diff options
Diffstat (limited to 'src/backend/executor/execMain.c')
| -rw-r--r-- | src/backend/executor/execMain.c | 47 |
1 files changed, 16 insertions, 31 deletions
diff --git a/src/backend/executor/execMain.c b/src/backend/executor/execMain.c index b009e73e105..ea9dce019b1 100644 --- a/src/backend/executor/execMain.c +++ b/src/backend/executor/execMain.c @@ -26,7 +26,7 @@ * * * IDENTIFICATION - * $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.237 2004/09/11 18:28:34 tgl Exp $ + * $PostgreSQL: pgsql/src/backend/executor/execMain.c,v 1.238 2004/09/13 20:06:46 tgl Exp $ * *------------------------------------------------------------------------- */ @@ -106,15 +106,6 @@ static void EvalPlanQualStop(evalPlanQual *epq); * field of the QueryDesc is filled in to describe the tuples that will be * returned, and the internal fields (estate and planstate) are set up. * - * If useCurrentSnapshot is true, run the query with the latest available - * snapshot, instead of the normal QuerySnapshot. Also, if it's an update - * or delete query, check that the rows to be updated or deleted would be - * visible to the normal QuerySnapshot. (This is a special-case behavior - * needed for referential integrity updates in serializable transactions. - * We must check all currently-committed rows, but we want to throw a - * can't-serialize error if any rows that would need updates would not be - * visible under the normal serializable snapshot.) - * * If explainOnly is true, we are not actually intending to run the plan, * only to set up for EXPLAIN; so skip unwanted side-effects. * @@ -123,7 +114,7 @@ static void EvalPlanQualStop(evalPlanQual *epq); * ---------------------------------------------------------------- */ void -ExecutorStart(QueryDesc *queryDesc, bool useCurrentSnapshot, bool explainOnly) +ExecutorStart(QueryDesc *queryDesc, bool explainOnly) { EState *estate; MemoryContext oldcontext; @@ -156,28 +147,12 @@ ExecutorStart(QueryDesc *queryDesc, bool useCurrentSnapshot, bool explainOnly) estate->es_param_exec_vals = (ParamExecData *) palloc0(queryDesc->plantree->nParamExec * sizeof(ParamExecData)); - estate->es_instrument = queryDesc->doInstrument; - /* - * Make our own private copy of the current query snapshot data. - * - * This "freezes" our idea of which tuples are good and which are not for - * the life of this query, even if it outlives the current command and - * current snapshot. + * Copy other important information into the EState */ - if (useCurrentSnapshot) - { - /* RI update/delete query --- must use an up-to-date snapshot */ - estate->es_snapshot = CopyCurrentSnapshot(); - /* crosscheck updates/deletes against transaction snapshot */ - estate->es_crosscheck_snapshot = CopyQuerySnapshot(); - } - else - { - /* normal query --- use query snapshot, no crosscheck */ - estate->es_snapshot = CopyQuerySnapshot(); - estate->es_crosscheck_snapshot = InvalidSnapshot; - } + estate->es_snapshot = queryDesc->snapshot; + estate->es_crosscheck_snapshot = queryDesc->crosscheck_snapshot; + estate->es_instrument = queryDesc->doInstrument; /* * Initialize the plan state tree @@ -1454,6 +1429,11 @@ ExecDelete(TupleTableSlot *slot, /* * delete the tuple + * + * Note: if es_crosscheck_snapshot isn't InvalidSnapshot, we check that + * the row to be deleted is visible to that snapshot, and throw a can't- + * serialize error if not. This is a special-case behavior needed for + * referential integrity updates in serializable transactions. */ ldelete:; result = heap_delete(resultRelationDesc, tupleid, @@ -1591,6 +1571,11 @@ lreplace:; /* * replace the heap tuple + * + * Note: if es_crosscheck_snapshot isn't InvalidSnapshot, we check that + * the row to be updated is visible to that snapshot, and throw a can't- + * serialize error if not. This is a special-case behavior needed for + * referential integrity updates in serializable transactions. */ result = heap_update(resultRelationDesc, tupleid, tuple, &ctid, |