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Commit2b1971c

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Fix DEFAULT-handling in multi-row VALUES lists for updatable views.
INSERT ... VALUES for a single VALUES row is implemented differentlyfrom a multi-row VALUES list, which causes inconsistent behaviour inthe way that DEFAULT items are handled. In particular, when insertinginto an auto-updatable view on top of a table with a column default, aDEFAULT item in a single VALUES row gets correctly replaced with thetable column's default, but for a multi-row VALUES list it is replacedwith NULL.Fix this by allowing rewriteValuesRTE() to leave DEFAULT items in theVALUES list untouched if the target relation is an auto-updatable viewand has no column default, deferring DEFAULT-expansion until the queryagainst the base relation is rewritten. For all other types of targetrelation, including tables and trigger- and rule-updatable views, wemust continue to replace DEFAULT items with NULL in the absence of acolumn default.This is somewhat complicated by the fact that if an auto-updatableview has DO ALSO rules attached, the VALUES lists for the productqueries need to be handled differently from the original query, sincethe product queries need to act like rule-updatable views whereas theoriginal query has auto-updatable view semantics.Back-patch to all supported versions.Reported by Roger Curley (bug #15623). Patch by Amit Langote and me.Discussion:https://postgr.es/m/15623-5d67a46788ec8b7f@postgresql.org
1 parenta80f5c2 commit2b1971c

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3 files changed

+369
-11
lines changed

3 files changed

+369
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‎src/backend/rewrite/rewriteHandler.c

Lines changed: 128 additions & 11 deletions
Original file line numberDiff line numberDiff line change
@@ -71,8 +71,8 @@ static TargetEntry *process_matched_tle(TargetEntry *src_tle,
7171
TargetEntry*prior_tle,
7272
constchar*attrName);
7373
staticNode*get_assignment_input(Node*node);
74-
staticvoidrewriteValuesRTE(RangeTblEntry*rte,Relationtarget_relation,
75-
List*attrnos);
74+
staticboolrewriteValuesRTE(Query*parsetree,RangeTblEntry*rte,
75+
Relationtarget_relation,List*attrnos,boolforce_nulls);
7676
staticvoidmarkQueryForLocking(Query*qry,Node*jtnode,
7777
LockClauseStrengthstrength,LockWaitPolicywaitPolicy,
7878
boolpushedDown);
@@ -1213,29 +1213,102 @@ searchForDefault(RangeTblEntry *rte)
12131213
* the appropriate default expressions. The other aspects of targetlist
12141214
* rewriting need be applied only to the query's targetlist proper.
12151215
*
1216+
* For an auto-updatable view, each DEFAULT item in the VALUES list is
1217+
* replaced with the default from the view, if it has one. Otherwise it is
1218+
* left untouched so that the underlying base relation's default can be
1219+
* applied instead (when we later recurse to here after rewriting the query
1220+
* to refer to the base relation instead of the view).
1221+
*
1222+
* For other types of relation, including rule- and trigger-updatable views,
1223+
* all DEFAULT items are replaced, and if the target relation doesn't have a
1224+
* default, the value is explicitly set to NULL.
1225+
*
1226+
* Additionally, if force_nulls is true, the target relation's defaults are
1227+
* ignored and all DEFAULT items in the VALUES list are explicitly set to
1228+
* NULL, regardless of the target relation's type. This is used for the
1229+
* product queries generated by DO ALSO rules attached to an auto-updatable
1230+
* view, for which we will have already called this function with force_nulls
1231+
* false. For these product queries, we must then force any remaining DEFAULT
1232+
* items to NULL to provide concrete values for the rule actions.
1233+
* Essentially, this is a mix of the 2 cases above --- the original query is
1234+
* an insert into an auto-updatable view, and the product queries are inserts
1235+
* into a rule-updatable view.
1236+
*
12161237
* Note that we currently can't support subscripted or field assignment
12171238
* in the multi-VALUES case. The targetlist will contain simple Vars
12181239
* referencing the VALUES RTE, and therefore process_matched_tle() will
12191240
* reject any such attempt with "multiple assignments to same column".
1241+
*
1242+
* Returns true if all DEFAULT items were replaced, and false if some were
1243+
* left untouched.
12201244
*/
1221-
staticvoid
1222-
rewriteValuesRTE(RangeTblEntry*rte,Relationtarget_relation,List*attrnos)
1245+
staticbool
1246+
rewriteValuesRTE(Query*parsetree,RangeTblEntry*rte,
1247+
Relationtarget_relation,List*attrnos,boolforce_nulls)
12231248
{
12241249
List*newValues;
12251250
ListCell*lc;
1251+
boolisAutoUpdatableView;
1252+
boolallReplaced;
12261253

12271254
/*
12281255
* Rebuilding all the lists is a pretty expensive proposition in a big
12291256
* VALUES list, and it's a waste of time if there aren't any DEFAULT
12301257
* placeholders. So first scan to see if there are any.
1258+
*
1259+
* We skip this check if force_nulls is true, because we know that there
1260+
* are DEFAULT items present in that case.
12311261
*/
1232-
if (!searchForDefault(rte))
1233-
return;/* nothing to do */
1262+
if (!force_nulls&& !searchForDefault(rte))
1263+
return true;/* nothing to do */
12341264

12351265
/* Check list lengths (we can assume all the VALUES sublists are alike) */
12361266
Assert(list_length(attrnos)==list_length(linitial(rte->values_lists)));
12371267

1268+
/*
1269+
* Check if the target relation is an auto-updatable view, in which case
1270+
* unresolved defaults will be left untouched rather than being set to
1271+
* NULL. If force_nulls is true, we always set DEFAULT items to NULL, so
1272+
* skip this check in that case --- it isn't an auto-updatable view.
1273+
*/
1274+
isAutoUpdatableView= false;
1275+
if (!force_nulls&&
1276+
target_relation->rd_rel->relkind==RELKIND_VIEW&&
1277+
!view_has_instead_trigger(target_relation,CMD_INSERT))
1278+
{
1279+
List*locks;
1280+
boolhasUpdate;
1281+
boolfound;
1282+
ListCell*l;
1283+
1284+
/* Look for an unconditional DO INSTEAD rule */
1285+
locks=matchLocks(CMD_INSERT,target_relation->rd_rules,
1286+
parsetree->resultRelation,parsetree,&hasUpdate);
1287+
1288+
found= false;
1289+
foreach(l,locks)
1290+
{
1291+
RewriteRule*rule_lock= (RewriteRule*)lfirst(l);
1292+
1293+
if (rule_lock->isInstead&&
1294+
rule_lock->qual==NULL)
1295+
{
1296+
found= true;
1297+
break;
1298+
}
1299+
}
1300+
1301+
/*
1302+
* If we didn't find an unconditional DO INSTEAD rule, assume that the
1303+
* view is auto-updatable. If it isn't, rewriteTargetView() will
1304+
* throw an error.
1305+
*/
1306+
if (!found)
1307+
isAutoUpdatableView= true;
1308+
}
1309+
12381310
newValues=NIL;
1311+
allReplaced= true;
12391312
foreach(lc,rte->values_lists)
12401313
{
12411314
List*sublist= (List*)lfirst(lc);
@@ -1255,17 +1328,26 @@ rewriteValuesRTE(RangeTblEntry *rte, Relation target_relation, List *attrnos)
12551328

12561329
att_tup=target_relation->rd_att->attrs[attrno-1];
12571330

1258-
if (!att_tup->attisdropped)
1331+
if (!force_nulls&& !att_tup->attisdropped)
12591332
new_expr=build_column_default(target_relation,attrno);
12601333
else
12611334
new_expr=NULL;/* force a NULL if dropped */
12621335

12631336
/*
12641337
* If there is no default (ie, default is effectively NULL),
1265-
* we've got to explicitly set the column to NULL.
1338+
* we've got to explicitly set the column to NULL, unless the
1339+
* target relation is an auto-updatable view.
12661340
*/
12671341
if (!new_expr)
12681342
{
1343+
if (isAutoUpdatableView)
1344+
{
1345+
/* Leave the value untouched */
1346+
newList=lappend(newList,col);
1347+
allReplaced= false;
1348+
continue;
1349+
}
1350+
12691351
new_expr= (Node*)makeConst(att_tup->atttypid,
12701352
-1,
12711353
att_tup->attcollation,
@@ -1290,6 +1372,8 @@ rewriteValuesRTE(RangeTblEntry *rte, Relation target_relation, List *attrnos)
12901372
newValues=lappend(newValues,newList);
12911373
}
12921374
rte->values_lists=newValues;
1375+
1376+
returnallReplaced;
12931377
}
12941378

12951379

@@ -3362,6 +3446,9 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
33623446
List*locks;
33633447
List*product_queries;
33643448
boolhasUpdate= false;
3449+
List*attrnos=NIL;
3450+
intvalues_rte_index=0;
3451+
booldefaults_remaining= false;
33653452

33663453
result_relation=parsetree->resultRelation;
33673454
Assert(result_relation!=0);
@@ -3395,14 +3482,15 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
33953482
parsetree->rtable);
33963483

33973484
if (rte->rtekind==RTE_VALUES)
3485+
{
33983486
values_rte=rte;
3487+
values_rte_index=rtr->rtindex;
3488+
}
33993489
}
34003490
}
34013491

34023492
if (values_rte)
34033493
{
3404-
List*attrnos;
3405-
34063494
/* Process the main targetlist ... */
34073495
parsetree->targetList=rewriteTargetListIU(parsetree->targetList,
34083496
parsetree->commandType,
@@ -3411,7 +3499,9 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
34113499
parsetree->resultRelation,
34123500
&attrnos);
34133501
/* ... and the VALUES expression lists */
3414-
rewriteValuesRTE(values_rte,rt_entry_relation,attrnos);
3502+
if (!rewriteValuesRTE(parsetree,values_rte,
3503+
rt_entry_relation,attrnos, false))
3504+
defaults_remaining= true;
34153505
}
34163506
else
34173507
{
@@ -3466,6 +3556,33 @@ RewriteQuery(Query *parsetree, List *rewrite_events)
34663556
&returning,
34673557
&qual_product);
34683558

3559+
/*
3560+
* If we have a VALUES RTE with any remaining untouched DEFAULT items,
3561+
* and we got any product queries, finalize the VALUES RTE for each
3562+
* product query (replacing the remaining DEFAULT items with NULLs).
3563+
* We don't do this for the original query, because we know that it
3564+
* must be an auto-insert on a view, and so should use the base
3565+
* relation's defaults for any remaining DEFAULT items.
3566+
*/
3567+
if (defaults_remaining&&product_queries!=NIL)
3568+
{
3569+
ListCell*n;
3570+
3571+
/*
3572+
* Each product query has its own copy of the VALUES RTE at the
3573+
* same index in the rangetable, so we must finalize each one.
3574+
*/
3575+
foreach(n,product_queries)
3576+
{
3577+
Query*pt= (Query*)lfirst(n);
3578+
RangeTblEntry*values_rte=rt_fetch(values_rte_index,
3579+
pt->rtable);
3580+
3581+
rewriteValuesRTE(pt,values_rte,rt_entry_relation,attrnos,
3582+
true);/* Force remaining defaults to NULL */
3583+
}
3584+
}
3585+
34693586
/*
34703587
* If there were no INSTEAD rules, and the target relation is a view
34713588
* without any INSTEAD OF triggers, see if the view can be

‎src/test/regress/expected/updatable_views.out

Lines changed: 153 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -2648,3 +2648,156 @@ drop view rw_view1;
26482648
drop table base_tbl;
26492649
drop user regress_view_user1;
26502650
drop user regress_view_user2;
2651+
-- Test single- and multi-row inserts with table and view defaults.
2652+
-- Table defaults should be used, unless overridden by view defaults.
2653+
create table base_tab_def (a int, b text default 'Table default',
2654+
c text default 'Table default', d text, e text);
2655+
create view base_tab_def_view as select * from base_tab_def;
2656+
alter view base_tab_def_view alter b set default 'View default';
2657+
alter view base_tab_def_view alter d set default 'View default';
2658+
insert into base_tab_def values (1);
2659+
insert into base_tab_def values (2), (3);
2660+
insert into base_tab_def values (4, default, default, default, default);
2661+
insert into base_tab_def values (5, default, default, default, default),
2662+
(6, default, default, default, default);
2663+
insert into base_tab_def_view values (11);
2664+
insert into base_tab_def_view values (12), (13);
2665+
insert into base_tab_def_view values (14, default, default, default, default);
2666+
insert into base_tab_def_view values (15, default, default, default, default),
2667+
(16, default, default, default, default);
2668+
select * from base_tab_def order by a;
2669+
a | b | c | d | e
2670+
----+---------------+---------------+--------------+---
2671+
1 | Table default | Table default | |
2672+
2 | Table default | Table default | |
2673+
3 | Table default | Table default | |
2674+
4 | Table default | Table default | |
2675+
5 | Table default | Table default | |
2676+
6 | Table default | Table default | |
2677+
11 | View default | Table default | View default |
2678+
12 | View default | Table default | View default |
2679+
13 | View default | Table default | View default |
2680+
14 | View default | Table default | View default |
2681+
15 | View default | Table default | View default |
2682+
16 | View default | Table default | View default |
2683+
(12 rows)
2684+
2685+
-- Adding an INSTEAD OF trigger should cause NULLs to be inserted instead of
2686+
-- table defaults, where there are no view defaults.
2687+
create function base_tab_def_view_instrig_func() returns trigger
2688+
as
2689+
$$
2690+
begin
2691+
insert into base_tab_def values (new.a, new.b, new.c, new.d, new.e);
2692+
return new;
2693+
end;
2694+
$$
2695+
language plpgsql;
2696+
create trigger base_tab_def_view_instrig instead of insert on base_tab_def_view
2697+
for each row execute procedure base_tab_def_view_instrig_func();
2698+
truncate base_tab_def;
2699+
insert into base_tab_def values (1);
2700+
insert into base_tab_def values (2), (3);
2701+
insert into base_tab_def values (4, default, default, default, default);
2702+
insert into base_tab_def values (5, default, default, default, default),
2703+
(6, default, default, default, default);
2704+
insert into base_tab_def_view values (11);
2705+
insert into base_tab_def_view values (12), (13);
2706+
insert into base_tab_def_view values (14, default, default, default, default);
2707+
insert into base_tab_def_view values (15, default, default, default, default),
2708+
(16, default, default, default, default);
2709+
select * from base_tab_def order by a;
2710+
a | b | c | d | e
2711+
----+---------------+---------------+--------------+---
2712+
1 | Table default | Table default | |
2713+
2 | Table default | Table default | |
2714+
3 | Table default | Table default | |
2715+
4 | Table default | Table default | |
2716+
5 | Table default | Table default | |
2717+
6 | Table default | Table default | |
2718+
11 | View default | | View default |
2719+
12 | View default | | View default |
2720+
13 | View default | | View default |
2721+
14 | View default | | View default |
2722+
15 | View default | | View default |
2723+
16 | View default | | View default |
2724+
(12 rows)
2725+
2726+
-- Using an unconditional DO INSTEAD rule should also cause NULLs to be
2727+
-- inserted where there are no view defaults.
2728+
drop trigger base_tab_def_view_instrig on base_tab_def_view;
2729+
drop function base_tab_def_view_instrig_func;
2730+
create rule base_tab_def_view_ins_rule as on insert to base_tab_def_view
2731+
do instead insert into base_tab_def values (new.a, new.b, new.c, new.d, new.e);
2732+
truncate base_tab_def;
2733+
insert into base_tab_def values (1);
2734+
insert into base_tab_def values (2), (3);
2735+
insert into base_tab_def values (4, default, default, default, default);
2736+
insert into base_tab_def values (5, default, default, default, default),
2737+
(6, default, default, default, default);
2738+
insert into base_tab_def_view values (11);
2739+
insert into base_tab_def_view values (12), (13);
2740+
insert into base_tab_def_view values (14, default, default, default, default);
2741+
insert into base_tab_def_view values (15, default, default, default, default),
2742+
(16, default, default, default, default);
2743+
select * from base_tab_def order by a;
2744+
a | b | c | d | e
2745+
----+---------------+---------------+--------------+---
2746+
1 | Table default | Table default | |
2747+
2 | Table default | Table default | |
2748+
3 | Table default | Table default | |
2749+
4 | Table default | Table default | |
2750+
5 | Table default | Table default | |
2751+
6 | Table default | Table default | |
2752+
11 | View default | | View default |
2753+
12 | View default | | View default |
2754+
13 | View default | | View default |
2755+
14 | View default | | View default |
2756+
15 | View default | | View default |
2757+
16 | View default | | View default |
2758+
(12 rows)
2759+
2760+
-- A DO ALSO rule should cause each row to be inserted twice. The first
2761+
-- insert should behave the same as an auto-updatable view (using table
2762+
-- defaults, unless overridden by view defaults). The second insert should
2763+
-- behave the same as a rule-updatable view (inserting NULLs where there are
2764+
-- no view defaults).
2765+
drop rule base_tab_def_view_ins_rule on base_tab_def_view;
2766+
create rule base_tab_def_view_ins_rule as on insert to base_tab_def_view
2767+
do also insert into base_tab_def values (new.a, new.b, new.c, new.d, new.e);
2768+
truncate base_tab_def;
2769+
insert into base_tab_def values (1);
2770+
insert into base_tab_def values (2), (3);
2771+
insert into base_tab_def values (4, default, default, default, default);
2772+
insert into base_tab_def values (5, default, default, default, default),
2773+
(6, default, default, default, default);
2774+
insert into base_tab_def_view values (11);
2775+
insert into base_tab_def_view values (12), (13);
2776+
insert into base_tab_def_view values (14, default, default, default, default);
2777+
insert into base_tab_def_view values (15, default, default, default, default),
2778+
(16, default, default, default, default);
2779+
select * from base_tab_def order by a, c NULLS LAST;
2780+
a | b | c | d | e
2781+
----+---------------+---------------+--------------+---
2782+
1 | Table default | Table default | |
2783+
2 | Table default | Table default | |
2784+
3 | Table default | Table default | |
2785+
4 | Table default | Table default | |
2786+
5 | Table default | Table default | |
2787+
6 | Table default | Table default | |
2788+
11 | View default | Table default | View default |
2789+
11 | View default | | View default |
2790+
12 | View default | Table default | View default |
2791+
12 | View default | | View default |
2792+
13 | View default | Table default | View default |
2793+
13 | View default | | View default |
2794+
14 | View default | Table default | View default |
2795+
14 | View default | | View default |
2796+
15 | View default | Table default | View default |
2797+
15 | View default | | View default |
2798+
16 | View default | Table default | View default |
2799+
16 | View default | | View default |
2800+
(18 rows)
2801+
2802+
drop view base_tab_def_view;
2803+
drop table base_tab_def;

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