execmain.c

关系型数据库 Postgresql 6.5.2

					slot = ExecStoreTuple(tuple, slot, InvalidBuffer, true);
					goto lreplace;
				}
			}
			return;

		default:
			elog(ERROR, "Unknown status %u from heap_replace", result);
			return;
	}

	IncrReplaced();
	(estate->es_processed)++;

	/*
	 * Note: instead of having to update the old index tuples associated
	 * with the heap tuple, all we do is form and insert new index
	 * tuples..  This is because replaces are actually deletes and inserts
	 * and index tuple deletion is done automagically by the vaccuum
	 * deamon.. All we do is insert new index tuples.  -cim 9/27/89
	 */

	/*
	 * process indices
	 *
	 * heap_replace updates a tuple in the base relation by invalidating it
	 * and then appending a new tuple to the relation.	As a side effect,
	 * the tupleid of the new tuple is placed in the new tuple's t_ctid
	 * field.  So we now insert index tuples using the new tupleid stored
	 * there.
	 */

	numIndices = resultRelationInfo->ri_NumIndices;
	if (numIndices > 0)
		ExecInsertIndexTuples(slot, &(tuple->t_self), estate, true);

	/* AFTER ROW UPDATE Triggers */
	if (resultRelationDesc->trigdesc &&
	 resultRelationDesc->trigdesc->n_after_row[TRIGGER_EVENT_UPDATE] > 0)
		ExecARUpdateTriggers(estate, tupleid, tuple);
}

#ifdef NOT_USED
static HeapTuple
ExecAttrDefault(Relation rel, HeapTuple tuple)
{
	int			ndef = rel->rd_att->constr->num_defval;
	AttrDefault *attrdef = rel->rd_att->constr->defval;
	ExprContext *econtext = makeNode(ExprContext);
	HeapTuple	newtuple;
	Node	   *expr;
	bool		isnull;
	bool		isdone;
	Datum		val;
	Datum	   *replValue = NULL;
	char	   *replNull = NULL;
	char	   *repl = NULL;
	int			i;

	econtext->ecxt_scantuple = NULL;	/* scan tuple slot */
	econtext->ecxt_innertuple = NULL;	/* inner tuple slot */
	econtext->ecxt_outertuple = NULL;	/* outer tuple slot */
	econtext->ecxt_relation = NULL;		/* relation */
	econtext->ecxt_relid = 0;	/* relid */
	econtext->ecxt_param_list_info = NULL;		/* param list info */
	econtext->ecxt_param_exec_vals = NULL;		/* exec param values */
	econtext->ecxt_range_table = NULL;	/* range table */
	for (i = 0; i < ndef; i++)
	{
		if (!heap_attisnull(tuple, attrdef[i].adnum))
			continue;
		expr = (Node *) stringToNode(attrdef[i].adbin);

		val = ExecEvalExpr(expr, econtext, &isnull, &isdone);

		pfree(expr);

		if (isnull)
			continue;

		if (repl == NULL)
		{
			repl = (char *) palloc(rel->rd_att->natts * sizeof(char));
			replNull = (char *) palloc(rel->rd_att->natts * sizeof(char));
			replValue = (Datum *) palloc(rel->rd_att->natts * sizeof(Datum));
			MemSet(repl, ' ', rel->rd_att->natts * sizeof(char));
		}

		repl[attrdef[i].adnum - 1] = 'r';
		replNull[attrdef[i].adnum - 1] = ' ';
		replValue[attrdef[i].adnum - 1] = val;

	}

	pfree(econtext);

	if (repl == NULL)
		return tuple;

	newtuple = heap_modifytuple(tuple, rel, replValue, replNull, repl);

	pfree(repl);
	pfree(tuple);
	pfree(replNull);
	pfree(replValue);

	return newtuple;

}

#endif

static char *
ExecRelCheck(Relation rel, HeapTuple tuple, EState *estate)
{
	int			ncheck = rel->rd_att->constr->num_check;
	ConstrCheck *check = rel->rd_att->constr->check;
	ExprContext *econtext = makeNode(ExprContext);
	TupleTableSlot *slot = makeNode(TupleTableSlot);
	RangeTblEntry *rte = makeNode(RangeTblEntry);
	List	   *rtlist;
	List	   *qual;
	bool		res;
	int			i;

	slot->val = tuple;
	slot->ttc_shouldFree = false;
	slot->ttc_descIsNew = true;
	slot->ttc_tupleDescriptor = rel->rd_att;
	slot->ttc_buffer = InvalidBuffer;
	slot->ttc_whichplan = -1;
	rte->relname = nameout(&(rel->rd_rel->relname));
	rte->refname = rte->relname;
	rte->relid = RelationGetRelid(rel);
	rte->inh = false;
	rte->inFromCl = true;
	rtlist = lcons(rte, NIL);
	econtext->ecxt_scantuple = slot;	/* scan tuple slot */
	econtext->ecxt_innertuple = NULL;	/* inner tuple slot */
	econtext->ecxt_outertuple = NULL;	/* outer tuple slot */
	econtext->ecxt_relation = rel;		/* relation */
	econtext->ecxt_relid = 0;	/* relid */
	econtext->ecxt_param_list_info = NULL;		/* param list info */
	econtext->ecxt_param_exec_vals = NULL;		/* exec param values */
	econtext->ecxt_range_table = rtlist;		/* range table */

	if (estate->es_result_relation_constraints == NULL)
	{
		estate->es_result_relation_constraints =
			(List **) palloc(ncheck * sizeof(List *));

		for (i = 0; i < ncheck; i++)
		{
			qual = (List *) stringToNode(check[i].ccbin);
			estate->es_result_relation_constraints[i] = qual;
		}
	}

	for (i = 0; i < ncheck; i++)
	{
		qual = estate->es_result_relation_constraints[i];

		res = ExecQual(qual, econtext);

		if (!res)
			return check[i].ccname;
	}

	pfree(slot);
	pfree(rte->relname);
	pfree(rte);
	pfree(rtlist);
	pfree(econtext);

	return (char *) NULL;

}

void
ExecConstraints(char *caller, Relation rel, HeapTuple tuple, EState *estate)
{

	Assert(rel->rd_att->constr);

	if (rel->rd_att->constr->has_not_null)
	{
		int			attrChk;

		for (attrChk = 1; attrChk <= rel->rd_att->natts; attrChk++)
		{
			if (rel->rd_att->attrs[attrChk - 1]->attnotnull && heap_attisnull(tuple, attrChk))
				elog(ERROR, "%s: Fail to add null value in not null attribute %s",
				  caller, rel->rd_att->attrs[attrChk - 1]->attname.data);
		}
	}

	if (rel->rd_att->constr->num_check > 0)
	{
		char	   *failed;

		if ((failed = ExecRelCheck(rel, tuple, estate)) != NULL)
			elog(ERROR, "%s: rejected due to CHECK constraint %s", caller, failed);
	}

	return;
}

TupleTableSlot *
EvalPlanQual(EState *estate, Index rti, ItemPointer tid)
{
	evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
	evalPlanQual *oldepq;
	EState	   *epqstate = NULL;
	Relation	relation;
	Buffer		buffer;
	HeapTupleData tuple;
	bool		endNode = true;

	Assert(rti != 0);

	if (epq != NULL && epq->rti == 0)
	{
		Assert(!(estate->es_useEvalPlan) &&
			   epq->estate.es_evalPlanQual == NULL);
		epq->rti = rti;
		endNode = false;
	}

	/*
	 * If this is request for another RTE - Ra, - then we have to check
	 * wasn't PlanQual requested for Ra already and if so then Ra' row was
	 * updated again and we have to re-start old execution for Ra and
	 * forget all what we done after Ra was suspended. Cool? -:))
	 */
	if (epq != NULL && epq->rti != rti &&
		epq->estate.es_evTuple[rti - 1] != NULL)
	{
		do
		{
			/* pop previous PlanQual from the stack */
			epqstate = &(epq->estate);
			oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
			Assert(oldepq->rti != 0);
			/* stop execution */
			ExecEndNode(epq->plan, epq->plan);
		    epqstate->es_tupleTable->next = 0;
			pfree(epqstate->es_evTuple[epq->rti - 1]);
			epqstate->es_evTuple[epq->rti - 1] = NULL;
			/* push current PQ to freePQ stack */
			oldepq->free = epq;
			epq = oldepq;
		} while (epq->rti != rti);
		estate->es_evalPlanQual = (Pointer) epq;
	}

	/*
	 * If we are requested for another RTE then we have to suspend
	 * execution of current PlanQual and start execution for new one.
	 */
	if (epq == NULL || epq->rti != rti)
	{
		/* try to reuse plan used previously */
		evalPlanQual *newepq = (epq != NULL) ? epq->free : NULL;

		if (newepq == NULL)		/* first call or freePQ stack is empty */
		{
			newepq = (evalPlanQual *) palloc(sizeof(evalPlanQual));
			/* Init EState */
			epqstate = &(newepq->estate);
			memset(epqstate, 0, sizeof(EState));
			epqstate->type = T_EState;
			epqstate->es_direction = ForwardScanDirection;
			epqstate->es_snapshot = estate->es_snapshot;
			epqstate->es_range_table = estate->es_range_table;
			epqstate->es_param_list_info = estate->es_param_list_info;
			if (estate->es_origPlan->nParamExec > 0)
				epqstate->es_param_exec_vals = (ParamExecData *)
					palloc(estate->es_origPlan->nParamExec *
						   sizeof(ParamExecData));
			epqstate->es_tupleTable =
				ExecCreateTupleTable(estate->es_tupleTable->size);
			epqstate->es_refcount = estate->es_refcount;
			/* ... rest */
			newepq->plan = copyObject(estate->es_origPlan);
			newepq->free = NULL;
			epqstate->es_evTupleNull = (bool *)
				palloc(length(estate->es_range_table) * sizeof(bool));
			if (epq == NULL)	/* first call */
			{
				epqstate->es_evTuple = (HeapTuple *)
					palloc(length(estate->es_range_table) * sizeof(HeapTuple));
				memset(epqstate->es_evTuple, 0,
					 length(estate->es_range_table) * sizeof(HeapTuple));
			}
			else
				epqstate->es_evTuple = epq->estate.es_evTuple;
		}
		else
			epqstate = &(newepq->estate);
		/* push current PQ to the stack */
		epqstate->es_evalPlanQual = (Pointer) epq;
		epq = newepq;
		estate->es_evalPlanQual = (Pointer) epq;
		epq->rti = rti;
		endNode = false;
	}

	epqstate = &(epq->estate);

	/*
	 * Ok - we're requested for the same RTE (-:)). I'm not sure about
	 * ability to use ExecReScan instead of ExecInitNode, so...
	 */
	if (endNode)
	{
		ExecEndNode(epq->plan, epq->plan);
	    epqstate->es_tupleTable->next = 0;
	}

	/* free old RTE' tuple */
	if (epqstate->es_evTuple[epq->rti - 1] != NULL)
	{
		pfree(epqstate->es_evTuple[epq->rti - 1]);
		epqstate->es_evTuple[epq->rti - 1] = NULL;
	}

	/* ** fetch tid tuple ** */
	if (estate->es_result_relation_info != NULL &&
		estate->es_result_relation_info->ri_RangeTableIndex == rti)
		relation = estate->es_result_relation_info->ri_RelationDesc;
	else
	{
		List	   *l;

		foreach(l, estate->es_rowMark)
		{
			if (((execRowMark *) lfirst(l))->rti == rti)
				break;
		}
		relation = ((execRowMark *) lfirst(l))->relation;
	}
	tuple.t_self = *tid;
	for (;;)
	{
		heap_fetch(relation, SnapshotDirty, &tuple, &buffer);
		if (tuple.t_data != NULL)
		{
			TransactionId xwait = SnapshotDirty->xmax;

			if (TransactionIdIsValid(SnapshotDirty->xmin))
			{
				elog(NOTICE, "EvalPlanQual: t_xmin is uncommitted ?!");
				Assert(!TransactionIdIsValid(SnapshotDirty->xmin));
				elog(ERROR, "Aborting this transaction");
			}

			/*
			 * If tuple is being updated by other transaction then we have
			 * to wait for its commit/abort.
			 */
			if (TransactionIdIsValid(xwait))
			{
				ReleaseBuffer(buffer);
				XactLockTableWait(xwait);
				continue;
			}

			/*
			 * Nice! We got tuple - now copy it.
			 */
			if (epqstate->es_evTuple[epq->rti - 1] != NULL)
				pfree(epqstate->es_evTuple[epq->rti - 1]);
			epqstate->es_evTuple[epq->rti - 1] = heap_copytuple(&tuple);
			ReleaseBuffer(buffer);
			break;
		}

		/*
		 * Ops! Invalid tuple. Have to check is it updated or deleted.
		 * Note that it's possible to get invalid SnapshotDirty->tid if
		 * tuple updated by this transaction. Have we to check this ?
		 */
		if (ItemPointerIsValid(&(SnapshotDirty->tid)) &&
			!(ItemPointerEquals(&(tuple.t_self), &(SnapshotDirty->tid))))
		{
			tuple.t_self = SnapshotDirty->tid;	/* updated ... */
			continue;
		}

		/*
		 * Deleted or updated by this transaction. Do not (re-)start
		 * execution of this PQ. Continue previous PQ.
		 */
		oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
		if (oldepq != NULL)
		{
			Assert(oldepq->rti != 0);
			/* push current PQ to freePQ stack */
			oldepq->free = epq;
			epq = oldepq;
			epqstate = &(epq->estate);
			estate->es_evalPlanQual = (Pointer) epq;
		}
		else
		{									
			epq->rti = 0;					/* this is the first (oldest) */
			estate->es_useEvalPlan = false;	/* PQ - mark as free and      */
			return (NULL);					/* continue Query execution   */
		}
	}

	if (estate->es_origPlan->nParamExec > 0)
		memset(epqstate->es_param_exec_vals, 0,
			   estate->es_origPlan->nParamExec * sizeof(ParamExecData));
	memset(epqstate->es_evTupleNull, false,
		   length(estate->es_range_table) * sizeof(bool));
    Assert(epqstate->es_tupleTable->next == 0);
	ExecInitNode(epq->plan, epqstate, NULL);

	/*
	 * For UPDATE/DELETE we have to return tid of actual row we're
	 * executing PQ for.
	 */
	*tid = tuple.t_self;

	return (EvalPlanQualNext(estate));
}

static TupleTableSlot *
EvalPlanQualNext(EState *estate)
{
	evalPlanQual *epq = (evalPlanQual *) estate->es_evalPlanQual;
	EState	   *epqstate = &(epq->estate);
	evalPlanQual *oldepq;
	TupleTableSlot *slot;

	Assert(epq->rti != 0);

lpqnext:;
	slot = ExecProcNode(epq->plan, epq->plan);

	/*
	 * No more tuples for this PQ. Continue previous one.
	 */
	if (TupIsNull(slot))
	{
		ExecEndNode(epq->plan, epq->plan);
	    epqstate->es_tupleTable->next = 0;
		pfree(epqstate->es_evTuple[epq->rti - 1]);
		epqstate->es_evTuple[epq->rti - 1] = NULL;
		/* pop old PQ from the stack */
		oldepq = (evalPlanQual *) epqstate->es_evalPlanQual;
		if (oldepq == (evalPlanQual *) NULL)
		{
			epq->rti = 0;					/* this is the first (oldest) */
			estate->es_useEvalPlan = false;	/* PQ - mark as free and	  */
			return (NULL);					/* continue Query execution   */
		}
		Assert(oldepq->rti != 0);
		/* push current PQ to freePQ stack */
		oldepq->free = epq;
		epq = oldepq;
		epqstate = &(epq->estate);
		estate->es_evalPlanQual = (Pointer) epq;
		goto lpqnext;
	}

	return (slot);
}