bug6123-v2.patch
text/plain
*** a/src/backend/executor/execMain.c
--- b/src/backend/executor/execMain.c
***************
*** 1847,1854 **** EvalPlanQualFetch(EState *estate, Relation relation, int lockmode,
switch (test)
{
case HeapTupleSelfUpdated:
- /* treat it as deleted; do not process */
ReleaseBuffer(buffer);
return NULL;
case HeapTupleMayBeUpdated:
--- 1847,1862 ----
switch (test)
{
case HeapTupleSelfUpdated:
ReleaseBuffer(buffer);
+ if (!ItemPointerEquals(&update_ctid, &tuple.t_self))
+ {
+ /* it was updated, so look at the updated version */
+ tuple.t_self = update_ctid;
+ /* updated row should have xmin matching this xmax */
+ priorXmax = update_xmax;
+ continue;
+ }
+ /* treat it as deleted; do not process */
return NULL;
case HeapTupleMayBeUpdated:
*** a/src/backend/executor/nodeModifyTable.c
--- b/src/backend/executor/nodeModifyTable.c
***************
*** 353,359 **** ldelete:;
--- 353,382 ----
true /* wait for commit */ );
switch (result)
{
+ /*
+ * Don't allow updates to a row during its BEFORE DELETE trigger
+ * to prevent the deletion. One example of where this might
+ * happen is that the BEFORE DELETE trigger could delete a child
+ * row, and a trigger on that child row might update some count or
+ * status column in the row originally being deleted.
+ */
case HeapTupleSelfUpdated:
+ if (!ItemPointerEquals(tupleid, &update_ctid))
+ {
+ HeapTuple copyTuple;
+
+ estate->es_output_cid = GetCurrentCommandId(false);
+ copyTuple = EvalPlanQualFetch(estate,
+ resultRelationDesc,
+ LockTupleExclusive,
+ &update_ctid,
+ update_xmax);
+ if (copyTuple != NULL)
+ {
+ *tupleid = update_ctid = copyTuple->t_self;
+ goto ldelete;
+ }
+ }
/* already deleted by self; nothing to do */
return NULL;
***************
*** 570,576 **** lreplace:;
switch (result)
{
case HeapTupleSelfUpdated:
! /* already deleted by self; nothing to do */
return NULL;
case HeapTupleMayBeUpdated:
--- 593,617 ----
switch (result)
{
case HeapTupleSelfUpdated:
! /*
! * There is no sensible action to take if the BEFORE UPDATE
! * trigger for a row issues another UPDATE for the same row,
! * either directly or by performing DML which fires other
! * triggers which do the update. We don't want to discard the
! * original UPDATE while keeping the triggered actions based
! * on its update; and it would be no better to allow the
! * original UPDATE while discarding some of its triggered
! * actions.
! */
! if (!ItemPointerEquals(tupleid, &update_ctid)
! && GetCurrentCommandId(false) != estate->es_output_cid)
! {
! ereport(ERROR,
! (errcode(ERRCODE_TRIGGERED_DATA_CHANGE_VIOLATION),
! errmsg("cannot update a row from its BEFORE UPDATE trigger"),
! errhint("Consider moving updates to the AFTER UPDATE trigger.")));
! }
! /* already deleted or updated by self; nothing to do */
return NULL;
case HeapTupleMayBeUpdated:
*** a/src/test/regress/expected/triggers.out
--- b/src/test/regress/expected/triggers.out
***************
*** 1414,1416 **** NOTICE: drop cascades to 2 other objects
--- 1414,1511 ----
DETAIL: drop cascades to view city_view
drop cascades to view european_city_view
DROP TABLE country_table;
+ --
+ -- Test updates to rows during firing of BEFORE ROW triggers.
+ --
+ create table parent (aid int not null primary key,
+ val1 text,
+ val2 text,
+ val3 text,
+ val4 text,
+ bcnt int not null default 0);
+ NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "parent_pkey" for table "parent"
+ create table child (bid int not null primary key,
+ aid int not null,
+ val1 text);
+ NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "child_pkey" for table "child"
+ create function parent_upd_func()
+ returns trigger language plpgsql as
+ $$
+ begin
+ if old.val1 <> new.val1 then
+ new.val2 = new.val1;
+ delete from child where child.aid = new.aid and child.val1 = new.val1;
+ end if;
+ return new;
+ end;
+ $$;
+ create trigger parent_upd_trig before update On parent
+ for each row execute procedure parent_upd_func();
+ create function parent_del_func()
+ returns trigger language plpgsql as
+ $$
+ begin
+ delete from child where aid = old.aid;
+ return old;
+ end;
+ $$;
+ create trigger parent_del_trig before delete On parent
+ for each row execute procedure parent_del_func();
+ create function child_ins_func()
+ returns trigger language plpgsql as
+ $$
+ begin
+ update parent set bcnt = bcnt + 1 where aid = new.aid;
+ return new;
+ end;
+ $$;
+ create trigger child_ins_trig after insert on child
+ for each row execute procedure child_ins_func();
+ create function child_del_func()
+ returns trigger language plpgsql as
+ $$
+ begin
+ update parent set bcnt = bcnt - 1 where aid = old.aid;
+ return old;
+ end;
+ $$;
+ create trigger child_del_trig after delete on child
+ for each row execute procedure child_del_func();
+ insert into parent values (1, 'a', 'a', 'a', 'a', 0);
+ insert into child values (10, 1, 'b');
+ select * from parent; select * from child;
+ aid | val1 | val2 | val3 | val4 | bcnt
+ -----+------+------+------+------+------
+ 1 | a | a | a | a | 1
+ (1 row)
+
+ bid | aid | val1
+ -----+-----+------
+ 10 | 1 | b
+ (1 row)
+
+ update parent set val1 = 'b' where aid = 1;
+ ERROR: cannot update a row from its BEFORE UPDATE trigger
+ HINT: Consider moving updates to the AFTER UPDATE trigger.
+ select * from parent; select * from child;
+ aid | val1 | val2 | val3 | val4 | bcnt
+ -----+------+------+------+------+------
+ 1 | a | a | a | a | 1
+ (1 row)
+
+ bid | aid | val1
+ -----+-----+------
+ 10 | 1 | b
+ (1 row)
+
+ delete from parent where aid = 1;
+ select * from parent; select * from child;
+ aid | val1 | val2 | val3 | val4 | bcnt
+ -----+------+------+------+------+------
+ (0 rows)
+
+ bid | aid | val1
+ -----+-----+------
+ (0 rows)
+
+ drop table parent, child;
*** a/src/test/regress/sql/triggers.sql
--- b/src/test/regress/sql/triggers.sql
***************
*** 935,937 **** SELECT * FROM city_view;
--- 935,1008 ----
DROP TABLE city_table CASCADE;
DROP TABLE country_table;
+
+ --
+ -- Test updates to rows during firing of BEFORE ROW triggers.
+ --
+
+ create table parent (aid int not null primary key,
+ val1 text,
+ val2 text,
+ val3 text,
+ val4 text,
+ bcnt int not null default 0);
+ create table child (bid int not null primary key,
+ aid int not null,
+ val1 text);
+
+ create function parent_upd_func()
+ returns trigger language plpgsql as
+ $$
+ begin
+ if old.val1 <> new.val1 then
+ new.val2 = new.val1;
+ delete from child where child.aid = new.aid and child.val1 = new.val1;
+ end if;
+ return new;
+ end;
+ $$;
+ create trigger parent_upd_trig before update On parent
+ for each row execute procedure parent_upd_func();
+
+ create function parent_del_func()
+ returns trigger language plpgsql as
+ $$
+ begin
+ delete from child where aid = old.aid;
+ return old;
+ end;
+ $$;
+ create trigger parent_del_trig before delete On parent
+ for each row execute procedure parent_del_func();
+
+ create function child_ins_func()
+ returns trigger language plpgsql as
+ $$
+ begin
+ update parent set bcnt = bcnt + 1 where aid = new.aid;
+ return new;
+ end;
+ $$;
+ create trigger child_ins_trig after insert on child
+ for each row execute procedure child_ins_func();
+
+ create function child_del_func()
+ returns trigger language plpgsql as
+ $$
+ begin
+ update parent set bcnt = bcnt - 1 where aid = old.aid;
+ return old;
+ end;
+ $$;
+ create trigger child_del_trig after delete on child
+ for each row execute procedure child_del_func();
+
+ insert into parent values (1, 'a', 'a', 'a', 'a', 0);
+ insert into child values (10, 1, 'b');
+ select * from parent; select * from child;
+ update parent set val1 = 'b' where aid = 1;
+ select * from parent; select * from child;
+ delete from parent where aid = 1;
+ select * from parent; select * from child;
+
+ drop table parent, child;