Fix trigger transition table capture for MERGE in CTE queries.

When executing a data-modifying CTE query containing MERGE and some
other DML operation on a table with statement-level AFTER triggers,
the transition tables passed to the triggers would fail to include the
rows affected by the MERGE.

The reason is that, when initializing a ModifyTable node for MERGE,
MakeTransitionCaptureState() would create a TransitionCaptureState
structure with a single "tcs_private" field pointing to an
AfterTriggersTableData structure with cmdType == CMD_MERGE. Tuples
captured there would then not be included in the sets of tuples
captured when executing INSERT/UPDATE/DELETE ModifyTable nodes in the
same query.

Since there are no MERGE triggers, we should only create
AfterTriggersTableData structures for INSERT/UPDATE/DELETE. Individual
MERGE actions should then use those, thereby sharing the same capture
tuplestores as any other DML commands executed in the same query.

This requires changing the TransitionCaptureState structure, replacing
"tcs_private" with 3 separate pointers to AfterTriggersTableData
structures, one for each of INSERT, UPDATE, and DELETE. Nominally,
this is an ABI break to a public structure in commands/trigger.h.
However, since this is a private field pointing to an opaque data
structure, the only way to create a valid TransitionCaptureState is by
calling MakeTransitionCaptureState(), and no extensions appear to be
doing that anyway, so it seems safe for back-patching.

Backpatch to v15, where MERGE was introduced.

Bug: #19380
Reported-by: Daniel Woelfel <dwwoelfel@gmail.com>
Author: Dean Rasheed <dean.a.rasheed@gmail.com>
Reviewed-by: Tom Lane <tgl@sss.pgh.pa.us>
Discussion: https://postgr.es/m/19380-4e293be2b4007248%40postgresql.org
Backpatch-through: 15

diff --git a/src/backend/commands/trigger.c b/src/backend/commands/trigger.c
index dda03a3c82346e1fb6754639bab43cda4ee970dd..f2a04b74fb796ffb8c27341125ab846165333755 100644 (file)
--- a/src/backend/commands/trigger.c
+++ b/src/backend/commands/trigger.c
@@ -3892,21 +3892,10 @@ struct AfterTriggersTableData
        bool            after_trig_done;        /* did we already queue AS triggers? */
        AfterTriggerEventList after_trig_events;        /* if so, saved list pointer */
 
-       /*
-        * We maintain separate transition tables for UPDATE/INSERT/DELETE since
-        * MERGE can run all three actions in a single statement. Note that UPDATE
-        * needs both old and new transition tables whereas INSERT needs only new,
-        * and DELETE needs only old.
-        */
-
-       /* "old" transition table for UPDATE, if any */
-       Tuplestorestate *old_upd_tuplestore;
-       /* "new" transition table for UPDATE, if any */
-       Tuplestorestate *new_upd_tuplestore;
-       /* "old" transition table for DELETE, if any */
-       Tuplestorestate *old_del_tuplestore;
-       /* "new" transition table for INSERT, if any */
-       Tuplestorestate *new_ins_tuplestore;
+       /* "old" transition table for UPDATE/DELETE, if any */
+       Tuplestorestate *old_tuplestore;
+       /* "new" transition table for INSERT/UPDATE, if any */
+       Tuplestorestate *new_tuplestore;
 
        TupleTableSlot *storeslot;      /* for converting to tuplestore's format */
 };
@@ -3933,6 +3922,7 @@ static Tuplestorestate *GetAfterTriggersTransitionTable(int event,
                                                                                                                TupleTableSlot *newslot,
                                                                                                                TransitionCaptureState *transition_capture);
 static void TransitionTableAddTuple(EState *estate,
+                                                                       int event,
                                                                        TransitionCaptureState *transition_capture,
                                                                        ResultRelInfo *relinfo,
                                                                        TupleTableSlot *slot,
@@ -4492,19 +4482,13 @@ AfterTriggerExecute(EState *estate,
        {
                if (LocTriggerData.tg_trigger->tgoldtable)
                {
-                       if (TRIGGER_FIRED_BY_UPDATE(evtshared->ats_event))
-                               LocTriggerData.tg_oldtable = evtshared->ats_table->old_upd_tuplestore;
-                       else
-                               LocTriggerData.tg_oldtable = evtshared->ats_table->old_del_tuplestore;
+                       LocTriggerData.tg_oldtable = evtshared->ats_table->old_tuplestore;
                        evtshared->ats_table->closed = true;
                }
 
                if (LocTriggerData.tg_trigger->tgnewtable)
                {
-                       if (TRIGGER_FIRED_BY_INSERT(evtshared->ats_event))
-                               LocTriggerData.tg_newtable = evtshared->ats_table->new_ins_tuplestore;
-                       else
-                               LocTriggerData.tg_newtable = evtshared->ats_table->new_upd_tuplestore;
+                       LocTriggerData.tg_newtable = evtshared->ats_table->new_tuplestore;
                        evtshared->ats_table->closed = true;
                }
        }
@@ -4836,6 +4820,11 @@ GetAfterTriggersTableData(Oid relid, CmdType cmdType)
        MemoryContext oldcxt;
        ListCell   *lc;
 
+       /* At this level, cmdType should not be, eg, CMD_MERGE */
+       Assert(cmdType == CMD_INSERT ||
+                  cmdType == CMD_UPDATE ||
+                  cmdType == CMD_DELETE);
+
        /* Caller should have ensured query_depth is OK. */
        Assert(afterTriggers.query_depth >= 0 &&
                   afterTriggers.query_depth < afterTriggers.maxquerydepth);
@@ -4922,7 +4911,9 @@ MakeTransitionCaptureState(TriggerDesc *trigdesc, Oid relid, CmdType cmdType)
                                need_new_upd,
                                need_old_del,
                                need_new_ins;
-       AfterTriggersTableData *table;
+       AfterTriggersTableData *ins_table;
+       AfterTriggersTableData *upd_table;
+       AfterTriggersTableData *del_table;
        MemoryContext oldcxt;
        ResourceOwner saveResourceOwner;
 
@@ -4969,10 +4960,15 @@ MakeTransitionCaptureState(TriggerDesc *trigdesc, Oid relid, CmdType cmdType)
                AfterTriggerEnlargeQueryState();
 
        /*
-        * Find or create an AfterTriggersTableData struct to hold the
+        * Find or create AfterTriggersTableData struct(s) to hold the
         * tuplestore(s).  If there's a matching struct but it's marked closed,
         * ignore it; we need a newer one.
         *
+        * Note: MERGE must use the same AfterTriggersTableData structs as INSERT,
+        * UPDATE, and DELETE, so that any MERGE'd tuples are added to the same
+        * tuplestores as tuples from any INSERT, UPDATE, or DELETE commands
+        * running in the same top-level command (e.g., in a writable CTE).
+        *
         * Note: the AfterTriggersTableData list, as well as the tuplestores, are
         * allocated in the current (sub)transaction's CurTransactionContext, and
         * the tuplestores are managed by the (sub)transaction's resource owner.
@@ -4980,21 +4976,34 @@ MakeTransitionCaptureState(TriggerDesc *trigdesc, Oid relid, CmdType cmdType)
         * transition tables to be deferrable; they will be fired during
         * AfterTriggerEndQuery, after which it's okay to delete the data.
         */
-       table = GetAfterTriggersTableData(relid, cmdType);
+       if (need_new_ins)
+               ins_table = GetAfterTriggersTableData(relid, CMD_INSERT);
+       else
+               ins_table = NULL;
+
+       if (need_old_upd || need_new_upd)
+               upd_table = GetAfterTriggersTableData(relid, CMD_UPDATE);
+       else
+               upd_table = NULL;
+
+       if (need_old_del)
+               del_table = GetAfterTriggersTableData(relid, CMD_DELETE);
+       else
+               del_table = NULL;
 
        /* Now create required tuplestore(s), if we don't have them already. */
        oldcxt = MemoryContextSwitchTo(CurTransactionContext);
        saveResourceOwner = CurrentResourceOwner;
        CurrentResourceOwner = CurTransactionResourceOwner;
 
-       if (need_old_upd && table->old_upd_tuplestore == NULL)
-               table->old_upd_tuplestore = tuplestore_begin_heap(false, false, work_mem);
-       if (need_new_upd && table->new_upd_tuplestore == NULL)
-               table->new_upd_tuplestore = tuplestore_begin_heap(false, false, work_mem);
-       if (need_old_del && table->old_del_tuplestore == NULL)
-               table->old_del_tuplestore = tuplestore_begin_heap(false, false, work_mem);
-       if (need_new_ins && table->new_ins_tuplestore == NULL)
-               table->new_ins_tuplestore = tuplestore_begin_heap(false, false, work_mem);
+       if (need_old_upd && upd_table->old_tuplestore == NULL)
+               upd_table->old_tuplestore = tuplestore_begin_heap(false, false, work_mem);
+       if (need_new_upd && upd_table->new_tuplestore == NULL)
+               upd_table->new_tuplestore = tuplestore_begin_heap(false, false, work_mem);
+       if (need_old_del && del_table->old_tuplestore == NULL)
+               del_table->old_tuplestore = tuplestore_begin_heap(false, false, work_mem);
+       if (need_new_ins && ins_table->new_tuplestore == NULL)
+               ins_table->new_tuplestore = tuplestore_begin_heap(false, false, work_mem);
 
        CurrentResourceOwner = saveResourceOwner;
        MemoryContextSwitchTo(oldcxt);
@@ -5005,7 +5014,9 @@ MakeTransitionCaptureState(TriggerDesc *trigdesc, Oid relid, CmdType cmdType)
        state->tcs_update_old_table = need_old_upd;
        state->tcs_update_new_table = need_new_upd;
        state->tcs_insert_new_table = need_new_ins;
-       state->tcs_private = table;
+       state->tcs_insert_private = ins_table;
+       state->tcs_update_private = upd_table;
+       state->tcs_delete_private = del_table;
 
        return state;
 }
@@ -5183,20 +5194,12 @@ AfterTriggerFreeQuery(AfterTriggersQueryData *qs)
        {
                AfterTriggersTableData *table = (AfterTriggersTableData *) lfirst(lc);
 
-               ts = table->old_upd_tuplestore;
-               table->old_upd_tuplestore = NULL;
-               if (ts)
-                       tuplestore_end(ts);
-               ts = table->new_upd_tuplestore;
-               table->new_upd_tuplestore = NULL;
-               if (ts)
-                       tuplestore_end(ts);
-               ts = table->old_del_tuplestore;
-               table->old_del_tuplestore = NULL;
+               ts = table->old_tuplestore;
+               table->old_tuplestore = NULL;
                if (ts)
                        tuplestore_end(ts);
-               ts = table->new_ins_tuplestore;
-               table->new_ins_tuplestore = NULL;
+               ts = table->new_tuplestore;
+               table->new_tuplestore = NULL;
                if (ts)
                        tuplestore_end(ts);
                if (table->storeslot)
@@ -5507,17 +5510,17 @@ GetAfterTriggersTransitionTable(int event,
        {
                Assert(TupIsNull(newslot));
                if (event == TRIGGER_EVENT_DELETE && delete_old_table)
-                       tuplestore = transition_capture->tcs_private->old_del_tuplestore;
+                       tuplestore = transition_capture->tcs_delete_private->old_tuplestore;
                else if (event == TRIGGER_EVENT_UPDATE && update_old_table)
-                       tuplestore = transition_capture->tcs_private->old_upd_tuplestore;
+                       tuplestore = transition_capture->tcs_update_private->old_tuplestore;
        }
        else if (!TupIsNull(newslot))
        {
                Assert(TupIsNull(oldslot));
                if (event == TRIGGER_EVENT_INSERT && insert_new_table)
-                       tuplestore = transition_capture->tcs_private->new_ins_tuplestore;
+                       tuplestore = transition_capture->tcs_insert_private->new_tuplestore;
                else if (event == TRIGGER_EVENT_UPDATE && update_new_table)
-                       tuplestore = transition_capture->tcs_private->new_upd_tuplestore;
+                       tuplestore = transition_capture->tcs_update_private->new_tuplestore;
        }
 
        return tuplestore;
@@ -5531,6 +5534,7 @@ GetAfterTriggersTransitionTable(int event,
  */
 static void
 TransitionTableAddTuple(EState *estate,
+                                               int event,
                                                TransitionCaptureState *transition_capture,
                                                ResultRelInfo *relinfo,
                                                TupleTableSlot *slot,
@@ -5549,9 +5553,26 @@ TransitionTableAddTuple(EState *estate,
                tuplestore_puttupleslot(tuplestore, original_insert_tuple);
        else if ((map = ExecGetChildToRootMap(relinfo)) != NULL)
        {
-               AfterTriggersTableData *table = transition_capture->tcs_private;
+               AfterTriggersTableData *table;
                TupleTableSlot *storeslot;
 
+               switch (event)
+               {
+                       case TRIGGER_EVENT_INSERT:
+                               table = transition_capture->tcs_insert_private;
+                               break;
+                       case TRIGGER_EVENT_UPDATE:
+                               table = transition_capture->tcs_update_private;
+                               break;
+                       case TRIGGER_EVENT_DELETE:
+                               table = transition_capture->tcs_delete_private;
+                               break;
+                       default:
+                               elog(ERROR, "invalid after-trigger event code: %d", event);
+                               table = NULL;   /* keep compiler quiet */
+                               break;
+               }
+
                storeslot = GetAfterTriggersStoreSlot(table, map->outdesc);
                execute_attr_map_slot(map->attrMap, slot, storeslot);
                tuplestore_puttupleslot(tuplestore, storeslot);
@@ -6145,7 +6166,7 @@ AfterTriggerSaveEvent(EState *estate, ResultRelInfo *relinfo,
                                                                                                                         oldslot,
                                                                                                                         NULL,
                                                                                                                         transition_capture);
-                       TransitionTableAddTuple(estate, transition_capture, relinfo,
+                       TransitionTableAddTuple(estate, event, transition_capture, relinfo,
                                                                        oldslot, NULL, old_tuplestore);
                }
 
@@ -6161,7 +6182,7 @@ AfterTriggerSaveEvent(EState *estate, ResultRelInfo *relinfo,
                                                                                                                         NULL,
                                                                                                                         newslot,
                                                                                                                         transition_capture);
-                       TransitionTableAddTuple(estate, transition_capture, relinfo,
+                       TransitionTableAddTuple(estate, event, transition_capture, relinfo,
                                                                        newslot, original_insert_tuple, new_tuplestore);
                }
 
@@ -6463,7 +6484,24 @@ AfterTriggerSaveEvent(EState *estate, ResultRelInfo *relinfo,
                new_shared.ats_firing_id = 0;
                if ((trigger->tgoldtable || trigger->tgnewtable) &&
                        transition_capture != NULL)
-                       new_shared.ats_table = transition_capture->tcs_private;
+               {
+                       switch (event)
+                       {
+                               case TRIGGER_EVENT_INSERT:
+                                       new_shared.ats_table = transition_capture->tcs_insert_private;
+                                       break;
+                               case TRIGGER_EVENT_UPDATE:
+                                       new_shared.ats_table = transition_capture->tcs_update_private;
+                                       break;
+                               case TRIGGER_EVENT_DELETE:
+                                       new_shared.ats_table = transition_capture->tcs_delete_private;
+                                       break;
+                               default:
+                                       /* Must be TRUNCATE, see switch above */
+                                       new_shared.ats_table = NULL;
+                                       break;
+                       }
+               }
                else
                        new_shared.ats_table = NULL;
                new_shared.ats_modifiedcols = modifiedCols;

diff --git a/src/include/commands/trigger.h b/src/include/commands/trigger.h
index 430e3ca7ddf35ff59db76e5e5e0bc9bf28db5d9a..d45fa49ac358c476b7e3fa1c87b370b841ccb2a8 100644 (file)
--- a/src/include/commands/trigger.h
+++ b/src/include/commands/trigger.h
@@ -78,7 +78,9 @@ typedef struct TransitionCaptureState
        /*
         * Private data including the tuplestore(s) into which to insert tuples.
         */
-       struct AfterTriggersTableData *tcs_private;
+       struct AfterTriggersTableData *tcs_insert_private;
+       struct AfterTriggersTableData *tcs_update_private;
+       struct AfterTriggersTableData *tcs_delete_private;
 } TransitionCaptureState;
 
 /*

diff --git a/src/test/regress/expected/triggers.out b/src/test/regress/expected/triggers.out
index a6786e204a3dada4c467ba0a29614ca8ad156b75..859e2317c94b2513920814806261c21f1eaf84f7 100644 (file)
--- a/src/test/regress/expected/triggers.out
+++ b/src/test/regress/expected/triggers.out
@@ -3280,13 +3280,19 @@ NOTICE:  trigger = table1_trig, new table = (42)
 with wcte as (insert into table1 values (43))
   insert into table1 values (44);
 NOTICE:  trigger = table1_trig, new table = (43), (44)
+with wcte as (insert into table1 values (45))
+  merge into table1 using (values (46)) as v(a) on table1.a = v.a
+    when not matched then insert values (v.a);
+NOTICE:  trigger = table1_trig, new table = (45), (46)
 select * from table1;
  a  
 ----
  42
  44
  43
-(3 rows)
+ 46
+ 45
+(5 rows)
 
 select * from table2;
       a      

diff --git a/src/test/regress/sql/triggers.sql b/src/test/regress/sql/triggers.sql
index 5a0fa012f1fbc7e625418aeed211f29e7729a28a..b6a5bd3d95f6a94a5ce9da826572558b2e8e7857 100644 (file)
--- a/src/test/regress/sql/triggers.sql
+++ b/src/test/regress/sql/triggers.sql
@@ -2403,6 +2403,10 @@ with wcte as (insert into table1 values (42))
 with wcte as (insert into table1 values (43))
   insert into table1 values (44);
 
+with wcte as (insert into table1 values (45))
+  merge into table1 using (values (46)) as v(a) on table1.a = v.a
+    when not matched then insert values (v.a);
+
 select * from table1;
 select * from table2;