lsyscache.c

来自「postgresql8.3.4源码,开源数据库」· C语言 代码 · 共 2,698 行 · 第 1/5 页

			 * Get the matching support function(s).  Failure probably
			 * shouldn't happen --- it implies a bogus opfamily --- but
			 * continue looking if so.
			 */
			if (lhs_procno)
			{
				*lhs_procno = get_opfamily_proc(aform->amopfamily,
												aform->amoplefttype,
												aform->amoplefttype,
												HASHPROC);
				if (!OidIsValid(*lhs_procno))
					continue;
				/* Matching LHS found, done if caller doesn't want RHS */
				if (!rhs_procno)
				{
					result = true;
					break;
				}
				/* Only one lookup needed if given operator is single-type */
				if (aform->amoplefttype == aform->amoprighttype)
				{
					*rhs_procno = *lhs_procno;
					result = true;
					break;
				}
			}
			if (rhs_procno)
			{
				*rhs_procno = get_opfamily_proc(aform->amopfamily,
												aform->amoprighttype,
												aform->amoprighttype,
												HASHPROC);
				if (!OidIsValid(*rhs_procno))
				{
					/* Forget any LHS function from this opfamily */
					if (lhs_procno)
						*lhs_procno = InvalidOid;
					continue;
				}
				/* Matching RHS found, so done */
				result = true;
				break;
			}
		}
	}

	ReleaseSysCacheList(catlist);

	return result;
}

/*
 * get_op_btree_interpretation
 *		Given an operator's OID, find out which btree opfamilies it belongs to,
 *		and what strategy number it has within each one.  The results are
 *		returned as an OID list and a parallel integer list.
 *
 * In addition to the normal btree operators, we consider a <> operator to be
 * a "member" of an opfamily if its negator is an equality operator of the
 * opfamily.  ROWCOMPARE_NE is returned as the strategy number for this case.
 */
void
get_op_btree_interpretation(Oid opno, List **opfamilies, List **opstrats)
{
	CatCList   *catlist;
	bool		op_negated;
	int			i;

	*opfamilies = NIL;
	*opstrats = NIL;

	/*
	 * Find all the pg_amop entries containing the operator.
	 */
	catlist = SearchSysCacheList(AMOPOPID, 1,
								 ObjectIdGetDatum(opno),
								 0, 0, 0);

	/*
	 * If we can't find any opfamily containing the op, perhaps it is a <>
	 * operator.  See if it has a negator that is in an opfamily.
	 */
	op_negated = false;
	if (catlist->n_members == 0)
	{
		Oid			op_negator = get_negator(opno);

		if (OidIsValid(op_negator))
		{
			op_negated = true;
			ReleaseSysCacheList(catlist);
			catlist = SearchSysCacheList(AMOPOPID, 1,
										 ObjectIdGetDatum(op_negator),
										 0, 0, 0);
		}
	}

	/* Now search the opfamilies */
	for (i = 0; i < catlist->n_members; i++)
	{
		HeapTuple	op_tuple = &catlist->members[i]->tuple;
		Form_pg_amop op_form = (Form_pg_amop) GETSTRUCT(op_tuple);
		Oid			opfamily_id;
		StrategyNumber op_strategy;

		/* must be btree */
		if (op_form->amopmethod != BTREE_AM_OID)
			continue;

		/* Get the operator's btree strategy number */
		opfamily_id = op_form->amopfamily;
		op_strategy = (StrategyNumber) op_form->amopstrategy;
		Assert(op_strategy >= 1 && op_strategy <= 5);

		if (op_negated)
		{
			/* Only consider negators that are = */
			if (op_strategy != BTEqualStrategyNumber)
				continue;
			op_strategy = ROWCOMPARE_NE;
		}

		*opfamilies = lappend_oid(*opfamilies, opfamily_id);
		*opstrats = lappend_int(*opstrats, op_strategy);
	}

	ReleaseSysCacheList(catlist);
}

/*
 * ops_in_same_btree_opfamily
 *		Return TRUE if there exists a btree opfamily containing both operators.
 *		(This implies that they have compatible notions of equality.)
 */
bool
ops_in_same_btree_opfamily(Oid opno1, Oid opno2)
{
	bool		result = false;
	CatCList   *catlist;
	int			i;

	/*
	 * We search through all the pg_amop entries for opno1.
	 */
	catlist = SearchSysCacheList(AMOPOPID, 1,
								 ObjectIdGetDatum(opno1),
								 0, 0, 0);
	for (i = 0; i < catlist->n_members; i++)
	{
		HeapTuple	op_tuple = &catlist->members[i]->tuple;
		Form_pg_amop op_form = (Form_pg_amop) GETSTRUCT(op_tuple);

		/* must be btree */
		if (op_form->amopmethod != BTREE_AM_OID)
			continue;

		if (op_in_opfamily(opno2, op_form->amopfamily))
		{
			result = true;
			break;
		}
	}

	ReleaseSysCacheList(catlist);

	return result;
}


/*				---------- AMPROC CACHES ----------						 */

/*
 * get_opfamily_proc
 *		Get the OID of the specified support function
 *		for the specified opfamily and datatypes.
 *
 * Returns InvalidOid if there is no pg_amproc entry for the given keys.
 */
Oid
get_opfamily_proc(Oid opfamily, Oid lefttype, Oid righttype, int16 procnum)
{
	HeapTuple	tp;
	Form_pg_amproc amproc_tup;
	RegProcedure result;

	tp = SearchSysCache(AMPROCNUM,
						ObjectIdGetDatum(opfamily),
						ObjectIdGetDatum(lefttype),
						ObjectIdGetDatum(righttype),
						Int16GetDatum(procnum));
	if (!HeapTupleIsValid(tp))
		return InvalidOid;
	amproc_tup = (Form_pg_amproc) GETSTRUCT(tp);
	result = amproc_tup->amproc;
	ReleaseSysCache(tp);
	return result;
}


/*				---------- ATTRIBUTE CACHES ----------					 */

/*
 * get_attname
 *		Given the relation id and the attribute number,
 *		return the "attname" field from the attribute relation.
 *
 * Note: returns a palloc'd copy of the string, or NULL if no such attribute.
 */
char *
get_attname(Oid relid, AttrNumber attnum)
{
	HeapTuple	tp;

	tp = SearchSysCache(ATTNUM,
						ObjectIdGetDatum(relid),
						Int16GetDatum(attnum),
						0, 0);
	if (HeapTupleIsValid(tp))
	{
		Form_pg_attribute att_tup = (Form_pg_attribute) GETSTRUCT(tp);
		char	   *result;

		result = pstrdup(NameStr(att_tup->attname));
		ReleaseSysCache(tp);
		return result;
	}
	else
		return NULL;
}

/*
 * get_relid_attribute_name
 *
 * Same as above routine get_attname(), except that error
 * is handled by elog() instead of returning NULL.
 */
char *
get_relid_attribute_name(Oid relid, AttrNumber attnum)
{
	char	   *attname;

	attname = get_attname(relid, attnum);
	if (attname == NULL)
		elog(ERROR, "cache lookup failed for attribute %d of relation %u",
			 attnum, relid);
	return attname;
}

/*
 * get_attnum
 *
 *		Given the relation id and the attribute name,
 *		return the "attnum" field from the attribute relation.
 *
 *		Returns InvalidAttrNumber if the attr doesn't exist (or is dropped).
 */
AttrNumber
get_attnum(Oid relid, const char *attname)
{
	HeapTuple	tp;

	tp = SearchSysCacheAttName(relid, attname);
	if (HeapTupleIsValid(tp))
	{
		Form_pg_attribute att_tup = (Form_pg_attribute) GETSTRUCT(tp);
		AttrNumber	result;

		result = att_tup->attnum;
		ReleaseSysCache(tp);
		return result;
	}
	else
		return InvalidAttrNumber;
}

/*
 * get_atttype
 *
 *		Given the relation OID and the attribute number with the relation,
 *		return the attribute type OID.
 */
Oid
get_atttype(Oid relid, AttrNumber attnum)
{
	HeapTuple	tp;

	tp = SearchSysCache(ATTNUM,
						ObjectIdGetDatum(relid),
						Int16GetDatum(attnum),
						0, 0);
	if (HeapTupleIsValid(tp))
	{
		Form_pg_attribute att_tup = (Form_pg_attribute) GETSTRUCT(tp);
		Oid			result;

		result = att_tup->atttypid;
		ReleaseSysCache(tp);
		return result;
	}
	else
		return InvalidOid;
}

/*
 * get_atttypmod
 *
 *		Given the relation id and the attribute number,
 *		return the "atttypmod" field from the attribute relation.
 */
int32
get_atttypmod(Oid relid, AttrNumber attnum)
{
	HeapTuple	tp;

	tp = SearchSysCache(ATTNUM,
						ObjectIdGetDatum(relid),
						Int16GetDatum(attnum),
						0, 0);
	if (HeapTupleIsValid(tp))
	{
		Form_pg_attribute att_tup = (Form_pg_attribute) GETSTRUCT(tp);
		int32		result;

		result = att_tup->atttypmod;
		ReleaseSysCache(tp);
		return result;
	}
	else
		return -1;
}

/*
 * get_atttypetypmod
 *
 *		A two-fer: given the relation id and the attribute number,
 *		fetch both type OID and atttypmod in a single cache lookup.
 *
 * Unlike the otherwise-similar get_atttype/get_atttypmod, this routine
 * raises an error if it can't obtain the information.
 */
void
get_atttypetypmod(Oid relid, AttrNumber attnum,
				  Oid *typid, int32 *typmod)
{
	HeapTuple	tp;
	Form_pg_attribute att_tup;

	tp = SearchSysCache(ATTNUM,
						ObjectIdGetDatum(relid),
						Int16GetDatum(attnum),
						0, 0);
	if (!HeapTupleIsValid(tp))
		elog(ERROR, "cache lookup failed for attribute %d of relation %u",
			 attnum, relid);
	att_tup = (Form_pg_attribute) GETSTRUCT(tp);

	*typid = att_tup->atttypid;
	*typmod = att_tup->atttypmod;
	ReleaseSysCache(tp);
}

/*				---------- CONSTRAINT CACHE ----------					 */

/*
 * get_constraint_name
 *		Returns the name of a given pg_constraint entry.
 *
 * Returns a palloc'd copy of the string, or NULL if no such constraint.
 *
 * NOTE: since constraint name is not unique, be wary of code that uses this
 * for anything except preparing error messages.
 */
char *
get_constraint_name(Oid conoid)
{
	HeapTuple	tp;

	tp = SearchSysCache(CONSTROID,
						ObjectIdGetDatum(conoid),
						0, 0, 0);
	if (HeapTupleIsValid(tp))
	{
		Form_pg_constraint contup = (Form_pg_constraint) GETSTRUCT(tp);
		char	   *result;

		result = pstrdup(NameStr(contup->conname));
		ReleaseSysCache(tp);
		return result;
	}
	else
		return NULL;
}

/*				---------- OPCLASS CACHE ----------						 */

/*
 * get_opclass_family
 *
 *		Returns the OID of the operator family the opclass belongs to.
 */
Oid
get_opclass_family(Oid opclass)
{
	HeapTuple	tp;
	Form_pg_opclass cla_tup;
	Oid			result;

	tp = SearchSysCache(CLAOID,
						ObjectIdGetDatum(opclass),
						0, 0, 0);
	if (!HeapTupleIsValid(tp))
		elog(ERROR, "cache lookup failed for opclass %u", opclass);
	cla_tup = (Form_pg_opclass) GETSTRUCT(tp);

	result = cla_tup->opcfamily;
	ReleaseSysCache(tp);
	return result;
}

/*
 * get_opclass_input_type
 *
 *		Returns the OID of the datatype the opclass indexes.
 */
Oid
get_opclass_input_type(Oid opclass)
{
	HeapTuple	tp;
	Form_pg_opclass cla_tup;
	Oid			result;

	tp = SearchSysCache(CLAOID,
						ObjectIdGetDatum(opclass),
						0, 0, 0);
	if (!HeapTupleIsValid(tp))
		elog(ERROR, "cache lookup failed for opclass %u", opclass);
	cla_tup = (Form_pg_opclass) GETSTRUCT(tp);

	result = cla_tup->opcintype;
	ReleaseSysCache(tp);
	return result;
}

/*				---------- OPERATOR CACHE ----------					 */

/*
 * get_opcode
 *
 *		Returns the regproc id of the routine used to implement an
 *		operator given the operator oid.
 */
RegProcedure
get_opcode(Oid opno)
{
	HeapTuple	tp;

	tp = SearchSysCache(OPEROID,
						ObjectIdGetDatum(opno),
						0, 0, 0);
	if (HeapTupleIsValid(tp))
	{
		Form_pg_operator optup = (Form_pg_operator) GETSTRUCT(tp);
		RegProcedure result;

		result = optup->oprcode;
		ReleaseSysCache(tp);
		return result;
	}
	else
		return (RegProcedure) InvalidOid;
}

/*
 * get_opname
 *	  returns the name of the operator with the given opno
 *
 * Note: returns a palloc'd copy of the string, or NULL if no such operator.
 */
char *
get_opname(Oid opno)
{
	HeapTuple	tp;

	tp = SearchSysCache(OPEROID,
						ObjectIdGetDatum(opno),
						0, 0, 0);
	if (HeapTupleIsValid(tp))
	{
		Form_pg_operator optup = (Form_pg_operator) GETSTRUCT(tp);
		char	   *result;

		result = pstrdup(NameStr(optup->oprname));
		ReleaseSysCache(tp);
		return result;
	}
	else
		return NULL;
}

/*
 * op_input_types
 *
 *		Returns the left and right input datatypes for an operator
 *		(InvalidOid if not relevant).
 */
void
op_input_types(Oid opno, Oid *lefttype, Oid *righttype)
{
	HeapTuple	tp;
	Form_pg_operator optup;

	tp = SearchSysCache(OPEROID,
						ObjectIdGetDatum(opno),
						0, 0, 0);
	if (!HeapTupleIsValid(tp))	/* shouldn't happen */
		elog(ERROR, "cache lookup failed for operator %u", opno);
	optup = (Form_pg_operator) GETSTRUCT(tp);
	*lefttype = optup->oprleft;
	*righttype = optup->oprright;
	ReleaseSysCache(tp);
}

/*
 * op_mergejoinable
 *
 * Returns true if the operator is potentially mergejoinable.  (The planner
 * will fail to find any mergejoin plans unless there are suitable btree
 * opfamily entries for this operator and associated sortops.  The pg_operator
 * flag is just a hint to tell the planner whether to bother looking.)
 */
bool
op_mergejoinable(Oid opno)
{
	HeapTuple	tp;
	bool		result = false;

	tp = SearchSysCache(OPEROID,
						ObjectIdGetDatum(opno),
						0, 0, 0);
	if (HeapTupleIsValid(tp))