, Node *clause,
10311043
if (outerjoin_delayed)
10321044
{
10331045
/* Should still be a subset of current scope ... */
1046+
#ifdefNOT_USED/* XXX temporarily disabled for LATERAL */
10341047
Assert(bms_is_subset(relids,qualscope));
1048+
#endif
10351049

10361050
/*
10371051
* Because application of the qual will be delayed by outer join,

‎src/backend/optimizer/plan/planner.c‎

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -334,7 +334,7 @@ subquery_planner(PlannerGlobal *glob, Query *parse,
334334
* query.
335335
*/
336336
parse->jointree= (FromExpr*)
337-
pull_up_subqueries(root, (Node*)parse->jointree,NULL,NULL);
337+
pull_up_subqueries(root, (Node*)parse->jointree);
338338

339339
/*
340340
* If this is a simple UNION ALL query, flatten it into an appendrel. We

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