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Commitcd4609e

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Change TRUNCATE's method for searching for foreign-key references so that
the order in which it visits tables is not dependent on the physical orderof pg_constraint entries, and neither are the error messages it gives.This should correct recently-noticed instability in regression tests.
1 parentbc9b6c2 commitcd4609e

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4 files changed

+115
-76
lines changed

4 files changed

+115
-76
lines changed

‎src/backend/catalog/heap.c

Lines changed: 92 additions & 53 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/catalog/heap.c,v 1.301 2006/06/27 18:35:05 momjian Exp $
11+
* $PostgreSQL: pgsql/src/backend/catalog/heap.c,v 1.302 2006/06/29 16:07:29 tgl Exp $
1212
*
1313
*
1414
* INTERFACE ROUTINES
@@ -75,6 +75,7 @@ static void RelationRemoveInheritance(Oid relid);
7575
staticvoidStoreRelCheck(Relationrel,char*ccname,char*ccbin);
7676
staticvoidStoreConstraints(Relationrel,TupleDesctupdesc);
7777
staticvoidSetRelationNumChecks(Relationrel,intnumchecks);
78+
staticList*insert_ordered_unique_oid(List*list,Oiddatum);
7879

7980

8081
/* ----------------------------------------------------------------
@@ -1990,7 +1991,7 @@ heap_truncate(List *relids)
19901991
/*
19911992
* heap_truncate_check_FKs
19921993
*Check for foreign keys referencing a list of relations that
1993-
*are to be truncated
1994+
*are to be truncated, and raise error if there are any
19941995
*
19951996
* We disallow such FKs (except self-referential ones) since the whole point
19961997
* of TRUNCATE is to not scan the individual rows to be thrown away.
@@ -2004,10 +2005,8 @@ void
20042005
heap_truncate_check_FKs(List*relations,booltempTables)
20052006
{
20062007
List*oids=NIL;
2008+
List*dependents;
20072009
ListCell*cell;
2008-
RelationfkeyRel;
2009-
SysScanDescfkeyScan;
2010-
HeapTupletuple;
20112010

20122011
/*
20132012
* Build a list of OIDs of the interesting relations.
@@ -2030,67 +2029,67 @@ heap_truncate_check_FKs(List *relations, bool tempTables)
20302029
return;
20312030

20322031
/*
2033-
* Otherwise, must scan pg_constraint.Right now, it is a seqscan because
2034-
*there is no available index on confrelid.
2032+
* Otherwise, must scan pg_constraint. We make one pass with all the
2033+
*relations considered; if this finds nothing, then all is well.
20352034
*/
2036-
fkeyRel=heap_open(ConstraintRelationId,AccessShareLock);
2037-
2038-
fkeyScan=systable_beginscan(fkeyRel,InvalidOid, false,
2039-
SnapshotNow,0,NULL);
2035+
dependents=heap_truncate_find_FKs(oids);
2036+
if (dependents==NIL)
2037+
return;
20402038

2041-
while (HeapTupleIsValid(tuple=systable_getnext(fkeyScan)))
2039+
/*
2040+
* Otherwise we repeat the scan once per relation to identify a particular
2041+
* pair of relations to complain about. This is pretty slow, but
2042+
* performance shouldn't matter much in a failure path. The reason for
2043+
* doing things this way is to ensure that the message produced is not
2044+
* dependent on chance row locations within pg_constraint.
2045+
*/
2046+
foreach(cell,oids)
20422047
{
2043-
Form_pg_constraintcon= (Form_pg_constraint)GETSTRUCT(tuple);
2044-
2045-
/* Not a foreign key */
2046-
if (con->contype!=CONSTRAINT_FOREIGN)
2047-
continue;
2048+
Oidrelid=lfirst_oid(cell);
2049+
ListCell*cell2;
20482050

2049-
/* Not referencing one of our list of tables */
2050-
if (!list_member_oid(oids,con->confrelid))
2051-
continue;
2051+
dependents=heap_truncate_find_FKs(list_make1_oid(relid));
20522052

2053-
/* The referencer should be in our list too */
2054-
if (!list_member_oid(oids,con->conrelid))
2053+
foreach(cell2,dependents)
20552054
{
2056-
if (tempTables)
2057-
ereport(ERROR,
2058-
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
2059-
errmsg("unsupported ON COMMIT and foreign key combination"),
2060-
errdetail("Table \"%s\" references \"%s\" via foreign key constraint \"%s\", but they do not have the same ON COMMIT setting.",
2061-
get_rel_name(con->conrelid),
2062-
get_rel_name(con->confrelid),
2063-
NameStr(con->conname))));
2064-
else
2065-
ereport(ERROR,
2066-
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
2067-
errmsg("cannot truncate a table referenced in a foreign key constraint"),
2068-
errdetail("Table \"%s\" references \"%s\" via foreign key constraint \"%s\".",
2069-
get_rel_name(con->conrelid),
2070-
get_rel_name(con->confrelid),
2071-
NameStr(con->conname)),
2072-
errhint("Truncate table \"%s\" at the same time, "
2073-
"or use TRUNCATE ... CASCADE.",
2074-
get_rel_name(con->conrelid))));
2055+
Oidrelid2=lfirst_oid(cell2);
2056+
2057+
if (!list_member_oid(oids,relid2))
2058+
{
2059+
char*relname=get_rel_name(relid);
2060+
char*relname2=get_rel_name(relid2);
2061+
2062+
if (tempTables)
2063+
ereport(ERROR,
2064+
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
2065+
errmsg("unsupported ON COMMIT and foreign key combination"),
2066+
errdetail("Table \"%s\" references \"%s\", but they do not have the same ON COMMIT setting.",
2067+
relname2,relname)));
2068+
else
2069+
ereport(ERROR,
2070+
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
2071+
errmsg("cannot truncate a table referenced in a foreign key constraint"),
2072+
errdetail("Table \"%s\" references \"%s\".",
2073+
relname2,relname),
2074+
errhint("Truncate table \"%s\" at the same time, "
2075+
"or use TRUNCATE ... CASCADE.",
2076+
relname2)));
2077+
}
20752078
}
20762079
}
2077-
2078-
systable_endscan(fkeyScan);
2079-
heap_close(fkeyRel,AccessShareLock);
20802080
}
20812081

20822082
/*
20832083
* heap_truncate_find_FKs
2084-
*Find relations having foreign keys referencing any relations that
2085-
*are to be truncated
2084+
*Find relations having foreign keys referencing any of the given rels
20862085
*
2087-
*This is almost the same code as heap_truncate_check_FKs, but we don't
2088-
*raise an error if we find such relations; instead we return a list of
2089-
*their OIDs. Also note that the input is a list of OIDs not a list
2090-
*of Relations. The result list does *not* include any rels that are
2091-
*already in the input list.
2086+
*Input and result are both lists of relation OIDs. The result contains
2087+
*no duplicates, does *not* include any rels that were already in the input
2088+
*list, and is sorted in OID order. (The last property is enforced mainly
2089+
*to guarantee consistent behavior in the regression tests; we don't want
2090+
*behavior to change depending on chance locations of rows in pg_constraint.)
20922091
*
2093-
* Note: caller should already haveexclusive lock on all rels mentioned
2092+
* Note: caller should already haveappropriate lock on all rels mentioned
20942093
* in relationIds. Since adding or dropping an FK requires exclusive lock
20952094
* on both rels, this ensures that the answer will be stable.
20962095
*/
@@ -2125,11 +2124,51 @@ heap_truncate_find_FKs(List *relationIds)
21252124

21262125
/* Add referencer unless already in input or result list */
21272126
if (!list_member_oid(relationIds,con->conrelid))
2128-
result=list_append_unique_oid(result,con->conrelid);
2127+
result=insert_ordered_unique_oid(result,con->conrelid);
21292128
}
21302129

21312130
systable_endscan(fkeyScan);
21322131
heap_close(fkeyRel,AccessShareLock);
21332132

21342133
returnresult;
21352134
}
2135+
2136+
/*
2137+
* insert_ordered_unique_oid
2138+
*Insert a new Oid into a sorted list of Oids, preserving ordering,
2139+
*and eliminating duplicates
2140+
*
2141+
* Building the ordered list this way is O(N^2), but with a pretty small
2142+
* constant, so for the number of entries we expect it will probably be
2143+
* faster than trying to apply qsort(). It seems unlikely someone would be
2144+
* trying to truncate a table with thousands of dependent tables ...
2145+
*/
2146+
staticList*
2147+
insert_ordered_unique_oid(List*list,Oiddatum)
2148+
{
2149+
ListCell*prev;
2150+
2151+
/* Does the datum belong at the front? */
2152+
if (list==NIL||datum<linitial_oid(list))
2153+
returnlcons_oid(datum,list);
2154+
/* Does it match the first entry? */
2155+
if (datum==linitial_oid(list))
2156+
returnlist;/* duplicate, so don't insert */
2157+
/* No, so find the entry it belongs after */
2158+
prev=list_head(list);
2159+
for (;;)
2160+
{
2161+
ListCell*curr=lnext(prev);
2162+
2163+
if (curr==NULL||datum<lfirst_oid(curr))
2164+
break;/* it belongs after 'prev', before 'curr' */
2165+
2166+
if (datum==lfirst_oid(curr))
2167+
returnlist;/* duplicate, so don't insert */
2168+
2169+
prev=curr;
2170+
}
2171+
/* Insert datum into list after 'prev' */
2172+
lappend_cell_oid(list,prev,datum);
2173+
returnlist;
2174+
}

‎src/test/regress/expected/temp.out

Lines changed: 1 addition & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -136,4 +136,4 @@ NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "temptest3_pkey"
136136
CREATE TEMP TABLE temptest4(col int REFERENCES temptest3);
137137
COMMIT;
138138
ERROR: unsupported ON COMMIT and foreign key combination
139-
DETAIL: Table "temptest4" references "temptest3" via foreign key constraint "temptest4_col_fkey", but they do not have the same ON COMMIT setting.
139+
DETAIL: Table "temptest4" references "temptest3", but they do not have the same ON COMMIT setting.

‎src/test/regress/expected/truncate.out

Lines changed: 18 additions & 18 deletions
Original file line numberDiff line numberDiff line change
@@ -39,34 +39,34 @@ CREATE TABLE trunc_d (a int REFERENCES trunc_c);
3939
CREATE TABLE trunc_e (a int REFERENCES truncate_a, b int REFERENCES trunc_c);
4040
TRUNCATE TABLE truncate_a;-- fail
4141
ERROR: cannot truncate a table referenced in a foreign key constraint
42-
DETAIL: Table "trunc_b" references "truncate_a" via foreign key constraint "trunc_b_a_fkey".
42+
DETAIL: Table "trunc_b" references "truncate_a".
4343
HINT: Truncate table "trunc_b" at the same time, or use TRUNCATE ... CASCADE.
4444
TRUNCATE TABLE truncate_a,trunc_b;-- fail
4545
ERROR: cannot truncate a table referenced in a foreign key constraint
46-
DETAIL: Table "trunc_e" references "truncate_a" via foreign key constraint "trunc_e_a_fkey".
46+
DETAIL: Table "trunc_e" references "truncate_a".
4747
HINT: Truncate table "trunc_e" at the same time, or use TRUNCATE ... CASCADE.
4848
TRUNCATE TABLE truncate_a,trunc_b,trunc_e;-- ok
4949
TRUNCATE TABLE truncate_a,trunc_e;-- fail
5050
ERROR: cannot truncate a table referenced in a foreign key constraint
51-
DETAIL: Table "trunc_b" references "truncate_a" via foreign key constraint "trunc_b_a_fkey".
51+
DETAIL: Table "trunc_b" references "truncate_a".
5252
HINT: Truncate table "trunc_b" at the same time, or use TRUNCATE ... CASCADE.
5353
TRUNCATE TABLE trunc_c;-- fail
5454
ERROR: cannot truncate a table referenced in a foreign key constraint
55-
DETAIL: Table "trunc_d" references "trunc_c" via foreign key constraint "trunc_d_a_fkey".
55+
DETAIL: Table "trunc_d" references "trunc_c".
5656
HINT: Truncate table "trunc_d" at the same time, or use TRUNCATE ... CASCADE.
5757
TRUNCATE TABLE trunc_c,trunc_d;-- fail
5858
ERROR: cannot truncate a table referenced in a foreign key constraint
59-
DETAIL: Table "trunc_e" references "trunc_c" via foreign key constraint "trunc_e_b_fkey".
59+
DETAIL: Table "trunc_e" references "trunc_c".
6060
HINT: Truncate table "trunc_e" at the same time, or use TRUNCATE ... CASCADE.
6161
TRUNCATE TABLE trunc_c,trunc_d,trunc_e;-- ok
6262
TRUNCATE TABLE trunc_c,trunc_d,trunc_e,truncate_a;-- fail
6363
ERROR: cannot truncate a table referenced in a foreign key constraint
64-
DETAIL: Table "trunc_b" references "truncate_a" via foreign key constraint "trunc_b_a_fkey".
64+
DETAIL: Table "trunc_b" references "truncate_a".
6565
HINT: Truncate table "trunc_b" at the same time, or use TRUNCATE ... CASCADE.
6666
TRUNCATE TABLE trunc_c,trunc_d,trunc_e,truncate_a,trunc_b;-- ok
6767
TRUNCATE TABLE truncate_a RESTRICT; -- fail
6868
ERROR: cannot truncate a table referenced in a foreign key constraint
69-
DETAIL: Table "trunc_b" references "truncate_a" via foreign key constraint "trunc_b_a_fkey".
69+
DETAIL: Table "trunc_b" references "truncate_a".
7070
HINT: Truncate table "trunc_b" at the same time, or use TRUNCATE ... CASCADE.
7171
TRUNCATE TABLE truncate_a CASCADE; -- ok
7272
NOTICE: truncate cascades to table "trunc_b"
@@ -81,21 +81,21 @@ INSERT INTO trunc_d VALUES (1);
8181
INSERT INTO trunc_e VALUES (1,1);
8282
TRUNCATE TABLE trunc_c;
8383
ERROR: cannot truncate a table referenced in a foreign key constraint
84-
DETAIL: Table "trunc_d" references "trunc_c" via foreign key constraint "trunc_d_a_fkey".
84+
DETAIL: Table "truncate_a" references "trunc_c".
85+
HINT: Truncate table "truncate_a" at the same time, or use TRUNCATE ... CASCADE.
86+
TRUNCATE TABLE trunc_c,truncate_a;
87+
ERROR: cannot truncate a table referenced in a foreign key constraint
88+
DETAIL: Table "trunc_d" references "trunc_c".
8589
HINT: Truncate table "trunc_d" at the same time, or use TRUNCATE ... CASCADE.
86-
TRUNCATE TABLE trunc_c,trunc_d;
90+
TRUNCATE TABLE trunc_c,truncate_a,trunc_d;
8791
ERROR: cannot truncate a table referenced in a foreign key constraint
88-
DETAIL: Table "trunc_e" references "trunc_c" via foreign key constraint "trunc_e_b_fkey".
92+
DETAIL: Table "trunc_e" references "trunc_c".
8993
HINT: Truncate table "trunc_e" at the same time, or use TRUNCATE ... CASCADE.
90-
TRUNCATE TABLE trunc_c,trunc_d,trunc_e;
91-
ERROR: cannot truncate a table referenced in a foreign key constraint
92-
DETAIL: Table "truncate_a" references "trunc_c" via foreign key constraint "truncate_a_col1_fkey".
93-
HINT: Truncate table "truncate_a" at the same time, or use TRUNCATE ... CASCADE.
94-
TRUNCATE TABLE trunc_c,trunc_d,trunc_e,truncate_a;
94+
TRUNCATE TABLE trunc_c,truncate_a,trunc_d,trunc_e;
9595
ERROR: cannot truncate a table referenced in a foreign key constraint
96-
DETAIL: Table "trunc_b" references "truncate_a" via foreign key constraint "trunc_b_a_fkey".
96+
DETAIL: Table "trunc_b" references "truncate_a".
9797
HINT: Truncate table "trunc_b" at the same time, or use TRUNCATE ... CASCADE.
98-
TRUNCATE TABLE trunc_c,trunc_d,trunc_e,truncate_a,trunc_b;
98+
TRUNCATE TABLE trunc_c,truncate_a,trunc_d,trunc_e,trunc_b;
9999
-- Verify that truncating did actually work
100100
SELECT * FROM truncate_a
101101
UNION ALL
@@ -120,9 +120,9 @@ INSERT INTO trunc_b VALUES (1);
120120
INSERT INTO trunc_d VALUES (1);
121121
INSERT INTO trunc_e VALUES (1,1);
122122
TRUNCATE TABLE trunc_c CASCADE; -- ok
123+
NOTICE: truncate cascades to table "truncate_a"
123124
NOTICE: truncate cascades to table "trunc_d"
124125
NOTICE: truncate cascades to table "trunc_e"
125-
NOTICE: truncate cascades to table "truncate_a"
126126
NOTICE: truncate cascades to table "trunc_b"
127127
SELECT * FROM truncate_a
128128
UNION ALL

‎src/test/regress/sql/truncate.sql

Lines changed: 4 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -43,10 +43,10 @@ INSERT INTO trunc_b VALUES (1);
4343
INSERT INTO trunc_dVALUES (1);
4444
INSERT INTO trunc_eVALUES (1,1);
4545
TRUNCATE TABLE trunc_c;
46-
TRUNCATE TABLE trunc_c,trunc_d;
47-
TRUNCATE TABLE trunc_c,trunc_d,trunc_e;
48-
TRUNCATE TABLE trunc_c,trunc_d,trunc_e,truncate_a;
49-
TRUNCATE TABLE trunc_c,trunc_d,trunc_e,truncate_a,trunc_b;
46+
TRUNCATE TABLE trunc_c,truncate_a;
47+
TRUNCATE TABLE trunc_c,truncate_a,trunc_d;
48+
TRUNCATE TABLE trunc_c,truncate_a,trunc_d,trunc_e;
49+
TRUNCATE TABLE trunc_c,truncate_a,trunc_d,trunc_e,trunc_b;
5050

5151
-- Verify that truncating did actually work
5252
SELECT*FROM truncate_a

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