C++ ItemPointerSetInvalid函数代码示例

/*
 * SQL function json_populate_record
 *
 * set fields in a record from the argument json
 *
 * Code adapted shamelessly from hstore's populate_record
 * which is in turn partly adapted from record_out.
 *
 * The json is decomposed into a hash table, in which each
 * field in the record is then looked up by name.
 */
Datum
json_populate_record(PG_FUNCTION_ARGS)
{
	Oid			argtype = get_fn_expr_argtype(fcinfo->flinfo, 0);
	text	   *json;
	bool		use_json_as_text;
	HTAB	   *json_hash;
	HeapTupleHeader rec;
	Oid			tupType;
	int32		tupTypmod;
	TupleDesc	tupdesc;
	HeapTupleData tuple;
	HeapTuple	rettuple;
	RecordIOData *my_extra;
	int			ncolumns;
	int			i;
	Datum	   *values;
	bool	   *nulls;
	char		fname[NAMEDATALEN];
	JsonHashEntry hashentry;

	use_json_as_text = PG_ARGISNULL(2) ? false : PG_GETARG_BOOL(2);

	if (!type_is_rowtype(argtype))
		ereport(ERROR,
				(errcode(ERRCODE_DATATYPE_MISMATCH),
				 errmsg("first argument must be a rowtype")));

	if (PG_ARGISNULL(0))
	{
		if (PG_ARGISNULL(1))
			PG_RETURN_NULL();

		rec = NULL;

		/*
		 * have no tuple to look at, so the only source of type info is the
		 * argtype. The lookup_rowtype_tupdesc call below will error out if we
		 * don't have a known composite type oid here.
		 */
		tupType = argtype;
		tupTypmod = -1;
	}
	else
	{
		rec = PG_GETARG_HEAPTUPLEHEADER(0);

		if (PG_ARGISNULL(1))
			PG_RETURN_POINTER(rec);

		/* Extract type info from the tuple itself */
		tupType = HeapTupleHeaderGetTypeId(rec);
		tupTypmod = HeapTupleHeaderGetTypMod(rec);
	}

	json = PG_GETARG_TEXT_P(1);

	json_hash = get_json_object_as_hash(json, "json_populate_record", use_json_as_text);

	/*
	 * if the input json is empty, we can only skip the rest if we were passed
	 * in a non-null record, since otherwise there may be issues with domain
	 * nulls.
	 */
	if (hash_get_num_entries(json_hash) == 0 && rec)
		PG_RETURN_POINTER(rec);


	tupdesc = lookup_rowtype_tupdesc(tupType, tupTypmod);
	ncolumns = tupdesc->natts;

	if (rec)
	{
		/* Build a temporary HeapTuple control structure */
		tuple.t_len = HeapTupleHeaderGetDatumLength(rec);
		ItemPointerSetInvalid(&(tuple.t_self));
		tuple.t_tableOid = InvalidOid;
		tuple.t_data = rec;
	}

	/*
	 * We arrange to look up the needed I/O info just once per series of
	 * calls, assuming the record type doesn't change underneath us.
	 */
	my_extra = (RecordIOData *) fcinfo->flinfo->fn_extra;
	if (my_extra == NULL ||
		my_extra->ncolumns != ncolumns)
	{
		fcinfo->flinfo->fn_extra =
//.........这里部分代码省略.........

/*
 *	_hash_first() -- Find the first item in a scan.
 *
 *		Find the first item in the index that
 *		satisfies the qualification associated with the scan descriptor. On
 *		success, the page containing the current index tuple is read locked
 *		and pinned, and the scan's opaque data entry is updated to
 *		include the buffer.
 */
bool
_hash_first(IndexScanDesc scan, ScanDirection dir)
{
	Relation	rel = scan->indexRelation;
	HashScanOpaque so = (HashScanOpaque) scan->opaque;
	ScanKey		cur;
	uint32		hashkey;
	Bucket		bucket;
	BlockNumber blkno;
	BlockNumber oldblkno = InvalidBuffer;
	bool		retry = false;
	Buffer		buf;
	Buffer		metabuf;
	Page		page;
	HashPageOpaque opaque;
	HashMetaPage metap;
	IndexTuple	itup;
	ItemPointer current;
	OffsetNumber offnum;

	pgstat_count_index_scan(rel);

	current = &(so->hashso_curpos);
	ItemPointerSetInvalid(current);

	/*
	 * We do not support hash scans with no index qualification, because we
	 * would have to read the whole index rather than just one bucket. That
	 * creates a whole raft of problems, since we haven't got a practical way
	 * to lock all the buckets against splits or compactions.
	 */
	if (scan->numberOfKeys < 1)
		ereport(ERROR,
				(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
				 errmsg("hash indexes do not support whole-index scans")));

	/* There may be more than one index qual, but we hash only the first */
	cur = &scan->keyData[0];

	/* We support only single-column hash indexes */
	Assert(cur->sk_attno == 1);
	/* And there's only one operator strategy, too */
	Assert(cur->sk_strategy == HTEqualStrategyNumber);

	/*
	 * If the constant in the index qual is NULL, assume it cannot match any
	 * items in the index.
	 */
	if (cur->sk_flags & SK_ISNULL)
		return false;

	/*
	 * Okay to compute the hash key.  We want to do this before acquiring any
	 * locks, in case a user-defined hash function happens to be slow.
	 *
	 * If scankey operator is not a cross-type comparison, we can use the
	 * cached hash function; otherwise gotta look it up in the catalogs.
	 *
	 * We support the convention that sk_subtype == InvalidOid means the
	 * opclass input type; this is a hack to simplify life for ScanKeyInit().
	 */
	if (cur->sk_subtype == rel->rd_opcintype[0] ||
		cur->sk_subtype == InvalidOid)
		hashkey = _hash_datum2hashkey(rel, cur->sk_argument);
	else
		hashkey = _hash_datum2hashkey_type(rel, cur->sk_argument,
										   cur->sk_subtype);

	so->hashso_sk_hash = hashkey;

	/* Read the metapage */
	metabuf = _hash_getbuf(rel, HASH_METAPAGE, HASH_READ, LH_META_PAGE);
	metap = HashPageGetMeta(BufferGetPage(metabuf));

	/*
	 * Loop until we get a lock on the correct target bucket.
	 */
	for (;;)
	{
		/*
		 * Compute the target bucket number, and convert to block number.
		 */
		bucket = _hash_hashkey2bucket(hashkey,
									  metap->hashm_maxbucket,
									  metap->hashm_highmask,
									  metap->hashm_lowmask);

		blkno = BUCKET_TO_BLKNO(metap, bucket);

		/* Release metapage lock, but keep pin. */
		_hash_chgbufaccess(rel, metabuf, HASH_READ, HASH_NOLOCK);
//.........这里部分代码省略.........

/*
 * record_out		- output routine for any composite type.
 */
Datum
record_out(PG_FUNCTION_ARGS)
{
	HeapTupleHeader rec = PG_GETARG_HEAPTUPLEHEADER(0);
	Oid			tupType;
	int32		tupTypmod;
	TupleDesc	tupdesc;
	HeapTupleData tuple;
	RecordIOData *my_extra;
	bool		needComma = false;
	int			ncolumns;
	int			i;
	Datum	   *values;
	bool	   *nulls;
	StringInfoData buf;

	/* Extract type info from the tuple itself */
	tupType = HeapTupleHeaderGetTypeId(rec);
	tupTypmod = HeapTupleHeaderGetTypMod(rec);
	tupdesc = lookup_rowtype_tupdesc(tupType, tupTypmod);
	ncolumns = tupdesc->natts;

	/* Build a temporary HeapTuple control structure */
	tuple.t_len = HeapTupleHeaderGetDatumLength(rec);
	ItemPointerSetInvalid(&(tuple.t_self));
	tuple.t_tableOid = InvalidOid;
	tuple.t_data = rec;

	/*
	 * We arrange to look up the needed I/O info just once per series of
	 * calls, assuming the record type doesn't change underneath us.
	 */
	my_extra = (RecordIOData *) fcinfo->flinfo->fn_extra;
	if (my_extra == NULL ||
		my_extra->ncolumns != ncolumns)
	{
		fcinfo->flinfo->fn_extra =
			MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
							   sizeof(RecordIOData) - sizeof(ColumnIOData)
							   + ncolumns * sizeof(ColumnIOData));
		my_extra = (RecordIOData *) fcinfo->flinfo->fn_extra;
		my_extra->record_type = InvalidOid;
		my_extra->record_typmod = 0;
	}

	if (my_extra->record_type != tupType ||
		my_extra->record_typmod != tupTypmod)
	{
		MemSet(my_extra, 0,
			   sizeof(RecordIOData) - sizeof(ColumnIOData)
			   + ncolumns * sizeof(ColumnIOData));
		my_extra->record_type = tupType;
		my_extra->record_typmod = tupTypmod;
		my_extra->ncolumns = ncolumns;
	}

	values = (Datum *) palloc(ncolumns * sizeof(Datum));
	nulls = (bool *) palloc(ncolumns * sizeof(bool));

	/* Break down the tuple into fields */
	heap_deform_tuple(&tuple, tupdesc, values, nulls);

	/* And build the result string */
	initStringInfo(&buf);

	appendStringInfoChar(&buf, '(');

	for (i = 0; i < ncolumns; i++)
	{
		ColumnIOData *column_info = &my_extra->columns[i];
		Oid			column_type = tupdesc->attrs[i]->atttypid;
		char	   *value;
		char	   *tmp;
		bool		nq;

		/* Ignore dropped columns in datatype */
		if (tupdesc->attrs[i]->attisdropped)
			continue;

		if (needComma)
			appendStringInfoChar(&buf, ',');
		needComma = true;

		if (nulls[i])
		{
			/* emit nothing... */
			continue;
		}

		/*
		 * Convert the column value to text
		 */
		if (column_info->column_type != column_type)
		{
			bool		typIsVarlena;

			getTypeOutputInfo(column_type,
//.........这里部分代码省略.........

Datum
hstore_from_record(PG_FUNCTION_ARGS)
{
	HeapTupleHeader rec;
	int4		buflen;
	HStore	   *out;
	Pairs	   *pairs;
	Oid			tupType;
	int32		tupTypmod;
	TupleDesc	tupdesc;
	HeapTupleData tuple;
	RecordIOData *my_extra;
	int			ncolumns;
	int			i,
				j;
	Datum	   *values;
	bool	   *nulls;

	if (PG_ARGISNULL(0))
	{
		Oid			argtype = get_fn_expr_argtype(fcinfo->flinfo, 0);

		/*
		 * have no tuple to look at, so the only source of type info is the
		 * argtype. The lookup_rowtype_tupdesc call below will error out if we
		 * don't have a known composite type oid here.
		 */
		tupType = argtype;
		tupTypmod = -1;

		rec = NULL;
	}
	else
	{
		rec = PG_GETARG_HEAPTUPLEHEADER(0);

		/* Extract type info from the tuple itself */
		tupType = HeapTupleHeaderGetTypeId(rec);
		tupTypmod = HeapTupleHeaderGetTypMod(rec);
	}

	tupdesc = lookup_rowtype_tupdesc(tupType, tupTypmod);
	ncolumns = tupdesc->natts;

	/*
	 * We arrange to look up the needed I/O info just once per series of
	 * calls, assuming the record type doesn't change underneath us.
	 */
	my_extra = (RecordIOData *) fcinfo->flinfo->fn_extra;
	if (my_extra == NULL ||
		my_extra->ncolumns != ncolumns)
	{
		fcinfo->flinfo->fn_extra =
			MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
							   sizeof(RecordIOData) - sizeof(ColumnIOData)
							   + ncolumns * sizeof(ColumnIOData));
		my_extra = (RecordIOData *) fcinfo->flinfo->fn_extra;
		my_extra->record_type = InvalidOid;
		my_extra->record_typmod = 0;
	}

	if (my_extra->record_type != tupType ||
		my_extra->record_typmod != tupTypmod)
	{
		MemSet(my_extra, 0,
			   sizeof(RecordIOData) - sizeof(ColumnIOData)
			   + ncolumns * sizeof(ColumnIOData));
		my_extra->record_type = tupType;
		my_extra->record_typmod = tupTypmod;
		my_extra->ncolumns = ncolumns;
	}

	pairs = palloc(ncolumns * sizeof(Pairs));

	if (rec)
	{
		/* Build a temporary HeapTuple control structure */
		tuple.t_len = HeapTupleHeaderGetDatumLength(rec);
		ItemPointerSetInvalid(&(tuple.t_self));
		tuple.t_tableOid = InvalidOid;
#ifdef PGXC
		tuple.t_xc_node_id = 0;
#endif
		tuple.t_data = rec;

		values = (Datum *) palloc(ncolumns * sizeof(Datum));
		nulls = (bool *) palloc(ncolumns * sizeof(bool));

		/* Break down the tuple into fields */
		heap_deform_tuple(&tuple, tupdesc, values, nulls);
	}
	else
	{
		values = NULL;
		nulls = NULL;
	}

	for (i = 0, j = 0; i < ncolumns; ++i)
	{
		ColumnIOData *column_info = &my_extra->columns[i];
//.........这里部分代码省略.........

/* ----------
 * toast_flatten_tuple_attribute -
 *
 *	If a Datum is of composite type, "flatten" it to contain no toasted fields.
 *	This must be invoked on any potentially-composite field that is to be
 *	inserted into a tuple.	Doing this preserves the invariant that toasting
 *	goes only one level deep in a tuple.
 * ----------
 */
Datum
toast_flatten_tuple_attribute(Datum value,
							  Oid typeId, int32 typeMod)
{
	TupleDesc	tupleDesc;
	HeapTupleHeader olddata;
	HeapTupleHeader new_data;
	int32		new_len;
	HeapTupleData tmptup;
	Form_pg_attribute *att;
	int			numAttrs;
	int			i;
	bool		need_change = false;
	bool		has_nulls = false;
	Datum		toast_values[MaxTupleAttributeNumber];
	bool		toast_isnull[MaxTupleAttributeNumber];
	bool		toast_free[MaxTupleAttributeNumber];

	/*
	 * See if it's a composite type, and get the tupdesc if so.
	 */
	tupleDesc = lookup_rowtype_tupdesc_noerror(typeId, typeMod, true);
	if (tupleDesc == NULL)
		return value;			/* not a composite type */

	tupleDesc = CreateTupleDescCopy(tupleDesc);
	att = tupleDesc->attrs;
	numAttrs = tupleDesc->natts;

	/*
	 * Break down the tuple into fields.
	 */
	olddata = DatumGetHeapTupleHeader(value);
	Assert(typeId == HeapTupleHeaderGetTypeId(olddata));
	Assert(typeMod == HeapTupleHeaderGetTypMod(olddata));
	/* Build a temporary HeapTuple control structure */
	tmptup.t_len = HeapTupleHeaderGetDatumLength(olddata);
	ItemPointerSetInvalid(&(tmptup.t_self));
	tmptup.t_tableOid = InvalidOid;
	tmptup.t_data = olddata;

	Assert(numAttrs <= MaxTupleAttributeNumber);
	heap_deform_tuple(&tmptup, tupleDesc, toast_values, toast_isnull);

	memset(toast_free, 0, numAttrs * sizeof(bool));

	for (i = 0; i < numAttrs; i++)
	{
		/*
		 * Look at non-null varlena attributes
		 */
		if (toast_isnull[i])
			has_nulls = true;
		else if (att[i]->attlen == -1)
		{
			varattrib  *new_value;

			new_value = (varattrib *) DatumGetPointer(toast_values[i]);
			if (VARATT_IS_EXTENDED(new_value))
			{
				new_value = heap_tuple_untoast_attr(new_value);
				toast_values[i] = PointerGetDatum(new_value);
				toast_free[i] = true;
				need_change = true;
			}
		}
	}

	/*
	 * If nothing to untoast, just return the original tuple.
	 */
	if (!need_change)
	{
		FreeTupleDesc(tupleDesc);
		return value;
	}

	/*
	 * Calculate the new size of the tuple.  Header size should not change,
	 * but data size might.
	 */
	new_len = offsetof(HeapTupleHeaderData, t_bits);
	if (has_nulls)
		new_len += BITMAPLEN(numAttrs);
	if (olddata->t_infomask & HEAP_HASOID)
		new_len += sizeof(Oid);
	new_len = MAXALIGN(new_len);
	Assert(new_len == olddata->t_hoff);
	new_len += heap_compute_data_size(tupleDesc, toast_values, toast_isnull);

	new_data = (HeapTupleHeader) palloc0(new_len);
//.........这里部分代码省略.........

/*
 * record_cmp()
 * Internal comparison function for records.
 *
 * Returns -1, 0 or 1
 *
 * Do not assume that the two inputs are exactly the same record type;
 * for instance we might be comparing an anonymous ROW() construct against a
 * named composite type.  We will compare as long as they have the same number
 * of non-dropped columns of the same types.
 */
static int
record_cmp(FunctionCallInfo fcinfo)
{
	HeapTupleHeader record1 = PG_GETARG_HEAPTUPLEHEADER(0);
	HeapTupleHeader record2 = PG_GETARG_HEAPTUPLEHEADER(1);
	int			result = 0;
	Oid			tupType1;
	Oid			tupType2;
	int32		tupTypmod1;
	int32		tupTypmod2;
	TupleDesc	tupdesc1;
	TupleDesc	tupdesc2;
	HeapTupleData tuple1;
	HeapTupleData tuple2;
	int			ncolumns1;
	int			ncolumns2;
	RecordCompareData *my_extra;
	int			ncols;
	Datum	   *values1;
	Datum	   *values2;
	bool	   *nulls1;
	bool	   *nulls2;
	int			i1;
	int			i2;
	int			j;

	/* Extract type info from the tuples */
	tupType1 = HeapTupleHeaderGetTypeId(record1);
	tupTypmod1 = HeapTupleHeaderGetTypMod(record1);
	tupdesc1 = lookup_rowtype_tupdesc(tupType1, tupTypmod1);
	ncolumns1 = tupdesc1->natts;
	tupType2 = HeapTupleHeaderGetTypeId(record2);
	tupTypmod2 = HeapTupleHeaderGetTypMod(record2);
	tupdesc2 = lookup_rowtype_tupdesc(tupType2, tupTypmod2);
	ncolumns2 = tupdesc2->natts;

	/* Build temporary HeapTuple control structures */
	tuple1.t_len = HeapTupleHeaderGetDatumLength(record1);
	ItemPointerSetInvalid(&(tuple1.t_self));
	tuple1.t_tableOid = InvalidOid;
	tuple1.t_data = record1;
	tuple2.t_len = HeapTupleHeaderGetDatumLength(record2);
	ItemPointerSetInvalid(&(tuple2.t_self));
	tuple2.t_tableOid = InvalidOid;
	tuple2.t_data = record2;

	/*
	 * We arrange to look up the needed comparison info just once per series
	 * of calls, assuming the record types don't change underneath us.
	 */
	ncols = Max(ncolumns1, ncolumns2);
	my_extra = (RecordCompareData *) fcinfo->flinfo->fn_extra;
	if (my_extra == NULL ||
		my_extra->ncolumns < ncols)
	{
		fcinfo->flinfo->fn_extra =
			MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
						sizeof(RecordCompareData) - sizeof(ColumnCompareData)
							   + ncols * sizeof(ColumnCompareData));
		my_extra = (RecordCompareData *) fcinfo->flinfo->fn_extra;
		my_extra->ncolumns = ncols;
		my_extra->record1_type = InvalidOid;
		my_extra->record1_typmod = 0;
		my_extra->record2_type = InvalidOid;
		my_extra->record2_typmod = 0;
	}

	if (my_extra->record1_type != tupType1 ||
		my_extra->record1_typmod != tupTypmod1 ||
		my_extra->record2_type != tupType2 ||
		my_extra->record2_typmod != tupTypmod2)
	{
		MemSet(my_extra->columns, 0, ncols * sizeof(ColumnCompareData));
		my_extra->record1_type = tupType1;
		my_extra->record1_typmod = tupTypmod1;
		my_extra->record2_type = tupType2;
		my_extra->record2_typmod = tupTypmod2;
	}

	/* Break down the tuples into fields */
	values1 = (Datum *) palloc(ncolumns1 * sizeof(Datum));
	nulls1 = (bool *) palloc(ncolumns1 * sizeof(bool));
	heap_deform_tuple(&tuple1, tupdesc1, values1, nulls1);
	values2 = (Datum *) palloc(ncolumns2 * sizeof(Datum));
	nulls2 = (bool *) palloc(ncolumns2 * sizeof(bool));
	heap_deform_tuple(&tuple2, tupdesc2, values2, nulls2);

	/*
	 * Scan corresponding columns, allowing for dropped columns in different
//.........这里部分代码省略.........

Datum
gistrescan(PG_FUNCTION_ARGS)
{
	IndexScanDesc scan = (IndexScanDesc) PG_GETARG_POINTER(0);
	ScanKey		key = (ScanKey) PG_GETARG_POINTER(1);
	GISTScanOpaque so;
	int			i;

	so = (GISTScanOpaque) scan->opaque;
	if (so != NULL)
	{
		/* rescan an existing indexscan --- reset state */
		gistfreestack(so->stack);
		so->stack = NULL;
		/* drop pins on buffers -- no locks held */
		if (BufferIsValid(so->curbuf))
		{
			ReleaseBuffer(so->curbuf);
			so->curbuf = InvalidBuffer;
		}
	}
	else
	{
		/* initialize opaque data */
		so = (GISTScanOpaque) palloc(sizeof(GISTScanOpaqueData));
		so->stack = NULL;
		so->tempCxt = createTempGistContext();
		so->curbuf = InvalidBuffer;
		so->giststate = (GISTSTATE *) palloc(sizeof(GISTSTATE));
		initGISTstate(so->giststate, scan->indexRelation);

		scan->opaque = so;
	}

	/*
	 * Clear all the pointers.
	 */
	ItemPointerSetInvalid(&so->curpos);
	so->nPageData = so->curPageData = 0;

	so->qual_ok = true;

	/* Update scan key, if a new one is given */
	if (key && scan->numberOfKeys > 0)
	{
		memmove(scan->keyData, key,
				scan->numberOfKeys * sizeof(ScanKeyData));

		/*
		 * Modify the scan key so that all the Consistent method is called for
		 * all comparisons. The original operator is passed to the Consistent
		 * function in the form of its strategy number, which is available
		 * from the sk_strategy field, and its subtype from the sk_subtype
		 * field.
		 *
		 * Next, if any of keys is a NULL and that key is not marked with
		 * SK_SEARCHNULL/SK_SEARCHNOTNULL then nothing can be found (ie, we
		 * assume all indexable operators are strict).
		 */
		for (i = 0; i < scan->numberOfKeys; i++)
		{
			ScanKey		skey = &(scan->keyData[i]);

			skey->sk_func = so->giststate->consistentFn[skey->sk_attno - 1];

			if (skey->sk_flags & SK_ISNULL)
			{
				if (!(skey->sk_flags & (SK_SEARCHNULL | SK_SEARCHNOTNULL)))
					so->qual_ok = false;
			}
		}
	}

	PG_RETURN_VOID();
}

/*
 * Helper method used to insert a new minipage entry in the block
 * directory relation.  Refer to AppendOnlyBlockDirectory_InsertEntry()
 * for more details.
 */
static bool
insert_new_entry(
		AppendOnlyBlockDirectory *blockDirectory,
		int columnGroupNo,
		int64 firstRowNum,
		int64 fileOffset,
		int64 rowCount,
		MinipagePerColumnGroup *minipageInfo)
{
	MinipageEntry *entry = NULL;
	int lastEntryNo;

	if (rowCount == 0)
		return false;
	
	if (blockDirectory->blkdirRel == NULL ||
		blockDirectory->blkdirIdx == NULL)
		return false;

	Assert(minipageInfo->numMinipageEntries <= (uint32)NUM_MINIPAGE_ENTRIES);

	lastEntryNo = minipageInfo->numMinipageEntries - 1;
	if (lastEntryNo >= 0)
	{
		entry = &(minipageInfo->minipage->entry[lastEntryNo]);

		Assert(entry->firstRowNum < firstRowNum);
		Assert(entry->fileOffset < fileOffset);
		
		if (gp_blockdirectory_entry_min_range > 0 &&
			fileOffset - entry->fileOffset < gp_blockdirectory_entry_min_range)
			return true;
		
		/* Update the rowCount in the latest entry */
		Assert(entry->rowCount <= firstRowNum - entry->firstRowNum);

		ereportif(Debug_appendonly_print_blockdirectory, LOG, 
					(errmsg("Append-only block directory update entry: "
							"(firstRowNum, columnGroupNo, fileOffset, rowCount) = (" INT64_FORMAT
							", %d, " INT64_FORMAT ", " INT64_FORMAT ") at index %d to "
							"(firstRowNum, columnGroupNo, fileOffset, rowCount) = (" INT64_FORMAT
							", %d, " INT64_FORMAT ", " INT64_FORMAT ")",
							entry->firstRowNum, columnGroupNo, entry->fileOffset, entry->rowCount,
							minipageInfo->numMinipageEntries - 1,
							entry->firstRowNum, columnGroupNo, entry->fileOffset,
							firstRowNum - entry->firstRowNum)));
		
		entry->rowCount = firstRowNum - entry->firstRowNum;
	}
	
	if (minipageInfo->numMinipageEntries >= (uint32)gp_blockdirectory_minipage_size)
	{
		write_minipage(blockDirectory, columnGroupNo, minipageInfo);

		/* Set tupleTid to invalid */
		ItemPointerSetInvalid(&minipageInfo->tupleTid);

		/*
		 * Clear out the entries.
		 */
		MemSet(minipageInfo->minipage->entry, 0,
			   minipageInfo->numMinipageEntries * sizeof(MinipageEntry));
		minipageInfo->numMinipageEntries = 0;
	}
	
	Assert(minipageInfo->numMinipageEntries < (uint32)gp_blockdirectory_minipage_size);

	entry = &(minipageInfo->minipage->entry[minipageInfo->numMinipageEntries]);
	entry->firstRowNum = firstRowNum;
	entry->fileOffset = fileOffset;
	entry->rowCount = rowCount;
	
	minipageInfo->numMinipageEntries++;
	
	ereportif(Debug_appendonly_print_blockdirectory, LOG,
				(errmsg("Append-only block directory insert entry: "
						"(firstRowNum, columnGroupNo, fileOffset, rowCount) = (" INT64_FORMAT
						", %d, " INT64_FORMAT ", " INT64_FORMAT ") at index %d",
						entry->firstRowNum, columnGroupNo, entry->fileOffset, entry->rowCount,
						minipageInfo->numMinipageEntries - 1)));

	return true;
}

/*
 *		heap_formtuple
 *
 *		construct a tuple from the given values[] and nulls[] arrays
 *
 *		Null attributes are indicated by a 'n' in the appropriate byte
 *		of nulls[]. Non-null attributes are indicated by a ' ' (space).
 *
 * OLD API with char 'n'/' ' convention for indicating nulls.
 * This is deprecated and should not be used in new code, but we keep it
 * around for use by old add-on modules.
 */
HeapTuple
heap_formtuple(TupleDesc tupleDescriptor,
			   Datum *values,
			   char *nulls)
{
	HeapTuple	tuple;			/* return tuple */
	HeapTupleHeader td;			/* tuple data */
	Size		len,
				data_len;
	int			hoff;
	bool		hasnull = false;
	Form_pg_attribute *att = tupleDescriptor->attrs;
	int			numberOfAttributes = tupleDescriptor->natts;
	int			i;

	if (numberOfAttributes > MaxTupleAttributeNumber)
		ereport(ERROR,
				(errcode(ERRCODE_TOO_MANY_COLUMNS),
				 errmsg("number of columns (%d) exceeds limit (%d)",
						numberOfAttributes, MaxTupleAttributeNumber)));

	/*
	 * Check for nulls and embedded tuples; expand any toasted attributes in
	 * embedded tuples.  This preserves the invariant that toasting can only
	 * go one level deep.
	 *
	 * We can skip calling toast_flatten_tuple_attribute() if the attribute
	 * couldn't possibly be of composite type.  All composite datums are
	 * varlena and have alignment 'd'; furthermore they aren't arrays. Also,
	 * if an attribute is already toasted, it must have been sent to disk
	 * already and so cannot contain toasted attributes.
	 */
	for (i = 0; i < numberOfAttributes; i++)
	{
		if (nulls[i] != ' ')
			hasnull = true;
		else if (att[i]->attlen == -1 &&
				 att[i]->attalign == 'd' &&
				 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));

	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;

//.........这里部分代码省略.........

static void *uri_char(HeapTupleHeader ud, bool hdr, bool term)
{
	TupleDesc td;
	HeapTupleData tuple;
	Datum d[URI_LEN];
	bool n[URI_LEN];
	text *scheme = NULL, *host = NULL, *path = NULL;
	int16 port;
	char portbuf[8];
	unsigned schemelen = 0, hostlen = 0, portlen = 0, pathlen = 0;
	unsigned len;
	void *out;
	char *p;

	td = lookup_rowtype_tupdesc(HeapTupleHeaderGetTypeId(ud), HeapTupleHeaderGetTypMod(ud));
	tuple.t_len = HeapTupleHeaderGetDatumLength(ud);
	ItemPointerSetInvalid(&(tuple.t_self));
	tuple.t_tableOid = InvalidOid;
	tuple.t_data = ud;
	heap_deform_tuple(&tuple, td, d, n);
	ReleaseTupleDesc(td);

	if (!n[URI_SCHEME])
	{
		scheme = DatumGetTextP(d[URI_SCHEME]);
		schemelen = VARSIZE_ANY_EXHDR(scheme);
	}
	if (!n[URI_HOST])
	{
		host = DatumGetTextP(d[URI_HOST]);
		hostlen = VARSIZE_ANY_EXHDR(host);
	}
	if (!n[URI_PORT])
	{
		port = DatumGetInt16(d[URI_PORT]);
		portlen = snprintf(portbuf, sizeof(portbuf)-1, ":%hu", port);
	}
	if (!n[URI_PATH])
	{
		path = DatumGetTextP(d[URI_PATH]);
		pathlen = VARSIZE_ANY_EXHDR(path);
	}

	len = (hdr ? VARHDRSZ : 0) + schemelen + (scheme ? 3 : 0) + hostlen + portlen + pathlen + term;
	out = palloc(len);
	if (hdr)
		SET_VARSIZE(out, len);
	p = hdr ? VARDATA(out) : out;

	if (scheme)
	{
		memcpy(p, VARDATA(scheme), schemelen);
		p += schemelen;
		*p++ = ':';
		*p++ = '/';
		*p++ = '/';
	}
	if (host)
	{
		domainname_flip(p, VARDATA(host), hostlen);
		p += hostlen;
	}
	memcpy(p, portbuf, portlen);
	p += portlen;
	if (path)
	{
		memcpy(p, VARDATA(path), pathlen);
		p += pathlen;
	}
	if (term)
		*p = '\0';

	return out;
}

Datum serialize_record( PG_FUNCTION_ARGS )
{
//	FILE* log;

//	log = fopen("/var/lib/postgresql/serializer.log", "a");
	HeapTupleHeader rec = PG_GETARG_HEAPTUPLEHEADER(0);

	HeapTupleData tuple;
	bool		needComma = false;
	int		 i;
	Datum	  *values;
	bool	   *nulls;
	StringInfoData buf;
	char *conversion_buf;

	/* Extract type info from the tuple itself */
	Oid tupType = HeapTupleHeaderGetTypeId(rec);
	int32 tupTypmod = HeapTupleHeaderGetTypMod(rec);
	TupleDesc tupdesc = lookup_rowtype_tupdesc(tupType, tupTypmod);
	int ncolumns = tupdesc->natts;

	/* Build a temporary HeapTuple control structure */
	tuple.t_len = HeapTupleHeaderGetDatumLength(rec);
	ItemPointerSetInvalid(&(tuple.t_self));
	tuple.t_tableOid = InvalidOid;
	tuple.t_data = rec;

//	fprintf(log, "Doing serialize_record\n");
//	fflush(log);

	values = (Datum *) palloc(ncolumns * sizeof(Datum));
	nulls = (bool *) palloc(ncolumns * sizeof(bool));

	/* Break down the tuple into fields */
	heap_deform_tuple(&tuple, tupdesc, values, nulls);

	/* And build the result string */
	initStringInfo(&buf);

	appendStringInfoChar(&buf, '{');

	for (i = 0; i < ncolumns; i++)
	{
		Oid		 column_type = tupdesc->attrs[ i ]->atttypid;
		char	   *value;
		char	   *column_name;
		char 		type_category;
		HeapTuple 	type_tuple;
		FmgrInfo flinfo;

		/* Ignore dropped columns in datatype */
		if (tupdesc->attrs[i]->attisdropped)
			continue;

		if (nulls[i])
		{
			/* emit nothing... */
			continue;
		}

		if (needComma)
			appendStringInfoChar(&buf, ',');

		needComma = true;


		/* obtain column name */
		column_name = SPI_fname( tupdesc, i + 1 );

		/* obtain type information from pg_catalog */
		type_tuple = SearchSysCache1( TYPEOID, ObjectIdGetDatum(column_type) );
		if (!HeapTupleIsValid( type_tuple ))
			elog(ERROR, "cache lookup failed for relation %u", column_type);

		type_category = ((Form_pg_type) GETSTRUCT( type_tuple ))->typcategory;

		ReleaseSysCache( type_tuple );

		/* append column name */
		appendStringInfoChar(&buf, '"');
		appendStringInfoString(&buf, column_name);
		appendStringInfoString(&buf, "\":");

		switch( type_category )
		{
			// http://www.postgresql.org/docs/current/static/catalog-pg-type.html#CATALOG-TYPCATEGORY-TABLE

			case 'A': //array
				//call to serialize_array( ... )

				MemSet( &flinfo, 0, sizeof( flinfo ) );
				flinfo.fn_addr = serialize_array;
				flinfo.fn_nargs = 1;
				flinfo.fn_mcxt = fcinfo->flinfo->fn_mcxt;

				value = PG_TEXT_DATUM_GET_CSTR( FunctionCall1( &flinfo, values[ i ] ) );

				appendStringInfoString(&buf, value);
			break;

//.........这里部分代码省略.........

void yorder_get_order(Datum eorder,Torder *orderp) {

    bool isnull;
    HeapTupleHeader tuple = ((HeapTupleHeader) PG_DETOAST_DATUM(eorder));
    Oid			tupType;
    int32		tupTypmod;
    TupleDesc	tupDesc;
    HeapTupleData tmptup;
    BOX *p;

    tupType = HeapTupleHeaderGetTypeId(tuple);
    tupTypmod = HeapTupleHeaderGetTypMod(tuple);
    tupDesc = lookup_rowtype_tupdesc(tupType, tupTypmod);

    tmptup.t_len = HeapTupleHeaderGetDatumLength(tuple);
    ItemPointerSetInvalid(&(tmptup.t_self));
    tmptup.t_tableOid = InvalidOid;
    tmptup.t_data = tuple;

    orderp->type = DatumGetInt32(heap_getattr(&tmptup,1,tupDesc,&isnull));
    if(isnull)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("the field type is null in yorder_get_order")));

    if(!ORDER_TYPE_IS_VALID(orderp->type))
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("order type incorrect in yorder_get_order")));

    orderp->id = DatumGetInt32(heap_getattr(&tmptup,2,tupDesc,&isnull));
    if(isnull)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("the field id is null in yorder_get_order")));

    orderp->own = DatumGetInt32(heap_getattr(&tmptup,3,tupDesc,&isnull));
    if(isnull)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("the field own is null in yorder_get_order")));

    orderp->oid = DatumGetInt32(heap_getattr(&tmptup,4,tupDesc,&isnull));
    if(isnull)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("the field oid is null in yorder_get_order")));

    orderp->qtt_requ = DatumGetInt64(heap_getattr(&tmptup,5,tupDesc,&isnull));
    if(isnull)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("the field qtt_requ is null in yorder_get_order")));

    //orderp->qua_requ = (HStore *) PG_DETOAST_DATUM(heap_getattr(&tmptup,6,tupDesc,&isnull));
    orderp->qua_requ = (Datum) PG_DETOAST_DATUM(heap_getattr(&tmptup,6,tupDesc,&isnull));
    if(isnull)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("the field qua_requ is null in yorder_get_order")));

    orderp->qtt_prov = DatumGetInt64(heap_getattr(&tmptup,7,tupDesc,&isnull));
    if(isnull)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("the field qtt_prov is null in yorder_get_order")));

    //orderp->qua_prov = (HStore *) PG_DETOAST_DATUM(heap_getattr(&tmptup,8,tupDesc,&isnull));
    orderp->qua_prov = (Datum) PG_DETOAST_DATUM(heap_getattr(&tmptup,8,tupDesc,&isnull));
    if(isnull)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("the field qua_prov is null in yorder_get_order")));

    orderp->qtt = DatumGetInt64(heap_getattr(&tmptup,9,tupDesc,&isnull));
    if(isnull)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("the field qtt is null in yorder_get_order")));

    // pos_requ box,
    p = DatumGetBoxP(heap_getattr(&tmptup,10,tupDesc,&isnull));
    if(isnull)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("the field pos_requ is null in yorder_get_order")));

    GL_CHECK_BOX_S0(p);
    orderp->pos_requ.x = p->low.x;
    orderp->pos_requ.y = p->low.y;

    // pos_prov box,
    p = DatumGetBoxP(heap_getattr(&tmptup,11,tupDesc,&isnull));
    if(isnull)
        ereport(ERROR,
                (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
                 errmsg("the field pos_prov is null in yorder_get_order")));

    GL_CHECK_BOX_S0(p);
    orderp->pos_prov.x = p->low.x;
//.........这里部分代码省略.........

/* ----------------------------------------------------------------
*		ExecInitExternalScan
* ----------------------------------------------------------------
*/
ExternalScanState *
ExecInitExternalScan(ExternalScan *node, EState *estate, int eflags)
{
	ResultRelSegFileInfo *segfileinfo = NULL;
	ExternalScanState *externalstate;
	Relation	currentRelation;
	FileScanDesc currentScanDesc;

	Assert(outerPlan(node) == NULL);
	Assert(innerPlan(node) == NULL);

	/*
	 * create state structure
	 */
	externalstate = makeNode(ExternalScanState);
	externalstate->ss.ps.plan = (Plan *) node;
	externalstate->ss.ps.state = estate;

	/*
	 * Miscellaneous initialization
	 *
	 * create expression context for node
	 */
	ExecAssignExprContext(estate, &externalstate->ss.ps);

	/*
	 * initialize child expressions
	 */
	externalstate->ss.ps.targetlist = (List *)
		ExecInitExpr((Expr *) node->scan.plan.targetlist,
					 (PlanState *) externalstate);
	externalstate->ss.ps.qual = (List *)
		ExecInitExpr((Expr *) node->scan.plan.qual,
					 (PlanState *) externalstate);

	/* Check if targetlist or qual contains a var node referencing the ctid column */
	externalstate->cdb_want_ctid = contain_ctid_var_reference(&node->scan);
	ItemPointerSetInvalid(&externalstate->cdb_fake_ctid);

#define EXTSCAN_NSLOTS 2

	/*
	 * tuple table initialization
	 */
	ExecInitResultTupleSlot(estate, &externalstate->ss.ps);
	ExecInitScanTupleSlot(estate, &externalstate->ss);

	/*
	 * get the relation object id from the relid'th entry in the range table
	 * and open that relation.
	 */
	currentRelation = ExecOpenScanExternalRelation(estate, node->scan.scanrelid);

	if (Gp_role == GP_ROLE_EXECUTE && node->err_aosegfileinfos)
	{
		segfileinfo = (ResultRelSegFileInfo *)list_nth(node->err_aosegfileinfos, GetQEIndex());
	}
	else
	{
		segfileinfo = NULL;
	}
	currentScanDesc = external_beginscan(currentRelation,
									 node->scan.scanrelid,
									 node->scancounter,
									 node->uriList,
									 node->fmtOpts,
									 node->fmtType,
									 node->isMasterOnly,
									 node->rejLimit,
									 node->rejLimitInRows,
									 node->fmterrtbl,
									 segfileinfo,
									 node->encoding,
									 node->scan.plan.qual);

	externalstate->ss.ss_currentRelation = currentRelation;
	externalstate->ess_ScanDesc = currentScanDesc;

	ExecAssignScanType(&externalstate->ss, RelationGetDescr(currentRelation));

	/*
	 * Initialize result tuple type and projection info.
	 */
	ExecAssignResultTypeFromTL(&externalstate->ss.ps);
	ExecAssignScanProjectionInfo(&externalstate->ss);

	/*
	 * If eflag contains EXEC_FLAG_REWIND or EXEC_FLAG_BACKWARD or EXEC_FLAG_MARK,
	 * then this node is not eager free safe.
	 */
	externalstate->ss.ps.delayEagerFree =
		((eflags & (EXEC_FLAG_REWIND | EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)) != 0);

	initGpmonPktForExternalScan((Plan *)node, &externalstate->ss.ps.gpmon_pkt, estate);

	return externalstate;
//.........这里部分代码省略.........

static void
populate_recordset_object_end(void *state)
{
	PopulateRecordsetState _state = (PopulateRecordsetState) state;
	HTAB	   *json_hash = _state->json_hash;
	Datum	   *values;
	bool	   *nulls;
	char		fname[NAMEDATALEN];
	int			i;
	RecordIOData *my_extra = _state->my_extra;
	int			ncolumns = my_extra->ncolumns;
	TupleDesc	tupdesc = _state->ret_tdesc;
	JsonHashEntry hashentry;
	HeapTupleHeader rec = _state->rec;
	HeapTuple	rettuple;

	if (_state->lex->lex_level > 1)
		return;

	values = (Datum *) palloc(ncolumns * sizeof(Datum));
	nulls = (bool *) palloc(ncolumns * sizeof(bool));

	if (_state->rec)
	{
		HeapTupleData tuple;

		/* Build a temporary HeapTuple control structure */
		tuple.t_len = HeapTupleHeaderGetDatumLength(_state->rec);
		ItemPointerSetInvalid(&(tuple.t_self));
		tuple.t_tableOid = InvalidOid;
		tuple.t_data = _state->rec;

		/* Break down the tuple into fields */
		heap_deform_tuple(&tuple, tupdesc, values, nulls);
	}
	else
	{
		for (i = 0; i < ncolumns; ++i)
		{
			values[i] = (Datum) 0;
			nulls[i] = true;
		}
	}

	for (i = 0; i < ncolumns; ++i)
	{
		ColumnIOData *column_info = &my_extra->columns[i];
		Oid			column_type = tupdesc->attrs[i]->atttypid;
		char	   *value;

		/* Ignore dropped columns in datatype */
		if (tupdesc->attrs[i]->attisdropped)
		{
			nulls[i] = true;
			continue;
		}

		memset(fname, 0, NAMEDATALEN);
		strncpy(fname, NameStr(tupdesc->attrs[i]->attname), NAMEDATALEN);
		hashentry = hash_search(json_hash, fname, HASH_FIND, NULL);

		/*
		 * we can't just skip here if the key wasn't found since we might have
		 * a domain to deal with. If we were passed in a non-null record
		 * datum, we assume that the existing values are valid (if they're
		 * not, then it's not our fault), but if we were passed in a null,
		 * then every field which we don't populate needs to be run through
		 * the input function just in case it's a domain type.
		 */
		if (hashentry == NULL && rec)
			continue;

		/*
		 * Prepare to convert the column value from text
		 */
		if (column_info->column_type != column_type)
		{
			getTypeInputInfo(column_type,
							 &column_info->typiofunc,
							 &column_info->typioparam);
			fmgr_info_cxt(column_info->typiofunc, &column_info->proc,
						  _state->fn_mcxt);
			column_info->column_type = column_type;
		}
		if (hashentry == NULL || hashentry->isnull)
		{
			/*
			 * need InputFunctionCall to happen even for nulls, so that domain
			 * checks are done
			 */
			values[i] = InputFunctionCall(&column_info->proc, NULL,
										  column_info->typioparam,
										  tupdesc->attrs[i]->atttypmod);
			nulls[i] = true;
		}
		else
		{
			value = hashentry->val;

			values[i] = InputFunctionCall(&column_info->proc, value,
//.........这里部分代码省略.........

static void
btree_xlog_mark_page_halfdead(uint8 info, XLogReaderState *record)
{
	XLogRecPtr	lsn = record->EndRecPtr;
	xl_btree_mark_page_halfdead *xlrec = (xl_btree_mark_page_halfdead *) XLogRecGetData(record);
	Buffer		buffer;
	Page		page;
	BTPageOpaque pageop;
	IndexTupleData trunctuple;

	/*
	 * In normal operation, we would lock all the pages this WAL record
	 * touches before changing any of them.  In WAL replay, it should be okay
	 * to lock just one page at a time, since no concurrent index updates can
	 * be happening, and readers should not care whether they arrive at the
	 * target page or not (since it's surely empty).
	 */

	/* parent page */
	if (XLogReadBufferForRedo(record, 1, &buffer) == BLK_NEEDS_REDO)
	{
		OffsetNumber poffset;
		ItemId		itemid;
		IndexTuple	itup;
		OffsetNumber nextoffset;
		BlockNumber rightsib;

		page = (Page) BufferGetPage(buffer);
		pageop = (BTPageOpaque) PageGetSpecialPointer(page);

		poffset = xlrec->poffset;

		nextoffset = OffsetNumberNext(poffset);
		itemid = PageGetItemId(page, nextoffset);
		itup = (IndexTuple) PageGetItem(page, itemid);
		rightsib = ItemPointerGetBlockNumber(&itup->t_tid);

		itemid = PageGetItemId(page, poffset);
		itup = (IndexTuple) PageGetItem(page, itemid);
		ItemPointerSet(&(itup->t_tid), rightsib, P_HIKEY);
		nextoffset = OffsetNumberNext(poffset);
		PageIndexTupleDelete(page, nextoffset);

		PageSetLSN(page, lsn);
		MarkBufferDirty(buffer);
	}
	if (BufferIsValid(buffer))
		UnlockReleaseBuffer(buffer);

	/* Rewrite the leaf page as a halfdead page */
	buffer = XLogInitBufferForRedo(record, 0);
	page = (Page) BufferGetPage(buffer);

	_bt_pageinit(page, BufferGetPageSize(buffer));
	pageop = (BTPageOpaque) PageGetSpecialPointer(page);

	pageop->btpo_prev = xlrec->leftblk;
	pageop->btpo_next = xlrec->rightblk;
	pageop->btpo.level = 0;
	pageop->btpo_flags = BTP_HALF_DEAD | BTP_LEAF;
	pageop->btpo_cycleid = 0;

	/*
	 * Construct a dummy hikey item that points to the next parent to be
	 * deleted (if any).
	 */
	MemSet(&trunctuple, 0, sizeof(IndexTupleData));
	trunctuple.t_info = sizeof(IndexTupleData);
	if (xlrec->topparent != InvalidBlockNumber)
		ItemPointerSet(&trunctuple.t_tid, xlrec->topparent, P_HIKEY);
	else
		ItemPointerSetInvalid(&trunctuple.t_tid);
	if (PageAddItem(page, (Item) &trunctuple, sizeof(IndexTupleData), P_HIKEY,
					false, false) == InvalidOffsetNumber)
		elog(ERROR, "could not add dummy high key to half-dead page");

	PageSetLSN(page, lsn);
	MarkBufferDirty(buffer);
	UnlockReleaseBuffer(buffer);
}