lsyscache.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

{
	HeapTuple	typeTuple;
	Form_pg_type type;
	Datum		datum;
	bool		isNull;
	Node	   *expr;

	typeTuple = SearchSysCache(TYPEOID,
							   ObjectIdGetDatum(typid),
							   0, 0, 0);
	if (!HeapTupleIsValid(typeTuple))
		elog(ERROR, "cache lookup failed for type %u", typid);
	type = (Form_pg_type) GETSTRUCT(typeTuple);

	/*
	 * typdefault and typdefaultbin are potentially null, so don't try to
	 * access 'em as struct fields. Must do it the hard way with
	 * SysCacheGetAttr.
	 */
	datum = SysCacheGetAttr(TYPEOID,
							typeTuple,
							Anum_pg_type_typdefaultbin,
							&isNull);

	if (!isNull)
	{
		/* We have an expression default */
		expr = stringToNode(DatumGetCString(DirectFunctionCall1(textout,
																datum)));
	}
	else
	{
		/* Perhaps we have a plain literal default */
		datum = SysCacheGetAttr(TYPEOID,
								typeTuple,
								Anum_pg_type_typdefault,
								&isNull);

		if (!isNull)
		{
			char	   *strDefaultVal;

			/* Convert text datum to C string */
			strDefaultVal = DatumGetCString(DirectFunctionCall1(textout,
																datum));
			/* Convert C string to a value of the given type */
			datum = OidFunctionCall3(type->typinput,
									 CStringGetDatum(strDefaultVal),
								 ObjectIdGetDatum(getTypeIOParam(typeTuple)),
									 Int32GetDatum(-1));
			/* Build a Const node containing the value */
			expr = (Node *) makeConst(typid,
									  type->typlen,
									  datum,
									  false,
									  type->typbyval);
			pfree(strDefaultVal);
		}
		else
		{
			/* No default */
			expr = NULL;
		}
	}

	ReleaseSysCache(typeTuple);

	return expr;
}

/*
 * getBaseType
 *		If the given type is a domain, return its base type;
 *		otherwise return the type's own OID.
 */
Oid
getBaseType(Oid typid)
{
	/*
	 * We loop to find the bottom base type in a stack of domains.
	 */
	for (;;)
	{
		HeapTuple	tup;
		Form_pg_type typTup;

		tup = SearchSysCache(TYPEOID,
							 ObjectIdGetDatum(typid),
							 0, 0, 0);
		if (!HeapTupleIsValid(tup))
			elog(ERROR, "cache lookup failed for type %u", typid);
		typTup = (Form_pg_type) GETSTRUCT(tup);
		if (typTup->typtype != 'd')
		{
			/* Not a domain, so done */
			ReleaseSysCache(tup);
			break;
		}

		typid = typTup->typbasetype;
		ReleaseSysCache(tup);
	}

	return typid;
}

/*
 * get_typavgwidth
 *
 *	  Given a type OID and a typmod value (pass -1 if typmod is unknown),
 *	  estimate the average width of values of the type.  This is used by
 *	  the planner, which doesn't require absolutely correct results;
 *	  it's OK (and expected) to guess if we don't know for sure.
 */
int32
get_typavgwidth(Oid typid, int32 typmod)
{
	int			typlen = get_typlen(typid);
	int32		maxwidth;

	/*
	 * Easy if it's a fixed-width type
	 */
	if (typlen > 0)
		return typlen;

	/*
	 * type_maximum_size knows the encoding of typmod for some datatypes;
	 * don't duplicate that knowledge here.
	 */
	maxwidth = type_maximum_size(typid, typmod);
	if (maxwidth > 0)
	{
		/*
		 * For BPCHAR, the max width is also the only width.  Otherwise we
		 * need to guess about the typical data width given the max. A sliding
		 * scale for percentage of max width seems reasonable.
		 */
		if (typid == BPCHAROID)
			return maxwidth;
		if (maxwidth <= 32)
			return maxwidth;	/* assume full width */
		if (maxwidth < 1000)
			return 32 + (maxwidth - 32) / 2;	/* assume 50% */

		/*
		 * Beyond 1000, assume we're looking at something like
		 * "varchar(10000)" where the limit isn't actually reached often, and
		 * use a fixed estimate.
		 */
		return 32 + (1000 - 32) / 2;
	}

	/*
	 * Ooops, we have no idea ... wild guess time.
	 */
	return 32;
}

/*
 * get_typtype
 *
 *		Given the type OID, find if it is a basic type, a complex type, etc.
 *		It returns the null char if the cache lookup fails...
 */
char
get_typtype(Oid typid)
{
	HeapTuple	tp;

	tp = SearchSysCache(TYPEOID,
						ObjectIdGetDatum(typid),
						0, 0, 0);
	if (HeapTupleIsValid(tp))
	{
		Form_pg_type typtup = (Form_pg_type) GETSTRUCT(tp);
		char		result;

		result = typtup->typtype;
		ReleaseSysCache(tp);
		return result;
	}
	else
		return '\0';
}

/*
 * get_typ_typrelid
 *
 *		Given the type OID, get the typrelid (InvalidOid if not a complex
 *		type).
 */
Oid
get_typ_typrelid(Oid typid)
{
	HeapTuple	tp;

	tp = SearchSysCache(TYPEOID,
						ObjectIdGetDatum(typid),
						0, 0, 0);
	if (HeapTupleIsValid(tp))
	{
		Form_pg_type typtup = (Form_pg_type) GETSTRUCT(tp);
		Oid			result;

		result = typtup->typrelid;
		ReleaseSysCache(tp);
		return result;
	}
	else
		return InvalidOid;
}

/*
 * get_element_type
 *
 *		Given the type OID, get the typelem (InvalidOid if not an array type).
 *
 * NB: this only considers varlena arrays to be true arrays; InvalidOid is
 * returned if the input is a fixed-length array type.
 */
Oid
get_element_type(Oid typid)
{
	HeapTuple	tp;

	tp = SearchSysCache(TYPEOID,
						ObjectIdGetDatum(typid),
						0, 0, 0);
	if (HeapTupleIsValid(tp))
	{
		Form_pg_type typtup = (Form_pg_type) GETSTRUCT(tp);
		Oid			result;

		if (typtup->typlen == -1)
			result = typtup->typelem;
		else
			result = InvalidOid;
		ReleaseSysCache(tp);
		return result;
	}
	else
		return InvalidOid;
}

/*
 * get_array_type
 *
 *		Given the type OID, get the corresponding array type.
 *		Returns InvalidOid if no array type can be found.
 *
 * NB: this only considers varlena arrays to be true arrays.
 */
Oid
get_array_type(Oid typid)
{
	HeapTuple	tp;

	tp = SearchSysCache(TYPEOID,
						ObjectIdGetDatum(typid),
						0, 0, 0);
	if (HeapTupleIsValid(tp))
	{
		Form_pg_type typtup = (Form_pg_type) GETSTRUCT(tp);
		char	   *array_typename;
		Oid			namespaceId;

		array_typename = makeArrayTypeName(NameStr(typtup->typname));
		namespaceId = typtup->typnamespace;
		ReleaseSysCache(tp);

		tp = SearchSysCache(TYPENAMENSP,
							PointerGetDatum(array_typename),
							ObjectIdGetDatum(namespaceId),
							0, 0);

		pfree(array_typename);

		if (HeapTupleIsValid(tp))
		{
			Oid			result;

			typtup = (Form_pg_type) GETSTRUCT(tp);
			if (typtup->typlen == -1 && typtup->typelem == typid)
				result = HeapTupleGetOid(tp);
			else
				result = InvalidOid;
			ReleaseSysCache(tp);
			return result;
		}
	}
	return InvalidOid;
}

/*
 * getTypeInputInfo
 *
 *		Get info needed for converting values of a type to internal form
 */
void
getTypeInputInfo(Oid type, Oid *typInput, Oid *typIOParam)
{
	HeapTuple	typeTuple;
	Form_pg_type pt;

	typeTuple = SearchSysCache(TYPEOID,
							   ObjectIdGetDatum(type),
							   0, 0, 0);
	if (!HeapTupleIsValid(typeTuple))
		elog(ERROR, "cache lookup failed for type %u", type);
	pt = (Form_pg_type) GETSTRUCT(typeTuple);

	if (!pt->typisdefined)
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("type %s is only a shell",
						format_type_be(type))));
	if (!OidIsValid(pt->typinput))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_FUNCTION),
				 errmsg("no input function available for type %s",
						format_type_be(type))));

	*typInput = pt->typinput;
	*typIOParam = getTypeIOParam(typeTuple);

	ReleaseSysCache(typeTuple);
}

/*
 * getTypeOutputInfo
 *
 *		Get info needed for printing values of a type
 */
void
getTypeOutputInfo(Oid type, Oid *typOutput, bool *typIsVarlena)
{
	HeapTuple	typeTuple;
	Form_pg_type pt;

	typeTuple = SearchSysCache(TYPEOID,
							   ObjectIdGetDatum(type),
							   0, 0, 0);
	if (!HeapTupleIsValid(typeTuple))
		elog(ERROR, "cache lookup failed for type %u", type);
	pt = (Form_pg_type) GETSTRUCT(typeTuple);

	if (!pt->typisdefined)
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("type %s is only a shell",
						format_type_be(type))));
	if (!OidIsValid(pt->typoutput))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_FUNCTION),
				 errmsg("no output function available for type %s",
						format_type_be(type))));

	*typOutput = pt->typoutput;
	*typIsVarlena = (!pt->typbyval) && (pt->typlen == -1);

	ReleaseSysCache(typeTuple);
}

/*
 * getTypeBinaryInputInfo
 *
 *		Get info needed for binary input of values of a type
 */
void
getTypeBinaryInputInfo(Oid type, Oid *typReceive, Oid *typIOParam)
{
	HeapTuple	typeTuple;
	Form_pg_type pt;

	typeTuple = SearchSysCache(TYPEOID,
							   ObjectIdGetDatum(type),
							   0, 0, 0);
	if (!HeapTupleIsValid(typeTuple))
		elog(ERROR, "cache lookup failed for type %u", type);
	pt = (Form_pg_type) GETSTRUCT(typeTuple);

	if (!pt->typisdefined)
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("type %s is only a shell",
						format_type_be(type))));
	if (!OidIsValid(pt->typreceive))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_FUNCTION),
				 errmsg("no binary input function available for type %s",
						format_type_be(type))));

	*typReceive = pt->typreceive;
	*typIOParam = getTypeIOParam(typeTuple);

	ReleaseSysCache(typeTuple);
}

/*
 * getTypeBinaryOutputInfo
 *
 *		Get info needed for binary output of values of a type
 */
void
getTypeBinaryOutputInfo(Oid type, Oid *typSend, bool *typIsVarlena)
{
	HeapTuple	typeTuple;
	Form_pg_type pt;

	typeTuple = SearchSysCache(TYPEOID,
							   ObjectIdGetDatum(type),
							   0, 0, 0);
	if (!HeapTupleIsValid(typeTuple))
		elog(ERROR, "cache lookup failed for type %u", type);
	pt = (Form_pg_type) GETSTRUCT(typeTuple);

	if (!pt->typisdefined)
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("type %s is only a shell",
						format_type_be(type))));
	if (!OidIsValid(pt->typsend))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_FUNCTION),
				 errmsg("no binary output function available for type %s",
						format_type_be(type))));

	*typSend = pt->typsend;
	*typIsVarlena = (!pt->typbyval) && (pt->typlen == -1);

	ReleaseSysCache(typeTuple);
}


/*				---------- STATISTICS CACHE ----------					 */

/*
 * get_attavgwidth
 *
 *	  Given the table and attribute number of a column, get the average
 *	  width of entries in the column.  Return zero if no data available.
 */
int32
get_attavgwidth(Oid relid, AttrNumber attnum)
{
	HeapTuple	tp;

	tp = SearchSysCache(STATRELATT,
						ObjectIdGetDatum(relid),
						Int16GetDatum(attnum),
						0, 0);
	if (HeapTupleIsValid(tp))
	{
		int32		stawidth = ((Form_pg_statistic) GETSTRUCT(tp))->stawidth;

		ReleaseSysCache(tp);
		if (stawidth > 0)
			return stawidth;
	}
	return 0;
}

/*
 * get_attstatsslot
 *
 *		Extract the contents of a "slot" of a pg_statistic tuple.
 *		Returns TRUE if requested slot type was found, else FALSE.
 *
 * Unlike other routines in this file, this takes a pointer to an
 * already-looked-up tuple in the pg_statistic cache.  We do this since
 * most callers will want to extract more than one value from the cache
 * entry, and we don't want to repeat the cache lookup unnecessarily.
 *
 * statstuple: pg_statistics tuple to be examined.
 * atttype: type OID of attribute (can be InvalidOid if values == NULL).
 * atttypmod: typmod of attribute (can be 0 if values == NULL).
 * reqkind: STAKIND code for desired statistics slot kind.
 * reqop: STAOP value wanted, or InvalidOid if don't care.
 * values, nvalues: if not NULL, the slot's stavalues are extracted.
 * numbers, nnumbers: if not NULL, the slot's stanumbers are extracted.
 *
 * If assigned, values and numbers are set to point to palloc'd arrays.
 * If the attribute type is pass-by-reference, the values referenced by
 * the values array are themselves palloc'd.  The palloc'd stuff can be
 * freed by calling free_attstatsslot.
 */
bool
get_attstatsslot(HeapTuple statstuple,
				 Oid atttype, int32 atttypmod,
				 int reqkind, Oid reqop,
				 Datum **values, int *nvalues,
				 float4 **numbers, int *nnumbers)
{
	Form_pg_statistic stats = (Form_pg_statistic) GETSTRUCT(statstuple);
	int			i,
				j;
	Datum		val;
	bool		isnull;
	ArrayType  *statarray;
	int			narrayelem;
	HeapTuple	typeTuple;
	Form_pg_type typeForm;

	for (i = 0; i < STATISTIC_NUM_SLOTS; i++)
	{
		if ((&stats->stakind1)[i] == reqkind &&
			(reqop == InvalidOid || (&stats->staop1)[i] == reqop))
			break;
	}
	if (i >= STATISTIC_NUM_SLOTS)
		return false;			/* not there */

	if (values)
	{
		val = SysCacheGetAttr(STATRELATT, statstuple,
							  Anum_pg_statistic_stavalues1 + i,
							  &isnull);
		if (isnull)
			elog(ERROR, "stavalues is null");
		statarray = DatumGetArrayTypeP(val);

		/* Need to get info about the array element type */
		typeTuple = SearchSysCache(TYPEOID,
								   ObjectIdGetDatum(atttype),
								   0, 0, 0);
		if (!HeapTupleIsValid(typeTuple))
			elog(ERROR, "cache lookup failed for type %u", atttype);
		typeForm = (Form_pg_type) GETSTRUCT(typeTuple);

		/* Deconstruct array into Datum elements */
		deconstruct_array(statarray,
						  atttype,
						  typeForm->typlen,
						  typeForm->typbyval,
						  typeForm->typalign,
						  values, nvalues);

		/*
		 * If the element type is pass-by-reference, we now have a bunch of
		 * Datums that are pointers into the syscache value.  Copy them to
		 * avoid problems if syscache decides to drop the entry.
		 */
		if (!typeForm->typbyval)
		{
			for (j = 0; j < *nvalues; j++)
			{
				(*values)[j] = datumCopy((*values)[j],
										 typeForm->typbyval,
										 typeForm->typlen);
			}
		}

		ReleaseSysCache(typeTuple);

		/*
		 * Free statarray if it's a detoasted copy.
		 */
		if ((Pointer) statarray != DatumGetPointer(val))
			pfree(statarray);
	}

	if (numbers)
	{
		val = SysCacheGetAttr(STATRELATT, statstuple,
							  Anum_pg_statistic_stanumbers1 + i,
							  &isnull);
		if (isnull)
			elog(ERROR, "stanumbers is null");
		statarray = DatumGetArrayTypeP(val);

		/*
		 * We expect the array to be a 1-D float4 array; verify that. We don't
		 * need to use deconstruct_array() since the array data is just going
		 * to look like a C array of float4 values.
		 */
		narrayelem = ARR_DIMS(statarray)[0];
		if (ARR_NDIM(statarray) != 1 || narrayelem <= 0 ||
			ARR_ELEMTYPE(statarray) != FLOAT4OID)
			elog(ERROR, "stanumbers is not a 1-D float4 array");
		*numbers = (float4 *) palloc(narrayelem * sizeof(float4));
		memcpy(*numbers, ARR_DATA_PTR(statarray), narrayelem * sizeof(float4));
		*nnumbers = narrayelem;

		/*
		 * Free statarray if it's a detoasted copy.
		 */
		if ((Pointer) statarray != DatumGetPointer(val))
			pfree(statarray);
	}

	return true;
}

/*
 * free_attstatsslot
 *		Free data allocated by get_attstatsslot
 *
 * atttype need be valid only if values != NULL.
 */
void
free_attstatsslot(Oid atttype,
				  Datum *values, int nvalues,
				  float4 *numbers, int nnumbers)
{
	if (values)
	{
		if (!get_typbyval(atttype))
		{
			int			i;

			for (i = 0; i < nvalues; i++)
				pfree(DatumGetPointer(values[i]));
		}
		pfree(values);
	}
	if (numbers)
		pfree(numbers);
}

/*				---------- PG_NAMESPACE CACHE ----------				 */

/*
 * get_namespace_name
 *		Returns the name of a given namespace
 *
 * Returns a palloc'd copy of the string, or NULL if no such namespace.
 */
char *
get_namespace_name(Oid nspid)
{
	HeapTuple	tp;

	tp = SearchSysCache(NAMESPACEOID,
						ObjectIdGetDatum(nspid),
						0, 0, 0);
	if (HeapTupleIsValid(tp))
	{
		Form_pg_namespace nsptup = (Form_pg_namespace) GETSTRUCT(tp);
		char	   *result;

		result = pstrdup(NameStr(nsptup->nspname));
		ReleaseSysCache(tp);
		return result;
	}
	else
		return NULL;
}

/*				---------- PG_AUTHID CACHE ----------					 */

/*
 * get_roleid
 *	  Given a role name, look up the role's OID.
 *	  Returns InvalidOid if no such role.
 */
Oid
get_roleid(const char *rolname)
{
	return GetSysCacheOid(AUTHNAME,
						  PointerGetDatum(rolname),
						  0, 0, 0);
}

/*
 * get_roleid_checked
 *	  Given a role name, look up the role's OID.
 *	  ereports if no such role.
 */
Oid
get_roleid_checked(const char *rolname)
{
	Oid			roleid;

	roleid = get_roleid(rolname);
	if (!OidIsValid(roleid))
		ereport(ERROR,
				(errcode(ERRCODE_UNDEFINED_OBJECT),
				 errmsg("role \"%s\" does not exist", rolname)));
	return roleid;
}