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Include all columns in default names for foreign key constraints
When creating a name for a foreign key constraint when none is specified, use all column names instead of only the first one, similar to how it is already done for index names. Author: Paul Martinez <hellopfm@gmail.com> Reviewed-by: Peter Eisentraut <peter.eisentraut@2ndquadrant.com> Discussion: https://www.postgresql.org/message-id/flat/CAF+2_SFjky6XRfLNRXpkG97W6PRbOO_mjAxqXzAAimU=c7w7_A@mail.gmail.com
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7 files changed

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‎src/backend/commands/indexcmds.c

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -2109,7 +2109,8 @@ ChooseIndexName(const char *tabname, Oid namespaceId,
21092109
* We know that less than NAMEDATALEN characters will actually be used,
21102110
* so we can truncate the result once we've generated that many.
21112111
*
2112-
* XXX See also ChooseExtendedStatisticNameAddition.
2112+
* XXX See also ChooseForeignKeyConstraintNameAddition and
2113+
* ChooseExtendedStatisticNameAddition.
21132114
*/
21142115
static char *
21152116
ChooseIndexNameAddition(List *colnames)

‎src/backend/commands/statscmds.c

Lines changed: 2 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -498,7 +498,8 @@ ChooseExtendedStatisticName(const char *name1, const char *name2,
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* We know that less than NAMEDATALEN characters will actually be used,
499499
* so we can truncate the result once we've generated that many.
500500
*
501-
* XXX see also ChooseIndexNameAddition.
501+
* XXX see also ChooseForeignKeyConstraintNameAddition and
502+
* ChooseIndexNameAddition.
502503
*/
503504
static char *
504505
ChooseExtendedStatisticNameAddition(List *exprs)

‎src/backend/commands/tablecmds.c

Lines changed: 41 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -402,6 +402,7 @@ static ObjectAddress ATExecAddConstraint(List **wqueue,
402402
AlteredTableInfo *tab, Relation rel,
403403
Constraint *newConstraint, bool recurse, bool is_readd,
404404
LOCKMODE lockmode);
405+
static char *ChooseForeignKeyConstraintNameAddition(List *colnames);
405406
static ObjectAddress ATExecAddIndexConstraint(AlteredTableInfo *tab, Relation rel,
406407
IndexStmt *stmt, LOCKMODE lockmode);
407408
static ObjectAddress ATAddCheckConstraint(List **wqueue,
@@ -7191,7 +7192,7 @@ ATExecAddConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
71917192
else
71927193
newConstraint->conname =
71937194
ChooseConstraintName(RelationGetRelationName(rel),
7194-
strVal(linitial(newConstraint->fk_attrs)),
7195+
ChooseForeignKeyConstraintNameAddition(newConstraint->fk_attrs),
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"fkey",
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RelationGetNamespace(rel),
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NIL);
@@ -7210,6 +7211,45 @@ ATExecAddConstraint(List **wqueue, AlteredTableInfo *tab, Relation rel,
72107211
return address;
72117212
}
72127213

7214+
/*
7215+
* Generate the column-name portion of the constraint name for a new foreign
7216+
* key given the list of column names that reference the referenced
7217+
* table. This will be passed to ChooseConstraintName along with the parent
7218+
* table name and the "fkey" suffix.
7219+
*
7220+
* We know that less than NAMEDATALEN characters will actually be used, so we
7221+
* can truncate the result once we've generated that many.
7222+
*
7223+
* XXX see also ChooseExtendedStatisticNameAddition and
7224+
* ChooseIndexNameAddition.
7225+
*/
7226+
static char *
7227+
ChooseForeignKeyConstraintNameAddition(List *colnames)
7228+
{
7229+
char buf[NAMEDATALEN * 2];
7230+
int buflen = 0;
7231+
ListCell *lc;
7232+
7233+
buf[0] = '\0';
7234+
foreach(lc, colnames)
7235+
{
7236+
const char *name = strVal(lfirst(lc));
7237+
7238+
if (buflen > 0)
7239+
buf[buflen++] = '_'; /* insert _ between names */
7240+
7241+
/*
7242+
* At this point we have buflen <= NAMEDATALEN. name should be less
7243+
* than NAMEDATALEN already, but use strlcpy for paranoia.
7244+
*/
7245+
strlcpy(buf + buflen, name, NAMEDATALEN);
7246+
buflen += strlen(buf + buflen);
7247+
if (buflen >= NAMEDATALEN)
7248+
break;
7249+
}
7250+
return pstrdup(buf);
7251+
}
7252+
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/*
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* Add a check constraint to a single table and its children. Returns the
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* address of the constraint added to the parent relation, if one gets added,

‎src/test/regress/expected/alter_table.out

Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -655,26 +655,26 @@ CREATE TEMP TABLE PKTABLE (ptest1 int, ptest2 inet,
655655
-- This should fail, because we just chose really odd types
656656
CREATE TEMP TABLE FKTABLE (ftest1 cidr, ftest2 timestamp);
657657
ALTER TABLE FKTABLE ADD FOREIGN KEY(ftest1, ftest2) references pktable;
658-
ERROR: foreign key constraint "fktable_ftest1_fkey" cannot be implemented
658+
ERROR: foreign key constraint "fktable_ftest1_ftest2_fkey" cannot be implemented
659659
DETAIL: Key columns "ftest1" and "ptest1" are of incompatible types: cidr and integer.
660660
DROP TABLE FKTABLE;
661661
-- Again, so should this...
662662
CREATE TEMP TABLE FKTABLE (ftest1 cidr, ftest2 timestamp);
663663
ALTER TABLE FKTABLE ADD FOREIGN KEY(ftest1, ftest2)
664664
references pktable(ptest1, ptest2);
665-
ERROR: foreign key constraint "fktable_ftest1_fkey" cannot be implemented
665+
ERROR: foreign key constraint "fktable_ftest1_ftest2_fkey" cannot be implemented
666666
DETAIL: Key columns "ftest1" and "ptest1" are of incompatible types: cidr and integer.
667667
DROP TABLE FKTABLE;
668668
-- This fails because we mixed up the column ordering
669669
CREATE TEMP TABLE FKTABLE (ftest1 int, ftest2 inet);
670670
ALTER TABLE FKTABLE ADD FOREIGN KEY(ftest1, ftest2)
671671
references pktable(ptest2, ptest1);
672-
ERROR: foreign key constraint "fktable_ftest1_fkey" cannot be implemented
672+
ERROR: foreign key constraint "fktable_ftest1_ftest2_fkey" cannot be implemented
673673
DETAIL: Key columns "ftest1" and "ptest2" are of incompatible types: integer and inet.
674674
-- As does this...
675675
ALTER TABLE FKTABLE ADD FOREIGN KEY(ftest2, ftest1)
676676
references pktable(ptest1, ptest2);
677-
ERROR: foreign key constraint "fktable_ftest2_fkey" cannot be implemented
677+
ERROR: foreign key constraint "fktable_ftest2_ftest1_fkey" cannot be implemented
678678
DETAIL: Key columns "ftest2" and "ptest1" are of incompatible types: inet and integer.
679679
DROP TABLE FKTABLE;
680680
DROP TABLE PKTABLE;

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