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Rename ResolveNew() to ReplaceVarsFromTargetList(), and tweak its API.
This function currently lacks the option to throw error if the provided targetlist doesn't have any matching entry for a Var to be replaced. Two of the four existing call sites would be better off with an error, as would the usage in the pending auto-updatable-views patch, so it seems past time to extend the API to support that. To do so, replace the "event" parameter (historically of type CmdType, though it was declared plain int) with a special-purpose enum type. It's unclear whether this function might be called by third-party code. Since many C compilers wouldn't warn about a call site continuing to use the old calling convention, rename the function to forcibly break any such code that hasn't been updated. The old name was none too well chosen anyhow.
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4 files changed

+106
-76
lines changed

4 files changed

+106
-76
lines changed

‎src/backend/optimizer/path/allpaths.c

+4-4
Original file line numberDiff line numberDiff line change
@@ -1835,10 +1835,10 @@ subquery_push_qual(Query *subquery, RangeTblEntry *rte, Index rti, Node *qual)
18351835
* This step also ensures that when we are pushing into a setop tree,
18361836
* each component query gets its own copy of the qual.
18371837
*/
1838-
qual = ResolveNew(qual, rti, 0, rte,
1839-
subquery->targetList,
1840-
CMD_SELECT, 0,
1841-
&subquery->hasSubLinks);
1838+
qual = ReplaceVarsFromTargetList(qual, rti, 0, rte,
1839+
subquery->targetList,
1840+
REPLACEVARS_REPORT_ERROR, 0,
1841+
&subquery->hasSubLinks);
18421842

18431843
/*
18441844
* Now attach the qual to the proper place: normally WHERE, but if the

‎src/backend/rewrite/rewriteHandler.c

+35-30
Original file line numberDiff line numberDiff line change
@@ -502,25 +502,27 @@ rewriteRuleAction(Query *parsetree,
502502
AddQual(sub_action, parsetree->jointree->quals);
503503

504504
/*
505-
* Rewrite new.attribute w/ right hand side of target-list entry for
505+
* Rewrite new.attribute with right hand side of target-list entry for
506506
* appropriate field name in insert/update.
507507
*
508-
* KLUGE ALERT: since ResolveNew returns a mutated copy, we can't just
509-
* apply it to sub_action; we have to remember to update the sublink
510-
* inside rule_action, too.
508+
* KLUGE ALERT: since ReplaceVarsFromTargetList returns a mutated copy, we
509+
* can't just apply it to sub_action; we have to remember to update the
510+
* sublink inside rule_action, too.
511511
*/
512512
if ((event == CMD_INSERT || event == CMD_UPDATE) &&
513513
sub_action->commandType != CMD_UTILITY)
514514
{
515-
sub_action = (Query *) ResolveNew((Node *) sub_action,
516-
new_varno,
517-
0,
518-
rt_fetch(new_varno,
519-
sub_action->rtable),
520-
parsetree->targetList,
521-
event,
522-
current_varno,
523-
NULL);
515+
sub_action = (Query *)
516+
ReplaceVarsFromTargetList((Node *) sub_action,
517+
new_varno,
518+
0,
519+
rt_fetch(new_varno, sub_action->rtable),
520+
parsetree->targetList,
521+
(event == CMD_UPDATE) ?
522+
REPLACEVARS_CHANGE_VARNO :
523+
REPLACEVARS_SUBSTITUTE_NULL,
524+
current_varno,
525+
NULL);
524526
if (sub_action_ptr)
525527
*sub_action_ptr = sub_action;
526528
else
@@ -543,15 +545,15 @@ rewriteRuleAction(Query *parsetree,
543545
errmsg("cannot have RETURNING lists in multiple rules")));
544546
*returning_flag = true;
545547
rule_action->returningList = (List *)
546-
ResolveNew((Node *) parsetree->returningList,
547-
parsetree->resultRelation,
548-
0,
549-
rt_fetch(parsetree->resultRelation,
550-
parsetree->rtable),
551-
rule_action->returningList,
552-
CMD_SELECT,
553-
0,
554-
&rule_action->hasSubLinks);
548+
ReplaceVarsFromTargetList((Node *) parsetree->returningList,
549+
parsetree->resultRelation,
550+
0,
551+
rt_fetch(parsetree->resultRelation,
552+
parsetree->rtable),
553+
rule_action->returningList,
554+
REPLACEVARS_REPORT_ERROR,
555+
0,
556+
&rule_action->hasSubLinks);
555557

556558
/*
557559
* There could have been some SubLinks in parsetree's returningList,
@@ -1703,14 +1705,17 @@ CopyAndAddInvertedQual(Query *parsetree,
17031705
ChangeVarNodes(new_qual, PRS2_OLD_VARNO, rt_index, 0);
17041706
/* Fix references to NEW */
17051707
if (event == CMD_INSERT || event == CMD_UPDATE)
1706-
new_qual = ResolveNew(new_qual,
1707-
PRS2_NEW_VARNO,
1708-
0,
1709-
rt_fetch(rt_index, parsetree->rtable),
1710-
parsetree->targetList,
1711-
event,
1712-
rt_index,
1713-
&parsetree->hasSubLinks);
1708+
new_qual = ReplaceVarsFromTargetList(new_qual,
1709+
PRS2_NEW_VARNO,
1710+
0,
1711+
rt_fetch(rt_index,
1712+
parsetree->rtable),
1713+
parsetree->targetList,
1714+
(event == CMD_UPDATE) ?
1715+
REPLACEVARS_CHANGE_VARNO :
1716+
REPLACEVARS_SUBSTITUTE_NULL,
1717+
rt_index,
1718+
&parsetree->hasSubLinks);
17141719
/* And attach the fixed qual */
17151720
AddInvertedQual(parsetree, new_qual);
17161721

‎src/backend/rewrite/rewriteManip.c

+53-38
Original file line numberDiff line numberDiff line change
@@ -1323,12 +1323,16 @@ map_variable_attnos(Node *node,
13231323

13241324

13251325
/*
1326-
* ResolveNew - replace Vars with corresponding items from a targetlist
1326+
* ReplaceVarsFromTargetList - replace Vars with items from a targetlist
13271327
*
13281328
* Vars matching target_varno and sublevels_up are replaced by the
13291329
* entry with matching resno from targetlist, if there is one.
1330-
* If not, we either change the unmatched Var's varno to update_varno
1331-
* (when event == CMD_UPDATE) or replace it with a constant NULL.
1330+
*
1331+
* If there is no matching resno for such a Var, the action depends on the
1332+
* nomatch_option:
1333+
* REPLACEVARS_REPORT_ERROR: throw an error
1334+
* REPLACEVARS_CHANGE_VARNO: change Var's varno to nomatch_varno
1335+
* REPLACEVARS_SUBSTITUTE_NULL: replace Var with a NULL Const of same type
13321336
*
13331337
* The caller must also provide target_rte, the RTE describing the target
13341338
* relation. This is needed to handle whole-row Vars referencing the target.
@@ -1341,15 +1345,15 @@ typedef struct
13411345
{
13421346
RangeTblEntry *target_rte;
13431347
List *targetlist;
1344-
int event;
1345-
int update_varno;
1346-
} ResolveNew_context;
1348+
ReplaceVarsNoMatchOption nomatch_option;
1349+
int nomatch_varno;
1350+
} ReplaceVarsFromTargetList_context;
13471351

13481352
static Node *
1349-
ResolveNew_callback(Var *var,
1350-
replace_rte_variables_context *context)
1353+
ReplaceVarsFromTargetList_callback(Var *var,
1354+
replace_rte_variables_context *context)
13511355
{
1352-
ResolveNew_context *rcon = (ResolveNew_context *) context->callback_arg;
1356+
ReplaceVarsFromTargetList_context *rcon = (ReplaceVarsFromTargetList_context *) context->callback_arg;
13531357
TargetEntry *tle;
13541358

13551359
if (var->varattno == InvalidAttrNumber)
@@ -1388,29 +1392,37 @@ ResolveNew_callback(Var *var,
13881392

13891393
if (tle == NULL || tle->resjunk)
13901394
{
1391-
/* Failed to find column in insert/update tlist */
1392-
if (rcon->event == CMD_UPDATE)
1393-
{
1394-
/* For update, just change unmatched var's varno */
1395-
var = (Var *) copyObject(var);
1396-
var->varno = rcon->update_varno;
1397-
var->varnoold = rcon->update_varno;
1398-
return (Node *) var;
1399-
}
1400-
else
1395+
/* Failed to find column in targetlist */
1396+
switch (rcon->nomatch_option)
14011397
{
1402-
/* Otherwise replace unmatched var with a null */
1403-
/* need coerce_to_domain in case of NOT NULL domain constraint */
1404-
return coerce_to_domain((Node *) makeNullConst(var->vartype,
1405-
var->vartypmod,
1406-
var->varcollid),
1407-
InvalidOid, -1,
1408-
var->vartype,
1409-
COERCE_IMPLICIT_CAST,
1410-
-1,
1411-
false,
1412-
false);
1398+
case REPLACEVARS_REPORT_ERROR:
1399+
/* fall through, throw error below */
1400+
break;
1401+
1402+
case REPLACEVARS_CHANGE_VARNO:
1403+
var = (Var *) copyObject(var);
1404+
var->varno = rcon->nomatch_varno;
1405+
var->varnoold = rcon->nomatch_varno;
1406+
return (Node *) var;
1407+
1408+
case REPLACEVARS_SUBSTITUTE_NULL:
1409+
/*
1410+
* If Var is of domain type, we should add a CoerceToDomain
1411+
* node, in case there is a NOT NULL domain constraint.
1412+
*/
1413+
return coerce_to_domain((Node *) makeNullConst(var->vartype,
1414+
var->vartypmod,
1415+
var->varcollid),
1416+
InvalidOid, -1,
1417+
var->vartype,
1418+
COERCE_IMPLICIT_CAST,
1419+
-1,
1420+
false,
1421+
false);
14131422
}
1423+
elog(ERROR, "could not find replacement targetlist entry for attno %d",
1424+
var->varattno);
1425+
return NULL; /* keep compiler quiet */
14141426
}
14151427
else
14161428
{
@@ -1426,20 +1438,23 @@ ResolveNew_callback(Var *var,
14261438
}
14271439

14281440
Node *
1429-
ResolveNew(Node *node, int target_varno, int sublevels_up,
1430-
RangeTblEntry *target_rte,
1431-
List *targetlist, int event, int update_varno,
1432-
bool *outer_hasSubLinks)
1441+
ReplaceVarsFromTargetList(Node *node,
1442+
int target_varno, int sublevels_up,
1443+
RangeTblEntry *target_rte,
1444+
List *targetlist,
1445+
ReplaceVarsNoMatchOption nomatch_option,
1446+
int nomatch_varno,
1447+
bool *outer_hasSubLinks)
14331448
{
1434-
ResolveNew_context context;
1449+
ReplaceVarsFromTargetList_context context;
14351450

14361451
context.target_rte = target_rte;
14371452
context.targetlist = targetlist;
1438-
context.event = event;
1439-
context.update_varno = update_varno;
1453+
context.nomatch_option = nomatch_option;
1454+
context.nomatch_varno = nomatch_varno;
14401455

14411456
return replace_rte_variables(node, target_varno, sublevels_up,
1442-
ResolveNew_callback,
1457+
ReplaceVarsFromTargetList_callback,
14431458
(void *) &context,
14441459
outer_hasSubLinks);
14451460
}

‎src/include/rewrite/rewriteManip.h

+14-4
Original file line numberDiff line numberDiff line change
@@ -31,6 +31,13 @@ struct replace_rte_variables_context
3131
bool inserted_sublink; /* have we inserted a SubLink? */
3232
};
3333

34+
typedef enum ReplaceVarsNoMatchOption
35+
{
36+
REPLACEVARS_REPORT_ERROR, /* throw error if no match */
37+
REPLACEVARS_CHANGE_VARNO, /* change the Var's varno, nothing else */
38+
REPLACEVARS_SUBSTITUTE_NULL /* replace with a NULL Const */
39+
} ReplaceVarsNoMatchOption;
40+
3441

3542
extern void OffsetVarNodes(Node *node, int offset, int sublevels_up);
3643
extern void ChangeVarNodes(Node *node, int old_varno, int new_varno,
@@ -69,9 +76,12 @@ extern Node *map_variable_attnos(Node *node,
6976
const AttrNumber *attno_map, int map_length,
7077
bool *found_whole_row);
7178

72-
extern Node *ResolveNew(Node *node, int target_varno, int sublevels_up,
73-
RangeTblEntry *target_rte,
74-
List *targetlist, int event, int update_varno,
75-
bool *outer_hasSubLinks);
79+
extern Node *ReplaceVarsFromTargetList(Node *node,
80+
int target_varno, int sublevels_up,
81+
RangeTblEntry *target_rte,
82+
List *targetlist,
83+
ReplaceVarsNoMatchOption nomatch_option,
84+
int nomatch_varno,
85+
bool *outer_hasSubLinks);
7686

7787
#endif /* REWRITEMANIP_H */

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