heaptuple.c

postgresql8.3.4源码,开源数据库

				 att[i]->attndims == 0 &&
				 !VARATT_IS_EXTENDED(values[i]))
		{
			values[i] = toast_flatten_tuple_attribute(values[i],
													  att[i]->atttypid,
													  att[i]->atttypmod);
		}
	}

	/*
	 * Determine total space needed
	 */
	len = offsetof(HeapTupleHeaderData, t_bits);

	if (hasnull)
		len += BITMAPLEN(numberOfAttributes);

	if (tupleDescriptor->tdhasoid)
		len += sizeof(Oid);

	hoff = len = MAXALIGN(len); /* align user data safely */

	data_len = ComputeDataSize(tupleDescriptor, values, nulls);

	len += data_len;

	/*
	 * Allocate and zero the space needed.	Note that the tuple body and
	 * HeapTupleData management structure are allocated in one chunk.
	 */
	tuple = (HeapTuple) palloc0(HEAPTUPLESIZE + len);
	tuple->t_data = td = (HeapTupleHeader) ((char *) tuple + HEAPTUPLESIZE);

	/*
	 * And fill in the information.  Note we fill the Datum fields even though
	 * this tuple may never become a Datum.
	 */
	tuple->t_len = len;
	ItemPointerSetInvalid(&(tuple->t_self));
	tuple->t_tableOid = InvalidOid;

	HeapTupleHeaderSetDatumLength(td, len);
	HeapTupleHeaderSetTypeId(td, tupleDescriptor->tdtypeid);
	HeapTupleHeaderSetTypMod(td, tupleDescriptor->tdtypmod);

	HeapTupleHeaderSetNatts(td, numberOfAttributes);
	td->t_hoff = hoff;

	if (tupleDescriptor->tdhasoid)		/* else leave infomask = 0 */
		td->t_infomask = HEAP_HASOID;

	DataFill(tupleDescriptor,
			 values,
			 nulls,
			 (char *) td + hoff,
			 data_len,
			 &td->t_infomask,
			 (hasnull ? td->t_bits : NULL));

	return tuple;
}


/*
 * heap_modify_tuple
 *		form a new tuple from an old tuple and a set of replacement values.
 *
 * The replValues, replIsnull, and doReplace arrays must be of the length
 * indicated by tupleDesc->natts.  The new tuple is constructed using the data
 * from replValues/replIsnull at columns where doReplace is true, and using
 * the data from the old tuple at columns where doReplace is false.
 *
 * The result is allocated in the current memory context.
 */
HeapTuple
heap_modify_tuple(HeapTuple tuple,
				  TupleDesc tupleDesc,
				  Datum *replValues,
				  bool *replIsnull,
				  bool *doReplace)
{
	int			numberOfAttributes = tupleDesc->natts;
	int			attoff;
	Datum	   *values;
	bool	   *isnull;
	HeapTuple	newTuple;

	/*
	 * allocate and fill values and isnull arrays from either the tuple or the
	 * repl information, as appropriate.
	 *
	 * NOTE: it's debatable whether to use heap_deform_tuple() here or just
	 * heap_getattr() only the non-replaced colums.  The latter could win if
	 * there are many replaced columns and few non-replaced ones. However,
	 * heap_deform_tuple costs only O(N) while the heap_getattr way would cost
	 * O(N^2) if there are many non-replaced columns, so it seems better to
	 * err on the side of linear cost.
	 */
	values = (Datum *) palloc(numberOfAttributes * sizeof(Datum));
	isnull = (bool *) palloc(numberOfAttributes * sizeof(bool));

	heap_deform_tuple(tuple, tupleDesc, values, isnull);

	for (attoff = 0; attoff < numberOfAttributes; attoff++)
	{
		if (doReplace[attoff])
		{
			values[attoff] = replValues[attoff];
			isnull[attoff] = replIsnull[attoff];
		}
	}

	/*
	 * create a new tuple from the values and isnull arrays
	 */
	newTuple = heap_form_tuple(tupleDesc, values, isnull);

	pfree(values);
	pfree(isnull);

	/*
	 * copy the identification info of the old tuple: t_ctid, t_self, and OID
	 * (if any)
	 */
	newTuple->t_data->t_ctid = tuple->t_data->t_ctid;
	newTuple->t_self = tuple->t_self;
	newTuple->t_tableOid = tuple->t_tableOid;
	if (tupleDesc->tdhasoid)
		HeapTupleSetOid(newTuple, HeapTupleGetOid(tuple));

	return newTuple;
}

/* ----------------
 *		heap_modifytuple
 *
 *		forms a new tuple from an old tuple and a set of replacement values.
 *		returns a new palloc'ed tuple.
 *
 * OLD API with char 'n'/' ' convention for indicating nulls, and
 * char 'r'/' ' convention for indicating whether to replace columns.
 * ----------------
 */
HeapTuple
heap_modifytuple(HeapTuple tuple,
				 TupleDesc tupleDesc,
				 Datum *replValues,
				 char *replNulls,
				 char *replActions)
{
	int			numberOfAttributes = tupleDesc->natts;
	int			attoff;
	Datum	   *values;
	char	   *nulls;
	HeapTuple	newTuple;

	/*
	 * allocate and fill values and nulls arrays from either the tuple or the
	 * repl information, as appropriate.
	 *
	 * NOTE: it's debatable whether to use heap_deformtuple() here or just
	 * heap_getattr() only the non-replaced colums.  The latter could win if
	 * there are many replaced columns and few non-replaced ones. However,
	 * heap_deformtuple costs only O(N) while the heap_getattr way would cost
	 * O(N^2) if there are many non-replaced columns, so it seems better to
	 * err on the side of linear cost.
	 */
	values = (Datum *) palloc(numberOfAttributes * sizeof(Datum));
	nulls = (char *) palloc(numberOfAttributes * sizeof(char));

	heap_deformtuple(tuple, tupleDesc, values, nulls);

	for (attoff = 0; attoff < numberOfAttributes; attoff++)
	{
		if (replActions[attoff] == 'r')
		{
			values[attoff] = replValues[attoff];
			nulls[attoff] = replNulls[attoff];
		}
		else if (replActions[attoff] != ' ')
			elog(ERROR, "unrecognized replace flag: %d",
				 (int) replActions[attoff]);
	}

	/*
	 * create a new tuple from the values and nulls arrays
	 */
	newTuple = heap_formtuple(tupleDesc, values, nulls);

	pfree(values);
	pfree(nulls);

	/*
	 * copy the identification info of the old tuple: t_ctid, t_self, and OID
	 * (if any)
	 */
	newTuple->t_data->t_ctid = tuple->t_data->t_ctid;
	newTuple->t_self = tuple->t_self;
	newTuple->t_tableOid = tuple->t_tableOid;
	if (tupleDesc->tdhasoid)
		HeapTupleSetOid(newTuple, HeapTupleGetOid(tuple));

	return newTuple;
}

/*
 * heap_deform_tuple
 *		Given a tuple, extract data into values/isnull arrays; this is
 *		the inverse of heap_form_tuple.
 *
 *		Storage for the values/isnull arrays is provided by the caller;
 *		it should be sized according to tupleDesc->natts not tuple->t_natts.
 *
 *		Note that for pass-by-reference datatypes, the pointer placed
 *		in the Datum will point into the given tuple.
 *
 *		When all or most of a tuple's fields need to be extracted,
 *		this routine will be significantly quicker than a loop around
 *		heap_getattr; the loop will become O(N^2) as soon as any
 *		noncacheable attribute offsets are involved.
 */
void
heap_deform_tuple(HeapTuple tuple, TupleDesc tupleDesc,
				  Datum *values, bool *isnull)
{
	HeapTupleHeader tup = tuple->t_data;
	bool		hasnulls = HeapTupleHasNulls(tuple);
	Form_pg_attribute *att = tupleDesc->attrs;
	int			tdesc_natts = tupleDesc->natts;
	int			natts;			/* number of atts to extract */
	int			attnum;
	char	   *tp;				/* ptr to tuple data */
	long		off;			/* offset in tuple data */
	bits8	   *bp = tup->t_bits;		/* ptr to null bitmap in tuple */
	bool		slow = false;	/* can we use/set attcacheoff? */

	natts = HeapTupleHeaderGetNatts(tup);

	/*
	 * In inheritance situations, it is possible that the given tuple actually
	 * has more fields than the caller is expecting.  Don't run off the end of
	 * the caller's arrays.
	 */
	natts = Min(natts, tdesc_natts);

	tp = (char *) tup + tup->t_hoff;

	off = 0;

	for (attnum = 0; attnum < natts; attnum++)
	{
		Form_pg_attribute thisatt = att[attnum];

		if (hasnulls && att_isnull(attnum, bp))
		{
			values[attnum] = (Datum) 0;
			isnull[attnum] = true;
			slow = true;		/* can't use attcacheoff anymore */
			continue;
		}

		isnull[attnum] = false;

		if (!slow && thisatt->attcacheoff >= 0)
			off = thisatt->attcacheoff;
		else if (thisatt->attlen == -1)
		{
			/*
			 * We can only cache the offset for a varlena attribute if the
			 * offset is already suitably aligned, so that there would be no
			 * pad bytes in any case: then the offset will be valid for either
			 * an aligned or unaligned value.
			 */
			if (!slow &&
				off == att_align_nominal(off, thisatt->attalign))
				thisatt->attcacheoff = off;
			else
			{
				off = att_align_pointer(off, thisatt->attalign, -1,
										tp + off);
				slow = true;
			}
		}
		else
		{
			/* not varlena, so safe to use att_align_nominal */
			off = att_align_nominal(off, thisatt->attalign);

			if (!slow)
				thisatt->attcacheoff = off;
		}

		values[attnum] = fetchatt(thisatt, tp + off);

		off = att_addlength_pointer(off, thisatt->attlen, tp + off);

		if (thisatt->attlen <= 0)
			slow = true;		/* can't use attcacheoff anymore */
	}

	/*
	 * If tuple doesn't have all the atts indicated by tupleDesc, read the
	 * rest as null
	 */
	for (; attnum < tdesc_natts; attnum++)
	{
		values[attnum] = (Datum) 0;
		isnull[attnum] = true;
	}
}

/* ----------------
 *		heap_deformtuple
 *
 *		Given a tuple, extract data into values/nulls arrays; this is
 *		the inverse of heap_formtuple.
 *
 *		Storage for the values/nulls arrays is provided by the caller;
 *		it should be sized according to tupleDesc->natts not tuple->t_natts.
 *
 *		Note that for pass-by-reference datatypes, the pointer placed
 *		in the Datum will point into the given tuple.
 *
 *		When all or most of a tuple's fields need to be extracted,
 *		this routine will be significantly quicker than a loop around
 *		heap_getattr; the loop will become O(N^2) as soon as any
 *		noncacheable attribute offsets are involved.
 *
 * OLD API with char 'n'/' ' convention for indicating nulls
 * ----------------
 */
void
heap_deformtuple(HeapTuple tuple,
				 TupleDesc tupleDesc,
				 Datum *values,
				 char *nulls)
{
	HeapTupleHeader tup = tuple->t_data;
	bool		hasnulls = HeapTupleHasNulls(tuple);
	Form_pg_attribute *att = tupleDesc->attrs;
	int			tdesc_natts = tupleDesc->natts;
	int			natts;			/* number of atts to extract */
	int			attnum;
	char	   *tp;				/* ptr to tuple data */
	long		off;			/* offset in tuple data */
	bits8	   *bp = tup->t_bits;		/* ptr to null bitmap in tuple */
	bool		slow = false;	/* can we use/set attcacheoff? */

	natts = HeapTupleHeaderGetNatts(tup);

	/*
	 * In inheritance situations, it is possible that the given tuple actually
	 * has more fields than the caller is expecting.  Don't run off the end of
	 * the caller's arrays.
	 */
	natts = Min(natts, tdesc_natts);

	tp = (char *) tup + tup->t_hoff;

	off = 0;

	for (attnum = 0; attnum < natts; attnum++)
	{
		Form_pg_attribute thisatt = att[attnum];

		if (hasnulls && att_isnull(attnum, bp))
		{
			values[attnum] = (Datum) 0;
			nulls[attnum] = 'n';
			slow = true;		/* can't use attcacheoff anymore */
			continue;
		}

		nulls[attnum] = ' ';

		if (!slow && thisatt->attcacheoff >= 0)
			off = thisatt->attcacheoff;
		else if (thisatt->attlen == -1)
		{
			/*
			 * We can only cache the offset for a varlena attribute if the
			 * offset is already suitably aligned, so that there would be no
			 * pad bytes in any case: then the offset will be valid for either
			 * an aligned or unaligned value.
			 */
			if (!slow &&
				off == att_align_nominal(off, thisatt->attalign))
				thisatt->attcacheoff = off;
			else
			{
				off = att_align_pointer(off, thisatt->attalign, -1,
										tp + off);
				slow = true;
			}
		}
		else
		{
			/* not varlena, so safe to use att_align_nominal */
			off = att_align_nominal(off, thisatt->attalign);

			if (!slow)
				thisatt->attcacheoff = off;
		}

		values[attnum] = fetchatt(thisatt, tp + off);

		off = att_addlength_pointer(off, thisatt->attlen, tp + off);

		if (thisatt->attlen <= 0)
			slow = true;		/* can't use attcacheoff anymore */
	}

	/*
	 * If tuple doesn't have all the atts indicated by tupleDesc, read the
	 * rest as null
	 */
	for (; attnum < tdesc_natts; attnum++)
	{
		values[attnum] = (Datum) 0;
		nulls[attnum] = 'n';
	}
}

/*
 * slot_deform_tuple
 *		Given a TupleTableSlot, extract data from the slot's physical tuple
 *		into its Datum/isnull arrays.  Data is extracted up through the
 *		natts'th column (caller must ensure this is a legal column number).
 *
 *		This is essentially an incremental version of heap_deform_tuple:
 *		on each call we extract attributes up to the one needed, without
 *		re-computing information about previously extracted attributes.
 *		slot->tts_nvalid is the number of attributes already extracted.
 */
static void
slot_deform_tuple(TupleTableSlot *slot, int natts)
{
	HeapTuple	tuple = slot->tts_tuple;
	TupleDesc	tupleDesc = slot->tts_tupleDescriptor;
	Datum	   *values = slot->tts_values;
	bool	   *isnull = slot->tts_isnull;
	HeapTupleHeader tup = tuple->t_data;
	bool		hasnulls = HeapTupleHasNulls(tuple);
	Form_pg_attribute *att = tupleDesc->attrs;
	int			attnum;
	char	   *tp;				/* ptr to tuple data */
	long		off;			/* offset in tuple data */
	bits8	   *bp = tup->t_bits;		/* ptr to null bitmap in tuple */
	bool		slow;			/* can we use/set attcacheoff? */

	/*
	 * Check whether the first call for this tuple, and initialize or restore
	 * loop state.
	 */
	attnum = slot->tts_nvalid;
	if (attnum == 0)
	{
		/* Start from the first attribute */
		off = 0;
		slow = false;
	}
	else
	{
		/* Restore state from previous execution */
		off = slot->tts_off;
		slow = slot->tts_slow;
	}

	tp = (char *) tup + tup->t_hoff;

	for (; attnum < natts; attnum++)
	{
		Form_pg_attribute thisatt = att[attnum];

		if (hasnulls && att_isnull(attnum, bp))
		{
			values[attnum] = (Datum) 0;
			isnull[attnum] = true;
			slow = true;		/* can't use attcacheoff anymore */
			continue;
		}

		isnull[attnum] = false;

		if (!slow && thisatt->attcacheoff >= 0)
			off = thisatt->attcacheoff;
		else if (thisatt->attlen == -1)
		{
			/*
			 * We can only cache the offset for a varlena attribute if the
			 * offset is already suitably aligned, so that there would be no
			 * pad bytes in any case: then the offset will be valid for either
			 * an aligned or unaligned value.
			 */
			if (!slow &&
				off == att_align_nominal(off, thisatt->attalign))
				thisatt->attcacheoff = off;
			else
			{
				off = att_align_pointer(off, thisatt->attalign, -1,
										tp + off);