Function create_lovitem

src/backend/access/bitmap/bitmapinsert.c:1618–1728

* create_lovitem() -- create a new LOV item. * * Create a new LOV item and append this item into the last LOV page. * Each LOV item is associated with one distinct value for attributes * to be indexed. This function also inserts this distinct value along * with this new LOV item's block number and offsetnumber into the * auxiliary heap and its b-tree of this bitmap index. * * This function

 * The caller should have an exclusive lock on metabuf.
 */
static void
create_lovitem(Relation rel, Buffer metabuf, uint64 tidnum,
			   TupleDesc tupDesc, Datum *attdata, bool *nulls,
			   Relation lovHeap, Relation lovIndex, BlockNumber *lovBlockP, 
			   OffsetNumber *lovOffsetP, bool use_wal)
{
	BMMetaPage		metapage;
	Buffer			currLovBuffer;
	Page			currLovPage;
	Datum*			lovDatum;
	bool*			lovNulls;
	OffsetNumber	itemSize;
	BMLOVItem		lovitem;
	int				numOfAttrs;
	bool			is_new_lov_blkno = false;

	numOfAttrs = tupDesc->natts;

	/* Get the last LOV page. Meta page should be locked. */
	metapage = _bitmap_get_metapage_data(rel, metabuf);
	*lovBlockP = metapage->bm_lov_lastpage;

	currLovBuffer = _bitmap_getbuf(rel, *lovBlockP, BM_WRITE);
	currLovPage = BufferGetPage(currLovBuffer);

	lovitem = _bitmap_formitem(tidnum);

	*lovOffsetP = OffsetNumberNext(PageGetMaxOffsetNumber(currLovPage));
	itemSize = sizeof(BMLOVItemData);

	/*
	 * If there is not enough space in the last LOV page for
	 * a new item, create a new LOV page, and update the metapage.
	 */
	if (itemSize > PageGetFreeSpace(currLovPage))
	{
		Buffer		newLovBuffer;

		/* create a new LOV page */
		newLovBuffer = _bitmap_getbuf(rel, P_NEW, BM_WRITE);
		_bitmap_init_lovpage(rel, newLovBuffer);

		_bitmap_relbuf(currLovBuffer);

		currLovBuffer = newLovBuffer;
		currLovPage = BufferGetPage(currLovBuffer);

		is_new_lov_blkno = true;
	}

	/* First create the LOV item. */
	START_CRIT_SECTION();

	if (is_new_lov_blkno)
	{
		MarkBufferDirty(metabuf);

		metapage->bm_lov_lastpage = BufferGetBlockNumber(currLovBuffer);