*
*
* IDENTIFICATION
- * $PostgreSQL: pgsql/src/backend/catalog/heap.c,v 1.301 2006/06/27 18:35:05 momjian Exp $
+ * $PostgreSQL: pgsql/src/backend/catalog/heap.c,v 1.302 2006/06/29 16:07:29 tgl Exp $
*
*
* INTERFACE ROUTINES
static void StoreRelCheck(Relation rel, char *ccname, char *ccbin);
static void StoreConstraints(Relation rel, TupleDesc tupdesc);
static void SetRelationNumChecks(Relation rel, int numchecks);
+static List *insert_ordered_unique_oid(List *list, Oid datum);
/* ----------------------------------------------------------------
/*
* heap_truncate_check_FKs
* Check for foreign keys referencing a list of relations that
- * are to be truncated
+ * are to be truncated, and raise error if there are any
*
* We disallow such FKs (except self-referential ones) since the whole point
* of TRUNCATE is to not scan the individual rows to be thrown away.
heap_truncate_check_FKs(List *relations, bool tempTables)
{
List *oids = NIL;
+ List *dependents;
ListCell *cell;
- Relation fkeyRel;
- SysScanDesc fkeyScan;
- HeapTuple tuple;
/*
* Build a list of OIDs of the interesting relations.
return;
/*
- * Otherwise, must scan pg_constraint. Right now, it is a seqscan because
- * there is no available index on confrelid.
+ * Otherwise, must scan pg_constraint. We make one pass with all the
+ * relations considered; if this finds nothing, then all is well.
*/
- fkeyRel = heap_open(ConstraintRelationId, AccessShareLock);
-
- fkeyScan = systable_beginscan(fkeyRel, InvalidOid, false,
- SnapshotNow, 0, NULL);
+ dependents = heap_truncate_find_FKs(oids);
+ if (dependents == NIL)
+ return;
- while (HeapTupleIsValid(tuple = systable_getnext(fkeyScan)))
+ /*
+ * Otherwise we repeat the scan once per relation to identify a particular
+ * pair of relations to complain about. This is pretty slow, but
+ * performance shouldn't matter much in a failure path. The reason for
+ * doing things this way is to ensure that the message produced is not
+ * dependent on chance row locations within pg_constraint.
+ */
+ foreach(cell, oids)
{
- Form_pg_constraint con = (Form_pg_constraint) GETSTRUCT(tuple);
-
- /* Not a foreign key */
- if (con->contype != CONSTRAINT_FOREIGN)
- continue;
+ Oid relid = lfirst_oid(cell);
+ ListCell *cell2;
- /* Not referencing one of our list of tables */
- if (!list_member_oid(oids, con->confrelid))
- continue;
+ dependents = heap_truncate_find_FKs(list_make1_oid(relid));
- /* The referencer should be in our list too */
- if (!list_member_oid(oids, con->conrelid))
+ foreach(cell2, dependents)
{
- if (tempTables)
- ereport(ERROR,
- (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
- errmsg("unsupported ON COMMIT and foreign key combination"),
- errdetail("Table \"%s\" references \"%s\" via foreign key constraint \"%s\", but they do not have the same ON COMMIT setting.",
- get_rel_name(con->conrelid),
- get_rel_name(con->confrelid),
- NameStr(con->conname))));
- else
- ereport(ERROR,
- (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
- errmsg("cannot truncate a table referenced in a foreign key constraint"),
- errdetail("Table \"%s\" references \"%s\" via foreign key constraint \"%s\".",
- get_rel_name(con->conrelid),
- get_rel_name(con->confrelid),
- NameStr(con->conname)),
- errhint("Truncate table \"%s\" at the same time, "
- "or use TRUNCATE ... CASCADE.",
- get_rel_name(con->conrelid))));
+ Oid relid2 = lfirst_oid(cell2);
+
+ if (!list_member_oid(oids, relid2))
+ {
+ char *relname = get_rel_name(relid);
+ char *relname2 = get_rel_name(relid2);
+
+ if (tempTables)
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("unsupported ON COMMIT and foreign key combination"),
+ errdetail("Table \"%s\" references \"%s\", but they do not have the same ON COMMIT setting.",
+ relname2, relname)));
+ else
+ ereport(ERROR,
+ (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+ errmsg("cannot truncate a table referenced in a foreign key constraint"),
+ errdetail("Table \"%s\" references \"%s\".",
+ relname2, relname),
+ errhint("Truncate table \"%s\" at the same time, "
+ "or use TRUNCATE ... CASCADE.",
+ relname2)));
+ }
}
}
-
- systable_endscan(fkeyScan);
- heap_close(fkeyRel, AccessShareLock);
}
/*
* heap_truncate_find_FKs
- * Find relations having foreign keys referencing any relations that
- * are to be truncated
+ * Find relations having foreign keys referencing any of the given rels
*
- * This is almost the same code as heap_truncate_check_FKs, but we don't
- * raise an error if we find such relations; instead we return a list of
- * their OIDs. Also note that the input is a list of OIDs not a list
- * of Relations. The result list does *not* include any rels that are
- * already in the input list.
+ * Input and result are both lists of relation OIDs. The result contains
+ * no duplicates, does *not* include any rels that were already in the input
+ * list, and is sorted in OID order. (The last property is enforced mainly
+ * to guarantee consistent behavior in the regression tests; we don't want
+ * behavior to change depending on chance locations of rows in pg_constraint.)
*
- * Note: caller should already have exclusive lock on all rels mentioned
+ * Note: caller should already have appropriate lock on all rels mentioned
* in relationIds. Since adding or dropping an FK requires exclusive lock
* on both rels, this ensures that the answer will be stable.
*/
/* Add referencer unless already in input or result list */
if (!list_member_oid(relationIds, con->conrelid))
- result = list_append_unique_oid(result, con->conrelid);
+ result = insert_ordered_unique_oid(result, con->conrelid);
}
systable_endscan(fkeyScan);
return result;
}
+
+/*
+ * insert_ordered_unique_oid
+ * Insert a new Oid into a sorted list of Oids, preserving ordering,
+ * and eliminating duplicates
+ *
+ * Building the ordered list this way is O(N^2), but with a pretty small
+ * constant, so for the number of entries we expect it will probably be
+ * faster than trying to apply qsort(). It seems unlikely someone would be
+ * trying to truncate a table with thousands of dependent tables ...
+ */
+static List *
+insert_ordered_unique_oid(List *list, Oid datum)
+{
+ ListCell *prev;
+
+ /* Does the datum belong at the front? */
+ if (list == NIL || datum < linitial_oid(list))
+ return lcons_oid(datum, list);
+ /* Does it match the first entry? */
+ if (datum == linitial_oid(list))
+ return list; /* duplicate, so don't insert */
+ /* No, so find the entry it belongs after */
+ prev = list_head(list);
+ for (;;)
+ {
+ ListCell *curr = lnext(prev);
+
+ if (curr == NULL || datum < lfirst_oid(curr))
+ break; /* it belongs after 'prev', before 'curr' */
+
+ if (datum == lfirst_oid(curr))
+ return list; /* duplicate, so don't insert */
+
+ prev = curr;
+ }
+ /* Insert datum into list after 'prev' */
+ lappend_cell_oid(list, prev, datum);
+ return list;
+}
CREATE TABLE trunc_e (a int REFERENCES truncate_a, b int REFERENCES trunc_c);
TRUNCATE TABLE truncate_a; -- fail
ERROR: cannot truncate a table referenced in a foreign key constraint
-DETAIL: Table "trunc_b" references "truncate_a" via foreign key constraint "trunc_b_a_fkey".
+DETAIL: Table "trunc_b" references "truncate_a".
HINT: Truncate table "trunc_b" at the same time, or use TRUNCATE ... CASCADE.
TRUNCATE TABLE truncate_a,trunc_b; -- fail
ERROR: cannot truncate a table referenced in a foreign key constraint
-DETAIL: Table "trunc_e" references "truncate_a" via foreign key constraint "trunc_e_a_fkey".
+DETAIL: Table "trunc_e" references "truncate_a".
HINT: Truncate table "trunc_e" at the same time, or use TRUNCATE ... CASCADE.
TRUNCATE TABLE truncate_a,trunc_b,trunc_e; -- ok
TRUNCATE TABLE truncate_a,trunc_e; -- fail
ERROR: cannot truncate a table referenced in a foreign key constraint
-DETAIL: Table "trunc_b" references "truncate_a" via foreign key constraint "trunc_b_a_fkey".
+DETAIL: Table "trunc_b" references "truncate_a".
HINT: Truncate table "trunc_b" at the same time, or use TRUNCATE ... CASCADE.
TRUNCATE TABLE trunc_c; -- fail
ERROR: cannot truncate a table referenced in a foreign key constraint
-DETAIL: Table "trunc_d" references "trunc_c" via foreign key constraint "trunc_d_a_fkey".
+DETAIL: Table "trunc_d" references "trunc_c".
HINT: Truncate table "trunc_d" at the same time, or use TRUNCATE ... CASCADE.
TRUNCATE TABLE trunc_c,trunc_d; -- fail
ERROR: cannot truncate a table referenced in a foreign key constraint
-DETAIL: Table "trunc_e" references "trunc_c" via foreign key constraint "trunc_e_b_fkey".
+DETAIL: Table "trunc_e" references "trunc_c".
HINT: Truncate table "trunc_e" at the same time, or use TRUNCATE ... CASCADE.
TRUNCATE TABLE trunc_c,trunc_d,trunc_e; -- ok
TRUNCATE TABLE trunc_c,trunc_d,trunc_e,truncate_a; -- fail
ERROR: cannot truncate a table referenced in a foreign key constraint
-DETAIL: Table "trunc_b" references "truncate_a" via foreign key constraint "trunc_b_a_fkey".
+DETAIL: Table "trunc_b" references "truncate_a".
HINT: Truncate table "trunc_b" at the same time, or use TRUNCATE ... CASCADE.
TRUNCATE TABLE trunc_c,trunc_d,trunc_e,truncate_a,trunc_b; -- ok
TRUNCATE TABLE truncate_a RESTRICT; -- fail
ERROR: cannot truncate a table referenced in a foreign key constraint
-DETAIL: Table "trunc_b" references "truncate_a" via foreign key constraint "trunc_b_a_fkey".
+DETAIL: Table "trunc_b" references "truncate_a".
HINT: Truncate table "trunc_b" at the same time, or use TRUNCATE ... CASCADE.
TRUNCATE TABLE truncate_a CASCADE; -- ok
NOTICE: truncate cascades to table "trunc_b"
INSERT INTO trunc_e VALUES (1,1);
TRUNCATE TABLE trunc_c;
ERROR: cannot truncate a table referenced in a foreign key constraint
-DETAIL: Table "trunc_d" references "trunc_c" via foreign key constraint "trunc_d_a_fkey".
+DETAIL: Table "truncate_a" references "trunc_c".
+HINT: Truncate table "truncate_a" at the same time, or use TRUNCATE ... CASCADE.
+TRUNCATE TABLE trunc_c,truncate_a;
+ERROR: cannot truncate a table referenced in a foreign key constraint
+DETAIL: Table "trunc_d" references "trunc_c".
HINT: Truncate table "trunc_d" at the same time, or use TRUNCATE ... CASCADE.
-TRUNCATE TABLE trunc_c,trunc_d;
+TRUNCATE TABLE trunc_c,truncate_a,trunc_d;
ERROR: cannot truncate a table referenced in a foreign key constraint
-DETAIL: Table "trunc_e" references "trunc_c" via foreign key constraint "trunc_e_b_fkey".
+DETAIL: Table "trunc_e" references "trunc_c".
HINT: Truncate table "trunc_e" at the same time, or use TRUNCATE ... CASCADE.
-TRUNCATE TABLE trunc_c,trunc_d,trunc_e;
-ERROR: cannot truncate a table referenced in a foreign key constraint
-DETAIL: Table "truncate_a" references "trunc_c" via foreign key constraint "truncate_a_col1_fkey".
-HINT: Truncate table "truncate_a" at the same time, or use TRUNCATE ... CASCADE.
-TRUNCATE TABLE trunc_c,trunc_d,trunc_e,truncate_a;
+TRUNCATE TABLE trunc_c,truncate_a,trunc_d,trunc_e;
ERROR: cannot truncate a table referenced in a foreign key constraint
-DETAIL: Table "trunc_b" references "truncate_a" via foreign key constraint "trunc_b_a_fkey".
+DETAIL: Table "trunc_b" references "truncate_a".
HINT: Truncate table "trunc_b" at the same time, or use TRUNCATE ... CASCADE.
-TRUNCATE TABLE trunc_c,trunc_d,trunc_e,truncate_a,trunc_b;
+TRUNCATE TABLE trunc_c,truncate_a,trunc_d,trunc_e,trunc_b;
-- Verify that truncating did actually work
SELECT * FROM truncate_a
UNION ALL
INSERT INTO trunc_d VALUES (1);
INSERT INTO trunc_e VALUES (1,1);
TRUNCATE TABLE trunc_c CASCADE; -- ok
+NOTICE: truncate cascades to table "truncate_a"
NOTICE: truncate cascades to table "trunc_d"
NOTICE: truncate cascades to table "trunc_e"
-NOTICE: truncate cascades to table "truncate_a"
NOTICE: truncate cascades to table "trunc_b"
SELECT * FROM truncate_a
UNION ALL
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