ri_triggers.c

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							 RI_KEYPAIR_PK_IDX))
			{
				heap_close(fk_rel, RowExclusiveLock);
				return PointerGetDatum(NULL);
			}

			if (SPI_connect() != SPI_OK_CONNECT)
				elog(ERROR, "SPI_connect failed");

			/*
			 * "MATCH <unspecified>" only changes columns corresponding to the
			 * referenced columns that have changed in pk_rel.	This means the
			 * "SET attrn=NULL [, attrn=NULL]" string will be change as well.
			 * In this case, we need to build a temporary plan rather than use
			 * our cached plan, unless the update happens to change all
			 * columns in the key.	Fortunately, for the most common case of a
			 * single-column foreign key, this will be true.
			 *
			 * In case you're wondering, the inequality check works because we
			 * know that the old key value has no NULLs (see above).
			 */

			use_cached_query = match_type == RI_MATCH_TYPE_FULL ||
				ri_AllKeysUnequal(pk_rel, old_row, new_row,
								  &qkey, RI_KEYPAIR_PK_IDX);

			/*
			 * Fetch or prepare a saved plan for the set null update operation
			 * if possible, or build a temporary plan if not.
			 */
			if (!use_cached_query ||
				(qplan = ri_FetchPreparedPlan(&qkey)) == NULL)
			{
				char		querystr[MAX_QUOTED_REL_NAME_LEN + 100 +
							(MAX_QUOTED_NAME_LEN + 32) * RI_MAX_NUMKEYS * 2];
				char		qualstr[(MAX_QUOTED_NAME_LEN + 32) * RI_MAX_NUMKEYS];
				char		fkrelname[MAX_QUOTED_REL_NAME_LEN];
				char		attname[MAX_QUOTED_NAME_LEN];
				const char *querysep;
				const char *qualsep;
				Oid			queryoids[RI_MAX_NUMKEYS];

				/* ----------
				 * The query string built is
				 *	UPDATE ONLY <fktable> SET fkatt1 = NULL [, ...]
				 *			WHERE fkatt1 = $1 [AND ...]
				 * The type id's for the $ parameters are those of the
				 * corresponding PK attributes. Thus, ri_PlanCheck could
				 * eventually fail if the parser cannot identify some way
				 * how to compare these two types by '='.
				 * ----------
				 */
				quoteRelationName(fkrelname, fk_rel);
				snprintf(querystr, sizeof(querystr), "UPDATE ONLY %s SET", fkrelname);
				qualstr[0] = '\0';
				querysep = "";
				qualsep = "WHERE";
				for (i = 0; i < qkey.nkeypairs; i++)
				{
					quoteOneName(attname,
								 tgargs[RI_FIRST_ATTNAME_ARGNO + i * 2 + RI_KEYPAIR_FK_IDX]);

					/*
					 * MATCH <unspecified> - only change columns corresponding
					 * to changed columns in pk_rel's key
					 */
					if (match_type == RI_MATCH_TYPE_FULL ||
						!ri_OneKeyEqual(pk_rel, i, old_row, new_row, &qkey,
										RI_KEYPAIR_PK_IDX))
					{
						snprintf(querystr + strlen(querystr), sizeof(querystr) - strlen(querystr), "%s %s = NULL",
								 querysep, attname);
						querysep = ",";
					}
					snprintf(qualstr + strlen(qualstr), sizeof(qualstr) - strlen(qualstr), " %s %s = $%d",
							 qualsep, attname, i + 1);
					qualsep = "AND";
					queryoids[i] = SPI_gettypeid(pk_rel->rd_att,
										 qkey.keypair[i][RI_KEYPAIR_PK_IDX]);
				}
				strcat(querystr, qualstr);

				/*
				 * Prepare the plan.  Save it only if we're building the
				 * "standard" plan.
				 */
				qplan = ri_PlanCheck(querystr, qkey.nkeypairs, queryoids,
									 &qkey, fk_rel, pk_rel,
									 use_cached_query);
			}

			/*
			 * We have a plan now. Run it to update the existing references.
			 */
			ri_PerformCheck(&qkey, qplan,
							fk_rel, pk_rel,
							old_row, NULL,
							true,		/* must detect new rows */
							SPI_OK_UPDATE,
							tgargs[RI_CONSTRAINT_NAME_ARGNO]);

			if (SPI_finish() != SPI_OK_FINISH)
				elog(ERROR, "SPI_finish failed");

			heap_close(fk_rel, RowExclusiveLock);

			return PointerGetDatum(NULL);

			/*
			 * Handle MATCH PARTIAL set null update.
			 */
		case RI_MATCH_TYPE_PARTIAL:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("MATCH PARTIAL not yet implemented")));
			return PointerGetDatum(NULL);
	}

	/*
	 * Never reached
	 */
	elog(ERROR, "invalid match_type");
	return PointerGetDatum(NULL);
}


/* ----------
 * RI_FKey_setdefault_del -
 *
 *	Set foreign key references to defaults at delete event on PK table.
 * ----------
 */
Datum
RI_FKey_setdefault_del(PG_FUNCTION_ARGS)
{
	TriggerData *trigdata = (TriggerData *) fcinfo->context;
	int			tgnargs;
	char	  **tgargs;
	Relation	fk_rel;
	Relation	pk_rel;
	HeapTuple	old_row;
	RI_QueryKey qkey;
	void	   *qplan;

	/*
	 * Check that this is a valid trigger call on the right time and event.
	 */
	ri_CheckTrigger(fcinfo, "RI_FKey_setdefault_del", RI_TRIGTYPE_DELETE);

	tgnargs = trigdata->tg_trigger->tgnargs;
	tgargs = trigdata->tg_trigger->tgargs;

	/*
	 * Nothing to do if no column names to compare given
	 */
	if (tgnargs == 4)
		return PointerGetDatum(NULL);

	/*
	 * Get the relation descriptors of the FK and PK tables and the old tuple.
	 *
	 * fk_rel is opened in RowExclusiveLock mode since that's what our
	 * eventual UPDATE will get on it.
	 */
	fk_rel = heap_open(trigdata->tg_trigger->tgconstrrelid, RowExclusiveLock);
	pk_rel = trigdata->tg_relation;
	old_row = trigdata->tg_trigtuple;

	switch (ri_DetermineMatchType(tgargs[RI_MATCH_TYPE_ARGNO]))
	{
			/* ----------
			 * SQL3 11.9 <referential constraint definition>
			 *	Gereral rules 6) a) iii):
			 *		MATCH <UNSPECIFIED> or MATCH FULL
			 *			... ON DELETE SET DEFAULT
			 * ----------
			 */
		case RI_MATCH_TYPE_UNSPECIFIED:
		case RI_MATCH_TYPE_FULL:
			ri_BuildQueryKeyFull(&qkey, trigdata->tg_trigger->tgoid,
								 RI_PLAN_SETNULL_DEL_DOUPDATE,
								 fk_rel, pk_rel,
								 tgnargs, tgargs);

			switch (ri_NullCheck(pk_rel, old_row, &qkey, RI_KEYPAIR_PK_IDX))
			{
				case RI_KEYS_ALL_NULL:
				case RI_KEYS_SOME_NULL:

					/*
					 * No update - MATCH FULL means there cannot be any
					 * reference to old key if it contains NULL
					 */
					heap_close(fk_rel, RowExclusiveLock);
					return PointerGetDatum(NULL);

				case RI_KEYS_NONE_NULL:

					/*
					 * Have a full qualified key - continue below
					 */
					break;
			}

			if (SPI_connect() != SPI_OK_CONNECT)
				elog(ERROR, "SPI_connect failed");

			/*
			 * Prepare a plan for the set default delete operation.
			 * Unfortunately we need to do it on every invocation because the
			 * default value could potentially change between calls.
			 */
			{
				char		querystr[MAX_QUOTED_REL_NAME_LEN + 100 +
							(MAX_QUOTED_NAME_LEN + 32) * RI_MAX_NUMKEYS * 2];
				char		qualstr[(MAX_QUOTED_NAME_LEN + 32) * RI_MAX_NUMKEYS];
				char		fkrelname[MAX_QUOTED_REL_NAME_LEN];
				char		attname[MAX_QUOTED_NAME_LEN];
				const char *querysep;
				const char *qualsep;
				Oid			queryoids[RI_MAX_NUMKEYS];
				int			i;

				/* ----------
				 * The query string built is
				 *	UPDATE ONLY <fktable> SET fkatt1 = DEFAULT [, ...]
				 *			WHERE fkatt1 = $1 [AND ...]
				 * The type id's for the $ parameters are those of the
				 * corresponding PK attributes. Thus, ri_PlanCheck could
				 * eventually fail if the parser cannot identify some way
				 * how to compare these two types by '='.
				 * ----------
				 */
				quoteRelationName(fkrelname, fk_rel);
				snprintf(querystr, sizeof(querystr), "UPDATE ONLY %s SET", fkrelname);
				qualstr[0] = '\0';
				querysep = "";
				qualsep = "WHERE";
				for (i = 0; i < qkey.nkeypairs; i++)
				{
					quoteOneName(attname,
								 tgargs[RI_FIRST_ATTNAME_ARGNO + i * 2 + RI_KEYPAIR_FK_IDX]);
					snprintf(querystr + strlen(querystr), sizeof(querystr) - strlen(querystr), "%s %s = DEFAULT",
							 querysep, attname);
					snprintf(qualstr + strlen(qualstr), sizeof(qualstr) - strlen(qualstr), " %s %s = $%d",
							 qualsep, attname, i + 1);
					querysep = ",";
					qualsep = "AND";
					queryoids[i] = SPI_gettypeid(pk_rel->rd_att,
										 qkey.keypair[i][RI_KEYPAIR_PK_IDX]);
				}
				strcat(querystr, qualstr);

				/* Prepare the plan, don't save it */
				qplan = ri_PlanCheck(querystr, qkey.nkeypairs, queryoids,
									 &qkey, fk_rel, pk_rel, false);
			}

			/*
			 * We have a plan now. Run it to update the existing references.
			 */
			ri_PerformCheck(&qkey, qplan,
							fk_rel, pk_rel,
							old_row, NULL,
							true,		/* must detect new rows */
							SPI_OK_UPDATE,
							tgargs[RI_CONSTRAINT_NAME_ARGNO]);

			if (SPI_finish() != SPI_OK_FINISH)
				elog(ERROR, "SPI_finish failed");

			heap_close(fk_rel, RowExclusiveLock);

			/*
			 * In the case we delete the row who's key is equal to the default
			 * values AND a referencing row in the foreign key table exists,
			 * we would just have updated it to the same values. We need to do
			 * another lookup now and in case a reference exists, abort the
			 * operation. That is already implemented in the NO ACTION
			 * trigger.
			 */
			RI_FKey_noaction_del(fcinfo);

			return PointerGetDatum(NULL);

			/*
			 * Handle MATCH PARTIAL set null delete.
			 */
		case RI_MATCH_TYPE_PARTIAL:
			ereport(ERROR,
					(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
					 errmsg("MATCH PARTIAL not yet implemented")));
			return PointerGetDatum(NULL);
	}

	/*
	 * Never reached
	 */
	elog(ERROR, "invalid match_type");
	return PointerGetDatum(NULL);
}


/* ----------
 * RI_FKey_setdefault_upd -
 *
 *	Set foreign key references to defaults at update event on PK table.
 * ----------
 */
Datum
RI_FKey_setdefault_upd(PG_FUNCTION_ARGS)
{
	TriggerData *trigdata = (TriggerData *) fcinfo->context;
	int			tgnargs;
	char	  **tgargs;
	Relation	fk_rel;
	Relation	pk_rel;
	HeapTuple	new_row;
	HeapTuple	old_row;
	RI_QueryKey qkey;
	void	   *qplan;
	int			match_type;

	/*
	 * Check that this is a valid trigger call on the right time and event.
	 */
	ri_CheckTrigger(fcinfo, "RI_FKey_setdefault_upd", RI_TRIGTYPE_UPDATE);

	tgnargs = trigdata->tg_trigger->tgnargs;
	tgargs = trigdata->tg_trigger->tgargs;

	/*
	 * Nothing to do if no column names to compare given
	 */
	if (tgnargs == 4)
		return PointerGetDatum(NULL);

	/*
	 * Get the relation descriptors of the FK and PK tables and the old tuple.
	 *
	 * fk_rel is opened in RowExclusiveLock mode since that's what our
	 * eventual UPDATE will get on it.
	 */
	fk_rel = heap_open(trigdata->tg_trigger->tgconstrrelid, RowExclusiveLock);
	pk_rel = trigdata->tg_relation;
	new_row = trigdata->tg_newtuple;
	old_row = trigdata->tg_trigtuple;

	match_type = ri_DetermineMatchType(tgargs[RI_MATCH_TYPE_ARGNO]);

	switch (match_type)
	{
			/* ----------
			 * SQL3 11.9 <referential constraint definition>
			 *	Gereral rules 7) a) iii):
			 *		MATCH <UNSPECIFIED> or MATCH FULL
			 *			... ON UPDATE SET DEFAULT
			 * ----------
			 */
		case RI_MATCH_TYPE_UNSPECIFIED:
		case RI_MATCH_TYPE_FULL:
			ri_BuildQueryKeyFull(&qkey, trigdata->tg_trigger->tgoid,
								 RI_PLAN_SETNULL_DEL_DOUPDATE,
								 fk_rel, pk_rel,
								 tgnargs, tgargs);

			switch (ri_NullCheck(pk_rel, old_row, &qkey, RI_KEYPAIR_PK_IDX))
			{
				case RI_KEYS_ALL_NULL:
				case RI_KEYS_SOME_NULL:

					/*
					 * No update - MATCH FULL means there cannot be any
					 * reference to old key if it contains NULL
					 */
					heap_close(fk_rel, RowExclusiveLock);
					return PointerGetDatum(NULL);

				case RI_KEYS_NONE_NULL:

					/*
					 * Have a full qualified key - continue below
					 */
					break;
			}

			/*
			 * No need to do anything if old and new keys are equal
			 */
			if (ri_KeysEqual(pk_rel, old_row, new_row, &qkey,
							 RI_KEYPAIR_PK_IDX))
			{
				heap_close(fk_rel, RowExclusiveLock);
				return PointerGetDatum(NULL);
			}

			if (SPI_connect() != SPI_OK_CONNECT)
				elog(ERROR, "SPI_connect failed");

			/*
			 * Prepare a plan for the set default delete operation.
			 * Unfortunately we need to do it on every invocation because the
			 * default value could potentially change between calls.
			 */
			{
				char		querystr[MAX_QUOTED_REL_NAME_LEN + 100 +
							(MAX_QUOTED_NAME_LEN + 32) * RI_MAX_NUMKEYS * 2];
				char		qualstr[(MAX_QUOTED_NAME_LEN + 32) * RI_MAX_NUMKEYS];
				char		fkrelname[MAX_QUOTED_REL_NAME_LEN];
				char		attname[MAX_QUOTED_NAME_LEN];
				const char *querysep;
				const char *qualsep;
				Oid			queryoids[RI_MAX_NUMKEYS];
				int			i;

				/* ----------
				 * The query string built is
				 *	UPDATE ONLY <fktable> SET fkatt1 = DEFAULT [, ...]
				 *			WHERE fkatt1 = $1 [AND ...]
				 * The type id's for the $ parameters are those of the
				 * corresponding PK attributes. Thus, ri_PlanCheck could
				 * eventually fail if the parser cannot identify some way
				 * how to compare these two types by '='.
				 * ----------
				 */
				quoteRelationName(fkrelname, fk_rel);
				snprintf(querystr, sizeof(querystr), "UPDATE ONLY %s SET", fkrelname);
				qualstr[0] = '\0';
				querysep = "";
				qualsep = "WHERE";
				for (i = 0; i < qkey.nkeypairs; i++)
				{
					quoteOneName(attname,
								 tgargs[RI_FIRST_ATTNAME_ARGNO + i * 2 + RI_KEYPAIR_FK_IDX]);

					/*
					 * MATCH <unspecified> - only change columns corresponding
					 * to changed columns in pk_rel's key
					 */
					if (match_type == RI_MATCH_TYPE_FULL ||
						!ri_OneKeyEqual(pk_rel, i, old_row,
										new_row, &qkey, RI_KEYPAIR_PK_IDX))
					{
						snprintf(querystr + strlen(querystr), sizeof(querystr) - strlen(querystr), "%s %s = DEFAULT",
								 querysep, attname);
						querysep = ",";
					}
					snprintf(qualstr + strlen(qualstr), sizeof(qualstr) - strlen(qualstr), " %s %s = $%d",
							 qualsep, attname, i + 1);
					qualsep = "AND";
					queryoids[i] = SPI_gettypeid(pk_rel->rd_att,
										 qkey.keypair[i][RI_KEYPAIR_PK_IDX]);
				}
				strcat(querystr, qualstr);

				/* Prepare the plan, don't save it */
				qplan = ri_PlanCheck(querystr, qkey.nkeypairs, queryoids,
									 &qkey, fk_rel, pk_rel, false);
			}

			/*
			 * We have a plan now. Run it to update the existing references.
			 */
			ri_PerformCheck(&qkey, qplan,
							fk_rel, pk_rel,
							old_row, NULL,
							true,		/* must detect new rows */
							SPI_OK_UPDATE,
							tgargs[RI_CONSTRAINT_NAME_ARGNO]);

			if (SPI_finish() != SPI_OK_FINISH)