diff options
Diffstat (limited to 'src/backend/commands/constraint.c')
| -rw-r--r-- | src/backend/commands/constraint.c | 68 |
1 files changed, 37 insertions, 31 deletions
diff --git a/src/backend/commands/constraint.c b/src/backend/commands/constraint.c index f9ada29af84..cd04e4ea81b 100644 --- a/src/backend/commands/constraint.c +++ b/src/backend/commands/constraint.c @@ -15,6 +15,7 @@ #include "access/genam.h" #include "access/heapam.h" +#include "access/tableam.h" #include "catalog/index.h" #include "commands/trigger.h" #include "executor/executor.h" @@ -41,7 +42,7 @@ unique_key_recheck(PG_FUNCTION_ARGS) { TriggerData *trigdata = castNode(TriggerData, fcinfo->context); const char *funcname = "unique_key_recheck"; - HeapTuple new_row; + ItemPointerData checktid; ItemPointerData tmptid; Relation indexRel; IndexInfo *indexInfo; @@ -73,28 +74,30 @@ unique_key_recheck(PG_FUNCTION_ARGS) * Get the new data that was inserted/updated. */ if (TRIGGER_FIRED_BY_INSERT(trigdata->tg_event)) - new_row = trigdata->tg_trigtuple; + checktid = trigdata->tg_trigslot->tts_tid; else if (TRIGGER_FIRED_BY_UPDATE(trigdata->tg_event)) - new_row = trigdata->tg_newtuple; + checktid = trigdata->tg_newslot->tts_tid; else { ereport(ERROR, (errcode(ERRCODE_E_R_I_E_TRIGGER_PROTOCOL_VIOLATED), errmsg("function \"%s\" must be fired for INSERT or UPDATE", funcname))); - new_row = NULL; /* keep compiler quiet */ + ItemPointerSetInvalid(&checktid); /* keep compiler quiet */ } + slot = table_slot_create(trigdata->tg_relation, NULL); + /* - * If the new_row is now dead (ie, inserted and then deleted within our - * transaction), we can skip the check. However, we have to be careful, - * because this trigger gets queued only in response to index insertions; - * which means it does not get queued for HOT updates. The row we are - * called for might now be dead, but have a live HOT child, in which case - * we still need to make the check --- effectively, we're applying the - * check against the live child row, although we can use the values from - * this row since by definition all columns of interest to us are the - * same. + * If the row pointed at by checktid is now dead (ie, inserted and then + * deleted within our transaction), we can skip the check. However, we + * have to be careful, because this trigger gets queued only in response + * to index insertions; which means it does not get queued e.g. for HOT + * updates. The row we are called for might now be dead, but have a live + * HOT child, in which case we still need to make the check --- + * effectively, we're applying the check against the live child row, + * although we can use the values from this row since by definition all + * columns of interest to us are the same. * * This might look like just an optimization, because the index AM will * make this identical test before throwing an error. But it's actually @@ -103,13 +106,23 @@ unique_key_recheck(PG_FUNCTION_ARGS) * it's possible the index entry has also been marked dead, and even * removed. */ - tmptid = new_row->t_self; - if (!heap_hot_search(&tmptid, trigdata->tg_relation, SnapshotSelf, NULL)) + tmptid = checktid; { - /* - * All rows in the HOT chain are dead, so skip the check. - */ - return PointerGetDatum(NULL); + IndexFetchTableData *scan = table_index_fetch_begin(trigdata->tg_relation); + bool call_again = false; + + if (!table_index_fetch_tuple(scan, &tmptid, SnapshotSelf, slot, + &call_again, NULL)) + { + /* + * All rows referenced by the index entry are dead, so skip the + * check. + */ + ExecDropSingleTupleTableSlot(slot); + table_index_fetch_end(scan); + return PointerGetDatum(NULL); + } + table_index_fetch_end(scan); } /* @@ -122,14 +135,6 @@ unique_key_recheck(PG_FUNCTION_ARGS) indexInfo = BuildIndexInfo(indexRel); /* - * The heap tuple must be put into a slot for FormIndexDatum. - */ - slot = MakeSingleTupleTableSlot(RelationGetDescr(trigdata->tg_relation), - &TTSOpsHeapTuple); - - ExecStoreHeapTuple(new_row, slot, false); - - /* * Typically the index won't have expressions, but if it does we need an * EState to evaluate them. We need it for exclusion constraints too, * even if they are just on simple columns. @@ -163,11 +168,12 @@ unique_key_recheck(PG_FUNCTION_ARGS) { /* * Note: this is not a real insert; it is a check that the index entry - * that has already been inserted is unique. Passing t_self is - * correct even if t_self is now dead, because that is the TID the - * index will know about. + * that has already been inserted is unique. Passing the tuple's tid + * (i.e. unmodified by table_index_fetch_tuple()) is correct even if + * the row is now dead, because that is the TID the index will know + * about. */ - index_insert(indexRel, values, isnull, &(new_row->t_self), + index_insert(indexRel, values, isnull, &checktid, trigdata->tg_relation, UNIQUE_CHECK_EXISTING, indexInfo); } |