/*
 * HeapTupleSatisfiesToast
 *		True iff heap tuple is valid as a TOAST row.
 *
 * This is a simplified version that only checks for VACUUM moving conditions.
 * It's appropriate for TOAST usage because TOAST really doesn't want to do
 * its own time qual checks; if you can see the main table row that contains
 * a TOAST reference, you should be able to see the TOASTed value.  However,
 * vacuuming a TOAST table is independent of the main table, and in case such
 * a vacuum fails partway through, we'd better do this much checking.
 *
 * Among other things, this means you can't do UPDATEs of rows in a TOAST
 * table.
 */
bool
HeapTupleSatisfiesToast(HeapTuple htup, Snapshot snapshot,
						Buffer buffer)
{
	HeapTupleHeader tuple = htup->t_data;

	Assert(ItemPointerIsValid(&htup->t_self));
	Assert(htup->t_tableOid != InvalidOid);

	if (!HeapTupleHeaderXminCommitted(tuple))
	{
		if (HeapTupleHeaderXminInvalid(tuple))
			return false;

		/* Used by pre-9.0 binary upgrades */
		if (tuple->t_infomask & HEAP_MOVED_OFF)
		{
			TransactionId xvac = HeapTupleHeaderGetXvac(tuple);

			if (TransactionIdIsCurrentTransactionId(xvac))
				return false;
			if (!TransactionIdIsInProgress(xvac))
			{
				if (TransactionIdDidCommit(xvac))
				{
					SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
								InvalidTransactionId);
					return false;
				}
				SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
							InvalidTransactionId);
			}
		}
		/* Used by pre-9.0 binary upgrades */
		else if (tuple->t_infomask & HEAP_MOVED_IN)
		{
			TransactionId xvac = HeapTupleHeaderGetXvac(tuple);

			if (!TransactionIdIsCurrentTransactionId(xvac))
			{
				if (TransactionIdIsInProgress(xvac))
					return false;
				if (TransactionIdDidCommit(xvac))
					SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
								InvalidTransactionId);
				else
				{
					SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
								InvalidTransactionId);
					return false;
				}
			}
		}
	}

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

/*
 * HeapTupleSatisfiesToast
 *		True iff heap tuple is valid as a TOAST row.
 *
 * This is a simplified version that only checks for VACUUM moving conditions.
 * It's appropriate for TOAST usage because TOAST really doesn't want to do
 * its own time qual checks; if you can see the main table row that contains
 * a TOAST reference, you should be able to see the TOASTed value.	However,
 * vacuuming a TOAST table is independent of the main table, and in case such
 * a vacuum fails partway through, we'd better do this much checking.
 *
 * Among other things, this means you can't do UPDATEs of rows in a TOAST
 * table.
 */
bool
HeapTupleSatisfiesToast(HeapTupleHeader tuple, Snapshot snapshot,
						Buffer buffer)
{
	if (!(tuple->t_infomask & HEAP_XMIN_COMMITTED))
	{
		if (tuple->t_infomask & HEAP_XMIN_INVALID)
			return false;

		/* Used by pre-9.0 binary upgrades */
		if (tuple->t_infomask & HEAP_MOVED_OFF)
		{
			TransactionId xvac = HeapTupleHeaderGetXvac(tuple);

			if (TransactionIdIsCurrentTransactionId(xvac))
				return false;
			if (!TransactionIdIsInProgress(xvac))
			{
				if (TransactionIdDidCommit(xvac))
				{
					SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
								InvalidTransactionId);
					return false;
				}
				SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
							InvalidTransactionId);
			}
		}
		/* Used by pre-9.0 binary upgrades */
		else if (tuple->t_infomask & HEAP_MOVED_IN)
		{
			TransactionId xvac = HeapTupleHeaderGetXvac(tuple);

			if (!TransactionIdIsCurrentTransactionId(xvac))
			{
				if (TransactionIdIsInProgress(xvac))
					return false;
				if (TransactionIdDidCommit(xvac))
					SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
								InvalidTransactionId);
				else
				{
					SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
								InvalidTransactionId);
					return false;
				}
			}
		}
	}

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

/*
 * HeapTupleSatisfiesToast
 *		True iff heap tuple is valid as a TOAST row.
 *
 * This is a simplified version that only checks for VACUUM moving conditions.
 * It's appropriate for TOAST usage because TOAST really doesn't want to do
 * its own time qual checks; if you can see the main table row that contains
 * a TOAST reference, you should be able to see the TOASTed value.	However,
 * vacuuming a TOAST table is independent of the main table, and in case such
 * a vacuum fails partway through, we'd better do this much checking.
 *
 * Among other things, this means you can't do UPDATEs of rows in a TOAST
 * table.
 */
bool
HeapTupleSatisfiesToast(HeapTupleHeader tuple)
{
	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;
					return false;
				}
				tuple->t_infomask |= HEAP_XMIN_COMMITTED;
			}
		}
		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;
				else
				{
					tuple->t_infomask |= HEAP_XMIN_INVALID;
					return false;
				}
			}
		}
	}

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

CommandId
HeapTupleHeaderGetCmax(HeapTupleHeader tup)
{
	CommandId	cid = HeapTupleHeaderGetRawCommandId(tup);

	Assert(!(tup->t_infomask & HEAP_MOVED));
	Assert(TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetUpdateXid(tup)));

	if (tup->t_infomask & HEAP_COMBOCID)
		return GetRealCmax(cid);
	else
		return cid;
}

CommandId
HeapTupleHeaderGetCmax(HeapTupleHeader tup)
{
	CommandId	cid = HeapTupleHeaderGetRawCommandId(tup);

	/* We do not store cmax when locking a tuple */
	Assert(!(tup->t_infomask & (HEAP_MOVED | HEAP_IS_LOCKED)));
	Assert(TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tup)));

	if (tup->t_infomask & HEAP_COMBOCID)
		return GetRealCmax(cid);
	else
		return cid;
}

CommandId
HeapTupleHeaderGetCmax(HeapTupleHeader tup)
{
	CommandId	cid = HeapTupleHeaderGetRawCommandId(tup);

	/* We do not store cmax when locking a tuple */
	Assert(!(tup->t_infomask & (HEAP_MOVED | HEAP_IS_LOCKED)));

	/*
	 * MPP-8317: cursors can't always *tell* that this is the current transaction.
	 */
	Assert(QEDtxContextInfo.cursorContext || TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tup)));

	if (tup->t_infomask & HEAP_COMBOCID)
		return GetRealCmax(HeapTupleHeaderGetXmin(tup), cid);
	else
		return cid;
}

/*
 * Is the tuple really only locked?  That is, is it not updated?
 *
 * It's easy to check just infomask bits if the locker is not a multi; but
 * otherwise we need to verify that the updating transaction has not aborted.
 *
 * This function is here because it follows the same time qualification rules
 * laid out at the top of this file.
 */
bool
HeapTupleHeaderIsOnlyLocked(HeapTupleHeader tuple)
{
	TransactionId xmax;

	/* if there's no valid Xmax, then there's obviously no update either */
	if (tuple->t_infomask & HEAP_XMAX_INVALID)
		return true;

	if (tuple->t_infomask & HEAP_XMAX_LOCK_ONLY)
		return true;

	/* invalid xmax means no update */
	if (!TransactionIdIsValid(HeapTupleHeaderGetRawXmax(tuple)))
		return true;

	/*
	 * if HEAP_XMAX_LOCK_ONLY is not set and not a multi, then this must
	 * necessarily have been updated
	 */
	if (!(tuple->t_infomask & HEAP_XMAX_IS_MULTI))
		return false;

	/* ... but if it's a multi, then perhaps the updating Xid aborted. */
	xmax = HeapTupleGetUpdateXid(tuple);

	/* not LOCKED_ONLY, so it has to have an xmax */
	Assert(TransactionIdIsValid(xmax));

	if (TransactionIdIsCurrentTransactionId(xmax))
		return false;
	if (TransactionIdIsInProgress(xmax))
		return false;
	if (TransactionIdDidCommit(xmax))
		return false;

	/*
	 * not current, not in progress, not committed -- must have aborted or
	 * crashed
	 */
	return true;
}

CommandId
HeapTupleHeaderGetCmax(HeapTupleHeader tup)
{
	CommandId	cid = HeapTupleHeaderGetRawCommandId(tup);

	Assert(!(tup->t_infomask & HEAP_MOVED));
	/*
	 * Because GetUpdateXid() performs memory allocations if xmax is a
	 * multixact we can't Assert() if we're inside a critical section. This
	 * weakens the check, but not using GetCmax() inside one would complicate
	 * things too much.
	 */
	Assert(CritSectionCount > 0 ||
		   TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetUpdateXid(tup)));

	if (tup->t_infomask & HEAP_COMBOCID)
		return GetRealCmax(cid);
	else
		return cid;
}

/*
 * Given a tuple we are about to delete, determine the correct value to store
 * into its t_cid field.
 *
 * If we don't need a combo CID, *cmax is unchanged and *iscombo is set to
 * FALSE.  If we do need one, *cmax is replaced by a combo CID and *iscombo
 * is set to TRUE.
 *
 * The reason this is separate from the actual HeapTupleHeaderSetCmax()
 * operation is that this could fail due to out-of-memory conditions.  Hence
 * we need to do this before entering the critical section that actually
 * changes the tuple in shared buffers.
 */
void
HeapTupleHeaderAdjustCmax(HeapTupleHeader tup,
						  CommandId *cmax,
						  bool *iscombo)
{
	/*
	 * If we're marking a tuple deleted that was inserted by (any
	 * subtransaction of) our transaction, we need to use a combo command id.
	 * Test for HeapTupleHeaderXminCommitted() first, because it's cheaper than a
	 * TransactionIdIsCurrentTransactionId call.
	 */
	if (!HeapTupleHeaderXminCommitted(tup) &&
		TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetRawXmin(tup)))
	{
		CommandId	cmin = HeapTupleHeaderGetCmin(tup);

		*cmax = GetComboCommandId(cmin, *cmax);
		*iscombo = true;
	}
	else
	{
		*iscombo = false;
	}
}

/*
 * HeapTupleSatisfiesMVCC
 *		True iff heap tuple is valid for the given MVCC 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
 *
 * (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
HeapTupleSatisfiesMVCC(HeapTuple htup, Snapshot snapshot,
					   Buffer buffer)
{
	HeapTupleHeader tuple = htup->t_data;

	Assert(ItemPointerIsValid(&htup->t_self));
	Assert(htup->t_tableOid != InvalidOid);

	if (!HeapTupleHeaderXminCommitted(tuple))
	{
		if (HeapTupleHeaderXminInvalid(tuple))
			return false;

		/* Used by pre-9.0 binary upgrades */
		if (tuple->t_infomask & HEAP_MOVED_OFF)
		{
			TransactionId xvac = HeapTupleHeaderGetXvac(tuple);

			if (TransactionIdIsCurrentTransactionId(xvac))
				return false;
			if (!TransactionIdIsInProgress(xvac))
			{
				if (TransactionIdDidCommit(xvac))
				{
					SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
								InvalidTransactionId);
					return false;
				}
				SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
							InvalidTransactionId);
			}
		}
		/* Used by pre-9.0 binary upgrades */
		else if (tuple->t_infomask & HEAP_MOVED_IN)
		{
			TransactionId xvac = HeapTupleHeaderGetXvac(tuple);

			if (!TransactionIdIsCurrentTransactionId(xvac))
			{
				if (TransactionIdIsInProgress(xvac))
					return false;
				if (TransactionIdDidCommit(xvac))
					SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
								InvalidTransactionId);
				else
				{
					SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
								InvalidTransactionId);
					return false;
				}
			}
		}
		else if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetRawXmin(tuple)))
		{
			if (HeapTupleHeaderGetCmin(tuple) >= snapshot->curcid)
				return false;	/* inserted after scan started */

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

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

			if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
			{
				TransactionId xmax;

				xmax = HeapTupleGetUpdateXid(tuple);

				/* not LOCKED_ONLY, so it has to have an xmax */
				Assert(TransactionIdIsValid(xmax));

				/* updating subtransaction must have aborted */
				if (!TransactionIdIsCurrentTransactionId(xmax))
					return true;
				else if (HeapTupleHeaderGetCmax(tuple) >= snapshot->curcid)
					return true;	/* updated after scan started */
				else
					return false;		/* updated before scan started */
			}

			if (!TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetRawXmax(tuple)))
//.........这里部分代码省略.........

/*
 * 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.  (Note: this includes
 *	the case where the tuple is share-locked by a MultiXact, even if the
 *	MultiXact includes the current transaction.  Callers that want to
 *	distinguish that case must test for it themselves.)
 */
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;

		/* Used by pre-9.0 binary upgrades */
		if (tuple->t_infomask & HEAP_MOVED_OFF)
		{
			TransactionId xvac = HeapTupleHeaderGetXvac(tuple);

			if (TransactionIdIsCurrentTransactionId(xvac))
				return HeapTupleInvisible;
			if (!TransactionIdIsInProgress(xvac))
			{
				if (TransactionIdDidCommit(xvac))
				{
					SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
								InvalidTransactionId);
					return HeapTupleInvisible;
				}
				SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
							InvalidTransactionId);
			}
		}
		/* Used by pre-9.0 binary upgrades */
		else if (tuple->t_infomask & HEAP_MOVED_IN)
		{
			TransactionId xvac = HeapTupleHeaderGetXvac(tuple);

			if (!TransactionIdIsCurrentTransactionId(xvac))
			{
				if (TransactionIdIsInProgress(xvac))
					return HeapTupleInvisible;
				if (TransactionIdDidCommit(xvac))
					SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
								InvalidTransactionId);
				else
				{
					SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
								InvalidTransactionId);
					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 (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask))	/* not deleter */
				return HeapTupleMayBeUpdated;

			if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
			{
				TransactionId xmax;

				xmax = HeapTupleGetUpdateXid(tuple);
				if (!TransactionIdIsValid(xmax))
					return HeapTupleMayBeUpdated;

				/* updating subtransaction must have aborted */
				if (!TransactionIdIsCurrentTransactionId(xmax))
					return HeapTupleMayBeUpdated;
				else
				{
					if (HeapTupleHeaderGetCmax(tuple) >= curcid)
//.........这里部分代码省略.........

/*
 * HeapTupleSatisfiesUpdate
 *
 *	This function returns a more detailed result code than most of the
 *	functions in this file, since UPDATE needs to know more than "is it
 *	visible?".  It also allows for user-supplied CommandId rather than
 *	relying on 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.  (Note: this includes
 *	the case where the tuple is share-locked by a MultiXact, even if the
 *	MultiXact includes the current transaction.  Callers that want to
 *	distinguish that case must test for it themselves.)
 */
HTSU_Result
HeapTupleSatisfiesUpdate(HeapTuple htup, CommandId curcid,
						 Buffer buffer)
{
	HeapTupleHeader tuple = htup->t_data;

	Assert(ItemPointerIsValid(&htup->t_self));
	Assert(htup->t_tableOid != InvalidOid);

	if (!HeapTupleHeaderXminCommitted(tuple))
	{
		if (HeapTupleHeaderXminInvalid(tuple))
			return HeapTupleInvisible;

		/* Used by pre-9.0 binary upgrades */
		if (tuple->t_infomask & HEAP_MOVED_OFF)
		{
			TransactionId xvac = HeapTupleHeaderGetXvac(tuple);

			if (TransactionIdIsCurrentTransactionId(xvac))
				return HeapTupleInvisible;
			if (!TransactionIdIsInProgress(xvac))
			{
				if (TransactionIdDidCommit(xvac))
				{
					SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
								InvalidTransactionId);
					return HeapTupleInvisible;
				}
				SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
							InvalidTransactionId);
			}
		}
		/* Used by pre-9.0 binary upgrades */
		else if (tuple->t_infomask & HEAP_MOVED_IN)
		{
			TransactionId xvac = HeapTupleHeaderGetXvac(tuple);

			if (!TransactionIdIsCurrentTransactionId(xvac))
			{
				if (TransactionIdIsInProgress(xvac))
					return HeapTupleInvisible;
				if (TransactionIdDidCommit(xvac))
					SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
								InvalidTransactionId);
				else
				{
					SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
								InvalidTransactionId);
					return HeapTupleInvisible;
				}
			}
		}
		else if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetRawXmin(tuple)))
		{
			if (HeapTupleHeaderGetCmin(tuple) >= curcid)
				return HeapTupleInvisible;		/* inserted after scan started */

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

			if (HEAP_XMAX_IS_LOCKED_ONLY(tuple->t_infomask))
			{
				TransactionId xmax;

				xmax = HeapTupleHeaderGetRawXmax(tuple);

				/*
				 * Careful here: even though this tuple was created by our own
				 * transaction, it might be locked by other transactions, if
				 * the original version was key-share locked when we updated
				 * it.
				 */
//.........这里部分代码省略.........

/*
 * 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 HeapTupleSatisfiesSelf 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.
 *
 * A special hack is that the passed-in snapshot struct is used as an
 * output argument to return the xids of concurrent xacts that affected the
 * tuple.  snapshot->xmin is set to the tuple's xmin if that is another
 * transaction that's still in progress; or to InvalidTransactionId if the
 * tuple's xmin is committed good, committed dead, or my own xact.  Similarly
 * for snapshot->xmax and the tuple's xmax.
 */
bool
HeapTupleSatisfiesDirty(HeapTuple htup, Snapshot snapshot,
						Buffer buffer)
{
	HeapTupleHeader tuple = htup->t_data;

	Assert(ItemPointerIsValid(&htup->t_self));
	Assert(htup->t_tableOid != InvalidOid);

	snapshot->xmin = snapshot->xmax = InvalidTransactionId;

	if (!HeapTupleHeaderXminCommitted(tuple))
	{
		if (HeapTupleHeaderXminInvalid(tuple))
			return false;

		/* Used by pre-9.0 binary upgrades */
		if (tuple->t_infomask & HEAP_MOVED_OFF)
		{
			TransactionId xvac = HeapTupleHeaderGetXvac(tuple);

			if (TransactionIdIsCurrentTransactionId(xvac))
				return false;
			if (!TransactionIdIsInProgress(xvac))
			{
				if (TransactionIdDidCommit(xvac))
				{
					SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
								InvalidTransactionId);
					return false;
				}
				SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
							InvalidTransactionId);
			}
		}
		/* Used by pre-9.0 binary upgrades */
		else if (tuple->t_infomask & HEAP_MOVED_IN)
		{
			TransactionId xvac = HeapTupleHeaderGetXvac(tuple);

			if (!TransactionIdIsCurrentTransactionId(xvac))
			{
				if (TransactionIdIsInProgress(xvac))
					return false;
				if (TransactionIdDidCommit(xvac))
					SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
								InvalidTransactionId);
				else
				{
					SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
								InvalidTransactionId);
					return false;
				}
			}
		}
		else if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetRawXmin(tuple)))
		{
			if (tuple->t_infomask & HEAP_XMAX_INVALID)	/* xid invalid */
				return true;

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

			if (tuple->t_infomask & HEAP_XMAX_IS_MULTI)
			{
				TransactionId xmax;

				xmax = HeapTupleGetUpdateXid(tuple);

				/* not LOCKED_ONLY, so it has to have an xmax */
				Assert(TransactionIdIsValid(xmax));

				/* updating subtransaction must have aborted */
				if (!TransactionIdIsCurrentTransactionId(xmax))
					return true;
				else
					return false;
			}

			if (!TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetRawXmax(tuple)))
//.........这里部分代码省略.........

/*
 * 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.
 */
int
HeapTupleSatisfiesUpdate(HeapTupleHeader tuple, CommandId curcid)
{
	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;
					return HeapTupleInvisible;
				}
				tuple->t_infomask |= HEAP_XMIN_COMMITTED;
			}
		}
		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;
				else
				{
					tuple->t_infomask |= HEAP_XMIN_INVALID;
					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;

			Assert(TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tuple)));

			if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
				return HeapTupleMayBeUpdated;

			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;
		else
		{
			/* it must have aborted or crashed */
			tuple->t_infomask |= HEAP_XMIN_INVALID;
			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_MARKED_FOR_UPDATE)
			return HeapTupleMayBeUpdated;
		return HeapTupleUpdated;	/* updated by other */
	}

	if (TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tuple)))
	{
		if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
			return HeapTupleMayBeUpdated;
		if (HeapTupleHeaderGetCmax(tuple) >= curcid)
			return HeapTupleSelfUpdated;		/* updated after scan
//.........这里部分代码省略.........

Datum
funny_dup17(PG_FUNCTION_ARGS)
{
	TriggerData *trigdata = (TriggerData *) fcinfo->context;
	TransactionId *xid;
	int		   *level;
	bool	   *recursion;
	Relation	rel;
	TupleDesc	tupdesc;
	HeapTuple	tuple;
	char	   *query,
			   *fieldval,
			   *fieldtype;
	char	   *when;
	int			inserted;
	int			selected = 0;
	int			ret;

	if (!CALLED_AS_TRIGGER(fcinfo))
		elog(ERROR, "funny_dup17: not fired by trigger manager");

	tuple = trigdata->tg_trigtuple;
	rel = trigdata->tg_relation;
	tupdesc = rel->rd_att;
	if (TRIGGER_FIRED_BEFORE(trigdata->tg_event))
	{
		xid = &fd17b_xid;
		level = &fd17b_level;
		recursion = &fd17b_recursion;
		when = "BEFORE";
	}
	else
	{
		xid = &fd17a_xid;
		level = &fd17a_level;
		recursion = &fd17a_recursion;
		when = "AFTER ";
	}

	if (!TransactionIdIsCurrentTransactionId(*xid))
	{
		*xid = GetCurrentTransactionId();
		*level = 0;
		*recursion = true;
	}

	if (*level == 17)
	{
		*recursion = false;
		return PointerGetDatum(tuple);
	}

	if (!(*recursion))
		return PointerGetDatum(tuple);

	(*level)++;

	SPI_connect();

	fieldval = SPI_getvalue(tuple, tupdesc, 1);
	fieldtype = SPI_gettype(tupdesc, 1);

	query = (char *) palloc(100 + NAMEDATALEN * 3 +
							strlen(fieldval) + strlen(fieldtype));

	sprintf(query, "insert into %s select * from %s where %s = '%s'::%s",
			SPI_getrelname(rel), SPI_getrelname(rel),
			SPI_fname(tupdesc, 1),
			fieldval, fieldtype);

	if ((ret = SPI_exec(query, 0)) < 0)
		elog(ERROR, "funny_dup17 (fired %s) on level %3d: SPI_exec (insert ...) returned %d",
			 when, *level, ret);

	inserted = SPI_processed;

	sprintf(query, "select count (*) from %s where %s = '%s'::%s",
			SPI_getrelname(rel),
			SPI_fname(tupdesc, 1),
			fieldval, fieldtype);

	if ((ret = SPI_exec(query, 0)) < 0)
		elog(ERROR, "funny_dup17 (fired %s) on level %3d: SPI_exec (select ...) returned %d",
			 when, *level, ret);

	if (SPI_processed > 0)
	{
		selected = DatumGetInt32(DirectFunctionCall1(int4in,
												CStringGetDatum(SPI_getvalue(
													   SPI_tuptable->vals[0],
													   SPI_tuptable->tupdesc,
																			 1
																		))));
	}

	elog(DEBUG4, "funny_dup17 (fired %s) on level %3d: %d/%d tuples inserted/selected",
		 when, *level, inserted, selected);

	SPI_finish();

//.........这里部分代码省略.........

/*
 * HeapTupleSatisfiesMVCC
 *		True iff heap tuple is valid for the given MVCC 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
HeapTupleSatisfiesMVCC(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))
				{
					SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
								InvalidTransactionId);
					return false;
				}
				SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
							InvalidTransactionId);
			}
		}
		else if (tuple->t_infomask & HEAP_MOVED_IN)
		{
			TransactionId xvac = HeapTupleHeaderGetXvac(tuple);

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

			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));

			if (!TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tuple)))
			{
				/* deleting subtransaction must have aborted */
				SetHintBits(tuple, buffer, HEAP_XMAX_INVALID,
							InvalidTransactionId);
				return true;
			}

			if (HeapTupleHeaderGetCmax(tuple) >= snapshot->curcid)
				return true;	/* deleted after scan started */
			else
				return false;	/* deleted before scan started */
		}
		else if (TransactionIdIsInProgress(HeapTupleHeaderGetXmin(tuple)))
			return false;
		else if (TransactionIdDidCommit(HeapTupleHeaderGetXmin(tuple)))
			SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
						HeapTupleHeaderGetXmin(tuple));
		else
		{
//.........这里部分代码省略.........

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

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

			Assert(TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tuple)));

			if (tuple->t_infomask & HEAP_MARKED_FOR_UPDATE)
				return true;

			if (HeapTupleHeaderGetCmax(tuple) >= snapshot->curcid)
				return true;	/* deleted after scan started */
			else
				return false;	/* deleted before scan started */
		}
		else if (TransactionIdIsInProgress(HeapTupleHeaderGetXmin(tuple)))
			return false;
		else if (TransactionIdDidCommit(HeapTupleHeaderGetXmin(tuple)))
			tuple->t_infomask |= HEAP_XMIN_COMMITTED;
		else
		{
			/* it must have aborted or crashed */
			tuple->t_infomask |= HEAP_XMIN_INVALID;
			return false;
		}
	}

	/*
	 * By here, the inserting transaction has committed - have to check
	 * when...
	 */
	if (TransactionIdFollowsOrEquals(HeapTupleHeaderGetXmin(tuple),
									 snapshot->xmin))
	{
		uint32		i;
//.........这里部分代码省略.........

/*
 * 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.  (Note: this includes
 *	the case where the tuple is share-locked by a MultiXact, even if the
 *	MultiXact includes the current transaction.  Callers that want to
 *	distinguish that case must test for it themselves.)
 */
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))
				{
					SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
								InvalidTransactionId);
					return HeapTupleInvisible;
				}
				SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
							InvalidTransactionId);
			}
		}
		else if (tuple->t_infomask & HEAP_MOVED_IN)
		{
			TransactionId xvac = HeapTupleHeaderGetXvac(tuple);

			if (!TransactionIdIsCurrentTransactionId(xvac))
			{
				if (TransactionIdIsInProgress(xvac))
					return HeapTupleInvisible;
				if (TransactionIdDidCommit(xvac))
					SetHintBits(tuple, buffer, HEAP_XMIN_COMMITTED,
								InvalidTransactionId);
				else
				{
					SetHintBits(tuple, buffer, HEAP_XMIN_INVALID,
								InvalidTransactionId);
					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));

			if (!TransactionIdIsCurrentTransactionId(HeapTupleHeaderGetXmax(tuple)))
			{
				/* deleting subtransaction must have aborted */
				SetHintBits(tuple, buffer, HEAP_XMAX_INVALID,
							InvalidTransactionId);
				return HeapTupleMayBeUpdated;
			}

			if (HeapTupleHeaderGetCmax(tuple) >= curcid)
				return HeapTupleSelfUpdated;	/* updated after scan started */
			else
				return HeapTupleInvisible;		/* updated before scan started */
		}
		else if (TransactionIdIsInProgress(HeapTupleHeaderGetXmin(tuple)))
//.........这里部分代码省略.........

/*
 * HeapTupleSatisfiesDirty
 *		True iff heap tuple is valid including effects of open tran