Beispiel #1
0
static Oid
findFunc(char *fname)
{
	FuncCandidateList clist,
				ptr;
	Oid			funcid = InvalidOid;
	List	   *names = makeList1(makeString(fname));

	ptr = clist = FuncnameGetCandidates(names, 1);
	freeList(names);

	if (!ptr)
		return funcid;

	while (ptr)
	{
		if (ptr->args[0] == TEXTOID && funcid == InvalidOid)
			funcid = ptr->oid;
		clist = ptr->next;
		pfree(ptr);
		ptr = clist;
	}

	return funcid;
}
Beispiel #2
0
/*
 * regprocout		- converts proc OID to "pro_name"
 */
Datum
regprocout(PG_FUNCTION_ARGS)
{
	RegProcedure proid = PG_GETARG_OID(0);
	char	   *result;
	HeapTuple	proctup;

	if (proid == InvalidOid)
	{
		result = pstrdup("-");
		PG_RETURN_CSTRING(result);
	}

	proctup = SearchSysCache(PROCOID,
							 ObjectIdGetDatum(proid),
							 0, 0, 0);

	if (HeapTupleIsValid(proctup))
	{
		Form_pg_proc procform = (Form_pg_proc) GETSTRUCT(proctup);
		char	   *proname = NameStr(procform->proname);

		/*
		 * In bootstrap mode, skip the fancy namespace stuff and just
		 * return the proc name.  (This path is only needed for debugging
		 * output anyway.)
		 */
		if (IsBootstrapProcessingMode())
			result = pstrdup(proname);
		else
		{
			char	   *nspname;
			FuncCandidateList clist;

			/*
			 * Would this proc be found (uniquely!) by regprocin? If not,
			 * qualify it.
			 */
			clist = FuncnameGetCandidates(makeList1(makeString(proname)), -1);
			if (clist != NULL && clist->next == NULL &&
				clist->oid == proid)
				nspname = NULL;
			else
				nspname = get_namespace_name(procform->pronamespace);

			result = quote_qualified_identifier(nspname, proname);
		}

		ReleaseSysCache(proctup);
	}
	else
	{
		/* If OID doesn't match any pg_proc entry, return it numerically */
		result = (char *) palloc(NAMEDATALEN);
		snprintf(result, NAMEDATALEN, "%u", proid);
	}

	PG_RETURN_CSTRING(result);
}
Beispiel #3
0
int main(int argc, char *argv[]) {
  pthread_t thr0, thr1, thr2, thr3;

  pthread_mutex_init(&buf_lock1, 0);

  bufs1 = makeList1(1000);

  pthread_create(&thr0, (void *)0, &thread_consumer1, (void *)0);
  pthread_create(&thr1, (void *)0, &thread_producer1, (void *)0);

  return 0;
}
Beispiel #4
0
/*
 * Pull up children of a UNION node that are identically-propertied UNIONs.
 *
 * NOTE: we can also pull a UNION ALL up into a UNION, since the distinct
 * output rows will be lost anyway.
 */
static List *
recurse_union_children(Node *setOp, Query *parse,
                       SetOperationStmt *top_union,
                       List *refnames_tlist)
{
    if (IsA(setOp, SetOperationStmt))
    {
        SetOperationStmt *op = (SetOperationStmt *) setOp;

        if (op->op == top_union->op &&
                (op->all == top_union->all || op->all) &&
                equalo(op->colTypes, top_union->colTypes))
        {
            /* Same UNION, so fold children into parent's subplan list */
            return nconc(recurse_union_children(op->larg, parse,
                                                top_union,
                                                refnames_tlist),
                         recurse_union_children(op->rarg, parse,
                                                top_union,
                                                refnames_tlist));
        }
    }

    /*
     * Not same, so plan this child separately.
     *
     * Note we disallow any resjunk columns in child results.  This is
     * necessary since the Append node that implements the union won't do
     * any projection, and upper levels will get confused if some of our
     * output tuples have junk and some don't.  This case only arises when
     * we have an EXCEPT or INTERSECT as child, else there won't be
     * resjunk anyway.
     */
    return makeList1(recurse_set_operations(setOp, parse,
                                            top_union->colTypes, false,
                                            -1, refnames_tlist));
}
Beispiel #5
0
/*
 * regoperout		- converts operator OID to "opr_name"
 */
Datum
regoperout(PG_FUNCTION_ARGS)
{
	Oid			oprid = PG_GETARG_OID(0);
	char	   *result;
	HeapTuple	opertup;

	if (oprid == InvalidOid)
	{
		result = pstrdup("0");
		PG_RETURN_CSTRING(result);
	}

	opertup = SearchSysCache(OPEROID,
							 ObjectIdGetDatum(oprid),
							 0, 0, 0);

	if (HeapTupleIsValid(opertup))
	{
		Form_pg_operator operform = (Form_pg_operator) GETSTRUCT(opertup);
		char	   *oprname = NameStr(operform->oprname);

		/*
		 * In bootstrap mode, skip the fancy namespace stuff and just
		 * return the oper name.  (This path is only needed for debugging
		 * output anyway.)
		 */
		if (IsBootstrapProcessingMode())
			result = pstrdup(oprname);
		else
		{
			FuncCandidateList clist;

			/*
			 * Would this oper be found (uniquely!) by regoperin? If not,
			 * qualify it.
			 */
			clist = OpernameGetCandidates(makeList1(makeString(oprname)),
										  '\0');
			if (clist != NULL && clist->next == NULL &&
				clist->oid == oprid)
				result = pstrdup(oprname);
			else
			{
				const char *nspname;

				nspname = get_namespace_name(operform->oprnamespace);
				nspname = quote_identifier(nspname);
				result = (char *) palloc(strlen(nspname) + strlen(oprname) + 2);
				sprintf(result, "%s.%s", nspname, oprname);
			}
		}

		ReleaseSysCache(opertup);
	}
	else
	{
		/*
		 * If OID doesn't match any pg_operator entry, return it
		 * numerically
		 */
		result = (char *) palloc(NAMEDATALEN);
		snprintf(result, NAMEDATALEN, "%u", oprid);
	}

	PG_RETURN_CSTRING(result);
}
Beispiel #6
0
Datum
_Slony_I_logTrigger(PG_FUNCTION_ARGS)
{
	TransactionId newXid = GetTopTransactionId();
	Slony_I_ClusterStatus *cs;
	TriggerData *tg;
	Datum		argv[4];
	text	   *cmdtype = NULL;
	int			rc;
	Name		cluster_name;
	int32		tab_id;
	char	   *attkind;
	int			attkind_idx;
	int			cmddata_need;

	/*
	 * Don't do any logging if the current session role isn't Origin.
	 */
	if (SessionReplicationRole != SESSION_REPLICATION_ROLE_ORIGIN)
		return PointerGetDatum(NULL);

	/*
	 * Get the trigger call context
	 */
	if (!CALLED_AS_TRIGGER(fcinfo))
		elog(ERROR, "Slony-I: logTrigger() not called as trigger");
	tg = (TriggerData *) (fcinfo->context);

	/*
	 * Check all logTrigger() calling conventions
	 */
	if (!TRIGGER_FIRED_AFTER(tg->tg_event))
		elog(ERROR, "Slony-I: logTrigger() must be fired AFTER");
	if (!TRIGGER_FIRED_FOR_ROW(tg->tg_event))
		elog(ERROR, "Slony-I: logTrigger() must be fired FOR EACH ROW");
	if (tg->tg_trigger->tgnargs != 3)
		elog(ERROR, "Slony-I: logTrigger() must be defined with 3 args");

	/*
	 * Connect to the SPI manager
	 */
	if ((rc = SPI_connect()) < 0)
		elog(ERROR, "Slony-I: SPI_connect() failed in createEvent()");

	/*
	 * Get all the trigger arguments
	 */
	cluster_name = DatumGetName(DirectFunctionCall1(namein,
								CStringGetDatum(tg->tg_trigger->tgargs[0])));
	tab_id = strtol(tg->tg_trigger->tgargs[1], NULL, 10);
	attkind = tg->tg_trigger->tgargs[2];

	/*
	 * Get or create the cluster status information and make sure it has the
	 * SPI plans that we need here.
	 */
	cs = getClusterStatus(cluster_name, PLAN_INSERT_LOG);

	/*
	 * Do the following only once per transaction.
	 */
	if (!TransactionIdEquals(cs->currentXid, newXid))
	{
		int32		log_status;
		bool isnull;

		/*
		 * Determine the currently active log table
		 */
		if (SPI_execp(cs->plan_get_logstatus, NULL, NULL, 0) < 0)
			elog(ERROR, "Slony-I: cannot determine log status");
		if (SPI_processed != 1)
			elog(ERROR, "Slony-I: cannot determine log status");

		log_status = DatumGetInt32(SPI_getbinval(SPI_tuptable->vals[0],
											SPI_tuptable->tupdesc, 1, &isnull));
		SPI_freetuptable(SPI_tuptable);

		switch (log_status)
		{
			case 0:
			case 2:
				cs->plan_active_log = cs->plan_insert_log_1;
				break;

			case 1:
			case 3:
				cs->plan_active_log = cs->plan_insert_log_2;
				break;

			default:
				elog(ERROR, "Slony-I: illegal log status %d", log_status);
				break;
		}

		cs->currentXid = newXid;
	}

	/*
	 * Determine cmdtype and cmddata depending on the command type
	 */
	if (TRIGGER_FIRED_BY_INSERT(tg->tg_event))
	{
		HeapTuple	new_row = tg->tg_trigtuple;
		TupleDesc	tupdesc = tg->tg_relation->rd_att;
		char	   *col_ident;
		char	   *col_value;

		int			len_ident;
		int			len_value;
		int			i;
		int			need_comma = false;
		char	   *OldDateStyle;
		char	   *cp = VARDATA(cs->cmddata_buf);

		/*
		 * INSERT
		 *
		 * cmdtype = 'I' cmddata = ("col" [, ...]) values ('value' [, ...])
		 */
		cmdtype = cs->cmdtype_I;

		/*
		 * Specify all the columns
		 */
		*cp++ = '(';
		for (i = 0; i < tg->tg_relation->rd_att->natts; i++)
		{
			/*
			 * Skip dropped columns
			 */
			if (tupdesc->attrs[i]->attisdropped)
				continue;

			col_ident = (char *) slon_quote_identifier(SPI_fname(tupdesc, i + 1));
			cmddata_need = (cp - (char *) (cs->cmddata_buf)) + 16 +
				(len_ident = strlen(col_ident));
			if (cs->cmddata_size < cmddata_need)
			{
				int			have = (cp - (char *) (cs->cmddata_buf));

				while (cs->cmddata_size < cmddata_need)
					cs->cmddata_size *= 2;
				cs->cmddata_buf = realloc(cs->cmddata_buf, cs->cmddata_size);
				cp = (char *) (cs->cmddata_buf) + have;
			}

			if (need_comma)
				*cp++ = ',';
			else
				need_comma = true;

			memcpy(cp, col_ident, len_ident);
			cp += len_ident;
		}

		/*
		 * Append the string ") values ("
		 */
		*cp++ = ')';
		*cp++ = ' ';
		*cp++ = 'v';
		*cp++ = 'a';
		*cp++ = 'l';
		*cp++ = 'u';
		*cp++ = 'e';
		*cp++ = 's';
		*cp++ = ' ';
		*cp++ = '(';

		/*
		 * Append the values
		 */
		need_comma = false;
		OldDateStyle = GetConfigOptionByName("DateStyle", NULL);
		if (!strstr(OldDateStyle, "ISO"))
			set_config_option("DateStyle", "ISO", PGC_USERSET, PGC_S_SESSION, true, true);
		for (i = 0; i < tg->tg_relation->rd_att->natts; i++)
		{
			/*
			 * Skip dropped columns
			 */
			if (tupdesc->attrs[i]->attisdropped)
				continue;


			if ((col_value = SPI_getvalue(new_row, tupdesc, i + 1)) == NULL)
			{
				col_value = "NULL";
			}
			else
			{
				col_value = slon_quote_literal(col_value);
			}

			cmddata_need = (cp - (char *) (cs->cmddata_buf)) + 16 +
				(len_value = strlen(col_value));
			if (cs->cmddata_size < cmddata_need)
			{
				int			have = (cp - (char *) (cs->cmddata_buf));

				while (cs->cmddata_size < cmddata_need)
					cs->cmddata_size *= 2;
				cs->cmddata_buf = realloc(cs->cmddata_buf, cs->cmddata_size);
				cp = (char *) (cs->cmddata_buf) + have;
			}

			if (need_comma)
				*cp++ = ',';
			else
				need_comma = true;

			memcpy(cp, col_value, len_value);
			cp += len_value;
		}

		if (!strstr(OldDateStyle, "ISO"))
			set_config_option("DateStyle", OldDateStyle, PGC_USERSET, PGC_S_SESSION, true, true);

		/*
		 * Terminate and done
		 */
		*cp++ = ')';
		*cp = '\0';
		SET_VARSIZE(cs->cmddata_buf,
					VARHDRSZ + (cp - VARDATA(cs->cmddata_buf)));
	}
	else if (TRIGGER_FIRED_BY_UPDATE(tg->tg_event))
	{
		HeapTuple	old_row = tg->tg_trigtuple;
		HeapTuple	new_row = tg->tg_newtuple;
		TupleDesc	tupdesc = tg->tg_relation->rd_att;
		Datum		old_value;
		Datum		new_value;
		bool		old_isnull;
		bool		new_isnull;

		char	   *col_ident;
		char	   *col_value;
		int			len_ident;
		int			len_value;
		int			i;
		int			need_comma = false;
		int			need_and = false;
		char	   *OldDateStyle;

		char	   *cp = VARDATA(cs->cmddata_buf);

		/*
		 * UPDATE
		 *
		 * cmdtype = 'U' cmddata = "col_ident"='value' [, ...] where
		 * "pk_ident" = 'value' [ and ...]
		 */
		cmdtype = cs->cmdtype_U;
		for (i = 0; i < tg->tg_relation->rd_att->natts; i++)
		{
			/*
			 * Ignore dropped columns
			 */
			if (tupdesc->attrs[i]->attisdropped)
				continue;

			old_value = SPI_getbinval(old_row, tupdesc, i + 1, &old_isnull);
			new_value = SPI_getbinval(new_row, tupdesc, i + 1, &new_isnull);

			/*
			 * If old and new value are NULL, the column is unchanged
			 */
			if (old_isnull && new_isnull)
				continue;

			/*
			 * If both are NOT NULL, we need to compare the values and skip
			 * setting the column if equal
			 */
			if (!old_isnull && !new_isnull)
			{
				Oid			opr_oid;
				FmgrInfo   *opr_finfo_p;

				/*
				 * Lookup the equal operators function call info using the
				 * typecache if available
				 */
#ifdef HAVE_TYPCACHE
				TypeCacheEntry *type_cache;

				type_cache = lookup_type_cache(
											   SPI_gettypeid(tupdesc, i + 1),
								  TYPECACHE_EQ_OPR | TYPECACHE_EQ_OPR_FINFO);
				opr_oid = type_cache->eq_opr;
				if (opr_oid == ARRAY_EQ_OP)
					opr_oid = InvalidOid;
				else
					opr_finfo_p = &(type_cache->eq_opr_finfo);
#else
				FmgrInfo	opr_finfo;

				opr_oid = compatible_oper_funcid(makeList1(makeString("=")),
											   SPI_gettypeid(tupdesc, i + 1),
										SPI_gettypeid(tupdesc, i + 1), true);
				if (OidIsValid(opr_oid))
				{
					fmgr_info(opr_oid, &opr_finfo);
					opr_finfo_p = &opr_finfo;
				}
#endif

				/*
				 * If we have an equal operator, use that to do binary
				 * comparision. Else get the string representation of both
				 * attributes and do string comparision.
				 */
				if (OidIsValid(opr_oid))
				{
					if (DatumGetBool(FunctionCall2(opr_finfo_p,
												   old_value, new_value)))
						continue;
				}
				else
				{
					char	   *old_strval = SPI_getvalue(old_row, tupdesc, i + 1);
					char	   *new_strval = SPI_getvalue(new_row, tupdesc, i + 1);

					if (strcmp(old_strval, new_strval) == 0)
						continue;
				}
			}

			if (need_comma)
				*cp++ = ',';
			else
				need_comma = true;

			col_ident = (char *) slon_quote_identifier(SPI_fname(tupdesc, i + 1));
			if (new_isnull)
				col_value = "NULL";
			else
			{
				OldDateStyle = GetConfigOptionByName("DateStyle", NULL);
				if (!strstr(OldDateStyle, "ISO"))
					set_config_option("DateStyle", "ISO", PGC_USERSET, PGC_S_SESSION, true, true);
				col_value = slon_quote_literal(SPI_getvalue(new_row, tupdesc, i + 1));
				if (!strstr(OldDateStyle, "ISO"))
					set_config_option("DateStyle", OldDateStyle, PGC_USERSET, PGC_S_SESSION, true, true);
			}
			cmddata_need = (cp - (char *) (cs->cmddata_buf)) + 16 +
				(len_ident = strlen(col_ident)) +
				(len_value = strlen(col_value));
			if (cs->cmddata_size < cmddata_need)
			{
				int			have = (cp - (char *) (cs->cmddata_buf));

				while (cs->cmddata_size < cmddata_need)
					cs->cmddata_size *= 2;
				cs->cmddata_buf = realloc(cs->cmddata_buf, cs->cmddata_size);
				cp = (char *) (cs->cmddata_buf) + have;
			}

			memcpy(cp, col_ident, len_ident);
			cp += len_ident;
			*cp++ = '=';
			memcpy(cp, col_value, len_value);
			cp += len_value;
		}

		/*
		 * It can happen that the only UPDATE an application does is to set a
		 * column to the same value again. In that case, we'd end up here with
		 * no columns in the SET clause yet. We add the first key column here
		 * with it's old value to simulate the same for the replication
		 * engine.
		 */
		if (!need_comma)
		{
			for (i = 0, attkind_idx = -1; i < tg->tg_relation->rd_att->natts; i++)
			{
				if (tupdesc->attrs[i]->attisdropped)
					continue;

				attkind_idx++;
				if (!attkind[attkind_idx])
					elog(ERROR, "Slony-I: no key columns found in logTrigger() attkind parameter");

				if (attkind[attkind_idx] == 'k')
					break;
			}
			col_ident = (char *) slon_quote_identifier(SPI_fname(tupdesc, i + 1));
			col_value = slon_quote_literal(SPI_getvalue(old_row, tupdesc, i + 1));

			cmddata_need = (cp - (char *) (cs->cmddata_buf)) + 16 +
				(len_ident = strlen(col_ident)) +
				(len_value = strlen(col_value));
			if (cs->cmddata_size < cmddata_need)
			{
				int			have = (cp - (char *) (cs->cmddata_buf));

				while (cs->cmddata_size < cmddata_need)
					cs->cmddata_size *= 2;
				cs->cmddata_buf = realloc(cs->cmddata_buf, cs->cmddata_size);
				cp = (char *) (cs->cmddata_buf) + have;
			}

			memcpy(cp, col_ident, len_ident);
			cp += len_ident;
			*cp++ = '=';
			memcpy(cp, col_value, len_value);
			cp += len_value;
		}

		*cp++ = ' ';
		*cp++ = 'w';
		*cp++ = 'h';
		*cp++ = 'e';
		*cp++ = 'r';
		*cp++ = 'e';
		*cp++ = ' ';

		for (i = 0, attkind_idx = -1; i < tg->tg_relation->rd_att->natts; i++)
		{
			/*
			 * Ignore dropped columns
			 */
			if (tupdesc->attrs[i]->attisdropped)
				continue;

			attkind_idx++;
			if (!attkind[attkind_idx])
				break;
			if (attkind[attkind_idx] != 'k')
				continue;
			col_ident = (char *) slon_quote_identifier(SPI_fname(tupdesc, i + 1));
			col_value = slon_quote_literal(SPI_getvalue(old_row, tupdesc, i + 1));
			if (col_value == NULL)
				elog(ERROR, "Slony-I: old key column %s.%s IS NULL on UPDATE",
					 NameStr(tg->tg_relation->rd_rel->relname), col_ident);

			cmddata_need = (cp - (char *) (cs->cmddata_buf)) + 16 +
				(len_ident = strlen(col_ident)) +
				(len_value = strlen(col_value));
			if (cs->cmddata_size < cmddata_need)
			{
				int			have = (cp - (char *) (cs->cmddata_buf));

				while (cs->cmddata_size < cmddata_need)
					cs->cmddata_size *= 2;
				cs->cmddata_buf = realloc(cs->cmddata_buf, cs->cmddata_size);
				cp = (char *) (cs->cmddata_buf) + have;
			}

			if (need_and)
			{
				*cp++ = ' ';
				*cp++ = 'a';
				*cp++ = 'n';
				*cp++ = 'd';
				*cp++ = ' ';
			}
			else
				need_and = true;

			memcpy(cp, col_ident, len_ident);
			cp += len_ident;
			*cp++ = '=';
			memcpy(cp, col_value, len_value);
			cp += len_value;
		}
		*cp = '\0';
		SET_VARSIZE(cs->cmddata_buf,
					VARHDRSZ + (cp - VARDATA(cs->cmddata_buf)));
	}
	else if (TRIGGER_FIRED_BY_DELETE(tg->tg_event))
	{
		HeapTuple	old_row = tg->tg_trigtuple;
		TupleDesc	tupdesc = tg->tg_relation->rd_att;
		char	   *col_ident;
		char	   *col_value;
		int			len_ident;
		int			len_value;
		int			i;
		int			need_and = false;
		char	   *cp = VARDATA(cs->cmddata_buf);

		/*
		 * DELETE
		 *
		 * cmdtype = 'D' cmddata = "pk_ident"='value' [and ...]
		 */
		cmdtype = cs->cmdtype_D;

		for (i = 0, attkind_idx = -1; i < tg->tg_relation->rd_att->natts; i++)
		{
			if (tupdesc->attrs[i]->attisdropped)
				continue;

			attkind_idx++;
			if (!attkind[attkind_idx])
				break;
			if (attkind[attkind_idx] != 'k')
				continue;
			col_ident = (char *) slon_quote_identifier(SPI_fname(tupdesc, i + 1));
			col_value = slon_quote_literal(SPI_getvalue(old_row, tupdesc, i + 1));
			if (col_value == NULL)
				elog(ERROR, "Slony-I: old key column %s.%s IS NULL on DELETE",
					 NameStr(tg->tg_relation->rd_rel->relname), col_ident);

			cmddata_need = (cp - (char *) (cs->cmddata_buf)) + 16 +
				(len_ident = strlen(col_ident)) +
				(len_value = strlen(col_value));
			if (cs->cmddata_size < cmddata_need)
			{
				int			have = (cp - (char *) (cs->cmddata_buf));

				while (cs->cmddata_size < cmddata_need)
					cs->cmddata_size *= 2;
				cs->cmddata_buf = realloc(cs->cmddata_buf, cs->cmddata_size);
				cp = (char *) (cs->cmddata_buf) + have;
			}

			if (need_and)
			{
				*cp++ = ' ';
				*cp++ = 'a';
				*cp++ = 'n';
				*cp++ = 'd';
				*cp++ = ' ';
			}
			else
				need_and = true;

			memcpy(cp, col_ident, len_ident);
			cp += len_ident;
			*cp++ = '=';
			memcpy(cp, col_value, len_value);
			cp += len_value;
		}
		*cp = '\0';
		SET_VARSIZE(cs->cmddata_buf,
					VARHDRSZ + (cp - VARDATA(cs->cmddata_buf)));
	}
	else
		elog(ERROR, "Slony-I: logTrigger() fired for unhandled event");

	/*
	 * Construct the parameter array and insert the log row.
	 */
	argv[0] = Int32GetDatum(tab_id);
	argv[1] = PointerGetDatum(cmdtype);
	argv[2] = PointerGetDatum(cs->cmddata_buf);
	SPI_execp(cs->plan_active_log, argv, NULL, 0);

	SPI_finish();
	return PointerGetDatum(NULL);
}
Beispiel #7
0
/*
 * PerformCursorOpen
 *		Execute SQL DECLARE CURSOR command.
 */
void
PerformCursorOpen(DeclareCursorStmt *stmt)
{
	List	   *rewritten;
	Query	   *query;
	Plan	   *plan;
	Portal		portal;
	MemoryContext oldContext;

	/*
	 * Disallow empty-string cursor name (conflicts with protocol-level
	 * unnamed portal).
	 */
	if (!stmt->portalname || stmt->portalname[0] == '\0')
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_CURSOR_NAME),
				 errmsg("invalid cursor name: must not be empty")));

	/*
	 * If this is a non-holdable cursor, we require that this statement
	 * has been executed inside a transaction block (or else, it would
	 * have no user-visible effect).
	 */
	if (!(stmt->options & CURSOR_OPT_HOLD))
		RequireTransactionChain((void *) stmt, "DECLARE CURSOR");

	/*
	 * Because the planner is not cool about not scribbling on its input,
	 * we make a preliminary copy of the source querytree.  This prevents
	 * problems in the case that the DECLARE CURSOR is in a portal and is
	 * executed repeatedly.  XXX the planner really shouldn't modify its
	 * input ... FIXME someday.
	 */
	query = copyObject(stmt->query);

	/*
	 * The query has been through parse analysis, but not rewriting or
	 * planning as yet.  Note that the grammar ensured we have a SELECT
	 * query, so we are not expecting rule rewriting to do anything
	 * strange.
	 */
	rewritten = QueryRewrite(query);
	if (length(rewritten) != 1 || !IsA(lfirst(rewritten), Query))
		elog(ERROR, "unexpected rewrite result");
	query = (Query *) lfirst(rewritten);
	if (query->commandType != CMD_SELECT)
		elog(ERROR, "unexpected rewrite result");

	if (query->into)
		ereport(ERROR,
				(errcode(ERRCODE_SYNTAX_ERROR),
				 errmsg("DECLARE CURSOR may not specify INTO")));
	if (query->rowMarks != NIL)
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("DECLARE CURSOR ... FOR UPDATE is not supported"),
				 errdetail("Cursors must be READ ONLY.")));

	plan = planner(query, true, stmt->options);

	/*
	 * Create a portal and copy the query and plan into its memory
	 * context.
	 */
	portal = CreatePortal(stmt->portalname, false, false);

	oldContext = MemoryContextSwitchTo(PortalGetHeapMemory(portal));

	query = copyObject(query);
	plan = copyObject(plan);

	PortalDefineQuery(portal,
					  NULL,		/* unfortunately don't have sourceText */
					  "SELECT", /* cursor's query is always a SELECT */
					  makeList1(query),
					  makeList1(plan),
					  PortalGetHeapMemory(portal));

	MemoryContextSwitchTo(oldContext);

	/*
	 * Set up options for portal.
	 *
	 * If the user didn't specify a SCROLL type, allow or disallow scrolling
	 * based on whether it would require any additional runtime overhead
	 * to do so.
	 */
	portal->cursorOptions = stmt->options;
	if (!(portal->cursorOptions & (CURSOR_OPT_SCROLL | CURSOR_OPT_NO_SCROLL)))
	{
		if (ExecSupportsBackwardScan(plan))
			portal->cursorOptions |= CURSOR_OPT_SCROLL;
		else
			portal->cursorOptions |= CURSOR_OPT_NO_SCROLL;
	}

	/*
	 * Start execution --- never any params for a cursor.
	 */
	PortalStart(portal, NULL);

	Assert(portal->strategy == PORTAL_ONE_SELECT);

	/*
	 * We're done; the query won't actually be run until
	 * PerformPortalFetch is called.
	 */
}