tqual.c

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

				if (TransactionIdDidCommit(xvac))
				{
					tuple->t_infomask |= HEAP_XMIN_INVALID;
					SetBufferCommitInfoNeedsSave(buffer);
					return false;
				}
				tuple->t_infomask |= HEAP_XMIN_COMMITTED;
				SetBufferCommitInfoNeedsSave(buffer);
			}
		}
		else if (tuple->t_infomask & HEAP_MOVED_IN)
		{
			TransactionId xvac = HeapTupleHeaderGetXvac(tuple);

			if (!TransactionIdIsCurrentTransactionId(xvac))
			{
				if (TransactionIdIsInProgress(xvac))
					return false;
				if (TransactionIdDidCommit(xvac))
				{
					tuple->t_infomask |= HEAP_XMIN_COMMITTED;
					SetBufferCommitInfoNeedsSave(buffer);
				}
				else
				{
					tuple->t_infomask |= HEAP_XMIN_INVALID;
					SetBufferCommitInfoNeedsSave(buffer);
					return false;
				}
			}
		}
	}

	/* otherwise assume the tuple is valid for TOAST. */
	return true;
}

/*
 * HeapTupleSatisfiesUpdate
 *
 *	Same logic as HeapTupleSatisfiesNow, but returns a more detailed result
 *	code, since UPDATE needs to know more than "is it visible?".  Also,
 *	tuples of my own xact are tested against the passed CommandId not
 *	CurrentCommandId.
 *
 *	The possible return codes are:
 *
 *	HeapTupleInvisible: the tuple didn't exist at all when the scan started,
 *	e.g. it was created by a later CommandId.
 *
 *	HeapTupleMayBeUpdated: The tuple is valid and visible, so it may be
 *	updated.
 *
 *	HeapTupleSelfUpdated: The tuple was updated by the current transaction,
 *	after the current scan started.
 *
 *	HeapTupleUpdated: The tuple was updated by a committed transaction.
 *
 *	HeapTupleBeingUpdated: The tuple is being updated by an in-progress
 *	transaction other than the current transaction.
 */
HTSU_Result
HeapTupleSatisfiesUpdate(HeapTupleHeader tuple, CommandId curcid,
						 Buffer buffer)
{
	if (!(tuple->t_infomask & HEAP_XMIN_COMMITTED))
	{
		if (tuple->t_infomask & HEAP_XMIN_INVALID)
			return HeapTupleInvisible;

		if (tuple->t_infomask & HEAP_MOVED_OFF)
		{
			TransactionId xvac = HeapTupleHeaderGetXvac(tuple);

			if (TransactionIdIsCurrentTransactionId(xvac))
				return HeapTupleInvisible;
			if (!TransactionIdIsInProgress(xvac))
			{
				if (TransactionIdDidCommit(xvac))
				{
					tuple->t_infomask |= HEAP_XMIN_INVALID;
					SetBufferCommitInfoNeedsSave(buffer);
					return HeapTupleInvisible;
				}
				tuple->t_infomask |= HEAP_XMIN_COMMITTED;
				SetBufferCommitInfoNeedsSave(buffer);
			}
		}
		else if (tuple->t_infomask & HEAP_MOVED_IN)
		{
			TransactionId xvac = HeapTupleHeaderGetXvac(tuple);

			if (!TransactionIdIsCurrentTransactionId(xvac))
			{
				if (TransactionIdIsInProgress(xvac))
					return HeapTupleInvisible;
				if (TransactionIdDidCommit(xvac))
				{
					tuple->t_infomask |= HEAP_XMIN_COMMITTED;
					SetBufferCommitInfoNeedsSave(buffer);
				}
				else
				{
					tuple->t_infomask |= HEAP_XMIN_INVALID;
					SetBufferCommitInfoNeedsSave(buffer);
					return HeapTupleInvisible;
				}
			}
		}
		else if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(tuple)))
		{
			if (HeapTupleHeaderGetCmin(tuple) >= curcid)
				return HeapTupleInvisible;		/* inserted after scan started */

			if (tuple->t_infomask & HEAP_XMAX_INVALID)	/* xid invalid */
				return HeapTupleMayBeUpdated;

			if (tuple->t_infomask & HEAP_IS_LOCKED)		/* not deleter */
				return HeapTupleMayBeUpdated;

			Assert(!(tuple->t_infomask & HEAP_XMAX_IS_MULTI));

			/* deleting subtransaction aborted? */
			if (TransactionIdDidAbort(HeapTupleHeaderGetXmax(tuple)))
			{
				tuple->t_infomask |= HEAP_XMAX_INVALID;
				SetBufferCommitInfoNeedsSave(buffer);
				return HeapTupleMayBeUpdated;
			}

			Assert(TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tuple)));

			if (HeapTupleHeaderGetCmax(tuple) >= curcid)
				return HeapTupleSelfUpdated;	/* updated after scan started */
			else
				return HeapTupleInvisible;		/* updated before scan started */
		}
		else if (TransactionIdIsInProgress(HeapTupleHeaderGetXmin(tuple)))
			return HeapTupleInvisible;
		else if (TransactionIdDidCommit(HeapTupleHeaderGetXmin(tuple)))
		{
			tuple->t_infomask |= HEAP_XMIN_COMMITTED;
			SetBufferCommitInfoNeedsSave(buffer);
		}
		else
		{
			/* it must have aborted or crashed */
			tuple->t_infomask |= HEAP_XMIN_INVALID;
			SetBufferCommitInfoNeedsSave(buffer);
			return HeapTupleInvisible;
		}
	}

	/* by here, the inserting transaction has committed */

	if (tuple->t_infomask & HEAP_XMAX_INVALID)	/* xid invalid or aborted */
		return HeapTupleMayBeUpdated;

	if (tuple->t_infomask & HEAP_XMAX_COMMITTED)
	{
		if (tuple->t_infomask & HEAP_IS_LOCKED)
			return HeapTupleMayBeUpdated;
		return HeapTupleUpdated;	/* updated by other */
	}

	if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
	{
		/* MultiXacts are currently only allowed to lock tuples */
		Assert(tuple->t_infomask & HEAP_IS_LOCKED);

		if (MultiXactIdIsRunning(HeapTupleHeaderGetXmax(tuple)))
			return HeapTupleBeingUpdated;
		tuple->t_infomask |= HEAP_XMAX_INVALID;
		SetBufferCommitInfoNeedsSave(buffer);
		return HeapTupleMayBeUpdated;
	}

	if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tuple)))
	{
		if (tuple->t_infomask & HEAP_IS_LOCKED)
			return HeapTupleMayBeUpdated;
		if (HeapTupleHeaderGetCmax(tuple) >= curcid)
			return HeapTupleSelfUpdated;		/* updated after scan started */
		else
			return HeapTupleInvisible;	/* updated before scan started */
	}

	if (TransactionIdIsInProgress(HeapTupleHeaderGetXmax(tuple)))
		return HeapTupleBeingUpdated;

	if (!TransactionIdDidCommit(HeapTupleHeaderGetXmax(tuple)))
	{
		/* it must have aborted or crashed */
		tuple->t_infomask |= HEAP_XMAX_INVALID;
		SetBufferCommitInfoNeedsSave(buffer);
		return HeapTupleMayBeUpdated;
	}

	/* xmax transaction committed */

	if (tuple->t_infomask & HEAP_IS_LOCKED)
	{
		tuple->t_infomask |= HEAP_XMAX_INVALID;
		SetBufferCommitInfoNeedsSave(buffer);
		return HeapTupleMayBeUpdated;
	}

	tuple->t_infomask |= HEAP_XMAX_COMMITTED;
	SetBufferCommitInfoNeedsSave(buffer);
	return HeapTupleUpdated;	/* updated by other */
}

/*
 * HeapTupleSatisfiesDirty
 *		True iff heap tuple is valid including effects of open transactions.
 *
 *	Here, we consider the effects of:
 *		all committed and in-progress transactions (as of the current instant)
 *		previous commands of this transaction
 *		changes made by the current command
 *
 * This is essentially like HeapTupleSatisfiesItself as far as effects of
 * the current transaction and committed/aborted xacts are concerned.
 * However, we also include the effects of other xacts still in progress.
 *
 * Returns extra information in the global variable SnapshotDirty, namely
 * xids of concurrent xacts that affected the tuple.  SnapshotDirty->xmin
 * is set to InvalidTransactionId if xmin is either committed good or
 * committed dead; or to xmin if that transaction is still in progress.
 * Similarly for SnapshotDirty->xmax.
 */
bool
HeapTupleSatisfiesDirty(HeapTupleHeader tuple, Buffer buffer)
{
	SnapshotDirty->xmin = SnapshotDirty->xmax = InvalidTransactionId;

	if (!(tuple->t_infomask & HEAP_XMIN_COMMITTED))
	{
		if (tuple->t_infomask & HEAP_XMIN_INVALID)
			return false;

		if (tuple->t_infomask & HEAP_MOVED_OFF)
		{
			TransactionId xvac = HeapTupleHeaderGetXvac(tuple);

			if (TransactionIdIsCurrentTransactionId(xvac))
				return false;
			if (!TransactionIdIsInProgress(xvac))
			{
				if (TransactionIdDidCommit(xvac))
				{
					tuple->t_infomask |= HEAP_XMIN_INVALID;
					SetBufferCommitInfoNeedsSave(buffer);
					return false;
				}
				tuple->t_infomask |= HEAP_XMIN_COMMITTED;
				SetBufferCommitInfoNeedsSave(buffer);
			}
		}
		else if (tuple->t_infomask & HEAP_MOVED_IN)
		{
			TransactionId xvac = HeapTupleHeaderGetXvac(tuple);

			if (!TransactionIdIsCurrentTransactionId(xvac))
			{
				if (TransactionIdIsInProgress(xvac))
					return false;
				if (TransactionIdDidCommit(xvac))
				{
					tuple->t_infomask |= HEAP_XMIN_COMMITTED;
					SetBufferCommitInfoNeedsSave(buffer);
				}
				else
				{
					tuple->t_infomask |= HEAP_XMIN_INVALID;
					SetBufferCommitInfoNeedsSave(buffer);
					return false;
				}
			}
		}
		else if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(tuple)))
		{
			if (tuple->t_infomask & HEAP_XMAX_INVALID)	/* xid invalid */
				return true;

			if (tuple->t_infomask & HEAP_IS_LOCKED)		/* not deleter */
				return true;

			Assert(!(tuple->t_infomask & HEAP_XMAX_IS_MULTI));

			/* deleting subtransaction aborted? */
			if (TransactionIdDidAbort(HeapTupleHeaderGetXmax(tuple)))
			{
				tuple->t_infomask |= HEAP_XMAX_INVALID;
				SetBufferCommitInfoNeedsSave(buffer);
				return true;
			}

			Assert(TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tuple)));

			return false;
		}
		else if (TransactionIdIsInProgress(HeapTupleHeaderGetXmin(tuple)))
		{
			SnapshotDirty->xmin = HeapTupleHeaderGetXmin(tuple);
			/* XXX shouldn't we fall through to look at xmax? */
			return true;		/* in insertion by other */
		}
		else if (TransactionIdDidCommit(HeapTupleHeaderGetXmin(tuple)))
		{
			tuple->t_infomask |= HEAP_XMIN_COMMITTED;
			SetBufferCommitInfoNeedsSave(buffer);
		}
		else
		{
			/* it must have aborted or crashed */
			tuple->t_infomask |= HEAP_XMIN_INVALID;
			SetBufferCommitInfoNeedsSave(buffer);
			return false;
		}
	}

	/* by here, the inserting transaction has committed */

	if (tuple->t_infomask & HEAP_XMAX_INVALID)	/* xid invalid or aborted */
		return true;

	if (tuple->t_infomask & HEAP_XMAX_COMMITTED)
	{
		if (tuple->t_infomask & HEAP_IS_LOCKED)
			return true;
		return false;			/* updated by other */
	}

	if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
	{
		/* MultiXacts are currently only allowed to lock tuples */
		Assert(tuple->t_infomask & HEAP_IS_LOCKED);
		return true;
	}

	if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tuple)))
	{
		if (tuple->t_infomask & HEAP_IS_LOCKED)
			return true;
		return false;
	}

	if (TransactionIdIsInProgress(HeapTupleHeaderGetXmax(tuple)))
	{
		SnapshotDirty->xmax = HeapTupleHeaderGetXmax(tuple);
		return true;
	}

	if (!TransactionIdDidCommit(HeapTupleHeaderGetXmax(tuple)))
	{
		/* it must have aborted or crashed */
		tuple->t_infomask |= HEAP_XMAX_INVALID;
		SetBufferCommitInfoNeedsSave(buffer);
		return true;
	}

	/* xmax transaction committed */

	if (tuple->t_infomask & HEAP_IS_LOCKED)
	{
		tuple->t_infomask |= HEAP_XMAX_INVALID;
		SetBufferCommitInfoNeedsSave(buffer);
		return true;
	}

	tuple->t_infomask |= HEAP_XMAX_COMMITTED;
	SetBufferCommitInfoNeedsSave(buffer);
	return false;				/* updated by other */
}

/*
 * HeapTupleSatisfiesSnapshot
 *		True iff heap tuple is valid for the given snapshot.
 *
 *	Here, we consider the effects of:
 *		all transactions committed as of the time of the given snapshot
 *		previous commands of this transaction
 *
 *	Does _not_ include:
 *		transactions shown as in-progress by the snapshot
 *		transactions started after the snapshot was taken
 *		changes made by the current command
 *
 * This is the same as HeapTupleSatisfiesNow, except that transactions that
 * were in progress or as yet unstarted when the snapshot was taken will
 * be treated as uncommitted, even if they have committed by now.
 *
 * (Notice, however, that the tuple status hint bits will be updated on the
 * basis of the true state of the transaction, even if we then pretend we
 * can't see it.)
 */
bool
HeapTupleSatisfiesSnapshot(HeapTupleHeader tuple, Snapshot snapshot,
						   Buffer buffer)
{
	if (!(tuple->t_infomask & HEAP_XMIN_COMMITTED))
	{
		if (tuple->t_infomask & HEAP_XMIN_INVALID)
			return false;

		if (tuple->t_infomask & HEAP_MOVED_OFF)
		{
			TransactionId xvac = HeapTupleHeaderGetXvac(tuple);

			if (TransactionIdIsCurrentTransactionId(xvac))
				return false;
			if (!TransactionIdIsInProgress(xvac))
			{
				if (TransactionIdDidCommit(xvac))
				{
					tuple->t_infomask |= HEAP_XMIN_INVALID;
					SetBufferCommitInfoNeedsSave(buffer);
					return false;
				}
				tuple->t_infomask |= HEAP_XMIN_COMMITTED;
				SetBufferCommitInfoNeedsSave(buffer);
			}
		}
		else if (tuple->t_infomask & HEAP_MOVED_IN)
		{
			TransactionId xvac = HeapTupleHeaderGetXvac(tuple);

			if (!TransactionIdIsCurrentTransactionId(xvac))
			{
				if (TransactionIdIsInProgress(xvac))
					return false;
				if (TransactionIdDidCommit(xvac))
				{
					tuple->t_infomask |= HEAP_XMIN_COMMITTED;
					SetBufferCommitInfoNeedsSave(buffer);
				}
				else
				{
					tuple->t_infomask |= HEAP_XMIN_INVALID;
					SetBufferCommitInfoNeedsSave(buffer);
					return false;
				}
			}
		}
		else if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmin(tuple)))
		{
			if (HeapTupleHeaderGetCmin(tuple) >= snapshot->curcid)
				return false;	/* inserted after scan started */