pg_operator.c

关系型数据库 Postgresql 6.5.2

	{
		rightTypeId = TypeGet(rightTypeName, &rightDefined);

		if (!OidIsValid(rightTypeId) || !rightDefined)
			elog(ERROR, "OperatorDef: right type '%s' nonexistent",
				 rightTypeName);
	}

	if (!((OidIsValid(leftTypeId) && leftDefined) ||
		  (OidIsValid(rightTypeId) && rightDefined)))
		elog(ERROR, "OperatorDef: must have at least one argument type");

	for (i = 0; i < Natts_pg_operator; ++i)
	{
		values[i] = (Datum) NULL;
		replaces[i] = 'r';
		nulls[i] = ' ';
	}

	/* ----------------
	 * Look up registered procedures -- find the return type
	 * of procedureName to place in "result" field.
	 * Do this before shells are created so we don't
	 * have to worry about deleting them later.
	 * ----------------
	 */
	MemSet(typeId, 0, 8 * sizeof(Oid));
	if (!leftTypeName)
	{
		typeId[0] = rightTypeId;
		nargs = 1;
	}
	else if (!rightTypeName)
	{
		typeId[0] = leftTypeId;
		nargs = 1;
	}
	else
	{
		typeId[0] = leftTypeId;
		typeId[1] = rightTypeId;
		nargs = 2;
	}
	tup = SearchSysCacheTuple(PRONAME,
							  PointerGetDatum(procedureName),
							  Int32GetDatum(nargs),
							  PointerGetDatum(typeId),
							  0);

	if (!HeapTupleIsValid(tup))
		func_error("OperatorDef", procedureName, nargs, typeId, NULL);

	values[Anum_pg_operator_oprcode - 1] = ObjectIdGetDatum(tup->t_data->t_oid);
	values[Anum_pg_operator_oprresult - 1] = ObjectIdGetDatum(((Form_pg_proc)
											GETSTRUCT(tup))->prorettype);

	/* ----------------
	 *	find restriction
	 * ----------------
	 */
	if (restrictionName)
	{							/* optional */
		MemSet(typeId, 0, 8 * sizeof(Oid));
		typeId[0] = OIDOID;		/* operator OID */
		typeId[1] = OIDOID;		/* relation OID */
		typeId[2] = INT2OID;	/* attribute number */
		typeId[3] = 0;			/* value - can be any type	*/
		typeId[4] = INT4OID;	/* flags - left or right selectivity */
		tup = SearchSysCacheTuple(PRONAME,
								  PointerGetDatum(restrictionName),
								  Int32GetDatum(5),
								  PointerGetDatum(typeId),
								  0);
		if (!HeapTupleIsValid(tup))
			func_error("OperatorDef", restrictionName, 5, typeId, NULL);

		values[Anum_pg_operator_oprrest - 1] = ObjectIdGetDatum(tup->t_data->t_oid);
	}
	else
		values[Anum_pg_operator_oprrest - 1] = ObjectIdGetDatum(InvalidOid);

	/* ----------------
	 *	find join - only valid for binary operators
	 * ----------------
	 */
	if (joinName)
	{							/* optional */
		MemSet(typeId, 0, 8 * sizeof(Oid));
		typeId[0] = OIDOID;		/* operator OID */
		typeId[1] = OIDOID;		/* relation OID 1 */
		typeId[2] = INT2OID;	/* attribute number 1 */
		typeId[3] = OIDOID;		/* relation OID 2 */
		typeId[4] = INT2OID;	/* attribute number 2 */

		tup = SearchSysCacheTuple(PRONAME,
								  PointerGetDatum(joinName),
								  Int32GetDatum(5),
								  PointerGetDatum(typeId),
								  0);
		if (!HeapTupleIsValid(tup))
			func_error("OperatorDef", joinName, 5, typeId, NULL);

		values[Anum_pg_operator_oprjoin - 1] = ObjectIdGetDatum(tup->t_data->t_oid);
	}
	else
		values[Anum_pg_operator_oprjoin - 1] = ObjectIdGetDatum(InvalidOid);

	/* ----------------
	 * set up values in the operator tuple
	 * ----------------
	 */
	i = 0;
	namestrcpy(&oname, operatorName);
	values[i++] = NameGetDatum(&oname);
	values[i++] = Int32GetDatum(GetUserId());
	values[i++] = UInt16GetDatum(precedence);
	values[i++] = leftTypeName ? (rightTypeName ? 'b' : 'r') : 'l';
	values[i++] = Int8GetDatum(isLeftAssociative);
	values[i++] = Int8GetDatum(canHash);
	values[i++] = ObjectIdGetDatum(leftTypeId);
	values[i++] = ObjectIdGetDatum(rightTypeId);

	++i;						/* Skip "oprresult", it was filled in
								 * above */

	/*
	 * Set up the other operators.	If they do not currently exist, create
	 * shells in order to get ObjectId's.
	 */
	name[0] = commutatorName;
	name[1] = negatorName;
	name[2] = leftSortName;
	name[3] = rightSortName;

	for (j = 0; j < 4; ++j)
	{
		if (name[j])
		{
			char	   *otherLeftTypeName = NULL;
			char	   *otherRightTypeName = NULL;
			Oid			otherLeftTypeId = InvalidOid;
			Oid			otherRightTypeId = InvalidOid;
			Oid			other_oid = InvalidOid;
			bool		otherDefined = false;

			switch (j)
			{
				case 0: /* commutator has reversed arg types */
					otherLeftTypeName = rightTypeName;
					otherRightTypeName = leftTypeName;
					otherLeftTypeId = rightTypeId;
					otherRightTypeId = leftTypeId;
					other_oid = OperatorGet(name[j],
											otherLeftTypeName,
											otherRightTypeName,
											&otherDefined);
					commutatorId = other_oid;
					break;
				case 1: /* negator has same arg types */
					otherLeftTypeName = leftTypeName;
					otherRightTypeName = rightTypeName;
					otherLeftTypeId = leftTypeId;
					otherRightTypeId = rightTypeId;
					other_oid = OperatorGet(name[j],
											otherLeftTypeName,
											otherRightTypeName,
											&otherDefined);
					negatorId = other_oid;
					break;
				case 2: /* left sort op takes left-side data type */
					otherLeftTypeName = leftTypeName;
					otherRightTypeName = leftTypeName;
					otherLeftTypeId = leftTypeId;
					otherRightTypeId = leftTypeId;
					other_oid = OperatorGet(name[j],
											otherLeftTypeName,
											otherRightTypeName,
											&otherDefined);
					break;
				case 3: /* right sort op takes right-side data
								 * type */
					otherLeftTypeName = rightTypeName;
					otherRightTypeName = rightTypeName;
					otherLeftTypeId = rightTypeId;
					otherRightTypeId = rightTypeId;
					other_oid = OperatorGet(name[j],
											otherLeftTypeName,
											otherRightTypeName,
											&otherDefined);
					break;
			}

			if (OidIsValid(other_oid))
			{
				/* other op already in catalogs */
				values[i++] = ObjectIdGetDatum(other_oid);
			}
			else if (strcmp(operatorName, name[j]) != 0 ||
					 otherLeftTypeId != leftTypeId ||
					 otherRightTypeId != rightTypeId)
			{
				/* not in catalogs, different from operator */
				other_oid = OperatorShellMake(name[j],
											  otherLeftTypeName,
											  otherRightTypeName);
				if (!OidIsValid(other_oid))
					elog(ERROR,
						 "OperatorDef: can't create operator shell '%s'",
						 name[j]);
				values[i++] = ObjectIdGetDatum(other_oid);
			}
			else
			{

				/*
				 * self-linkage to this operator; will fix below. Note
				 * that only self-linkage for commutation makes sense.
				 */
				if (j != 0)
					elog(ERROR,
						 "OperatorDef: operator can't be its own negator or sort op");
				selfCommutator = true;
				values[i++] = ObjectIdGetDatum(InvalidOid);
			}
		}
		else
		{
			/* other operator is omitted */
			values[i++] = ObjectIdGetDatum(InvalidOid);
		}
	}

	/* last three fields were filled in above */

	/*
	 * If we are adding to an operator shell, get its t_self
	 */
	pg_operator_desc = heap_openr(OperatorRelationName);

	if (operatorObjectId)
	{
		opKey[0].sk_argument = PointerGetDatum(operatorName);
		opKey[1].sk_argument = ObjectIdGetDatum(leftTypeId);
		opKey[2].sk_argument = ObjectIdGetDatum(rightTypeId);

		pg_operator_scan = heap_beginscan(pg_operator_desc,
										  0,
										  SnapshotSelf, /* no cache? */
										  3,
										  opKey);

		tup = heap_getnext(pg_operator_scan, 0);
		if (HeapTupleIsValid(tup))
		{
			tup = heap_modifytuple(tup,
								   pg_operator_desc,
								   values,
								   nulls,
								   replaces);

			setheapoverride(true);
			heap_replace(pg_operator_desc, &tup->t_self, tup, NULL);
			setheapoverride(false);
		}
		else
			elog(ERROR, "OperatorDef: no operator %u", operatorObjectId);

		heap_endscan(pg_operator_scan);
	}
	else
	{
		tupDesc = pg_operator_desc->rd_att;
		tup = heap_formtuple(tupDesc, values, nulls);

		heap_insert(pg_operator_desc, tup);
		operatorObjectId = tup->t_data->t_oid;
	}

	heap_close(pg_operator_desc);

	/*
	 * If a commutator and/or negator link is provided, update the other
	 * operator(s) to point at this one, if they don't already have a
	 * link. This supports an alternate style of operator definition
	 * wherein the user first defines one operator without giving negator
	 * or commutator, then defines the other operator of the pair with the
	 * proper commutator or negator attribute.	That style doesn't require
	 * creation of a shell, and it's the only style that worked right
	 * before Postgres version 6.5. This code also takes care of the
	 * situation where the new operator is its own commutator.
	 */
	if (selfCommutator)
		commutatorId = operatorObjectId;

	if (OidIsValid(commutatorId) || OidIsValid(negatorId))
		OperatorUpd(operatorObjectId, commutatorId, negatorId);
}

/* ----------------------------------------------------------------
 * OperatorUpd
 *
 *	For a given operator, look up its negator and commutator operators.
 *	If they are defined, but their negator and commutator fields
 *	(respectively) are empty, then use the new operator for neg or comm.
 *	This solves a problem for users who need to insert two new operators
 *	which are the negator or commutator of each other.
 * ----------------------------------------------------------------
 */
static void
OperatorUpd(Oid baseId, Oid commId, Oid negId)
{
	int			i;
	Relation	pg_operator_desc;
	HeapScanDesc pg_operator_scan;
	HeapTuple	tup;
	char		nulls[Natts_pg_operator];
	char		replaces[Natts_pg_operator];
	Datum		values[Natts_pg_operator];

	static ScanKeyData opKey[1] = {
		{0, ObjectIdAttributeNumber, F_OIDEQ},
	};

	fmgr_info(F_OIDEQ, &opKey[0].sk_func);
	opKey[0].sk_nargs = opKey[0].sk_func.fn_nargs;

	for (i = 0; i < Natts_pg_operator; ++i)
	{
		values[i] = (Datum) NULL;
		replaces[i] = ' ';
		nulls[i] = ' ';
	}

	pg_operator_desc = heap_openr(OperatorRelationName);

	/* check and update the commutator, if necessary */
	opKey[0].sk_argument = ObjectIdGetDatum(commId);

	pg_operator_scan = heap_beginscan(pg_operator_desc,
									  0,
									  SnapshotSelf,		/* no cache? */
									  1,
									  opKey);

	tup = heap_getnext(pg_operator_scan, 0);

	/*
	 * if the commutator and negator are the same operator, do one update.
	 * XXX this is probably useless code --- I doubt it ever makes sense
	 * for commutator and negator to be the same thing...
	 */
	if (commId == negId)
	{
		if (HeapTupleIsValid(tup))
		{
			Form_pg_operator t;

			t = (Form_pg_operator) GETSTRUCT(tup);
			if (!OidIsValid(t->oprcom)
				|| !OidIsValid(t->oprnegate))
			{

				if (!OidIsValid(t->oprnegate))
				{
					values[Anum_pg_operator_oprnegate - 1] = ObjectIdGetDatum(baseId);
					replaces[Anum_pg_operator_oprnegate - 1] = 'r';
				}

				if (!OidIsValid(t->oprcom))
				{
					values[Anum_pg_operator_oprcom - 1] = ObjectIdGetDatum(baseId);
					replaces[Anum_pg_operator_oprcom - 1] = 'r';
				}

				tup = heap_modifytuple(tup,
									   pg_operator_desc,
									   values,
									   nulls,
									   replaces);

				setheapoverride(true);
				heap_replace(pg_operator_desc, &tup->t_self, tup, NULL);
				setheapoverride(false);

			}
		}
		heap_endscan(pg_operator_scan);

		heap_close(pg_operator_desc);

		return;
	}

	/* if commutator and negator are different, do two updates */

	if (HeapTupleIsValid(tup) &&
		!(OidIsValid(((Form_pg_operator) GETSTRUCT(tup))->oprcom)))
	{
		values[Anum_pg_operator_oprcom - 1] = ObjectIdGetDatum(baseId);
		replaces[Anum_pg_operator_oprcom - 1] = 'r';
		tup = heap_modifytuple(tup,
							   pg_operator_desc,
							   values,
							   nulls,
							   replaces);

		setheapoverride(true);
		heap_replace(pg_operator_desc, &tup->t_self, tup, NULL);
		setheapoverride(false);

		values[Anum_pg_operator_oprcom - 1] = (Datum) NULL;
		replaces[Anum_pg_operator_oprcom - 1] = ' ';
	}

	heap_endscan(pg_operator_scan);

	/* check and update the negator, if necessary */
	opKey[0].sk_argument = ObjectIdGetDatum(negId);

	pg_operator_scan = heap_beginscan(pg_operator_desc,
									  0,
									  SnapshotSelf,		/* no cache? */
									  1,
									  opKey);

	tup = heap_getnext(pg_operator_scan, 0);
	if (HeapTupleIsValid(tup) &&
		!(OidIsValid(((Form_pg_operator) GETSTRUCT(tup))->oprnegate)))
	{
		values[Anum_pg_operator_oprnegate - 1] = ObjectIdGetDatum(baseId);
		replaces[Anum_pg_operator_oprnegate - 1] = 'r';
		tup = heap_modifytuple(tup,
							   pg_operator_desc,
							   values,
							   nulls,
							   replaces);

		setheapoverride(true);
		heap_replace(pg_operator_desc, &tup->t_self, tup, NULL);
		setheapoverride(false);
	}

	heap_endscan(pg_operator_scan);

	heap_close(pg_operator_desc);
}


/* ----------------------------------------------------------------
 * OperatorCreate
 *
 * This is now just an interface procedure for OperatorDef ...
 *
 * "X" indicates an optional argument (i.e. one that can be NULL)
 *		operatorName;			-- operator name
 *		leftTypeName;			-- X left type name
 *		rightTypeName;			-- X right type name
 *		procedureName;			-- procedure for operator
 *		precedence;				-- operator precedence
 *		isLeftAssociative;		-- operator is left associative
 *		commutatorName;			-- X commutator operator name
 *		negatorName;			-- X negator operator name
 *		restrictionName;		-- X restriction sel. procedure
 *		joinName;				-- X join sel. procedure
 *		canHash;				-- hash join can be used with this operator
 *		leftSortName;			-- X left sort operator (for merge join)
 *		rightSortName;			-- X right sort operator (for merge join)
 */
void
OperatorCreate(char *operatorName,
			   char *leftTypeName,
			   char *rightTypeName,
			   char *procedureName,
			   uint16 precedence,
			   bool isLeftAssociative,
			   char *commutatorName,
			   char *negatorName,
			   char *restrictionName,
			   char *joinName,
			   bool canHash,
			   char *leftSortName,
			   char *rightSortName)
{
	if (!leftTypeName && !rightTypeName)
		elog(ERROR, "OperatorCreate: at least one of leftarg or rightarg must be defined");

	if (!(leftTypeName && rightTypeName))
	{
		/* If it's not a binary op, these things mustn't be set: */
		if (commutatorName)
			elog(ERROR, "OperatorCreate: only binary operators can have commutators");
		if (negatorName)
			elog(ERROR, "OperatorCreate: only binary operators can have negators");
		if (restrictionName || joinName)
			elog(ERROR, "OperatorCreate: only binary operators can have selectivity");
		if (canHash)
			elog(ERROR, "OperatorCreate: only binary operators can hash");
		if (leftSortName || rightSortName)
			elog(ERROR, "OperatorCreate: only binary operators can have sort links");
	}

	/* ----------------
	 *	Use OperatorDef() to define the specified operator and
	 *	also create shells for the operator's associated operators
	 *	if they don't already exist.
	 * ----------------
	 */
	OperatorDef(operatorName,
				leftTypeName,
				rightTypeName,
				procedureName,
				precedence,
				isLeftAssociative,
				commutatorName,
				negatorName,
				restrictionName,
				joinName,
				canHash,
				leftSortName,
				rightSortName);
}