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Commite18f501

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committed
Complain if the same column name is inherited from multiple parents
with different default values, unless the child table redeclares thecolumn with an explicit default. This was judged to be the approachleast likely to cause unpleasant surprises.
1 parent39f0357 commite18f501

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1 file changed

+57
-15
lines changed

1 file changed

+57
-15
lines changed

‎src/backend/commands/creatinh.c‎

Lines changed: 57 additions & 15 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $Header: /cvsroot/pgsql/src/backend/commands/Attic/creatinh.c,v 1.75 2001/03/30 20:50:36 tgl Exp $
11+
* $Header: /cvsroot/pgsql/src/backend/commands/Attic/creatinh.c,v 1.76 2001/04/02 18:30:49 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -276,6 +276,20 @@ TruncateRelation(char *name)
276276
*
277277
* If the same attribute name appears multiple times, then it appears
278278
* in the result table in the proper location for its first appearance.
279+
*
280+
* Constraints (including NOT NULL constraints) for the child table
281+
* are the union of all relevant constraints, from both the child schema
282+
* and parent tables.
283+
*
284+
* The default value for a child column is defined as:
285+
*(1) If the child schema specifies a default, that value is used.
286+
*(2) If neither the child nor any parent specifies a default, then
287+
*the column will not have a default.
288+
*(3) If conflicting defaults are inherited from different parents
289+
*(and not overridden by the child), an error is raised.
290+
*(4) Otherwise the inherited default is used.
291+
*Rule (3) is new in Postgres 7.1; in earlier releases you got a
292+
*rather arbitrary choice of which parent default to use.
279293
*----------
280294
*/
281295
staticList*
@@ -286,6 +300,8 @@ MergeAttributes(List *schema, List *supers, bool istemp,
286300
List*inhSchema=NIL;
287301
List*parentOids=NIL;
288302
List*constraints=NIL;
303+
boolhave_bogus_defaults= false;
304+
char*bogus_marker="Bogus!";/* marks conflicting defaults */
289305
intchild_attno;
290306

291307
/*
@@ -305,10 +321,8 @@ MergeAttributes(List *schema, List *supers, bool istemp,
305321
ColumnDef*restdef=lfirst(rest);
306322

307323
if (strcmp(coldef->colname,restdef->colname)==0)
308-
{
309324
elog(ERROR,"CREATE TABLE: attribute \"%s\" duplicated",
310325
coldef->colname);
311-
}
312326
}
313327
}
314328
/*
@@ -321,10 +335,8 @@ MergeAttributes(List *schema, List *supers, bool istemp,
321335
foreach(rest,lnext(entry))
322336
{
323337
if (strcmp(strVal(lfirst(entry)),strVal(lfirst(rest)))==0)
324-
{
325338
elog(ERROR,"CREATE TABLE: inherited relation \"%s\" duplicated",
326339
strVal(lfirst(entry)));
327-
}
328340
}
329341
}
330342

@@ -436,31 +448,44 @@ MergeAttributes(List *schema, List *supers, bool istemp,
436448
newattno[parent_attno-1]=++child_attno;
437449
}
438450
/*
439-
* Copy default if any, overriding any default from earlier parent
451+
* Copy default if any
440452
*/
441453
if (attribute->atthasdef)
442454
{
455+
char*this_default=NULL;
443456
AttrDefault*attrdef;
444457
inti;
445458

446-
def->raw_default=NULL;
447-
def->cooked_default=NULL;
448-
459+
/* Find default in constraint structure */
449460
Assert(constr!=NULL);
450461
attrdef=constr->defval;
451462
for (i=0;i<constr->num_defval;i++)
452463
{
453464
if (attrdef[i].adnum==parent_attno)
454465
{
455-
/*
456-
* if default expr could contain any vars, we'd
457-
* need to fix 'em, but it can't ...
458-
*/
459-
def->cooked_default=pstrdup(attrdef[i].adbin);
466+
this_default=attrdef[i].adbin;
460467
break;
461468
}
462469
}
463-
Assert(def->cooked_default!=NULL);
470+
Assert(this_default!=NULL);
471+
/*
472+
* If default expr could contain any vars, we'd need to fix
473+
* 'em, but it can't; so default is ready to apply to child.
474+
*
475+
* If we already had a default from some prior parent,
476+
* check to see if they are the same. If so, no problem;
477+
* if not, mark the column as having a bogus default.
478+
* Below, we will complain if the bogus default isn't
479+
* overridden by the child schema.
480+
*/
481+
Assert(def->raw_default==NULL);
482+
if (def->cooked_default==NULL)
483+
def->cooked_default=pstrdup(this_default);
484+
elseif (strcmp(def->cooked_default,this_default)!=0)
485+
{
486+
def->cooked_default=bogus_marker;
487+
have_bogus_defaults= true;
488+
}
464489
}
465490
}
466491
/*
@@ -555,6 +580,23 @@ MergeAttributes(List *schema, List *supers, bool istemp,
555580
schema=inhSchema;
556581
}
557582

583+
/*
584+
* If we found any conflicting parent default values, check to make
585+
* sure they were overridden by the child.
586+
*/
587+
if (have_bogus_defaults)
588+
{
589+
foreach(entry,schema)
590+
{
591+
ColumnDef*def=lfirst(entry);
592+
593+
if (def->cooked_default==bogus_marker)
594+
elog(ERROR,"CREATE TABLE: attribute \"%s\" inherits conflicting default values"
595+
"\n\tTo resolve the conflict, specify a default explicitly",
596+
def->colname);
597+
}
598+
}
599+
558600
*supOids=parentOids;
559601
*supconstr=constraints;
560602
returnschema;

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